‫ﻣﺠﻠﺔ ﭘﮋﻭﻫﺶ ﻓﻴﺰﻳﻚ ﺍﻳﺮﺍﻥ‪ ،‬ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪ ،۴‬ﺯﻣﺴﺘﺎﻥ‪۱۳۹۴‬‬

‫ﻓﻴﺰﻳﻚ ﮐﺎﺭﺑﺮﺩﻱ‪ :۱ -‬ﻣﻘﺪﻣﻪﺍﻱ ﺑﺮ ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ‬

‫‪۱‬‬
‫ﺭﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﻳﻲ‪۱‬ﻭ‪ ۲‬ﻭ ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬
‫‪ .۱‬ﮔﺮﻭﻩ ﻓﻴﺰﻳﮏ‪ ،‬ﺩﺍﻧﺸﮕﺎﻩ ﺻﻨﻌﺘﻲ ﻧﻮﺷﻴﺮﻭﺍﻧﻲ ﺑﺎﺑﻞ‪ ،‬ﺑﺎﺑﻞ‬
‫‪ .۲‬ﺩﺍﻧﺸﮑﺪﺓ ﻓﻴﺰﻳﮏ‪ ،‬ﺩﺍﻧﺸﮕﺎﻩ ﺍﺗﺎﻭﺍ‪ ،‬ﮐﺎﻧﺎﺩﺍ‬

‫‪rkhanbabaie@nit.ac.ir‬‬ ‫ﭘﺴﺖ ﺍﻟﻜﺘﺮﻭﻧﻴﻜﻲ‪:‬‬

‫)ﺩﺭﻳﺎﻓﺖ ﻣﻘﺎﻟﻪ‪ ۱۳۹۴/۱/۲۰:‬؛ ﺩﺭﻳﺎﻓﺖ ﻧﺴﺨﺔ ﻧﻬﺎﻳﻲ‪(۱۳۹۴/۶/۱۱:‬‬

‫ﭼﻜﻴﺪﻩ‬
‫ﺩﺭ ﺳﺎﻝﻫﺎﻱ ﺍﺧﻴﺮ ﻓﻴﺰﻳﮏ ﺍﺯ ﻳﮏ ﻋﻠﻢ ﻣﺤﺾ ﺑﻪ ﻳﮏ ﻋﻠﻢ ﮐﺎﺭﺑﺮﺩﻱ ﺭﻭﺯﻣﺮﻩ ﺗﺒﺪﻳﻞ ﺷﺪﻩ ﺍﺳﺖ ﻭ ﺩﻳﮕﺮ ﺩﺭ ﮐﻤﺘﺮ ﺟﺎﻳﻲ ﻓﻴﺰﻳﮏ ﺻـﺮﻓﺎً ﺑـﻪ ﺻـﻮﺭﺕ ﻳـﮏ‬
‫ﺭﺷﺘﻪ ﮐﺎﺭﺷﻨﺎﺳﻲ ﻭ ﻳﺎ ﻣﻘﺎﻃﻊ ﺑﺎﻻﺗﺮ ﺑﺪﻭﻥ ﮐﺎﺭﺑﺮﺩ ﻣﺸﺨﺺ ﺗﺪﺭﻳﺲ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﺍﻣﺮ ﺑﻪ ﺩﻟﻴﻞ ﺭﺍﻩﮐﺎﺭﻫﺎﻳﻲ ﺍﺳﺖ ﮐﻪ ﻓﻴﺰﻳﮏ ﺑﺮﺍﻱ ﭘﮋﻭﻫﺶﮔﺮﺍﻥ ﺭﺷﺘﻪﻫﺎﻱ‬
‫ﻣﺨﺘﻠﻒ ﺑﻪ ﺍﺭﻣﻐﺎﻥ ﺁﻭﺭﺩﻩ ﺍﺳﺖ‪ ،‬ﮐﻪ ﻋﻠﺖ ﺁﻥ ﻫﻢ ﺑﻪ ﻭﺍﺳﻄﻪ ﻣﻬﺎﺭﺕﻫﺎﻱ ﺗﺤﻠﻴﻠﻲ ﻓﻴﺰﻳﮏﭘﻴﺸﮕﺎﻥ ﺍﺳﺖ‪ .‬ﺍﺯ ﺍﻭﻟـﻴﻦ ﻣﻌﺎﺩﻟـﺔ ﺩﻳﻔﺮﺍﻧﺴـﻴﻞ ﺍﺭﺍﺋـﻪ ﺷـﺪﻩ ﺑـﺮﺍﻱ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﻧﻮﺭﻭﻥﻫﺎﻱ ﻣﻐﺰ ﻭ ﺍﻋﺼﺎﺏ ﺗﻮﺳﻂ ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴﻠﻲ ﮔﺮﻓﺘﻪ ﺗﺎ ﭘﻴﺸﻨﻬﺎﺩ ﻧﺎﻧﻮﻓﻨﺎﻭﺭﻱ ﺗﻮﺳﻂ ﻓﺎﻳﻨﻤﻦ ﻫﻤﻪ ﺭﺍﻩﮐﺎﺭﻫﺎﻳﻲ ﺍﺳﺖ ﮐﻪ ﻋﻠﻮﻡ ﭘﺎﻳـﻪ‪،‬‬
‫ﻭ ﺑﻪ ﺧﺼﻮﺹ ﻓﻴﺰﻳﮏ ﺑﻪ ﺟﺎﻣﻌﻪ ﭘﺰﺷﮑﻲ‪ ،‬ﺻﻨﻌﺖ ﻭ ﭘﮋﻭﻫﺶﮔﺮﺍﻥ ﺭﺷﺘﻪﻫﺎﻱ ﻣﺨﺘﻠﻒ ﺍﺭﺍﺋﻪ ﺩﺍﺩﻩ ﺍﺳﺖ‪ .‬ﺩﺭ ﺍﻳﻦ ﻣﻘﺎﻟﻪ ﻣـﺮﻭﺭﻱ ﺳـﻌﻲ ﻣـﻲﺷـﻮﺩ ﺟﺎﻳﮕـﺎﻩ‬
‫ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﺑﻪ ﻋﻨﻮﺍﻥ ﺯﻳﺮﺷﺎﺧﻪﺍﻱ ﺍﺯ ﺑﻴﻮﻓﻴﺰﻳﮏ ﺑﻪ ﺩﺍﻧﺸﺠﻮﻳﺎﻥ ﻭ ﭘﮋﻭﻫﺶﮔﺮﺍﻥ ﻓﻴﺰﻳﮏ ﻣﻌﺮﻓﻲ ﺷﻮﺩ ﺗﺎ ﺍﻫﻤﻴـﺖ ﻫﻤـﺮﺍﻩ ﺷـﺪﻥ ﺑـﺎ ﺟﺎﻣﻌـﻪ ﺟﻬـﺎﻧﻲ ﻭ‬
‫ﺁﻣﻮﺯﺵ ﺩﺍﻧﺸﺠﻮﻳﺎﻥ ﻓﻴﺰﻳﮏ ﻣﻄﺎﺑﻖ ﮐﺎﺭﺑﺮﺩﻫﺎﻱ ﺭﻭﺯ ﺭﻭﺷﻦﺗﺮ ﮔﺮﺩﺩ‪ .‬ﻣﺎ ﺍﺑﺘﺪﺍ ﺑﺎ ﻣﻌﺮﻓﻲ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﻣﺮﮐﺰﻱ ﺍﺯ ﺩﻳﺪﮔﺎﻩ ﻓﻴﺰﻳﮏ ﺷﺮﻭﻉ ﮐـﺮﺩﻩ ﻭ ﺳـﭙﺲ‬
‫ﺑﻪ ﻣﻌﺮﻓﻲ ﻗﻮﺍﻧﻴﻦ ﻭ ﻣﻌﺎﺩﻻﺕ ﺑﻨﻴﺎﺩﻱ ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﻣﻲﭘﺮﺩﺍﺯﻳﻢ‪ .‬ﺩﺭ ﺁﺧﺮ ﺑﻪ ﻓﻴﺰﻳﮏ ﻳﺎﺩﮔﻴﺮﻱ ﻭ ﺣﺎﻓﻈﻪ ﺍﺷﺎﺭﻩﺍﻱ ﺧﻮﺍﻫﻴﻢ ﺩﺍﺷﺖ‪.‬‬

‫ﻭﺍﮊﻩﻫﺎﻱ ﻛﻠﻴﺪﻱ‪:‬ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ‪ ،‬ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ‪ ،‬ﻧﻮﺭﻭﻥ‪ ،‬ﺳﻴﻨﺎﭘﺲ‪ ،‬ﺣﺎﻓﻈﻪ‬

‫ﻣﺨﺘﻠﻔﻲ ﻭﺟﻮﺩ ﺩﺍﺭﺩ‪ .‬ﺑﺮﺧﻲ ﺍﺯ ﻓﻴﺰﻳﮑﺪﺍﻧﺎﻥ ﺍﻋﺼـﺎﺏ‪ ١‬ﻇﻬـﻮﺭ ﭼﻨـﻴﻦ‬ ‫‪..۱‬ﻣﻘﺪﻣﻪ‬

‫ﻧﻈﺮﻳﻪﺍﻱ ﺭﺍ ﺩﺭ ﻗﺮﻥ ﺟﺎﺭﻱ ﻫﻤﺎﻧﻨﺪ ﻇﻬﻮﺭ ﻣﮑﺎﻧﻴﮏ ﮐﻮﺍﻧﺘﻤﻲ ﺩﺭ ﻗـﺮﻥ‬ ‫ﺍﺯ ﺁﻧﺠﺎ ﮐﻪ ﺑﺪﻥ ﻭ ﻣﻐﺰ ﻗﺴﻤﺖﻫﺎﻳﻲ ﺍﺯ ﻳﮏ ﺩﻧﻴـﺎﻱ ﻓﻴﺰﻳﮑـﻲ ﻫﺴـﺘﻨﺪ‬
‫ﮔﺬﺷﺘﻪ ﻣﻲﺩﺍﻧﻨﺪ‪ ،‬ﮐﻪ ﺧﻮﺩ ﺟﺎﻱ ﺑﺴﻴﺎﺭ ﺑﺤﺚ ﺩﺍﺭﺩ‪.‬‬ ‫ﺑﺎﻳﺪ ﻳﮏ ﻧﻈﺮﻳﺔ ﮐﺎﻣﻞ ﻭﺟﻮﺩ ﺩﺍﺷﺘﻪ ﺑﺎﺷﺪ ﮐﻪ ﺑﺘﻮﺍﻧﺪ ﺑﺪﻥ ﻭ ﻣﻐﺰ ﺭﺍ ﺩﺭ‬
‫ﺍﺯ ﺯﻣـــﺎﻧﻲ ﮐـــﻪ ﻧﻘـــﺶ ﺍﻟﮑﺘﺮﻳﺴـــﻴﺘﻪ ﺩﺭ ﺍﻋﺼـــﺎﺏ ﺗﻮﺳـــﻂ‬ ‫ﻏﺎﻟﺐ ﻳﮏ ﻧﻈﺮﻳﺔ ﻓﻴﺰﻳﮑﻲ ﺗﻮﺿﻴﺢ ﺩﻫﺪ‪ .‬ﺳﺎﺧﺘﺎﺭ ﺍﻳﻦ ﻧﻈﺮﻳﺔ ﻓﻴﺰﻳﮑـﻲ‬
‫ﻟﻮﻳﻴﺠﻲﮔﺎﻟﻮﺍﻧﻲ‪ ٢‬ﺩﺭ ﻧﻴﻤﻪ ﺩﻭﻡ ﻗﺮﻥ ‪ ۱۸‬ﻫﻨﮕﺎﻡ ﻣﻄﺎﻟﻌﺔ ﺑﺪﻥ ﻗﻮﺭﺑﺎﻏـﻪ‬ ‫ﺑﻪ ﺷﺪﺕ ﺑﻪ ﺟﻨﺒﻪﻫﺎﻳﻲ ﮐﻪ ﺑﻪ ﺯﺑﺎﻥ ﺫﻫﻦ ﺑﻪ ﺻﻮﺭﺕ ﻋﻤﻠﮑﺮﺩ ﻋﻤﺪﻱ‬
‫____________________________________________‬ ‫ﻭ ﺑﺎﺯﺧﻮﺭﺩﻫﺎﻱ ﺗﺠﺮﺑﻲ ﺗﻮﺿﻴﺢ ﺩﺍﺩﻩ ﻣﻲﺷﻮﺩ ﺑﺴﺘﮕﻲ ﺧﻮﺍﻫﺪ ﺩﺍﺷﺖ‬
‫‪1. Neurophysicists‬‬
‫]‪ .[۱‬ﺩﺭ ﻣﻮﺭﺩ ﺧﺼﻮﺻﻴﺎﺕ ﺍﻳﻦ ﻧﻈﺮﻳﺔ ﻭ ﺍﺻﻮﻝ ﺁﻥ ﻧﻈﺮﻳـﺎﺕ ﺑﺴـﻴﺎﺭ‬
‫‪2. Luigi Galvani‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۴۸‬‬

‫ﺍﺯ ﻳﮏ ﮐﺎﻧﺎﻝ ﺗﻨﻬﺎﻱ ﻳﻮﻧﻲ ﺗﻮﺳﻂ ﺑﻴﻮﻓﻴﺰﻳﮑﺪﺍﻧﻲ ﺑﻨـﺎﻡ ﻧِﻬِـﺮ‪ ٢‬ﻭ ﻳـﮏ‬
‫ﻓﻴﺰﻳﻮﻟﻮﮊﻳﺴﺖ ﺑﻨﺎﻡ ﺳَﮑﻤﻦ‪ ٣‬ﺭﺍﻩ ﺑﺮﺍﻱ ﮐﺸﻒ ﺟﺰﺋﻴﺎﺕ ﮐﺎﻧـﺎﻝﻫـﺎﻱ‬
‫ﺗﺒﺎﺩﻝ ﻳﻮﻧﻲ ﻫﻤﻮﺍﺭ ﺷﺪ ]‪ ۱۲‬ﻭ‪ .[۱۳‬ﻫﻢ ﺍﮐﻨﻮﻥ ﺑﻪ ﮐﻤﮏ ﺭﻭﺵﻫـﺎﻱ‬
‫ﻣﻮﻟﮑﻮﻟﻲ ﺣﺘﻲ ﻣﻲﺗﻮﺍﻥ ﻣﻌﺎﺩﻻﺕ ﻓﻴﺰﻳﮑﻲ ﻏﻴﺮﺧﻄﻲ ﺍﻳﻦ ﮐﺎﻧﺎﻝﻫﺎ ﺭﺍ‬
‫ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ ]‪ .[۱۴‬ﺑﺎ ﺗﺤﻘﻴﻘﺎﺕ ﻳﮏ ﺑﻴﻮﻓﻴﺰﻳﮑﺪﺍﻥ ﺩﻳﮕـﺮ ﺑـﻪ ﻧـﺎﻡ‬
‫ﺑﺮﻧﺎﺭﺩ ﮐﺘﺰ‪ ٤‬ﺩﺭ ﻣﻮﺭﺩ ﺳﻴﻨﺎﭘﺲﻫـﺎ ﺭﺍﻩ ﺑـﺮﺍﻱ ﺍﺭﺍﺋـﺔ ﻧﻈﺮﻳـﺔ ﺣﺎﻓﻈـﻪ‬
‫ﻫﻤﻮﺍﺭ ﺷﺪ ]‪.[۱۷-۱۵‬‬
‫ﺩﺭ ﺍﻳﻦ ﻣﻘﺎﻟﻪ ﺑﻌﺪ ﺍﺯ ﺗﻮﺻﻴﻒ ﺳـﺎﺩﻩ ﺳـﺎﺧﺘﺎﺭ ﻓﻴﺰﻳﮑـﻲ ﻣﻐـﺰ ﻭ‬
‫ﺍﻋﺼﺎﺏ‪ ،‬ﺑﻪ ﻣﻌﺮﻓﻲ ﻗﻮﺍﻧﻴﻦ ﻓﻴﺰﻳﮑﻲ ﺣﺎﮐﻢ ﺑﺮ ﺁﻥ ﻣـﻲﭘـﺮﺩﺍﺯﻳﻢ‪ .‬ﺑـﻪ‬ ‫ﺷﮑﻞ‪ .١‬ﻃﺮﺡ ﻧﻤﺎﺩﻳﻦ ﻣﻐﺰ ﻫﻤﺮﺍﻩ ﺑﺎ ﻳﮏ ﻣﺮﮐﺰ ﻧﻮﺭﻭﻧﻲ‪ ،‬ﻳـﮏ ﻧـﻮﺭﻭﻥ ﻭ‬
‫ﺩﻧﺒﺎﻝ ﺁﻥ ﺑﺎ ﻣﻌﺮﻓﻲ ﺍﻧﻮﺍﻉ ﺳﻴﻨﺎﭘﺲﻫﺎ‪ ،‬ﻣﺒﻨﺎﻱ ﺷﮑﻞﮔﻴﺮﻱ ﺣﺎﻓﻈـﻪ ﺭﺍ‬ ‫ﻳﮏ ﮐﺎﻧﺎﻝ ﻳﻮﻧﻲ‪.‬‬
‫ﻣﻮﺭﺩ ﺑﺮﺭﺳﻲ ﻗﺮﺍﺭ ﻣﻲﺩﻫﻴﻢ‪.‬‬
‫ﺗﺸﺮﻳﺢ ﺷﺪﻩ ﻣﺸﺨﺺ ﺷﺪ‪ ،‬ﻋﻤﻼً ﻓﻴﺰﻳﮏ ﻭﺍﺭﺩ ﺗﺤﻘﻴﻘـﺎﺕ ﻋﻠـﻮﻡ‬
‫‪ .۱‬ﺩﺳﺘﮕﺎﻩ ﻣﻐﺰ ﻭ ﺍﻋﺼﺎﺏ ﺍﺯ ﺩﻳﺪﮔﺎﻩ ﻓﻴﺰﻳﮏ‬ ‫ﺍﻋﺼﺎﺏ ﺷﺪ ]‪ .[۲‬ﺑﻌﺪ ﺍﺯ ﺍﺧﺘﺮﺍﻉ ﻣﻴﮑﺮﻭﺳﮑﻮﭖ‪ ،‬ﻋﻠﻮﻡ ﺍﻋﺼـﺎﺏ‬
‫ﮐﺎﺭ ﺍﺻﻠﻲ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﺑﺮﻗﺮﺍﻱ ﺍﺭﺗﺒﺎﻁ ﻭ ﺗﺤﻠﻴـﻞ ﺍﻃﻼﻋـﺎﺕ‬ ‫ﻭﺍﺭﺩ ﻓﺎﺯ ﺟﺪﻳﺪﻱ ﺷﺪ‪ .‬ﺩﺭ ‪ ۶۰‬ﺳﺎﻝ ﺍﺧﻴﺮ ﻭ ﺑﻪ ﺧﺼﻮﺹ ﺑﻌـﺪ ﺍﺯ‬
‫ﺍﺳﺖ ]‪ .[۳‬ﺑﻪ ﻋﻨـﻮﺍﻥ ﻣﺜـﺎﻝ ﻭﻗﺘـﻲ ﮐﺘـﺎﺑﻲ ﺭﺍ ﻣﻄﺎﻟﻌـﻪ ﻣـﻲﮐﻨـﻴﻢ‬ ‫ﺷﮑﻞﮔﻴﺮﻱ ﻧﻈﺮﻳﺔ ﻧﻮﺭﻭﻥ‪ ،‬ﺑﻪ ﻋﻨﻮﺍﻥ ﻭﺍﺣﺪ ﺑﻨﻴﺎﺩﻱ ﻋﻤﻠﮕـﺮ ﻣﻐـﺰ‬
‫ﺍﻃﻼﻋﺎﺕ ﺑﻴﻨﺎﻳﻲ ﺍﺯ ﻃﺮﻳﻖ ﭼﺸﻢ ﻭ ﻳﺎﺧﺘﻪﻫﺎﻱ ﺩﺭﻳﺎﻓﺖﮐﻨﻨﺪﻩ ﻧﻮﺭ‬ ‫ﻭ ﺗﺄﻳﻴﺪ ﺁﺯﻣﺎﻳﺸﮕﺎﻫﻲ ﺁﻥ‪ ،‬ﻭ ﻫﻤﭽﻨﻴﻦ ﮔﺰﺍﺭﺵ ﺗﺤﺮﻳـﮏﭘـﺬﻳﺮﻱ‬
‫ﺩﺭ ﺷﺒﮑﻴﻪ ﺑﻪ ﺻﻮﺭﺕ ﭘﻴﺎﻡﻫﺎﻱ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺭﻣﺰﮔﺬﺍﺭﻱ ﺷﺪﻩ ﻭ ﺑـﻪ‬ ‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﻧﻮﺭﻭﻥﻫﺎ ﻭ ﺗﺄﺛﻴﺮ ﺁﻥ ﺑﺮ ﺣﺎﻟـﺖ ﻧـﻮﺭﻭﻥﻫـﺎﻱ ﻣﺠـﺎﻭﺭ‬
‫ﻗﺴﻤﺖﻫﺎﻱ ﺧﺎﺻﻲ ﺩﺭ ﻣﻐﺰ ﻣﻨﺘﻘﻞ ﻣﻲﺷـﻮﺩ‪ .‬ﺍﻳـﻦ ﺍﻃﻼﻋـﺎﺕ ﺩﺭ‬ ‫ﻓﻴﺰﻳﮏﺩﺍﻧﺎﻥ ﺯﻳﺎﺩﻱ ﺑﻪ ﺍﻳﻦ ﺳﻴﺴﺘﻢ ﻋﻼﻗـﻪﻣﻨـﺪ ﺷـﺪﻧﺪ ]‪ ۳‬ﻭ ‪.[۴‬‬
‫ﻣﺮﮐﺰﻫﺎﻱ ﻧﻮﺭﻭﻧﻲ ﻣﺮﺑﻮﻃﻪ ﺗﺤﻠﻴﻞ ﺷﺪﻩ ﻭ ﺩﺭ ﻧﻬﺎﻳـﺖ ﻣﻨﺠـﺮ ﺑـﻪ‬ ‫ﺑﻌﺪ ﺍﺯ ﻭﺭﻭﺩ ﺑﻴﻮﻓﻴﺰﻳﮏﺩﺍﻧﺎﻧﻲ ﭼـﻮﻥ ﻫـﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴـﻠﻲ‪ ١‬ﺑـﻪ‬
‫ﺗﻔﺴﻴﺮ ﺧﺎﺻـﻲ ﺍﺯ ﺁﻥ ﺟﺴـﻢ ﻣـﻲﺷـﻮﺩ‪ ،‬ﮐـﻪ ﻣـﺎ ﺁﻥ ﺭﺍ »ﺩﻳـﺪﻥ«‬ ‫ﺍﻳﻦ ﺗﺤﻘﻴﻘﺎﺕ‪ ،‬ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ ﮐﻪ ﺗﺎ ﺁﻥ ﺯﻣﺎﻥ ﺑﻴﺸﺘﺮ ﺑـﻪ ﺻـﻮﺭﺕ‬
‫ﻣﻲﮔﻮﻳﻴﻢ ]‪ .[۱۸‬ﻣﻐﺰ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺁﻥ ﺗﻔﺴـﻴﺮ‪ ،‬ﺩﺳـﺘﻮﺭﺍﺕ ﻻﺯﻡ ﺭﺍ‬ ‫ﺷﺎﺧﻪﺍﻱ ﺍﺯ ﺭﻭﺍﻧﺸﻨﺎﺳﻲ ﺑﺤﺚ ﻣﻲﺷﺪ ﺷﮑﻠﻲ ﺑﻨﻴـﺎﺩﻱ ﻫﻤـﺮﺍﻩ ﺑـﺎ‬
‫ﺑﻪ ﻗﺴﻤﺖﻫﺎﻱ ﺣﺮﮐﺘﻲ ﺩﺍﺩﻩ ﻭ ﺑﻪ ﺍﻳﻦ ﺗﺮﺗﻴﺐ ﺑﺎ ﻣﺤـﻴﻂ ﺍﻃـﺮﺍﻑ‬ ‫ﺍﻧﺪﺍﺯﻩﮔﻴﺮﻱ ﻭ ﻣﺤﺎﺳﺒﺎﺕ ﺑﻪ ﺧﻮﺩ ﮔﺮﻓﺖ‪ .‬ﺑﻪ ﻋﻨﻮﺍﻥ ﻣﺜﺎﻝ ﻗـﻮﺍﻧﻴﻦ‬
‫ﺧﻮﺩ ﺍﺭﺗﺒﺎﻁ ﺑﺮﻗﺮﺍﺭ ﻣﻲﮐﻨﺪ‪ .‬ﺩﻗﺖ ﺩﺭ ﺩﺭﻳﺎﻓﺖ‪ ،‬ﺍﺭﺳﺎﻝ ﻭ ﺗﺠﺰﻳـﻪ‬ ‫ﮔﺬﺭﺩﻫﻴﻴﻮﻥﻫﺎ ﻭ ﺑﺎﺯ ﻭ ﺑﺴﺘﻪ ﺷﺪﻥ ﺩﺭﻭﺍﺯﺓ ﮐﺎﻧﺎﻝﻫـﺎﻱ ﻳـﻮﻧﻲ ﮐـﻪ‬
‫ﻭ ﺗﺤﻠﻴﻞ ﺍﻳﻦ ﭘﻴﺎﻡﻫﺎ ﺟﻬﺖ ﺑﻘﺎ ﻭ ﺗﺎﻣﻴﻦ ﻣﺎﻳﺤﺘﺎﺝ ﺭﻭﺯﺍﻧـﻪ ﺑﺴـﻴﺎﺭ‬ ‫ﺣﺪﻭﺩ ‪ ۵۰‬ﺳﺎﻝ ﻣﻮﺿﻮﻉ ﺗﺤﻘﻴﻖ ﻓﻴﺰﻳﻮﻟﻮﮊﯼ ﺍﻋﺼﺎﺏ ﺑﻮﺩ ﺗﻮﺳﻂ‬
‫ﻣﻬﻢ ﻭ ﺣﻴـﺎﺗﻲ ﺍﺳـﺖ‪ .‬ﺑـﻪ ﻫﻤـﻴﻦ ﺗﺮﺗﻴـﺐ ﺍﻃﻼﻋـﺎﺕ ﺷـﻨﻮﺍﻳﻲ‪،‬‬ ‫ﺍﻳ ـﻦ ﺩﻭ ﻧﻔــﺮ ﺑــﻪ ﺻــﻮﺭﺕ ﺁﺯﻣﺎﻳﺸــﮕﺎﻫﻲ ﻫﻤــﺮﺍﻩ ﺑــﺎ ﻣﻌــﺎﺩﻻﺕ‬
‫ﺑﻮﻳﺎﻳﻲ‪ ،‬ﭼﺸﺎﻳﻲ ﻭ ﻻﻣﺴﻪ ﻧﻴﺰ ﺩﺭ ﻗﺴﻤﺖﻫـﺎﻱ ﻣﺮﺑﻮﻃـﻪ ﺩﺭ ﻣﻐـﺰ‬ ‫ﺩﻳﻔﺮﺍﻧﺴﻴﻞ ﻣﺤﺎﺳﺒﺎﺗﻲ ﻣﺮﺑﻮﻃﻪ ﺍﺭﺍﺋﻪ ﺷﺪ ]‪.[۹ -۵‬‬
‫ﺗﺠﺰﻳﻪ ﻭ ﺗﺤﻠﻴﻞ ﻣﻲﺷﻮﻧﺪ‪ .‬ﺍﻳـﻦ ﻣﺮﺍﮐـﺰ ﻧـﻮﺭﻭﻧﻲ ﺷـﺎﻣﻞ ﺗﻌـﺪﺍﺩ‬ ‫ﺑﻌﺪ ﺍﺯ ﻣـﺪﻝ ﻓﻴﺰﻳﮑـﻲ‪ -‬ﺭﻳﺎﺿـﻲ ﻫـﺎﺟﮑﻴﻦ‪ -‬ﻫﺎﮐﺴـﻠﻲ ﻋﻠـﻮﻡ‬
‫ﺯﻳﺎﺩﻱ ﻧﻮﺭﻭﻥ ﻣﻲﺑﺎﺷﻨﺪ ﮐﻪ ﺑﺎ ﻧﻈﻢ ﺧﺎﺻﻲ ﺑـﺎ ﻳﮑـﺪﻳﮕﺮ ﺍﺭﺗﺒـﺎﻁ‬ ‫ﺍﻋﺼﺎﺏ ﺑﺎ ﺷﺘﺎﺏ ﺑﺴﻴﺎﺭ ﺯﻳﺎﺩﻱ ﺭﺷﺪ ﮐﺮﺩﻩ ﻭ ﺑﻪ ﺻـﻮﺭﺕ ﻳﮑـﻲ ﺍﺯ‬
‫ﺩﺍﺭﻧﺪ ﺷﮑﻞ ‪ ۱‬ﻭﺍﺣﺪﻫﺎﻱ ﺳﺎﺧﺘﺎﺭﻱ ﺑﻨﻴﺎﺩﻱ ﺍﻳﻦ ﻣﺮﺍﮐﺰ ﻧـﻮﺭﻭﻧﻲ‪،‬‬ ‫ﻭﺳﻴﻊﺗﺮﻳﻦ ﺭﺷﺘﻪﻫﺎﻱ ﺑﻴﻦ ﺭﺷـﺘﻪﺍﻱ ﺩﺭﺁﻣـﺪﻩ ﺍﺳـﺖ‪ .‬ﺩﺭ ﺍﻳـﻦ ﺑـﻴﻦ‬
‫ﻧﻮﺭﻭﻥﻫﺎ ﻫﺴﺘﻨﺪ‪ .‬ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﺑﺪﻥ ﻣﺎ ﺣـﺪﻭﺩ ‪ ۱۰۱۲‬ﻧـﻮﺭﻭﻥ‬ ‫ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﺧﻮﺩ ﺑـﻪ ﮔـﺮﺍﻳﺶﻫـﺎﻱ ﻣﺨﺘﻠﻔـﻲ ﺍﻋـﻢ ﺍﺯ ﻓﻴﺰﻳـﮏ‬
‫ﺩﺍﺷــﺘﻪ ﻭ ﺩﺭ ﻫــﺮ ﻣﻴﻠــﻲ ﻣﺘــﺮ ﻣﮑﻌــﺐ ﺍﺯ ﻣــﺎﺩﺓ ﻣﻐــﺰﻱ ﺣــﺪﻭﺩ‬ ‫ﺍﻋﺼﺎﺏ ﺗﺠﺮﺑﻲ‪ ،‬ﻣﺤﺎﺳﺒﺎﺗﻲ‪ ،‬ﺁﻣﺎﺭﻱ ﻭ ﻓﻠﺴﻔﻲ ﺗﻘﺴﻴﻢ ﺷـﺪﻩ ﺍﺳـﺖ‬
‫____________________________________________‬ ‫]‪ ۱۰‬ﻭ‪ .[۱۱‬ﺑﺎ ﺍﺑﺪﺍﻉ ﻳﮏ ﺭﻭﺵ ﻓﻴﺰﻳﮑﻲ ﺑﺮﺍﻱ ﺛﺒﺖ ﺟﺮﻳﺎﻥ ﮔﺬﺭﻧـﺪﻩ‬
‫‪2. Neher‬‬
‫‪3. Sekmen‬‬ ‫____________________________________________‬
‫‪4. Bernard Katz‬‬ ‫‪1 Hodgkin and Huxley‬‬
‫‪۳۴۹‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﺷﮑﻞ‪ .٢‬ﻳﮏ ﻧﻮﺭﻭﻥ ﻫﻤﺮﺍﻩ ﺑﺎ ﺍﺗﺼﺎﻝ ﺳﻴﻨﺎﭘﺴﻲ‪.‬‬

‫ﺍﻃﻼﻋـﺎﺕ ﺭﺍ ﺗﺠﺰﻳـﻪ ﻭ ﺗﺤﻠﻴـﻞ ﮐــﺮﺩﻩ ﻭ ﺑـﻪ ﻭﺳـﻴﻠﺔ ﭘﻴـﺎﻡﻫــﺎﻱ‬ ‫‪ ۱۰۵‬ﻧﻮﺭﻭﻥ ﻭﺟﻮﺩ ﺩﺍﺭﺩ ]‪ .[۱۹‬ﺑﺮﺧﻼﻑ ﺳـﺎﻳﺮ ﻳﺎﺧﺘـﻪﻫـﺎﻱ ﺑـﺪﻥ‪،‬‬
‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﻭ ﺷﻴﻤﻴﺎﻳﻲ ﺑﻪ ﺳﺎﻳﺮ ﻧﻮﺭﻭﻥﻫﺎ ﻣﻨﺘﻘﻞ ﻣﻲﮐﻨﺪ‪ .‬ﺳـﺎﺧﺘﺎﺭ‬ ‫ﻣﺪﺕ ﮐﻮﺗﺎﻫﻲ ﺑﻌﺪ ﺍﺯ ﺗﻮﻟﺪ‪ ،‬ﺗﻘﺴﻴﻢ ﻳﺎﺧﺘـﻪﺍﯼ ﻧـﻮﺭﻭﻥﻫـﺎ ﻣﺘﻮﻗـﻒ‬
‫ﻧﻮﺭﻭﻥﻫﺎ ﻣﺘﺸﮑﻞ ﺍﺯ ﺳﻪ ﻗﺴﻤﺖ ﺍﺻﻠﻲ ﺍﺳـﺖ‪ :‬ﺩﻧـﺪﺭﻳﺖ‪ ،‬ﺑﺪﻧـﺔ‬ ‫ﻣﻲﺷﻮﺩ‪ .‬ﺑﻪ ﻫﻤﻴﻦ ﺩﻟﻴﻞ ﺑﺮﺧﻲ ﻗﺴﻤﺖﻫﺎﻱ ﻣﻐﺰ ﺩﺭ ﺩﻭﺭﺍﻥ ﮐـﻮﺩﮐﻲ‬
‫ﻧﻮﺭﻭﻥ ﻭ ﺁﮐﺴﻮﻥ )ﺷﮑﻞ ‪ .(۲‬ﭘﻴﺎﻡ ﺍﺯ ﻃﺮﻳـﻖ ﺩﻧـﺪﺭﻳﺖ ﺑـﻪ ﺑﺪﻧـﺔ‬ ‫ﺩﺍﺭﺍﻱ ﺗﻌﺪﺍﺩ ﻧﻮﺭﻭﻥﻫـﺎﻱ ﺑﻴﺸـﺘﺮﻱ ﻧﺴـﺒﺖ ﺑـﻪ ﺩﻭﺭﺍﻥ ﺑﺰﺭﮔﺴـﺎﻟﻲ‬
‫ﻧﻮﺭﻭﻥ ﻣﻲﺭﺳﺪ ﻭ ﺩﺭ ﺁﻧﺠﺎ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺷﺮﺍﻳﻂ ﻣﺨﺘﻠﻒ ﻣﻨﺠﺮ ﺑـﻪ‬ ‫ﺍﺳﺖ‪ ،‬ﺯﻳﺮﺍ ﻧﻮﺭﻭﻥﻫﺎﻱ ﻣﺮﺩﻩ ﺟﺎﻳﮕﺰﻳﻦ ﻧﻤﻲﺷﻮﻧﺪ‪ .‬ﺍﻣـﺎ ﺩﺭ ﻋـﻮﺽ‬
‫ﺗﻮﻟﻴﺪ ﻳﺎ ﻋﺪﻡ ﺗﻮﻟﻴﺪ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﻣﻲﺷـﻮﺩ‪ .‬ﺩﺭ ﺻـﻮﺭﺕ ﺗﻮﻟﻴـﺪ‬ ‫ﺩﺭ ﺗﻤﺎﻡ ﻃﻮﻝ ﺯﻧﺪﮔﻲ‪ ،‬ﻧﻮﺭﻭﻥﻫﺎ ﺩﺭ ﺣﺎﻝ ﺍﻳﺠﺎﺩ ﺍﺭﺗﺒﺎﻃﺎﺕ ﺟﺪﻳﺪﻱ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‪ ،‬ﺍﻳﻦ ﭘﻴﺎﻡ ﺍﺯ ﻃﺮﻳﻖ ﺁﮐﺴﻮﻥ ﺑﻪ ﻧﻮﺭﻭﻥﻫـﺎﻱ ﺩﻳﮕـﺮ‬ ‫ﺑﺎ ﻳﮑﺪﻳﮕﺮ ﻫﺴﺘﻨﺪ ﮐﻪ ﺍﻳﻦ ﻧﻘـﺺ ﺭﺍ ﺟﺒـﺮﺍﻥ ﻣـﻲﮐﻨـﺪ ]‪ ۲۰‬ﻭ ‪.[۲۱‬‬
‫ﻣﻨﺘﻘﻞ ﻣﻲﺷﻮﺩ ]‪ ۲۳‬ﻭ‪.[۲۴‬‬ ‫ﺧﺎﺻﻴﺖ ﺍﺻﻠﻲ ﻧﻮﺭﻭﻥﻫﺎ ﺩﺭ ﺗﺤﺮﻳﮏﭘﺬﻳﺮ ﺑﻮﺩﻥ ﺁﻧﻬﺎ ﺍﺳﺖ‪ .‬ﺑﻪ ﺍﻳﻦ‬
‫ﻣﻌﻨﻲ ﮐﻪ ﻫﺮﮔﺎﻩ ﺗﺤﺮﻳﮑﻲ ﺑﻪ ﺍﻳﻦ ﻳﺎﺧﺘﻪﻫـﺎﻱ ﻣﻐـﺰﻱ ﻭﺍﺭﺩ ﺷـﻮﺩ ﺍﺯ‬
‫‪ .۱.۱.۲‬ﺁﮐﺴﻮﻥ‬ ‫ﺧﻮﺩ ﭘﻴﺎﻡ )ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‪ (١‬ﺗﻮﻟﻴﺪ ﻣﻲﮐﻨﻨﺪ‪ .‬ﺑﻌﻀـﻲ ﺍﺯ ﻳﺎﺧﺘـﻪﻫـﺎﻱ‬
‫ﺁﮐﺴﻮﻥ ﺯﺍﺋﺪﻩﺍﻱ ﺑﺎﺭﻳﮏ ﻭ ﻣﻌﻤﻮﻻً ﺑﻠﻨﺪ ﺍﺳﺖ ﮐﻪ ﻧﻘـﺶ ﺧﺮﻭﺟـﻲ ﺭﺍ‬ ‫ﺩﻳﮕﺮ ﺑﺪﻥ ﻫﻤﺎﻧﻨﺪ ﻳﺎﺧﺘﻪﻫﺎﻱ ﻋﻀـﻼﻧﻲ )ﺍﺯ ﺟﻤﻠـﻪ ﻗﻠـﺐ( ﻭ ﻏـﺪﺩ‬
‫ﺩﺭ ﻧﻮﺭﻭﻥ ﺩﺍﺷﺘﻪ ﻭ ﭘﻴﺎﻡﻫﺎﻱ ﻋﺼﺒﻲ ﺭﺍ ﺑﻪ ﻧﻮﺭﻭﻥﻫﺎﻱ ﺑﻌﺪﻱ ﻫـﺪﺍﻳﺖ‬ ‫ﺩﺭﻭﻥﺭﻳﺰ‪ ،‬ﻭ ﻫﻤﭽﻨﻴﻦ ﻳﺎﺧﺘﻪﻫﺎﻱ ﮔﻴﺎﻫﻲ ﻧﻴﺰ ﺗﺤﺮﻳﮏﭘـﺬﻳﺮ ﻫﺴـﺘﻨﺪ‬
‫ﻣﻲﮐﻨﺪ‪ .‬ﺁﮐﺴﻮﻥ ﺩﺍﺭﺍﻱ ﻳﮏ ﺳﺎﺧﺘﺎﺭ ﻟﻮﻟـﻪﺍﻱ ﺑـﺎ ﻗﻄـﺮ ﺗﻘﺮﻳﺒـﺎً ﺛﺎﺑـﺖ‬ ‫ﻭﻟﻲ ﻳﺎﺧﺘﻪﻫﺎﻱ ﺗﺤﺮﻳﮏﭘﺬﻳﺮ ﺍﺻﻠﻲ ﻫﻤﺎﻥ ﻧﻮﺭﻭﻥﻫﺎ ﻫﺴـﺘﻨﺪ ]‪.[۲۲‬‬
‫ﺍﺳﺖ ﮐﻪ ﻃﻮﻝ ﺁﻥ ﺍﺯ ﭼﻨﺪ ﻣﻴﻠﻲﻣﺘﺮ ﺗﺎ ‪ ۲‬ﻣﺘﺮ ﺩﺭ ﺑﻌﻀﻲ ﻣـﻮﺍﺭﺩ ﺗﻐﻴﻴـﺮ‬ ‫ﺍﻳﻦ ﭘﺘﺎﻧﺴﻴﻞﻫﺎﻱ ﻋﻤﻞ ﺍﺯ ﻃﺮﻳﻖ ﺷﺎﺧﮏﻫـﺎﻱ ﻭﺭﻭﺩﻱ ﻭ ﺧﺮﻭﺟـﻲ‬
‫ﻣﻲﮐﻨﺪ‪ .‬ﺁﮐﺴﻮﻥﻫﺎ ﺑـﻪ ﺩﻭ ﮔـﺮﻭﻩ ﻣﻴﻠـﻴﻦﺩﺍﺭ ﻭ ﺑـﺪﻭﻥ ﻣﻴﻠـﻴﻦ ﺗﻘﺴـﻴﻢ‬ ‫ﻣﺨﺼﻮﺻﻲ ﺑﻪ ﻧﺎﻡ ﺩﻧﺪﺭﻳﺖ‪ ٢‬ﻭ ﺁﮐﺴﻮﻥ‪ ٣‬ﺑﻪ ﻧﻮﺭﻭﻥﻫﺎﻱ ﺩﻳﮕﺮ ﻣﻨﺘﻘﻞ‬
‫ﻣﻲﺷﻮﻧﺪ‪ .‬ﻣﻴﻠﻴﻦ ﻳﮏ ﻣﺎﺩﺓ ﭘﺮﻭﺗﺌﻴﻨﻲ ﻭ ﭼﺮﺑـﻲ ﻓﺴـﻔﺮﺩﺍﺭ ﺳـﻔﻴﺪﺭﻧﮕﻲ‬ ‫ﻣﻲﺷﻮﻧﺪ‪ .‬ﺟﺰﺋﻴﺎﺕ ﻓﻴﺰﻳﮑﻲ ﺗﻮﻟﻴﺪ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﮐـﻪ ﻋﺎﻣـﻞ ﺍﺻـﻠﻲ‬
‫ﺍﺳﺖ ﮐﻪ ﺑﻌﻀﻲ ﺍﺯ ﺁﮐﺴﻮﻥﻫﺎ ﺭﺍ ﺑﻪ ﺻـﻮﺭﺕ ﻳـﮏ ﻏـﻼﻑ ﻧﺎﭘﻴﻮﺳـﺘﻪ‬ ‫ﺍﻧﺘﻘﺎﻝ ﭘﻴﺎﻡﻫﺎﻱ ﻋﺼﺒﻲ ﺑﻴﻦ ﻧﻮﺭﻭﻥﻫﺎ ﺍﺳﺖ ﺩﺭ ﺍﺩﺍﻣﻪ ﺧﻮﺍﻫﺪ ﺁﻣﺪ‪.‬‬
‫ﻣﻲﭘﻮﺷﺎﻧﺪ‪ .‬ﻫﻤﻴﻦ ﻣﺎﺩﻩ ﺍﺳﺖ ﮐﻪ ﺑﺎﻋﺚ ﺭﻧﮓ ﺳﻔﻴﺪ ﺑﺮﺧـﻲ ﺍﻋﺼـﺎﺏ‬
‫‪ .۱.۲‬ﺳﺎﺧﺘﺎﺭ ﻧﻮﺭﻭﻥ‬
‫ﻭ ﺑﻌﻀﻲ ﺍﺯ ﻧﻮﺍﺣﻲ ﻣﻐﺰ ﻭ ﻧﺨﺎﻉ ﻣﻲﺷﻮﺩ‪ .‬ﻣﻴﻠﻴﻦ ﺑﺎ ﺍﻳﺠﺎﺩ ﻧﺎﺭﺳـﺎﻧﺎﻳﻲ‬
‫ﻧﻮﺭﻭﻥ ﻳﺎ ﻳﺎﺧﺘﻪ ﻋﺼﺒﻲ‪ ،‬ﻭﺍﺣﺪ ﺑﻨﻴﺎﺩﻱ ﺳﺎﺯﻧﺪﺓ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼـﺎﺏ‬
‫ﺑﻴﺸﺘﺮ ﺑـﺮ ﺭﻭﻱ ﺳـﻄﺢ ﺗﺎﺭﻫـﺎﻱ ﻋﺼـﺒﻲ ﺑﺎﻋـﺚ ﺍﻓـﺰﺍﻳﺶ ﺭﺳـﺎﻧﺎﻳﻲ‬
‫ﻣﺮﮐﺰﻱ‪ (CNS) ٤‬ﺷﺎﻣﻞ ﻣﻐﺰ‪ ،‬ﻧﺨـﺎﻉ ﻭ ﺍﻋﺼـﺎﺏ ﺟـﺎﻧﺒﻲ ﺍﺳـﺖ‪.‬‬
‫ﭘﻴﺎﻡﻫﺎﻱ ﻋﺼﺒﻲ ﺩﺭ ﻃﻮﻝ ﺭﺷﺘﻪﻫﺎﻱ ﻋﺼﺒﻲ ﻣﻲﺷﻮﺩ ﻭ ﻋﻼﻭﻩ ﺑـﺮ ﺁﻥ‬
‫ﻳﮏ ﻧﻮﺭﻭﻥ ﻳـﮏ ﻳﺎﺧﺘـﺔ ﺗﺤﺮﻳـﮏﭘـﺬﻳﺮ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺍﺳـﺖ ﮐـﻪ‬
‫ﻭﻇﻴﻔﺔ ﻧﮕﻬﺪﺍﺭﻱ ﺍﺯ ﻳﺎﺧﺘﻪﻫـﺎﻱ ﻋﺼـﺒﻲ ﺭﺍ ﺑـﻪ ﻋﻬـﺪﻩ ﺩﺍﺭﺩ‪ .‬ﺍﺯ ﻧﻈـﺮ‬
‫____________________________________________‬
‫ﻋﻤﻠﮑﺮﺩ‪ ،‬ﺁﮐﺴﻮﻥ ﻣﻌﻤﻮﻻً ﭘﻴﺎﻡﻫﺎ ﺭﺍ ﺍﻧﺘﻘـﺎﻝ ﻣـﻲﺩﻫـﺪ ﺩﺭ ﺣـﺎﻟﻲ ﮐـﻪ‬ ‫‪1. Action potential‬‬
‫ﺩﻧﺪﺭﻳﺖﻫﺎ ﭘﻴﺎﻡﻫﺎ ﺭﺍ ﺩﺭﻳﺎﻓﺖ ﻣﻲﮐﻨﻨـﺪ‪ .‬ﺑـﺎ ﺍﻳـﻦ ﺣـﺎﻝ ﺍﺳـﺘﺜﻨﺎﺀ ﻫـﻢ‬ ‫‪2. Dendrite‬‬
‫‪3. Axon‬‬
‫ﻭﺟــﻮﺩ ﺩﺍﺭﺩ‪ .‬ﺑﻌﻀــﻲ ﺍﺯ ﻧــﻮﺭﻭﻥﻫــﺎ ﺩﺍﺭﺍﻱ ﺁﮐﺴــﻮﻥ ﻧﻴﺴــﺘﻨﺪ ﻭ‬
‫)‪4. Central Nervous system (CNS‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۵۰‬‬

‫ﺷﮑﻞ‪.٤‬ﻗﺴﻤﺘﻲ ﺍﺯ ﻏﺸﺎﺀ ﺩﻭﻻﻳﻪﺍﻱ ﺑﺪﻧﺔ ﻧﻮﺭﻭﻥ )ﺳﻮﻣﺎ(‪.‬‬ ‫ﺷﮑﻞ‪ .٣‬ﺍﺳﭙﺎﻳﻦ ﺩﺭ ﺍﻧﺘﻬﺎﻱ ﺩﻧﺪﺭﻳﺖﻫﺎ‪.‬‬

‫ﺣﻞ ﻫﺴﺘﻨﺪ‪ .‬ﺩﺭ ﻣﺤﻴﻂ ﺁﺑﻲ‪ ،‬ﺍﻳـﻦ ﻣﻮﻟﮑـﻮﻝﻫـﺎ ﺑـﻪ ﻃـﻮﺭ ﻃﺒﻴﻌـﻲ‬ ‫ﺟﺎﻟﺐ ﺍﻳﻨﺠﺎﺳﺖ ﮐﻪ ﻗﺎﺩﺭﻧﺪ ﭘﻴـﺎﻡ ﺭﺍ ﺍﺯ ﻃﺮﻳـﻖ ﺩﻧـﺪﺭﻳﺖ ﺍﻧﺘﻘـﺎﻝ‬
‫ﺗﺸﮑﻴﻞ ﺳﺎﺧﺘﺎﺭ ﺩﻭﻻﻳﻪ ﻣﻲﺩﻫﻨﺪ‪ ،‬ﺑﻪ ﻃﻮﺭﻱ ﮐﻪ ﺳﺮ ﻗﺎﺑـﻞ ﺣـﻞ ﺩﺭ‬ ‫ﺩﻫﻨﺪ‪ .‬ﻣﺤﻠﻲ ﮐﻪ ﺁﮐﺴﻮﻥﻫﺎ ﺑﻪ ﻳﺎﺧﺘﻪﻫﺎﻱ ﺑﻌﺪﻱ ﻣﺘﺼﻞ ﻣﻲﺷـﻮﻧﺪ‬
‫ﭼﺮﺑﻲ ﺍﻳﻦ ﻣﻮﻟﮑﻮﻝﻫﺎ )ﻫﻴﺪﺭﻭﻓﻮﺑﻴﮏ(‪٣‬ﺩﺭ ﻭﺳﻂ ﺳـﺎﻧﺪﻭﻳﭻ ﺷـﺪﻩ‬ ‫ﺳﻴﻨﺎﭘﺲ ﻧﺎﻡ ﺩﺍﺭﺩ‪ ،‬ﮐـﻪ ﺩﺭ ﻗﺴـﻤﺖ ﻫـﺎﻱ ﺑﻌـﺪﻱ ﺑـﻪ ﺁﻥ ﺍﺷـﺎﺭﻩ‬
‫ﻭ ﺳﺮ ﻗﺎﺑﻞ ﺣﻞ ﺩﺭ ﺁﺏ )ﻫﻴﺪﺭﻭﻓﻴﻠﻴﮏ(‪ ٤‬ﺑﻪ ﺳﻤﺖ ﺑﻴﺮﻭﻥ ﻣـﻲﺭﻭﺩ‬ ‫ﻣﻲﮐﻨﻴﻢ ]‪ ۳‬ﻭ‪.[۴‬‬
‫]‪.[۳‬‬
‫ﺩﺭ ﺳﺮﺗﺎﺳﺮ ﺍﻳﻦ ﻏﺸـﺎﺀ ﮐﺎﻧـﺎﻝﻫـﺎﻱ ﻳـﻮﻧﻲ ﻭﺟـﻮﺩ ﺩﺍﺭﺩ )ﺷـﮑﻞ ‪.(۵‬‬ ‫‪ .۲.۱.۲‬ﺩﻧﺪﺭﻳﺖ‬
‫ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﺍﺯ ﭘﺮﻭﺗﺌﻴﻦﻫﺎﻳﻲ ﺗﺸﮑﻴﻞ ﺷﺪﻩﺍﻧﺪ ﮐﻪ ﺩﺭﻭﻥ ﻭ ﺑﻴـﺮﻭﻥ‬ ‫ﺩﻧﺪﺭﻳﺖ ﺗﺤﺮﻳﮏﻫﺎﻱ ﺍﻟﮑﺘﺮﻭﺷﻴﻤﻴﺎﻳﻲ ﺭﺳﻴﺪﻩ ﺍﺯ ﺳﺎﻳﺮ ﻧـﻮﺭﻭﻥﻫـﺎ‬
‫ﻧﻮﺭﻭﻥ ﺭﺍ ﺑﻪ ﻫﻢ ﻣﺮﺗﺒﻂ ﻣﻲﮐﻨﺪ‪ .‬ﺍﻳﻦ ﮐﺎﻧـﺎﻝﻫـﺎ ﻓﻘـﻂ ﺑـﻪ ﻳـﻮﻥﻫـﺎﻱ‬ ‫ﺭﺍ ﺑﻪ ﺑﺪﻧﺔ ﻧﻮﺭﻭﻥ ﻣﻮﺭﺩ ﻧﻈﺮ ﻣﻲﺭﺳﺎﻧﺪ‪ .‬ﻣﻌﻤﻮﻻً ﺩﻧﺪﺭﻳﺖﻫـﺎ ﺩﺍﺭﺍﻱ‬
‫ﺧﺎﺻﻲ ﺍﺟﺎﺯﺓ ﻋﺒﻮﺭ ﻣﻲﺩﻫﻨﺪ ﮐﻪ ﺑﻪ ﺁﻥ ﻧﻔﻮﺫﭘﺬﻳﺮﻱ ﻏﺸﺎﺀ ﻧﺴـﺒﺖ ﺑـﻪ‬ ‫ﺷﺎﺧﻪﻫﺎﻱ ﻣﺘﻌﺪﺩﻱ ﻫﺴﺘﻨﺪ )ﺷﮑﻞ ‪ .(۲‬ﺩﺭ ﺳﺮﺗﺎﺳﺮ ﺍﻳﻦ ﺷﺎﺧﻪﻫـﺎ‬
‫ﺁﻥ ﻳﻮﻥ ﺧﺎﺹ ﮔﻔﺘﻪ ﻣﻲﺷـﻮﺩ ﻭ ﻗﺎﺑـﻞ ﻣﺤﺎﺳـﺒﻪ ﺍﺳـﺖ‪ .‬ﺩﺭ ﻏﺸـﺎﯼ‬ ‫ﺯﺍﺋﺪﻩﻫﺎﻱ ﺑﺴﻴﺎﺭ ﮐﻮﭼﮑﻲ ﺑﻪ ﻧﺎﻡ ﺍﺳـﭙﺎﻳﻦ‪ ١‬ﺣﻀـﻮﺭ ﺩﺍﺭﻧـﺪ ﮐـﻪ ﺩﺭ‬
‫ﻧﻮﺭﻭﻥ ﭘﻤﭗﻫﺎﻱ ﻳﻮﻧﻲ ﻭﺟﻮﺩ ﺩﺍﺭﻧﺪ ﮐﻪ ﺑﺎ ﺻـﺮﻑ ﺍﻧـﺮﮊﻱ ﻧﺎﺷـﻲ ﺍﺯ‬ ‫ﺗﺸﮑﻴﻞ ﺳﻴﻨﺎﭘﺲ ﺑﺎ ﺁﮐﺴﻮﻥ ﻧﻮﺭﻭﻥ ﻗﺒﻠﻲ ﺷﺮﮐﺖ ﻣﻲﮐﻨـﺪ )ﺷـﮑﻞ‬
‫ﺁﺩﻧﻮﺯﻳﻦ ﺗﺮﻱ ﻓﺴـﻔﺎﺕ‪ (ATP)٥‬ﻳـﻮﻥﻫـﺎ ﺭﺍ ﺑـﻪ ﺳـﻤﺖ ﻣـﻮﺭﺩ ﻧﻈـﺮ‬ ‫‪ .(۳‬ﻋﻤﻠﮑﺮﺩ ﺩﻗﻴﻖ ﻓﻴﺰﻳﮑﻲ ﻭ ﺳﺎﺯﻭﮐﺎﺭﻫﺎﻱ ﺩﺍﺧﻠﻲ ﺍﺳﭙﺎﻳﻦ ﻫﻨـﻮﺯ‬
‫ﻣﻲﺭﺍﻧﻨﺪ‪ .‬ﺗﺤﻘﻴﻘﺎﺕ ﺗﺠﺮﺑﻲ ﻭ ﻣﺤﺎﺳﺒﺎﺗﻲ ﮔﺴﺘﺮﺩﻩﺍﻱ ﺩﺭ ﺣﺎﻝ ﺣﺎﺿـﺮ‬ ‫ﺑﻪ ﻃﻮﺭ ﮐﺎﻣﻞ ﺷﻨﺎﺧﺘﻪ ﺷﺪﻩ ﻧﻴﺴﺖ ﻭ ﺗﺤﻘﻴﻘﺎﺕ ﺑﻪ ﺭﻭﺯﻱ ﺩﺭ ﺍﻳـﻦ‬
‫ﺑﺮﺍﻱ ﮐﺸﻒ ﻣﻌـﺎﺩﻻﺕ ﻏﻴﺮﺧﻄـﻲ ﺣـﺎﮐﻢ ﺑـﺮ ﻧﺤـﻮﺓ ﻋﻤﻠﮑـﺮﺩ ﺍﻳـﻦ‬ ‫ﺯﻣﻴﻨﻪ ﺩﺭ ﺣﺎﻝ ﺍﻧﺠﺎﻡ ﺍﺳـﺖ‪ .‬ﺧﻮﺷـﺒﺨﺘﺎﻧﻪ ﺍﺳـﭙﺎﻳﻦﻫـﺎ ﺑـﻪ ﮐﻤـﮏ‬
‫ﭘﺮﻭﺗﺌﻴﻦﻫﺎ ﺩﺭ ﺣﺎﻝ ﺍﻧﺠﺎﻡ ﺍﺳﺖ‪ .‬ﺳـﺎﺯﻭﮐﺎﺭ ﺑـﺎﺯ ﻭ ﺑﺴـﺘﻪ ﺷـﺪﻥ ﺍﻳـﻦ‬ ‫ﻣﻴﮑﺮﻭﺳﮑﻮﭖ ﻫﺎﻱ ﺍﺳﮑﻦﮐﻨﻨﺪﺓ ﻟﻴﺰﺭﻱ ﺩﻭﻓﻮﺗﻮﻧﻲ ﻗﺎﺑـﻞ ﻣﺸـﺎﻫﺪﻩ‬
‫ﮐﺎﻧﺎﻝﻫﺎ ﺑﻪ ﭘﺎﺭﺍﻣﺘﺮﻫﺎﻱ ﺯﻳﺎﺩﻱ ﺍﺯ ﺟﻤﻠﻪ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺑﺴﺘﮕﻲ ﺩﺍﺭﺩ‪.‬‬ ‫ﻫﺴﺘﻨﺪ ]‪.[۲۷-۲۵‬‬
‫ﺍﻳﻦ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﻣﺴﺌﻮﻝ ﺗﺤﺮﻳﮏﭘﺬﻳﺮ ﺑﻮﺩﻥ ﻏﺸﺎﺀ ﻫﺴـﺘﻨﺪ ]‪-۲۸‬‬
‫‪ .[۳۱‬ﺗﺤﻘﻴﻘﺎﺕ ﺍﺧﻴﺮ ﻧﺸﺎﻥ ﻣﻲﺩﻫﺪ ﮐﻪ ﺗﺤﺮﻳـﮏﭘـﺬﻳﺮﺗﺮﻳﻦ ﻗﺴـﻤﺖ‬ ‫‪ .۳.۱.۲‬ﺑﺪﻧﺔ ﻧﻮﺭﻭﻥ )ﺳﻮﻣﺎ‪(٢‬‬

‫ﺑﺪﻧﺔ ﻧﻮﺭﻭﻥ ﻗﺴﻤﺘﻲ ﺍﺳﺖ ﮐﻪ ﺁﮐﺴﻮﻥ ﺍﺯ ﺁﻧﺠﺎ ﺧﺎﺭﺝ ﻣﻲﺷﻮﺩ‪.[۳۲] ٦‬‬ ‫ﻫﻤﺎﻥ ﻃﻮﺭ ﮐﻪ ﺩﺭ ﺷﮑﻞ ‪ ۴‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷـﺪﻩ ﺍﺳـﺖ‪ ،‬ﺑﺪﻧـﺔ ﻧـﻮﺭﻭﻥ‬

‫]‪ .[۳۲‬ﺩﺭ ﺍﺛﺮ ﻧﻔﻮﺫﭘﺬﻳﺮﻱ ﻏﺸـﺎﺀ ﻧﺴـﺒﺖ ﺑـﻪ ﺑﻌﻀـﻲ ﻳـﻮﻥﻫـﺎ‪ ،‬ﻳـﮏ‬ ‫ﻫﻤﺎﻧﻨﺪ ﺳﺎﻳﺮ ﻳﺎﺧﺘﻪﻫﺎ ﺩﺍﺭﻱ ﻳﮏ ﻏﺸﺎﯼ ﺩﻭﻻﻳﻪﺍﻱ ﻓﺴﻔﺎﺕ ﭼﺮﺑﻲ‬

‫ﺍﺧﺘﻼﻑ ﻏﻠﻈﺖ ﻳﻮﻧﻲ ﺑﻴﻦ ﺩﺭﻭﻥ ﻭ ﺑﻴﺮﻭﻥ ﻏﺸﺎﺀ ﺍﻳﺠﺎﺩ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳـﻦ‬ ‫)ﻓﺴﻔﻮﻟﻴﭙﻴﺪ( ﺍﺳﺖ ﮐﻪ ﻣﺎﻳﻊ ﺩﺭﻭﻥ ﻳﺎﺧﺘـﻪﺍﯼ ﺭﺍ ﺍﺯ ﻣﺤـﻴﻂ ﺑﻴـﺮﻭﻥ‬

‫ﺍﺧﺘﻼﻑ ﻏﻠﻈﺖ ﻣﻨﺠﺮ ﺑـﻪ ﻳـﮏ ﺍﺧـﺘﻼﻑ ﭘﺘﺎﻧﺴـﻴﻞ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺑـﻴﻦ‬ ‫ﻧﻮﺭﻭﻥ ﺟﺪﺍ ﻣﻲﮐﻨﺪ‪ .‬ﻣﻮﻟﮑﻮﻝﻫـﺎﻱ ﺍﻳـﻦ ﻏﺸـﺎﯼ ﺩﺍﺭﺍﻱ ﻳـﮏ ﺳـﺮ‬
‫____________________________________________‬ ‫ﻗﻄﺒﻲ ﻫﺴﺘﻨﺪ ﮐﻪ ﺩﺭ ﺁﺏ ﻳﺎ ﻣﺤﻠﻮﻝﻫﺎﻱ ﺁﺑﻲ )ﺳﻴﺘﻮﭘﻼﺳـﻢ( ﻗﺎﺑـﻞ‬
‫‪3. Hydrophobic‬‬ ‫ﺣﻞ ﻫﺴﺘﻨﺪ‪ .‬ﻭﻟﻲ ﺳﺮ ﺩﻳﮕﺮ ﺁﻧﻬﺎ )ﺍﺳﻴﺪ ﭼﺮﺏ( ﺩﺭ ﭼﺮﺑﻲﻫﺎ ﻗﺎﺑـﻞ‬
‫‪4.Hydrophilic‬‬ ‫____________________________________________‬
‫)‪5. Adenosine triphosphate (ATP‬‬ ‫‪1. Spine‬‬
‫‪6. Axon hillock‬‬ ‫‪2. Soma‬‬
‫‪۳۵۱‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﺷﮑﻞ ‪) .٥‬ﺭﻧﮕﯽ ﺩﺭ ﻧﺴﺨﺔ ﺍﻟﮑﺘﺮﻭﻧﻴﮑﻲ( ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﻭﺍﻗﻊ ﺩﺭ ﻏﺸﺎﯼ ﻧﻮﺭﻭﻥ‪.‬‬

‫ﺩﺭﻭﻥ ﻭ ﺑﻴﺮﻭﻥ ﺍﻳﻦ ﻧﻮﺭﻭﻥﻫﺎ ﻣﻲﺷـﻮﺩ ﮐـﻪ ﺑـﻪ ﺁﻥ ﭘﺘﺎﻧﺴـﻴﻞ ﻏﺸـﺎﺀ‬

‫ﮔﻔﺘﻪ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﻗﻄﺒﺶ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺩﺭ ﺗﻤﺎﻡ ﻃﻮﻝ ﻋﻤﺮ ﻧﻮﺭﻭﻥﻫـﺎ‬
‫ﻭﺟﻮﺩ ﺧﻮﺍﻫﺪ ﺩﺍﺷﺖ‪ .‬ﻧﻮﺭﻭﻧﻲ ﮐﻪ ﺍﻳﻦ ﺍﺧﺘﻼﻑ ﭘﺘﺎﻧﺴﻴﻞ ﺍﻟﮑﺘﺮﻳﮑﻲ‬
‫ﺭﺍ ﺍﺯ ﺩﺳﺖ ﺑﺪﻫﺪ ﻳﮏ ﻳﺎﺧﺘﺔ ﻣﺮﺩﻩ ﻣﺤﺴـﻮﺏ ﻣـﻲﺷـﻮﺩ‪ .‬ﭘﺘﺎﻧﺴـﻴﻞ‬

‫ﺷﮑﻞ‪) .٦‬ﺭﻧﮕﯽ ﺩﺭ ﻧﺴﺨﺔ ﺍﻟﮑﺘﺮﻭﻧﻴﮑﻲ( ﻧﺎﻡﮔﺬﺍﺭﻱ ﻧﻮﺭﻭﻥﻫﺎ ﺑـﺮ ﺍﺳـﺎﺱ‬ ‫ﻏﺸــﺎﯼ ﻧــﻮﺭﻭﻥﻫــﺎ ﺩﺭ ﻣﻐــﺰ ﺣﻴﻮﺍﻧــﺎﺕ ﺣــﺪﻭﺩ ‪ 65 mV‬ﺍﺳــﺖ‬
‫ﻭﻇﺎﻳﻒ ﺁﻧﻬﺎ ﺍﺳﺖ‪.‬‬ ‫)ﻫﻤﻴﺸﻪ ﺩﺭﻭﻥ ﻳﺎﺧﺘﻪ ﻣﻨﻔﻲ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﻣـﻲﺷـﻮﺩ(‪ .‬ﺑـﻪ ﺳـﺎﺩﮔﻲ‬
‫ﻣﻲﺗﻮﺍﻥ ﻓﻬﻤﻴـﺪ ﮐـﻪ ﺍﻳـﻦ ﺍﺧـﺘﻼﻑ ﭘﺘﺎﻧﺴـﻴﻞ ﺗﻮﻟﻴـﺪ ﻳـﮏ ﻣﻴـﺪﺍﻥ‬
‫ﺟﺎﻟﺐ ﻭ ﺩﺭﺧﻮﺭ ﺗﺤﻘﻴﻖ ﺍﺳﺖ ]‪ .[۳۴‬ﻧﻮﺭﻭﻥﻫﺎﻱ ﺣﺮﮐﺘﻲ ﻭﻇﻴﻔـﺔ‬ ‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﺩﺭ ﻋﺮﺽ ﻏﺸﺎﯼ ﻧﻮﺭﻭﻥ ﻣﻲﮐﻨﺪ‪ .‬ﺍﺯ ﺁﻧﺠﺎ ﮐـﻪ ﺿـﺨﺎﻣﺖ‬
‫ﺍﻧﺘﻘﺎﻝ ﺍﻃﻼﻋﺎﺕ ﺍﺯ ﻣﻐﺰ ﺑﻪ ﻋﻀﻼﺕ ﻭ ﻧﻮﺭﻭﻥﻫـﺎﻱ ﺑـﻴﻦ ﻧـﻮﺭﻭﻧﻲ‬ ‫ﻏﺸﺎﺀ ﻧﻮﺭﻭﻥ ﺑﺴﻴﺎﺭ ﮐﻢ ﺍﺳـﺖ )ﺣـﺪﻭﺩ ‪ ،( 3 / 5 nm‬ﺍﻳـﻦ ﺍﺧـﺘﻼﻑ‬
‫)ﻭﺍﺳﻄﻪ( ﻭﻇﻴﻔﺔ ﺍﻧﺘﻘﺎﻝ ﺍﻃﻼﻋﺎﺕ ﺑﻴﻦ ﻧﻮﺭﻭﻥﻫﺎﻱ ﻣﺨﺘﻠـﻒ ﺭﺍ ﺑـﻪ‬ ‫ﭘﺘﺎﻧﺴﻴﻞ ﮐﻮﭼـﮏ ‪ 65 mV‬ﻣـﻲﺗﻮﺍﻧـﺪ ﮔﺮﺍﺩﻳـﺎﻥ ﭘﺘﺎﻧﺴـﻴﻞ )ﻣﻴـﺪﺍﻥ‬
‫ﻋﻬﺪﻩ ﺩﺍﺭﻧﺪ‪ .‬ﺍﻧﺘﻘﺎﻝ ﺍﻳﻦ ﭘﻴﺎﻡﻫﺎ ﺍﺯ ﻃﺮﻳﻖ ﺍﺗﺼﺎﻻﺕ ﻣﺨﺼﻮﺹ ﺑﻴﻦ‬ ‫ﺍﻟﮑﺘﺮﻳﮑﻲ( ﺑﺴﻴﺎﺭ ﺑﺰﺭﮔﻲ )ﺣﺪﻭﺩ ‪ ( 190000 V / cm‬ﺭﺍ ﺍﻳﺠﺎﺩ ﮐﻨـﺪ‪.‬‬
‫ﻧﻮﺭﻭﻥﻫـﺎ ﺑـﻪ ﻧـﺎﻡ ﺳـﻴﻨﺎﭘﺲ ﺍﻧﺠـﺎﻡ ﻣـﻲﮔﻴـﺮﺩ‪ .‬ﺗﻌـﺪﺍﺩﻱ ﺍﺯ ﺍﻳـﻦ‬ ‫ﺍﮔﺮ ﺍﻳﻦ ﮔﺮﺍﺩﻳﺎﻥ ﺭﺍ ﺑﺎ ﺍﻧﺪﺍﺯﺓ ﮔﺮﺍﺩﻳﺎﻥ ﭘﺘﺎﻧﺴﻴﻞ ﻳﮏ ﺧﻂ ﺍﻧﺘﻘﺎﻝ ﺑﺮﻕ‬
‫ﻧﻮﺭﻭﻥﻫﺎ ﻣﻲﺗﻮﺍﻧﻨﺪ ﺑﺎ ﻫﻤﺪﻳﮕﺮ ﻣﺮﺗﺒﻂ ﺷﺪﻩ ﻭ ﺗﺸﮑﻴﻞ ﻳﮏ ﺷـﺒﮑﺔ‬ ‫ﻓﺸﺎﺭﻗﻮﻱ )ﺣﺪﻭﺩ ‪ ( 200000 V / cm‬ﻣﻘﺎﻳﺴﻪ ﮐﻨﻴﻢ‪ ،‬ﺑﻪ ﺑﺰﺭﮔـﻲ ﺁﻥ‬
‫ﻋﺼﺒﻲ ﺩﻫﻨﺪ ]‪.[۲۴‬‬ ‫ﭘﻲ ﻣﻲﺑﺮﻳﻢ‪ .‬ﻫﻤﭽﻨﻴﻦ ﻣﻲ ﺗﻮﺍﻥ ﺳﺎﺧﺘﺎﺭ ﻳﮏ ﺧﺎﺯﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺭﺍ ﺩﺭ‬
‫ﻳﮏ ﻧﻮﺭﻭﻥ ﺩﻳﺪ‪ .‬ﺩﺭ ﺁﺯﻣﺎﻳﺶ ﻣﺸﺨﺺ ﺷﺪﻩ ﺍﺳﺖ ﻇﺮﻓﻴﺖ ﻏﺸـﺎﯼ‬
‫‪ .۴.۱.۲‬ﻣﺪﻝ ﻓﻴﺰﻳﮑﻲ ﺑﺪﻧﺔ ﻧﻮﺭﻭﻥ‬ ‫ﻳﮏ ﻳﺎﺧﺘﻪ ﻧﻮﻋﻲ ﺣﺪﻭﺩ ‪ 1 µF / cm2‬ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﻇﺮﻓﻴـﺖ ﺑـﻪ ﺍﻳـﻦ‬
‫ﺑﺎ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﻧﻮﺭﻭﻥ ﺑﻪ ﺻﻮﺭﺕ ﻳﮏ ﺧﺎﺯﻥ ﻭ ﻫﻤﭽﻨﻴﻦ ﺑﺎ ﺩﺭ ﻧﻈـﺮ‬ ‫ﻣﻌﻨﻲ ﺍﺳﺖ ﮐﻪ ﺑﺮﺍﻱ ﺩﺍﺷﺘﻦ ‪ 1 V‬ﺍﺧﺘﻼﻑ ﭘﺘﺎﻧﺴﻴﻞ ﺑﻴﻦ ﺩﻭ ﻃـﺮﻑ‬
‫ﮔﺮﻓﺘﻦ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﻣﻲﺗﻮﺍﻥ ﻣﺪﻝ ﻓﻴﺰﻳﮑﻲ ﺳـﺎﺩﻩﺍﻱ ﺑـﺮﺍﻱ ﻏﺸـﺎﻱ‬ ‫ﻏﺸﺎﺀ ﻧﻴﺎﺯ ﺑﻪ ﻭﺟﻮﺩ‪ ۱۰ -۶‬ﮐﻮﻟﻦ ﺑﺎﺭ ﺧﻨﺜﻲ ﻧﺸـﺪﻩ ﺩﺭ ﻫـﺮ ﻃـﺮﻑ ﺍﺯ‬
‫‪R‬‬ ‫ﻧﻮﺭﻭﻥ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺖ‪ .‬ﺍﮔﺮ ‪ Vrest‬ﺭﺍ ﭘﺘﺎﺳﻴﻞ ﺍﺳـﺘﺮﺍﺣﺖ ﻧـﻮﺭﻭﻥ‪،‬‬ ‫ﻏﺸﺎﻳﻲ ﺑﻪ ﻣﺴﺎﺣﺖ ‪ 1 cm2‬ﻣﻲﺑﺎﺷﺪ ]‪ ۳۲ ،۳‬ﻭ‪.[۳۳‬‬
‫ﻇﺮﻓﻴـﺖ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﻏﺸـﺎﺀ ﻭ ‪ Vm‬ﺭﺍ‬ ‫‪C‬‬ ‫ﻣﻘﺎﻭﻣﺖ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﻏﺸـﺎ‪،‬‬ ‫ﻫﻤﺎﻥ ﻃﻮﺭ ﮐﻪ ﺩﺭ ﺷﮑﻞ ‪ ۶‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷﺪﻩ ﺍﺳـﺖ‪ ،‬ﻧـﻮﺭﻭﻥﻫـﺎ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﻢ ﻣﻲﺗﻮﺍﻧﻴﻢ ﻣﺪﺍﺭ ﻣﻌﺎﺩﻝ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺳﻤﺖ‬ ‫ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺗﺨﺼﺺ ﺁﻧﻬﺎ ﺩﺭ ﺗﺤﻠﻴـﻞ ﺍﻧـﻮﺍﻉ ﺧﺎﺻـﻲ ﺍﺯ ﺍﻃﻼﻋـﺎﺕ‬
‫ﺭﺍﺳﺖ ﺷﮑﻞ ‪ ۷‬ﺭﺍ ﺑﺮﺍﻱ ﺁﻥ ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﻢ‪ .‬ﻫﻤﭽﻨﻴﻦ ﻣﻲﺗﻮﺍﻥ ﻧـﻮﺭﻭﻥ‬ ‫ﻧﺎﻡﮔﺬﺍﺭﻱ ﻣﻲﺷﻮﻧﺪ‪ .‬ﻧﻮﺭﻭﻥﻫﺎﻱ ﺣﺴﻲ ﻭﻇﻴﻔـﺔ ﺗﺤﻠﻴـﻞ ﺍﻃﻼﻋـﺎﺕ‬
‫ﺭﺍ ﺑﺎ ﺗﺰﺭﻳﻖ ﺟﺮﻳﺎﻥ ﺑﺴـﻴﺎﺭ ﮐﻮﭼـﮏ ﺍﻟﮑﺘﺮﻳﮑـﻲ ‪ Iinj‬ﺩﺭ ﺣـﺪ ﻧـﺎﻧﻮﺁﻣﭙﺮ‬ ‫ﺣﺴﻲ )ﺑﻴﻨﺎﻳﻲ‪ ،‬ﺷـﻨﻮﺍﻳﻲ‪ ،‬ﺑﻮﻳـﺎﻳﻲ‪ ،‬ﭼﺸـﺎﻳﻲ ﻭ ﻻﻣﺴـﻪ( ﺭﺍ ﺩﺍﺭﻧـﺪ‪.‬‬
‫ﺗﺤﺮﻳﮏ ﻣﺼﻨﻮﻋﻲ ﮐﺮﺩ ﻭ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﺪﻝ ﺳـﺎﺩﺓ ﺁﻥ ﺭﺍ ﺗﺤﻠﻴـﻞ ﮐـﺮﺩ‪.‬‬ ‫ﺍﺧﻴﺮﺍً ﻧﻴﺰ ﺣﺲ ﺩﻳﮕﺮﻱ ﮐﻪ ﺑﻪ ﺣﺲ ﺷﺸﻢ ﻣﻌـﺮﻭﻑ ﺷـﺪﻩ ﺍﺳـﺖ‬
‫ﻣﺪﻝﺳﺎﺯﻱ ﻏﺸﺎﻱ ﻧـﻮﺭﻭﻥ ﺟﻬـﺖ ﻣﺤﺎﺳـﺒﻪ ﻭ ﭘـﻴﺶﮔـﻮﻳﻲ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫ﺩﺭ ﻟﻴﺴﺖ ﺣﻮﺍﺱ ﺟﺎﻱ ﮔﺮﻓﺘﻪ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺣـﺲ ﮐـﻪ ﻣﻌﻤـﻮﻻً ﺩﺭ‬
‫ﻏﺸﺎﻱ ﺁﻥ ﻣﻮﺿـﻮﻉ ﺗﺤﻘﻴـﻖ ﺭﻭﺯ ﺍﻓـﺮﺍﺩ ﺑﺴـﻴﺎﺭﻱ ﺍﺯ ﺯﻳﺴـﺖﺷﻨﺎﺳـﻲ‪،‬‬ ‫ﻣﺎﻫﻲ ﻫﺎﻱ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑـﻪ ﻋﻨـﻮﺍﻥ ﺣـﺲ ﺟـﺎﻳﮕﺰﻳﻦ ﺑﻴﻨـﺎﻳﻲ ﻋﻤـﻞ‬
‫ﻓﻴﺰﻳﮏ‪ ،‬ﺭﻳﺎﺿﻲ‪ ،‬ﺷﻴﻤﻲ ﻭ ﻣﻬﻨﺪﺳﻲ ﺍﺳﺖ ]‪ ۳‬ﻭ‪.[۳۵‬‬ ‫ﻣﻲﮐﻨﺪ‪ ،‬ﺣﺲ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻧﺎﻡ ﺩﺍﺭﺩ‪ .‬ﻓﻴﺰﻳﮏ ﺣﺲ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑﺴـﻴﺎﺭ‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۵۲‬‬

‫ﺷﮑﻞ ‪ .٧‬ﻣﺪﺍﺭ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻌﺎﺩﻝ ﻏﺸﺎﯼ ﻳﮏ ﻧﻮﺭﻭﻥ‪.‬‬

‫ﺷﮑﻞ ‪) .٨‬ﺭﻧﮕﯽ ﺩﺭ ﻧﺴﺨﺔ ﺍﻟﮑﺘﺮﻭﻧﻴﮑﻲ( ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‪.‬‬

‫ﺑﺪﻭﻥ ﺗﺤﺮﻳﮏ ﺑﻪ ﻃﻮﺭ ﻣﺪﺍﻭﻡ ﻭ ﺑﺎ ﺁﻫﻨﮓ ﺧﺎﺻﻲ ﺍﺯ ﺧﻮﺩ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫‪ .۵.۱.۲‬ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳﺘﺮﺍﺣﺖ ﻭ ﭘﺘﺎﻧﺴﻴﻞ ﺁﺳﺘﺎﻧﻪ‬
‫ﻋﻤﻞ ﺻﺎﺩﺭ ﻣﻲﮐﻨﻨﺪ )ﻓﻌﺎﻟﻴﺖ ﺧﻮﺩﺑﻪﺧﻮﺩﻱ( ﻭ ﺑﺮﺧﻲ ﺩﻳﮕﺮ ﮐـﺎﻣﻼً‬ ‫ﻭﻗﺘﻲ ﻳﮏ ﻧﻮﺭﻭﻥ ﺩﺭ ﺣﺎﻟﺖ ﺍﺳﺘﺮﺍﺣﺖ ﺑﻮﺩﻩ ﻭ ﻫﻴﭻ ﺗﺤﺮﻳﮑﻲ ﺑﻪ ﺁﻥ‬
‫ﺳﺎﮐﺖ ﻫﺴﺘﻨﺪ‪ .‬ﺷﮑﻞ ﻇﺎﻫﺮﻱ ﻭ ﻧـﻮﻉ ﻓﻌﺎﻟﻴـﺖ ﻧـﻮﺭﻭﻥﻫـﺎ ﺑـﺎ ﻫـﻢ‬ ‫ﻭﺍﺭﺩ ﻧﺸﻮﺩ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﻱ ﺁﻥ ﻳﮏ ﻣﻘﺪﺍﺭ ﺛﺎﺑـﺖ ﺍﺳـﺖ ﮐـﻪ ﺑـﻪ ﺁﻥ‬
‫ﺍﺧﺘﻼﻑ ﺑﺴﻴﺎﺭ ﺯﻳﺎﺩﻱ ﺩﺍﺭﻧﺪ‪ .‬ﺗﻨﻮﻉ ﻧﻮﺭﻭﻥﻫﺎ ﺩﺭ ﺩﺳﺘﺔ ﻣﻬﺮﻩﺩﺍﺭﺍﻥ ﺑﻪ‬ ‫ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳﺘﺮﺍﺣﺖ ﻣﻲﮔﻮﻳﻨﺪ‪ .‬ﻭﻗﺘﻲ ﭘﻴﺎﻣﻲ )ﻳﮏ ﺍﺧﺘﻼﻝ ﺍﻟﮑﺘﺮﻳﮑﻲ(‬
‫‪ ۱۰۰۰۰‬ﻧﻮﻉ ﻣﻲﺭﺳﺪ‪ .‬ﺣﺘﻲ ﺑﻌﻀﻲ ﺍﺯ ﻧﻮﺭﻭﻥﻫﺎﻱ ﻫﻢﺷﮑﻞ ﻫﻢ ﻣﻲ‬ ‫ﺑﻪ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﻣﻲﺭﺳﺪ‪ ،‬ﻣﻲﺗﻮﺍﻧﺪ ﺳﺒﺐ ﻭﺍﻗﻄﺒﻴﺪﮔﻲ‪) ١‬ﻣﺜﺒﺖﺗﺮ‬
‫ﺗﻮﺍﻧﻨﺪ ﻋﻤﻞﮐﺮﺩﻫﺎﻱ ﻣﺨﺘﻠﻒ ﺩﺍﺷﺘﻪ ﺑﺎﺷﻨﺪ‪ .‬ﺑـﺎ ﺗﺰﺭﻳـﻖ ﺭﻧـﮓﻫـﺎﻱ‬ ‫ﺷﺪﻥ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎ( ﻭ ﻳﺎ ﻓﺮﺍﻗﻄﺒﻴﺪﮔﻲ‪) ٢‬ﻣﻨﻔـﻲﺗـﺮ ﺷـﺪﻥ ﭘﺘﺎﻧﺴـﻴﻞ‬
‫ﻣﺨﺼﻮﺻﻲ‪ ٤‬ﺑﻪ ﺩﺭﻭﻥ ﺍﻳﻦ ﻧﻮﺭﻭﻥﻫﺎ ﻣﻲﺗﻮﺍﻥ ﺳﺎﺧﺘﺎﺭ ﻧـﻮﺭﻭﻥﻫـﺎ ﺭﺍ‬ ‫ﻏﺸــﺎ( ﺷــﻮﺩ‪ .‬ﺩﺭ ﺻــﻮﺭﺗﻲ ﮐــﻪ ﻗﻄﺒﻴـﺪﮔﻲ ﻏﺸــﺎﺀ ﺍﺯ ﺣــﺪ ﺁﺳــﺘﺎﻧﻪ‬
‫ﺑﻪ ﻭﺿﻮﺡ ﻣﺸﺎﻫﺪﻩ ﮐﺮﺩ‪ .‬ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺗﻌﺪﺍﺩ ﺯﻳﺎﺩ ﺍﻧﻮﺍﻉ ﻧـﻮﺭﻭﻥﻫـﺎ ﻭ‬ ‫)ﭘﺘﺎﻧﺴﻴﻞ ﺁﺳﺘﺎﻧﻪ( ﺑﻴﺸﺘﺮ ﺷﻮﺩ‪ ،‬ﻧﺎﮔﻬﺎﻥ ﻏﺸـﺎﻱ ﻧـﻮﺭﻭﻥ ﺑـﻪ ﻗﻄـﺒﺶ‬
‫ﺍﺣﺘﻤﺎﻝ ﻋﻤﻠﮑﺮﺩ ﻣﺨﺘﻠﻒ ﺑﺎ ﺩﺍﺷﺘﻦ ﺷﮑﻞ ﻇﺎﻫﺮﻱ ﻳﮑﺴﺎﻥ ﻣﻲﺗـﻮﺍﻥ‬ ‫ﺧﻮﺩ ﺍﺩﺍﻣﻪ ﺩﺍﺩﻩ ﻭ ﺗﺎ ﺣﺪﻭﺩ ‪ 100 mV‬ﻣﻲﺭﺳﺪ‪ .‬ﺳـﭙﺲ ﺑـﻪ ﻃـﻮﺭ‬
‫ﺗﺎ ﺣﺪﻭﺩﻱ ﺑﻪ ﭘﻴﭽﻴﺪﮔﻲ ﺳﺎﺯ ﻭ ﮐﺎﺭ ﻓﻌﺎﻟﻴﺖ ﻧﻮﺭﻭﻥﻫﺎ ﭘﻲ ﺑﺮﺩ ]‪.[۳‬‬ ‫ﺧﻴﻠﻲ ﺳﺮﻳﻊ ﺑﻪ ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳﺘﺮﺍﺣﺖ ﺧﻮﺩ ﺑﺮﻣﻲﮔـﺮﺩﺩ ﺷـﮑﻞ ‪ .۸‬ﺑـﻪ‬
‫ﮐﻤــﮏ ﺍﻳــﻦ ﻣﺸﺨﺼــﺎﺕ ﻓﻴﺰﻳﮑــﻲ ﻣــﻲﺗــﻮﺍﻥ ﻳــﮏ ﺷﻨﺎﺳــﻨﺎﻣﺔ‬
‫‪ .۲.۲‬ﻗﻮﺍﻧﻴﻦ ﻓﻴﺰﻳﮑﻲ ﺣﺎﮐﻢ ﺑﺮ ﻧﻮﺭﻭﻥﻫﺎ‬ ‫ﺍﻟﮑﺘﺮﻭﻓﻴﺰﻳﻮﻟﻮﮊﻱ ﺑﺮﺍﻱ ﻫﺮ ﻧﻮﻉ ﻧﻮﺭﻭﻥ ﺗﻬﻴﻪ ﮐـﺮﺩ‪ .‬ﺑـﻪ ﺍﻳـﻦ ﺗﻐﻴﻴـﺮ‬
‫ﺑﺎ ﻭﺟﻮﺩ ﺗﻨﻮﻉ ﻓﺮﺍﻭﺍﻥ ﺩﺭ ﺍﻧﻮﺍﻉ ﻧﻮﺭﻭﻥﻫﺎ ﻭ ﺷﮑﻞ ﻭ ﻋﻤﻠﮑـﺮﺩ ﺁﻧﻬـﺎ‬ ‫ﭘﺘﺎﻧﺴﻴﻞ ﻧﺎﮔﻬﺎﻧﻲ ﻏﺸﺎﻱ ﻧﻮﺭﻭﻥ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‪ ٣‬ﻣﻲﮔﻮﻳﻨـﺪ‪ ،‬ﮐـﻪ ﺩﺭ‬
‫ﺑﻪ ﻧﻈﺮ ﻣﻲﺭﺳﻴﺪ ﮐﻪ ﺗﻮﺟﻴﺢ ﻫﻤﺔ ﺍﻳﻦ ﻧﺘﺎﻳﺞ ﺩﺭ ﻏﺎﻟﺐ ﭼﻨـﺪ ﻗـﺎﻧﻮﻥ‬ ‫ﻣﺪﺕ ﺯﻣﺎﻧﻲ ﺍﺯ ﻣﺮﺗﺒﺔ ﻣﻴﻠﻲﺛﺎﻧﻴﻪ ﺍﺗﻔﺎﻕ ﻣﻲﺍﻓﺘﺪ‪ .‬ﺷﮑﻞ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‬
‫ﻏﻴﺮ ﻣﻤﮑﻦ ﺑﺎﺷﺪ‪ .‬ﻭﻟﻲ ﺧﻮﺷـﺒﺨﺘﺎﻧﻪ ﭘـﺲ ﺍﺯ ﺗـﻼﺵﻫـﺎﻱ ﻓـﺮﺍﻭﺍﻥ‬ ‫ﻧﻮﺭﻭﻥﻫﺎ ﺗﻘﺮﻳﺒﺎً ﻣﺸﺎﺑﻪ ﻫﻢ ﻫﺴﺘﻨﺪ‪ ،‬ﺩﺍﻣﻨﺔ ﺁﻧﻬﺎ ﻳﮑﻲ ﺍﺳـﺖ ﻭ ﻃـﻮﻝ‬
‫ﻣﺸﺎﻫﺪﻩ ﺷﺪ ﮐﻪ ﺑﺎ ﭼﻨﺪ ﻗﺎﻧﻮﻥ ﻓﻴﺰﻳﮑﻲ ﻧﺴﺒﺘﺎً ﺳﺎﺩﻩ ﻣﻲﺗﻮﺍﻥ ﺑﺨـﺶ‬ ‫ﺯﻣﺎﻧﻲ ﺁﻧﻬﺎ ﺗﻘﺮﻳﺒﺎً ﻳﮑﺴﺎﻥ ﺍﺳـﺖ ]‪ ۳۶ ،۳‬ﻭ‪ .[۳۷‬ﺑـﻪ ﺗﺤﺮﻳﮑـﻲ ﮐـﻪ‬
‫ﻣﻬﻤﻲ ﺍﺯ ﻭﻳﮋﮔﻲﻫـﺎ ﻭ ﻋﻤﻠﮑـﺮﺩ ﻧـﻮﺭﻭﻥﻫـﺎ ﺭﺍ ﺗﻮﺿـﻴﺢ ﺩﺍﺩ‪ .‬ﻫﻤـﺔ‬ ‫ﻣﻨﺠﺮ ﺑﻪ ﺻﺪﻭﺭ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ )ﻭﺍﻗﻄﺒﻴـﺪﮔﻲ ﻏﺸـﺎﺀ ﻳـﺎ ﺍﻓـﺰﺍﻳﺶ‬
‫ﭘﻴﺎﻡﻫﺎﻱ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺩﺭ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﺍﻧﺴﺎﻥ ﻭ ﺣﻴﻮﺍﻧـﺎﺕ ﺗﻮﺳـﻂ‬ ‫ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎ‪ ،‬ﻣﺜﻼً ﺍﺯ ‪ -۶۰‬ﻣﻴﻠﻲ ﻭﻟﺖ ﺑﻪ ‪ +۴۰‬ﻣﻴﻠﻲ ﻭﻟـﺖ( ﺷـﻮﺩ‬

‫ﻳﻮﻥﻫﺎﻱ ﻣﺠﺰﺍ ‪ Ca2 ، K  ، Cl‬ﻭ ‪ Na ‬ﺣﻤﻞ ﻣﻲﺷـﻮﺩ‪ .‬ﺩﺭ‬ ‫ﺗﺤﺮﻳﮏ ﻭﺍﺩﺍﺭﻧﺪﻩ ﻭ ﺍﮔﺮ ﻣﻨﺠـﺮ ﺑـﻪ ﻋـﺪﻡ ﺻـﺪﻭﺭ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ‬

‫ﻳﺎﺧﺘﻪﻫﺎﻱ ﺗﺤﺮﻳﮏﭘﺬﻳﺮ‪ ،‬ﺣﺮﮐﺖ ﺍﻳﻦ ﻳﻮﻥﻫـﺎ ﺳـﺒﺐ ﺍﻳﺠـﺎﺩ ﺗﻐﻴﻴـﺮ‬ ‫)ﻓﺮﺍﻗﻄﺒﻴﺪﮔﻲ ﻳﺎ ﮐﺎﻫﺶ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎ‪ ،‬ﻣﺜﻼً ﺍﺯ ‪ -۶۰‬ﻣﻴﻠﻲﻭﻟـﺖ ﺑـﻪ‬

‫ﭘﺘﺎﻧﺴﻴﻞ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺩﺭ ﻋﺮﺽ ﭘﻼﺳﻤﺎﻱ ﻏﺸﺎﺀ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳـﻦ ﺗﻐﻴﻴـﺮ‬ ‫‪ -۸۵‬ﻣﻴﻠﻲﻭﻟﺖ( ﺷﻮﺩ ﺗﺤﺮﻳﮏ ﺑﺎﺯﺩﺍﺭﻧﺪﻩ )ﻣﻬﺎﺭﻱ( ﮔﻔﺘﻪ ﻣـﻲﺷـﻮﺩ‪.‬‬

‫ﭘﺘﺎﻧﺴﻴﻞﻫﺎ ﻫﻤﺎﻥ ﻋﻼﻣﺖﻫﺎﻳﻲ ﻫﺴﺘﻨﺪ ﮐﻪ ﭘﻴﺎﻡﻫﺎﻱ ﺑﻴﻮﻟﻮﮊﻳﮑﻲ ﺭﺍ ﺍﺯ‬ ‫ﺷﺪﺕ ﺗﺤﺮﻳﮏ ﺗﺄﺛﻴﺮﻱ ﺩﺭ ﺷﮑﻞ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﻧﺪﺍﺭﺩ‪ ،‬ﺑﻠﮑﻪ ﺳـﺒﺐ‬

‫ﻳﮏ ﻧﻘﻄﺔ ﻳﺎﺧﺘﻪ ﺑﻪ ﻧﻘﻄﺔ ﺩﻳﮕﺮ‪ ،‬ﻳﺎ ﺍﺯ ﻳﮏ ﻳﺎﺧﺘﻪ ﺑﻪ ﻳﺎﺧﺘﺔ ﺩﻳﮕـﺮ ﻭ‬ ‫ﺻﺪﻭﺭ ﻗﻄﺎﺭﻱ ﺍﺯ ﭘﺘﺎﻧﺴﻴﻞﻫﺎﻱ ﻋﻤﻞ ﻣﻲﺷﻮﺩ‪ .‬ﺑﺮﺧﻲ ﺍﺯ ﻧـﻮﺭﻭﻥﻫـﺎ‬

‫ﻳﺎ ﺍﺯ ﻳﮏ ﻗﺴﻤﺖ ﺑﺪﻥ ﺑﻪ ﻗﺴﻤﺖ ﺩﻳﮕﺮ ﺑﺪﻥ ﺣﻤﻞ ﻣﻲﮐﻨﻨﺪ‪ .‬ﻏﻠﻈﺖ‬

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‫ﺍﻳﻦ ﻳﻮﻥﻫﺎ ﺩﺭ ﺩﺭﻭﻥ ﻭ ﺑﻴﺮﻭﻥ ﻧﻮﺭﻭﻥﻫﺎ ﻳﮑﺴﺎﻥ ﻧﻴﺴﺖ‪ .‬ﺑـﻪ ﻋﻨـﻮﺍﻥ‬ ‫‪1. Depolarization‬‬
‫‪2. Hyperpolarization‬‬
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‫‪4. Dye‬‬ ‫‪3. Action potential‬‬
‫‪۳۵۳‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫‪) x‬ﻳﮏ ﺑﻌﺪﻱ( ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﻢ‪ ،‬ﺑﺮﻫﻢﮐـﻨﺶ ﺑـﻴﻦ ﺑـﺎﺭ ﺍﻟﮑﺘﺮﻳﮑـﻲ‬ ‫ﺩﺭﻭﻥ ﻳﺎﺧﺘﻪﻫﺎﻱ ﺍﮐﺜﺮ ﺣﻴﻮﺍﻧﺎﺕ ﺑﺴـﻴﺎﺭ‬ ‫‪K‬‬ ‫ﻣﺜﺎﻝ ﻏﻠﻈﺖ ﻳﻮﻥﻫﺎﻱ‬
‫ﻳﻮﻥﻫﺎ ﻭ ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻮﺟـﻮﺩ ﺩﺭ ﻋـﺮﺽ ﻏﺸـﺎﺀ ﺳـﺒﺐ ﻭﺍﺭﺩ‬ ‫ﺑﻴﺸﺘﺮ ﺍﺯ ﻏﻠﻈـﺖ ﺁﻥ ﺩﺭ ﻓﻀـﺎﻱ ﺑﻴـﺮﻭﻥ ﺁﻧﻬﺎﺳـﺖ‪ .‬ﺍﻳـﻦ ﺍﺧـﺘﻼﻑ‬
‫ﺁﻣﺪﻥ ﻧﻴﺮﻭﻱ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑﺮ ﺍﻳﻦ ﺫﺭﺍﺕ ﺑﺎﺭﺩﺍﺭ ﻣﻲﺷـﻮﻧﺪ‪ .‬ﺍﮔـﺮ ﺷـﺎﺭ‬ ‫ﻏﻠﻈﺖ ﻣﻨﺠﺮ ﺑﻪ ﮔﺮﺍﺩﻳﺎﻥ ﻏﻠﻈـﺖ ﻣـﻲﺷـﻮﺩ‪ ،‬ﮐـﻪ ﺑـﻪ ﺁﻥ ﭘﺘﺎﻧﺴـﻴﻞ‬

‫(‪ el ،‬ﺭﺳـﺎﻧﺎﻳﻲ ﻭﻳـﮋﻩ‬

‫‪molecules‬‬
‫ﺳﻮﻕ ﺭﺍ ﺑﺎ ‪ J drift‬ﺑﺎ ﻳﮑـﺎﻱ )‬ ‫ﺷﻴﻤﻴﺎﻳﻲ ﮔﻔﺘﻪ ﻣﻲﺷﻮﺩ‪ .‬ﺑﻨﺎ ﺑـﺮ ﺍﺻـﻮﻝ ﺗﺮﻣﻮﺩﻳﻨﺎﻣﻴـﮏ‪ ،‬ﻳـﻮﻥﻫـﺎ ﺍﺯ‬
‫‪sec cm2‬‬ ‫ﻧﺎﺣﻴﻪﺍﻱ ﺑﺎ ﻏﻠﻈﺖ ﺑﺎﻻ ﺑﻪ ﻧﺎﺣﻴﻪﺍﻱ ﺑﺎ ﻏﻠﻈﺖ ﭘﺎﻳﻴﻦ ﻣﻲﺭﻭﻧﺪ ﮐﻪ ﺑـﻪ‬
‫‪molecules‬‬
‫( ‪ E ،‬ﻣﻴـﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑـﻲ )‪ (V / cm‬ﺑﺎﺷـﺪ‬ ‫ﻏﺸﺎﺀ )‬ ‫ﺁﻥ ﭘﺪﻳﺪﺓ ﭘﺨﺶ ﮔﻔﺘﻪ ﻣﻲﺷـﻮﺩ ]‪ .[۳‬ﻗـﺎﻧﻮﻥ ﭘﺨـﺶ ﺍﻭﻟـﻴﻦ ﻗـﺎﻧﻮﻥ‬
‫‪V  sec cm‬‬
‫ﺩﺍﺭﻳﻢ‪:‬‬ ‫ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﺍﺳﺖ‪.‬‬
‫‪V‬‬
‫] ‪J drift   el E    z[C‬‬ ‫‪,‬‬ ‫)‪(۲‬‬
‫‪x‬‬
‫‪ .۱.۲.۲‬ﻗﺎﻧﻮﻥ ﺍﻭﻝ ‪ :‬ﻗﺎﻧﻮﻥ ﻓﻴﮏ‪ ١‬ﺑﺮﺍﻱ ﭘﺨﺶ‬
‫ﮐـــﻪ ﺩﺭ ﺁﻥ ‪ V‬ﭘﺘﺎﻧﺴـ ـﻴﻞ ﺍﻟﮑﺘﺮﻳﮑـ ـﻲ ) ‪  ، (V‬ﺗﺤـــﺮﮎ ﺫﺭﻩ‬
‫‪molecules‬‬
‫‪cm2‬‬ ‫( ‪ D ،‬ﺿـﺮﻳﺐ ﭘﺨـﺶ‬ ‫ﺍﮔﺮ ‪ Jdiff‬ﺷﺎﺭ ﭘﺨﺶ ﺑﺎ ﻳﮑـﺎﻱ )‬
‫( ‪ z ،‬ﻇﺮﻓﻴﺖ ﻳﻮﻥ )ﺑﺪﻭﻥ ﺑﻌـﺪ(‪ ،‬ﻭ ] ‪ [C‬ﻏﻠﻈـﺖ ﻳـﻮﻥ‬ ‫)‬ ‫‪sec cm2‬‬
‫‪V  sec‬‬
‫‪molecules‬‬ ‫‪cm2‬‬
‫ﻣﻮﺭﺩ ﻧﻈﺮ ﺍﺳﺖ‪ .‬ﻣﺠﺪﺩﺍً ﻋﻼﻣﺖ ﻣﻨﻔـﻲ ﺑـﻪ ﺍﻳـﻦ ﻣﻌﻨـﻲ ﺍﺳـﺖ ﮐـﻪ‬ ‫( ﻣـﻮﺭﺩ ﻧﻈـﺮ ﺑﺎﺷـﺪ‬ ‫‪3‬‬
‫( ‪ ،‬ﻭ ] ‪ [C‬ﻏﻠﻈﺖ ﻳﻮﻥ )‬ ‫)‬
‫‪cm‬‬ ‫‪sec‬‬
‫ﺫﺭﺍﺕ ﺑﺎ ﺑﺎﺭ ﻣﺜﺒﺖ ﺑﻪ ﺳﻤﺖ ﭘـﺎﻳﻴﻦ ﮔﺮﺍﺩﻳـﺎﻥ ﭘﺘﺎﻧﺴـﻴﻞ ﺍﻟﮑﺘﺮﻳﮑـﻲ‬ ‫ﺩﺍﺭﻳﻢ‬
‫ﺳﻮﻕ ﻣﻲﻳﺎﺑﻨﺪ‪ .‬ﺍﻳﻦ ﺳﻮﻕ ﺩﺭ ﻫﺮ ﺟﺎ ﻣﺴﺘﻘﻴﻤﺎً ﻣﺘﻨﺎﺳﺐ ﺑﺎ ﺍﻧـﺪﺍﺯﺓ ﺁﻥ‬ ‫] ‪[C‬‬
‫‪J diff   D‬‬ ‫‪,‬‬ ‫)‪(۱‬‬
‫ﮔﺮﺍﺩﻳﺎﻥ ﺑﺎ ﺿﺮﻳﺐ ﺗﻨﺎﺳﺐ ] ‪  z[C‬ﺍﺳﺖ‪ .‬ﺩﻭ ﻗـﺎﻧﻮﻥ ﺍﻭﻝ ﻣﺮﺑـﻮﻁ‬ ‫‪x‬‬
‫ﻋﻼﻣﺖ ﻣﻨﻔﻲ ﺑﻪ ﺟﺮﻳﺎﻥ ﻳﻮﻥﻫـﺎ ﺍﺯ ﻏﻠﻈـﺖ ﺑـﺎﻻ ﺑـﻪ ﻏﻠﻈـﺖ ﭘـﺎﻳﻴﻦ‬
‫ﺑـﻪ ﺩﻭ ﻓﺮﺁﻳﻨـﺪ ﭘﺨـﺶ ﺫﺭﺍﺕ ﺩﺭ ﺍﺛـﺮ ﺍﺧـﺘﻼﻑ ﻏﻠﻈـﺖ )ﭘﺘﺎﻧﺴـﻴﻞ‬
‫ﺩﻻﻟﺖ ﺩﺍﺭﺩ‪ .‬ﺍﻳﻦ ﻗﺎﻧﻮﻥ ﺑﻴﺎﻥ ﻣﻲﺩﺍﺭﺩ ﮐﻪ ﮔﺮﺍﺩﻳﺎﻥ ﻏﻠﻈـﺖ ﺩﺭ ﻫﻤـﻪ ﺟـﺎ‬
‫ﺷﻴﻤﻴﺎﻳﻲ( ﻭ ﺳﻮﻕ ﺫﺭﺍﺕ ﺑﺎﺭﺩﺍﺭ ﺩﺭ ﺍﺛﺮ ﺍﺧﺘﻼﻑ ﭘﺘﺎﻧﺴﻴﻞ ﺍﻟﮑﺘﺮﻳﮑﻲ‬
‫ﺍﺳـﺖ‪ .‬ﺍﺯ‬ ‫‪D‬‬ ‫ﻣﺴﺘﻘﻴﻤﺎً ﻣﺘﻨﺎﺳﺐ ﺑﺎ ﺍﻧﺪﺍﺯﺓ ﺁﻥ ﮔﺮﺍﺩﻳﺎﻥ ﺑﺎ ﺿﺮﻳﺐ ﺗﻨﺎﺳﺐ‬
‫ﺍﺳﺖ‪ .‬ﺍﻣﺎ ﻗﺎﻧﻮﻥ ﺳﻮﻡ ﻣﺮﺑﻮﻁ ﺑﻪ ﺍﺭﺗﺒﺎﻁ ﺑـﻴﻦ ﺿـﺮﺍﻳﺐ ﺗﻨﺎﺳـﺐ ﺩﻭ‬
‫ﺁﻧﺠﺎ ﮐﻪ ﻳﻮﻥﻫﺎﻱ ﻣﺠﺰﺍ ﺣﺎﻣﻞ ﺑﺎﺭﻫﺎﻱ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻫﺴﺘﻨﺪ‪ ،‬ﺣﺮﮐـﺖ ﺁﻧﻬـﺎ‬
‫ﻭ ﺿﺮﻳﺐ ﺗﺤﺮﮎ ﺳﻮﻕ ‪ ( ‬ﺍﺳـﺖ‬ ‫ﭘﺨﺶ ‪D‬‬ ‫ﻓﺮﺁﻳﻨﺪ ﺍﻭﻝ )ﺿﺮﻳﺐ‬
‫ﻧﻪ ﺗﻨﻬﺎ ﺑﻪ ﺩﻟﻴﻞ ﮔﺮﺍﺩﻳﺎﻥﻫـﺎﻱ ﻏﻠﻈـﺖ ﺑﻠﮑـﻪ ﺗﺤـﺖ ﺗـﺄﺛﻴﺮ ﻣﻴـﺪﺍﻥﻫـﺎﻱ‬
‫]‪.[۳‬‬
‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﻧﻴﺰ ﻣﻲﺑﺎﺷـﺪ‪ .‬ﺩﺭ ﺑﻴﺸـﺘﺮ ﻗﺴـﻤﺖﻫـﺎﻱ ﺑـﺪﻥ ﺑـﺎﺭ ﺍﻟﮑﺘﺮﻳﮑـﻲ‬
‫ﺧﺎﻟﺺ ﻣﻮﻟﮑﻮﻝﻫﺎﻱ ﺯﻳﺴﺘﻲ ﺻﻔﺮ ﺍﺳﺖ‪ ،‬ﮐﻪ ﺑﻪ ﺁﻥ ﺍﺻـﻞ ﺧﻨﺜـﻲ ﺑـﻮﺩﻥ‬
‫‪ .۳.۲.۲‬ﻗﺎﻧﻮﻥ ﺳﻮﻡ‪ :‬ﺭﺍﺑﻄﺔ ﺍﻳﻨﺸﺘﻴﻦ ﺑﻴﻦ ﭘﺨﺶ ﻭ ﺗﺤﺮﮎ‬
‫ﺑﺎﺭ‪ -‬ﻓﻀﺎ ﻣﻲﮔﻮﻳﻨﺪ‪ .‬ﻳﮑﻲ ﺍﺯ ﺟﺎﻫﺎﻳﻲ ﮐﻪ ﺍﻳﻦ ﺍﺻﻞ ﻧﻘﺾ ﻣـﻲﺷـﻮﺩ ﺩﺭ‬
‫ﺍﻳﻨﺸﺘﻴﻦ ﺩﺭ ﺳﺎﻝ ‪ ۱۹۰۵‬ﭘﺨﺶ ﺭﺍ ﺑﻪ ﺻﻮﺭﺕ ﻳﮏ ﻓﺮﺁﻳﻨﺪ ﺗﺼـﺎﺩﻓﻲ‬
‫ﭘﻼﺳﻤﺎﻱ ﻏﺸﺎﻱ ﻳﺎﺧﺘﻪﻫﺎﺳﺖ‪ .‬ﻫﻤﺎﻥ ﻃﻮﺭ ﮐﻪ ﺩﺭ ﺑﺎﻻ ﺗﻮﺿﻴﺢ ﺩﺍﺩﻩ ﺷـﺪ‬
‫ﺗﻮﺿﻴﺢ ﺩﺍﺩ‪ .‬ﺍﻭ ﻧﺸﺎﻥ ﺩﺍﺩ ﮐﻪ ﻣﻘﺎﻭﻣـﺖ ﺍﺻـﻄﮑﺎﮐﻲ ﮐـﻪ ﺑـﻪ ﻭﺳـﻴﻠﺔ‬
‫ﻏﺸﺎﺀ ﺑﻪ ﮐﻤﮏ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﻧﺴﺒﺖ ﺑﻪ ﺑﻌﻀﻲ ﺍﺯ ﻳﻮﻥﻫﺎ ﻧﻔـﻮﺫ ﭘـﺬﻳﺮ‬
‫ﻣﺤﻴﻂ ﺳﻴﺎﻝ ﺩﺭ ﭘﺪﻳﺪﺓ ﺳﻮﻕ ﻭﺍﺭﺩ ﻣﻲﺷﻮﺩ ﻫﻤﺎﻧﻨﺪ ﻣﻘﺎﻭﻣﺘﻲ ﺍﺳـﺖ‬
‫ﻭ ﻧﺴﺒﺖ ﺑﻪ ﺑﻌﻀﻲ ﺩﻳﮕﺮ ﻧﻔﻮﺫ ﻧﺎﭘﺬﻳﺮ ﺍﺳﺖ ﻭ ﻟﺬﺍ ﻳـﮏ ﺟﺪﺍﺳـﺎﺯﻱ ﺑـﺎﺭ‬
‫ﮐﻪ ﺩﺭ ﺗﻌﺎﺩﻝ ﺣﺮﺍﺭﺗﻲ ﺑﺮﺍﻱ ﭘﺨﺶ ﺍﺗﻔﺎﻕ ﻣﻲﺍﻓﺘﺪ‪ .‬ﺿﺮﻳﺐ ﭘﺨﺶ ﻭ‬
‫ﺍﺗﻔﺎﻕ ﻣﻲﺍﻓﺘﺪ‪ .‬ﺍﻳﻦ ﺍﻣﺮ ﻣﻨﺠﺮ ﺑﻪ ﺍﻳﺠﺎﺩ ﻳﮏ ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺷـﺪﻩ ﻭ ﺑـﺎ‬
‫ﺿﺮﻳﺐ ﺗﺤﺮﮎ ﺑﺎ ﺭﺍﺑﻄﺔ ﺯﻳﺮ ﺑﻪ ﻫﻢ ﻣﺮﺑﻮﻁ ﻣﻲﺷﻮﻧﺪ‬
‫ﻗﺪﺭﺕ ﺳﺒﺐ ﺣﺮﮐﺖ ﻳﻮﻥﻫﺎﻱ ﺑﺎﺭﺩﺍﺭ ﺍﺯ ﻣﻴﺎﻥ ﮐﺎﻧـﺎﻝﻫـﺎ ﺍﺯ ﻳـﮏ ﻃـﺮﻑ‬
‫‪kT‬‬
‫‪D‬‬ ‫‪,‬‬ ‫)‪(۳‬‬
‫‪q‬‬ ‫ﻏﺸﺎﺀ ﺑﻪ ﻃﺮﻑ ﺩﻳﮕﺮ ﺁﻥ ﻣﻲﺷﻮﺩ ]‪.[۳۸‬‬
‫‪23‬‬
‫ﺩﻣـﺎﻱ‬ ‫‪T‬‬ ‫‪، 1/ 38  10‬‬ ‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ k‬ﺿﺮﻳﺐ ﺑﻮﻟﺘﺰﻣﻦ ‪joule / k‬‬

‫ﻣﻄﻠﻖ )‪ (k‬ﻭ ‪ q‬ﺑﺎﺭﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻮﻟﮑﻮﻟﻲ ) ‪ ( C‬ﻣﻲﺑﺎﺷﺪ‪ .‬ﺍﻳﻦ ﺭﺍﺑﻄـﻪ‬ ‫‪ .۲.۲.۲‬ﻗﺎﻧﻮﻥ ﺩﻭﻡ‪ :‬ﻗﺎﻧﻮﻥ ﺍﻫﻢ ﺑﺮﺍﻱ ﺳﻮﻕ‬
‫ﺑﻴﺎﻥ ﻣﻲﺩﺍﺭﺩ ﮐﻪ ﻓﺮﺁﻳﻨﺪﻫﺎﻱ ﭘﺨﺶ ﻭ ﺳﻮﻕ ﺩﺭ ﻳﮏ ﻣﺤﻴﻂ ﺑﺎ ﻫـﻢ‬ ‫ﺍﮔﺮ ﺣﺮﮐﺖ ﻳﻮﻥﻫﺎ ﺍﺯ ﻣﻴﺎﻥ ﻳﮑﻲ ﺍﺯ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﺭﺍ ﺩﺭ ﺭﺍﺳـﺘﺎﻱ‬
‫ﻗﺎﺑﻞ ﺟﻤﻊ ﺷﺪﻥ ﻫﺴـﺘﻨﺪ‪ ،‬ﺯﻳـﺮﺍ ﻣﻘﺎﻭﻣـﺖﻫـﺎﻱ ﻧﺎﺷـﻲ ﺍﺯ ﻫـﺮ ﺩﻭ‬
‫____________________________________________‬
‫ﻓﺮﺍﻳﻨﺪ ﺍﺯ ﻳﮏ ﺟﻨﺲ ﻫﺴﺘﻨﺪ‪ .‬ﺍﻳﻦ ﺭﺍﺑﻄـﻪ ﮐـﺎﺭ ﺭﺍ ﺑـﺮﺍﻱ ﺗﻮﺻـﻴﻒ‬
‫‪1. Fick‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۵۴‬‬

‫ﺳﻄﺢ ﮔﺎﺅﺳﻲ ﻓﺮﺿﻲ ﺩﺭ ﻓﻀﺎﻱ ﻏﺸﺎﺀ ﺩﺍﺭﻳﻢ‪.‬‬

‫‪ ‬‬ ‫‪qenc‬‬
‫‪ E.ds ‬‬ ‫‪‬‬
‫‪1‬‬
‫‪‬‬ ‫‪ dv,‬‬ ‫)‪(۵‬‬
‫‪‬‬ ‫‪‬‬
‫‪s1‬‬ ‫‪v1‬‬
‫‪‬‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ E‬ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻏﺸـﺎﯼ ﻧـﻮﺭﻭﻥ‪ s1 ،‬ﺳـﻄﺢ ﺑﺴـﺘﺔ‬
‫ﮔﺎﺅﺳﻲ‪ qenc ،‬ﺑﺎﺭ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺧﺎﻟﺺ ﻣﻮﺟﻮﺩ ﺩﺭ ﺳﻄﺢ ﮔﺎﺅﺳـﻲ‪ ،‬‬
‫ﭼﮕﺎﻟﻲ ﺣﺠﻤـﻲ ﺑـﺎﺭ ﺩﺭ ﻓﻀـﺎﻱ‬ ‫‪‬‬ ‫ﮔﺬﺭﺩﻫﻲ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﺤﻴﻂ ﻏﺸﺎ‪،‬‬
‫ﻏﺸﺎﺀ ﻭ ‪ v1‬ﺣﺠﻢ ﻏﺸﺎﺀ ﻣﺤﺼﻮﺭ ﺑﻪ ﻭﺳﻴﻠﺔ ﺳﻄﺢ ﮔﺎﺅﺳﻲ ﺍﺳﺖ‪.‬‬
‫ﺷﮑﻞ‪ .٩‬ﺳﻄﺢ ﮔﺎﺅﺳﻲ ﺑﺮﺍﻱ ﻏﺸﺎﺀ ﻧﻮﺭﻭﻥ‪.‬‬
‫ﻫﻤــﺎﻥ ﻃــﻮﺭ ﮐــﻪ ﺩﺭ ﺷــﮑﻞ ‪ ۹‬ﻣﺸــﺎﻫﺪﻩ ﻣ ـﻲﺷــﻮﺩ‪ ،‬ﺍﻳ ـﻦ ﻣﻴ ـﺪﺍﻥ‬
‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑﺎ ﺩﺍﻧﺴﺘﻦ ﻣﻘﺪﺍﺭ ﺧـﺎﻟﺺ ﺑـﺎﺭ ﺑـﻪ ﺳـﺎﺩﮔﻲ ﻗﺎﺑـﻞ ﻣﺤﺎﺳـﺒﻪ‬ ‫ﺭﻳﺎﺿﻲ ﺣﺮﮐﺖ ﻳﻮﻥﻫﺎ ﺩﺭ ﺩﺳﺘﮕﺎﻩﻫﺎﻱ ﺯﻳﺴـﺘﻲ ﺑﺴـﻴﺎﺭ ﺳـﺎﺩﻩﺗـﺮ‬
‫ﺍﺳﺖ‪ .‬ﺑﺎ ﺍﻋﻤﺎﻝ ﻗﺎﻧﻮﻥ ﮔﺎﺅﺱ ﺑﺮﺍﻱ ﺳﻄﺢ ﮔﺎﺅﺳﻲ ‪ s2‬ﺩﻳـﺪﻩ ﻣـﻲﺷـﻮﺩ‬ ‫ﻣﻲﮐﻨﺪ ]‪ ۳۹‬ﻭ ‪.[۴۰‬‬
‫ﮐﻪ ﻫﻴﭻ ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺩﺭ ﻓﻀﺎﻱ ﺑﻴﺮﻭﻥ ﻏﺸـﺎﺀ ﻭﺟـﻮﺩ ﻧـﺪﺍﺭﺩ‪ .‬ﺑـﻪ‬
‫ﻧﻈﺮ ﻣﻲﺭﺳﺪ ﭼﻬﺎﺭ ﻗﺎﻧﻮﻥ ﻓﻴﺰﻳﮑﻲ ﻓـﻮﻕ ﻧﻘﻄـﺔ ﺷـﺮﻭﻉ ﺧـﻮﺑﻲ ﺑـﺮﺍﻱ‬ ‫‪ .۴.۲.۲‬ﻗﺎﻧﻮﻥ ﭼﻬﺎﺭﻡ‪ :‬ﺍﺻﻞ ﺧﻨﺜﻲ ﺑﻮﺩﻥ ﺑﺎﺭ‪ -‬ﻓﻀﺎ‬
‫ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﻣﺤﺎﺳﺒﺎﺗﻲ ﺑﺎﺷﻨﺪ‪ .‬ﺑـﻪ ﮐﻤـﮏ ﺍﻳـﻦ ﻗـﻮﺍﻧﻴﻦ ﻣـﻲﺗـﻮﺍﻥ‬ ‫ﺍﻳﻦ ﻗﺎﻧﻮﻥ ﺍﺻﻞ ﺍﺳﺎﺳﻲ ﺟـﺪﺍﻳﻲ ﺑﺎﺭﻫـﺎ ﺩﺭ ﺩﺳـﺘﮕﺎﻩﻫـﺎﻱ ﺯﻳﺴـﺘﻲ‬
‫ﻣﻌﺎﺩﻻﺕ ﻣﻔﻴﺪﻱ ﺩﺭ ﻓﻴﺰﻳـﮏ ﺍﻋﺼـﺎﺏ‪ ،‬ﻫﻤﺎﻧﻨـﺪ ﻣﻌـﺎﺩﻻﺕ ﻧِﺮﻧﺴـﺖ‪-‬‬ ‫ﺍﺳﺖ‪ .‬ﺑﻪ ﺍﻳﻦ ﻣﻌﻨﻲ ﮐﻪ ﺩﺭ ﻳﮏ ﺣﺠﻢ ﻣﻌﻴﻦ‪ ،‬ﮐﻞ ﺑﺎﺭﻫﺎﻱ ﺁﻧﻴﻮﻥﻫﺎ ﺑﺎ‬
‫ﭘﻼﻧﮏ‪ ،(NPE) ٢‬ﻧِﺮﻧﺴﺖ‪ ،(NE)٣‬ﮔُﻠﺪﻣﻦ‪ -‬ﻫـﺎﺟﮑﻴﻦ‪ -‬ﮐﺘـﺰ‪،(GHK)٤‬‬ ‫ﮐﻞ ﺑﺎﺭ ﮐﺎﺗﻴﻮﻥﻫﺎ ﺗﻘﺮﻳﺒﺎً ﺑﺎ ﻫﻢ ﺑﺮﺍﺑﺮ ﺍﺳﺖ‪ .‬ﺑﻪ ﻋﺒﺎﺭﺕ ﺩﻳﮕﺮ‪:‬‬
‫ﻭ ﻣﻌﺎﺩﻻﺕ ﺗﻌﺎﺩﻝ ﺩُﻧﺎﻥ‪ ٥‬ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ ]‪ ۴۰‬ﻭ‪ .[۴۱‬ﺍﺯ ﺁﻧﺠﺎ ﮐﻪ ﻫﻨـﻮﺯ‬ ‫] ‪zice [Ci ]  z Aj e[Cj‬‬ ‫)‪(۴‬‬
‫ﺗﻮﺍﻓﻖ ﺧﺎﺻﻲ ﺑﺮ ﻣﻌﺎﺩﻻﺕ ﺑﻨﻴﺎﺩﻱ ﻓﻴﺰﻳـﮏ ﺍﻋﺼـﺎﺏ ﻭﺟـﻮﺩ ﻧـﺪﺍﺭﺩ ﻭ‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ zic‬ﻇﺮﻓﻴﺖ ﮐﺎﺗﻴﻮﻥﻫﺎﻱ ﻧﻮﻉ ‪ zcj ، i‬ﻇﺮﻓﻴﺖ ﺁﻧﻴﻮﻥﻫـﺎﻱ‬
‫ﻫﻨﻮﺯ ﺩﺭ ﺣﺎﻝ ﺗﮑﻤﻴـﻞ ﺷـﺪﻥ ﺍﺳـﺖ‪ ،‬ﻣـﺎ ﺍﺯ ﺍﻳـﻦ ﻗـﻮﺍﻧﻴﻦ ﺑـﻪ ﻋﻨـﻮﺍﻥ‬
‫‪ e ،‬ﺑﺎﺭ ﻳﮏ ﻳﻮﻥ ﺗﮏ ﻇﺮﻓﻴﺘـﻲ‪ ،‬ﻭ ] ‪ [C j‬ﻭ ] ‪ [C j‬ﻏﻠﻈـﺖ‬ ‫‪j‬‬ ‫ﻧﻮﻉ‬
‫ﻣﻌﺎﺩﻻﺕ ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﻧﺎﻡ ﻣﻲﺑﺮﻳﻢ‪.‬‬
‫ﻳﻮﻥﻫـﺎﻱ ﻣﺨﺘﻠـﻒ ﻫﺴـﺘﻨﺪ‪ .‬ﺧﻨﺜـﻲ ﺑـﻮﺩﻥ ﺑـﺎﺭ ﻓﻀـﺎ ﺑـﺮﺍﻱ ﺍﮐﺜـﺮ‬
‫ﻗﺴﻤﺖﻫﺎﻱ ﺑﺪﻥ ﺑﺮﻗﺮﺍﺭ ﺍﺳﺖ‪ ،‬ﺑﻪ ﺟـﺰ ﺩﺭ ﻓﻀـﺎﻱ ﺍﻃـﺮﺍﻑ ﻏﺸـﺎﺀ‬
‫‪ .۳.۲‬ﭼﻬﺎﺭ ﻣﻌﺎﺩﻟﻪ ﺩﺭ ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ‬
‫ﻳﺎﺧﺘﻪ ﮐﻪ ﺁﻥ ﻫﻢ ﺑﻪ ﺩﻟﻴﻞ ﺟﺪﺍﻳﻲ ﺑﺎﺭﻫﺎ ﺍﺯ ﻫﻢ ﻣﻲﺑﺎﺷـﺪ‪ .‬ﺩﺭ ﻋﻤـﻞ‬
‫)‪(NPE‬‬ ‫‪ .۱.۳.۲‬ﻣﻌﺎﺩﻟﺔ ﻧﺮﻧﺴﺖ ﭘﻼﻧﮏ‬
‫ﺩﺭ ﺍﮐﺜﺮ ﻣﻮﺍﺭﺩ ﺑﻴﺶ ﺍﺯ ‪ ۹۹%‬ﺑﺎﺭ ﻳﻮﻥﻫﺎ ﺑﻪ ﻭﺳﻴﻠﺔ ﺑﺎﺭﻫـﺎﻱ ﻣﺨـﺎﻟﻒ‬
‫ﺩﺭ ﺷﺮﺍﻳﻂ ﻓﻴﺰﻳﻮﻟﻮﮊﻳﮑﻲ‪ ،‬ﺣﺮﮐﺖ ﻳﻮﻥﻫـﺎ ﺗﺤـﺖ ﺗـﺄﺛﻴﺮ ﻫـﺮﺩﻭ ﻋﺎﻣـﻞ‬ ‫ﺧﻨﺜﻲ ﻣﻲﺷﻮﻧﺪ‪ .‬ﺟﺪﺍﻳﻲ ﺑﺎﺭﻫﺎ ﻣﻌﻤﻮﻻً ﺑﻪ ﺩﻟﻴﻞ ﻧﻔﻮﺫﭘﺬﻳﺮﻱ ﺍﻧﺘﺨﺎﺑﻲ‬
‫ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻭ ﮔﺮﺍﺩﻳﺎﻥ ﻏﻠﻈﺖ )ﭘﺘﺎﻧﺴﻴﻞﻫـﺎﻱ ﺍﻟﮑﺘـﺮﻭ ﺷـﻴﻤﻴﺎﻳﻲ(‬ ‫ﻏﺸﺎﺀ )ﺗﻌﺎﺩﻝ ﺩُﻧﺎﻥ‪١‬ﻳﺎ ﺗﻮﺯﻳﻊ ﻏﻴﺮﻓﻌﺎﻝ ﻳﻮﻥﻫﺎ( ﺑﺮﺍﻱ ﺑﻌﻀﻲ ﻳﻮﻥﻫـﺎ‬
‫ﺍﺳﺖ‪ .‬ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻗﺎﻧﻮﻥ ﺍﻳﻨﺸﺘﻴﻦ ﻣﻲﺗﻮﺍﻥ ﺷﺎﺭ ﻳﻮﻧﻲ ﺭﺍ ﺑﺎ ﺗﺮﮐﻴـﺐ ﻫـﺮ‬ ‫ﺍﺗﻔﺎﻕ ﻣﻲﺍﻓﺘﺪ‪ .‬ﺑﻪ ﺍﻳﻦ ﻣﻌﻨﻲ ﮐﻪ ﻳﻮﻥ ﭘﺘﺎﺳﻴﻢ ﺩﺭ ﺭﺍﺳﺘﺎﻱ‬ ‫‪K‬‬ ‫ﻣﺎﻧﻨﺪ‬
‫ﺩﻭ ﻋﺎﻣﻞ ﭼﻨﻴﻦ ﻧﻮﺷﺖ‪:‬‬ ‫‪ ([K in+ ]  [K out‬ﺑــﻪ ﺑﻴــﺮﻭﻥ ﻳﺎﺧﺘــﻪ ﭘﺨــﺶ‬
‫‪+‬‬
‫ﮔﺮﺍﺩﻳــﺎﻥ ﻏﻠﻈــﺖ )]‬
‫‪J  J drift  J diff ‬‬
‫ﻣﻲﺷﻮﺩ ﻭ ﻣﻨﺠﺮ ﺑﻪ ﺑﺎﺭ ﺧﺎﻟﺺ ﻣﻨﻔﻲ ﺩﺭﻭﻥ ﻳﺎﺧﺘﻪ ﻭ ﺑـﺎﺭ ﻣﺜﺒـﺖ ﺩﺭ‬
‫‪V‬‬ ‫] ‪[C‬‬ ‫)‪V  kT [C ] (۶‬‬
‫] ‪  z[C‬‬ ‫‪D‬‬ ‫] ‪  (  z[C‬‬ ‫‪‬‬ ‫‪),‬‬
‫‪x‬‬ ‫‪x‬‬ ‫‪x‬‬ ‫‪q x‬‬ ‫ﺑﻴﺮﻭﻥ ﺁﻥ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳـﻦ ﺟﺪﺍﺷـﺪﮔﻲ ﺑﺎﺭﻫـﺎ ﺩﺭ ﺣﺎﻟـﺖ ﺍﺳـﺘﺮﺍﺣﺖ‬
‫‪NPE‬‬ ‫ﺑﺮ ﻋﺪﺩ ﺁﻭﻭﮔﺎﺩﺭﻭ ﻣﻲﺗﻮﺍﻥ ﺷﮑﻞ ﻣـﻮﻟﻲ ﻣﻌﺎﺩﻟـﺔ‬ ‫‪J‬‬ ‫ﺑﺎ ﺗﻘﺴﻴﻢ‬ ‫ﻳﺎﺧﺘﻪ ﺳﺒﺐ ﺍﻳﺠﺎﺩ ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑﻪ ﺳـﻤﺖ ﺩﺭﻭﻥ ﻏﺸـﺎﺀ ﻣـﻲ‪-‬‬
‫____________________________________________‬ ‫ﺷﻮﺩ‪ .‬ﺟﻬﺖ ﻭﺿﻮﺡ ﺑﻴﺸﺘﺮ ﺍﻳﻦ ﺍﺻﻞ‪ ،‬ﺍﺯ ﻗﺎﻧﻮﻥ ﮔـﺎﺅﺱ ﺩﺭ ﺣﺠـﻢ‬
‫‪2. Nernst-Planck Equation‬‬ ‫ﻏﺸﺎﯼ ﻧﻮﺭﻭﻥ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲﮐﻨﻴﻢ‪ .‬ﻣﻄـﺎﺑﻖ ﺷـﮑﻞ ‪ ۹‬ﺑـﺎ ﺗﺼـﻮﺭ ﻳـﮏ‬
‫‪3. Nernst‬‬
‫‪4. Goldman- Hodgkin- Katz‬‬ ‫____________________________________________‬
‫‪5. Donan equilibrium‬‬ ‫‪1. Donan‬‬
‫‪۳۵۵‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﭼﻨﻴﻦ ﻣﺤﺎﺳﺒﻪ ﮐﺮﺩ‪.‬‬ ‫ﺣﺴﺐ ‪mV‬‬ ‫ﺑﺮ‬ ‫ﺭﺍ ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ‬

‫‪[C ]out‬‬ ‫‪J‬‬ ‫‪V‬‬ ‫] ‪RT [C‬‬
‫‪Ei  62 log10‬‬ ‫‪.‬‬ ‫)‪(۱۱‬‬ ‫‪J‬‬ ‫] ‪  (uz[C‬‬ ‫‪u‬‬ ‫‪),‬‬ ‫)‪(۷‬‬
‫‪[C ]in‬‬ ‫‪NA‬‬ ‫‪x‬‬ ‫‪F x‬‬
‫ﺍﻳﻦ ﻧﺘﺎﻳﺞ ﺑﻪ ﻃﻮﺭ ﺁﺯﻣﺎﻳﺸﮕﺎﻫﻲ ﺗﺄﻳﻴﺪ ﺷﺪﻩﺍﻧﺪ‪ .‬ﺩﺭ ﺍﮐﺜـﺮ ﺣﻴﻮﺍﻧـﺎﺕ‬ ‫‪mol‬‬
‫ﺑﻴـﺎﻥ ﻣـﻲﺷـﻮﺩ‪ N A .‬ﻋـﺪﺩ‬ ‫ﺑﺮﺣﺴﺐ‬ ‫‪J‬‬ ‫ﮐﻪ ﺩﺭ ﺁﻥ‬
‫ﻏﻠﻈﺖ ﻳﻮﻥﻫﺎ ﺩﺭ ﺩﺭﻭﻥ ﻭ ﺑﻴﺮﻭﻥ ﻧﻮﺭﻭﻥﻫﺎ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮﺍﺳﺖ‪:‬‬ ‫‪sec - cm2‬‬
‫‪cal‬‬
‫‪[ K  ]in  [ K  ]out ,‬‬ ‫‪ F ، (1/98‬ﺛﺎﺑــﺖ ﻓــﺎﺭﺍﺩﻩ‬ ‫ﺁﻭﻭﮔــﺎﺩﺭﻭ‪ R ،‬ﺛﺎﺑــﺖ ﮔﺎﺯﻫــﺎ )‬
‫‪K - mol‬‬
‫‪[ Na  ]in  [ Na  ]out ,‬‬ ‫)‪(۱۲‬‬ ‫‪‬‬ ‫‪C‬‬ ‫‪‬‬
‫‪ u ‬ﺗﺤــﺮﮎ ﻣــﻮﻟﻲ ﻳــﻮﻥ ﺑــﺮ ﺣﺴــﺐ‬ ‫) ‪ (96480‬ﻭ‬
‫‪[Cl  ]in  [Cl  ]out , [Ca2 ]in  [Ca2 ]out .‬‬ ‫‪NA‬‬ ‫‪mol‬‬
‫ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺗﻮﺯﻳﻊ ﻳﻮﻧﻲ ﻓﻮﻕ ﻭ ﺑﻪ ﮐﻤﮏ ﻣﻌﺎﺩﻟﺔ ﻧِﺮﻧﺴﺖ ﻣـﻲﺗـﻮﺍﻥ‬ ‫‪cm2‬‬
‫ﺍﺳﺖ‪ .‬ﺑﺎ ﺿﺮﺏ ﺷﺎﺭ ﻣﻮﻟﻲ ﻳﻮﻥ ﺩﺭ ﺑﺎﺭ ﺍﻟﮑﺘﺮﻳﮑﻲ‬
‫‪V  sec mol‬‬
‫ﺩﻳﺪ ‪ ECa‬ﻭ ‪ ENa‬ﻣﺜﺒﺖ ﻭ ‪ EK‬ﻭ ‪ ECl‬ﻣﻨﻔﻲ ﻫﺴﺘﻨﺪ ]‪.[۳‬‬
‫ﻣﻮﻟﻲ ﮐﻞ ﺁﻥ ﻣﻲﺗﻮﺍﻥ ﺷﮑﻞ ﭼﮕﺎﻟﻲ ﺟﺮﻳﺎﻥ ﻣﻌﺎﺩﻟﻪ ‪ NPE‬ﺭﺍ ﭼﻨـﻴﻦ‬
‫ﻧﻮﺷﺖ‪:‬‬
‫‪ .۳.۳.۲‬ﻣﻌﺎﺩﻟﺔ ﺩُﻧﺎﻥ‬ ‫‪V‬‬ ‫] ‪[C‬‬
‫] ‪I  J .zF   (uz2 F[C‬‬ ‫‪ uzRT‬‬ ‫‪),‬‬ ‫)‪(۸‬‬
‫‪‬‬ ‫‪x‬‬ ‫‪x‬‬
‫ﺍﮐﺜﺮ ﻏﺸﺎﻫﺎﻱ ﺯﻳﺴﺘﻲ ﺑﺮﺍﻳﻴﻮﻥﻫـﺎﻱ ﮐـﻮﭼﮑﻲ ﭼـﻮﻥ ‪ K ‬ﻭ ‪Cl‬‬
‫‪A‬‬
‫ﻧﻔﻮﺫﭘﺬﻳﺮ ﻫﺴﺘﻨﺪ‪ .‬ﻟﺬﺍ ﺍﮔﺮ ﺳﺎﺯ ﻭ ﮐﺎﺭﻱ ﺑـﺮﺍﻱ ﻧﮕﻬـﺪﺍﺭﻱ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﻣﻌﺎﺩﻟﻪ ﺑﻴﺸﺘﺮﻳﻦ ﺍﺳـﺘﻔﺎﺩﻩ ﺭﺍ‬ ‫ﺑﺮ ﺣﺴﺐ‬ ‫‪I‬‬ ‫ﮐﻪ‬
‫‪cm2‬‬
‫ﻏﺸﺎﺀ ﻧﺒﺎﺷﺪ ﺑﻌﺪ ﺍﺯ ﻣﺪﺗﻲ ﻏﻠﻈﺖ ﻳﻮﻥﻫﺎ ﺩﺭ ﺩﺭﻭﻥ ﻭ ﺑﻴﺮﻭﻥ ﻳﺎﺧﺘـﻪ‬ ‫ﺩﺭ ﻣﺤﺎﺳﺒﺎﺕ ﺷﺎﺭ ﻳـﻮﻧﻲ ﺩﺭ ﻓﻴﺰﻳﻮﻟـﻮﮊﻱ ﺍﻋﺼـﺎﺏ ﺩﺍﺭﺩ‪ .‬ﭼﻨـﺪﻳﻦ‬
‫ﺑﺎ ﻫﻢ ﺑﺮﺍﺑﺮ ﺷﺪﻩ ﻭ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺍﺯ ﺑﻴﻦ ﻣـﻲﺭﻭﺩ‪ .‬ﺩﺭ ﻳﺎﺧﺘـﻪﻫـﺎﻱ‬ ‫ﻣﻌﺎﺩﻟﺔ ﺍﺳﺎﺳﻲ ﺗﻮﺻﻴﻒﮐﻨﻨﺪﺓ ﺟﺮﻳﺎﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﮔﺬﺭﻧﺪﻩ ﺍﺯ ﻋـﺮﺽ‬
‫ﺯﻧﺪﻩ ﺩﻭ ﺳﺎﺯﻭﮐﺎﺭ ﺑﺮﺍﻱ ﺣﻔﻆ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸـﺎﺀ ﻭﺟـﻮﺩ ﺩﺍﺭﺩ‪ ،‬ﺍﻧﺘﻘـﺎﻝ‬ ‫ﻏﺸﺎﺀ ﺑﻪ ﮐﻤﮏ ﺍﻳﻦ ﻣﻌﺎﺩﻟﻪ ﺑﻪ ﺩﺳﺖ ﻣﻲﺁﻳﺪ ]‪.[۳‬‬
‫ﻓﻌﺎﻝ ﻳﻮﻥﻫﺎ )ﭘﻤﭗﻫﺎﻱ ﻳـﻮﻧﻲ( ﻭ ﺗﻮﺯﻳـﻊ ﻏﻴـﺮﻓﻌـﺎﻝ ﻳـﻮﻥﻫـﺎ ﺑـﻪ‬
‫ﺩﻣﻨﺪﻩ ﻫﺎﻱ ﻳﻮﻧﻲ ﻗﺒﻼً ﺍﺷﺎﺭﻩ ﺷﺪ‪ ،‬ﻭﻟﻲ ﺗﻮﺯﻳـﻊ ﻏﻴﺮﻓﻌـﺎﻝ ﻳـﻮﻧﻲ ﺑـﻪ‬ ‫)‪(NE‬‬ ‫‪ .۲.۳.۲‬ﻣﻌﺎﺩﻟﺔ ﻧﺮﻧﺴﺖ‬
‫ﻭﺍﺳﻄﺔ ﻋﺒﻮﺭ ﺍﻧﺘﺨﺎﺑﻲ ﻏﺸﺎﺀ ﺑﺮﺍﻱ ﻳـﻮﻥﻫـﺎﻱ ﺑـﺰﺭﮒﺗـﺮﻱ ﻫﻤﺎﻧﻨـﺪ‬ ‫ﻳﺎﺧﺘﻪﻫﺎ ﺩﺭ ﺍﮐﺜﺮ ﺯﻣﺎﻥﻫﺎ ﺩﺭ ﺣﺎﻟﺖ ﺍﺳﺘﺮﺍﺣﺖ ﻫﺴﺘﻨﺪ‪ ،‬ﺑﻪ ﺍﻳﻦ ﻣﻌﻨﻲ‬
‫‪2‬‬
‫ﻫﻤﺎﻧﻨﺪ ‪SO24‬‬ ‫‪ Na‬ﻭ ‪ Ca‬ﻭ ﻳﺎ ﺑﺮﺍﻱ ﺁﻧﻴﻮﻥﻫﺎﻱ ﻧﻔﻮﺫ ﻧﺎﭘﺬﻳﺮﻱ‬ ‫‪‬‬
‫ﮐﻪ ﺗﺤﺮﻳﮏ ﺧﺎﺻﻲ ﺑﻪ ﺁﻧﻬﺎ ﻭﺍﺭﺩ ﻧﻤﻲﺷﻮﺩ‪ .‬ﺷﺮﻁ ﻻﺯﻡ ﺑﺮﺍﻱ ﺣﺎﻟﺖ‬
‫ﻭ ﭘﺮﻭﺗﺌﻴﻦﻫﺎﻱ ﺑﺎﺭﺩﺍﺭ ﮐﻮﭼﮏ ﺩﺭﻭﻥ ﻳﺎﺧﺘﻪ ﺍﺳﺖ‪ .‬ﺗﻮﺯﻳﻊ ﻏﻴﺮﻓﻌـﺎﻝ‬ ‫ﺍﺳﺘﺮﺍﺣﺖ ﻳﺎﺧﺘﻪ ﺍﻳﻦ ﺍﺳﺖ ﮐﻪ ﺟﺮﻳﺎﻥ ﺧﺎﻟﺺ ﮔﺬﺭﺍﻧـﺪﻩ ﺍﺯ ﻋـﺮﺽ‬
‫ﻳﻮﻥ ﻧﻴﺎﺯﻱ ﺑﻪ ﺍﻧﺮﮊﻱ ﻧﺪﺍﺭﺩ‪ .‬ﺩﺭ ﺻﻮﺭﺗﻲ ﮐﻪ ﺩﺭ ﻳﮏ ﻳﺎﺧﺘـﺔ ﺍﻧﺘﻘـﺎﻝ‬ ‫ﻏﺸﺎﺀ ﺑﺮﺍﺑﺮ ﺻﻔﺮ ﺑﺎﺷﺪ )ﭘﺘﺎﻧﺴﻴﻞ ﺗﻌﺎﺩﻝ ﻳﻮﻥ(‪ .‬ﺍﮔﺮ ﭼﮕـﺎﻟﻲ ﺟﺮﻳـﺎﻥ‬
‫ﻓﻌﺎﻝ ﻳﻮﻧﻲ ﻭﺟﻮﺩ ﻧﺪﺍﺷﺘﻪ ﺑﺎﺷـﺪ‪ ،‬ﺗﻮﺯﻳـﻊ ﻏﻴﺮﻓﻌـﺎﻝ ﻳـﻮﻧﻲ ﻣﺴـﺌﻮﻝ‬ ‫ﺭﺍ ﺩﺭ ﻣﻌﺎﺩﻟﺔ ‪ NPE‬ﺑﺮﺍﺑﺮ ﺻﻔﺮ ﻗﺮﺍﺭ ﺩﻫﻴﻢ )‪ ، ( I  0‬ﺷـﺮﻁ ﻣـﻮﺭﺩ‬
‫ﺍﻳﺠﺎﺩ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺍﺳﺖ‪ .‬ﺩﺭ ﺍﻳﻦ ﺻﻮﺭﺕ ﺍﮔـﺮ ‪ Cm‬ﮐـﺎﺗﻴﻮﻥ ﺑـﺎ‬ ‫ﻧﻈﺮ ﺑﻪ ﺩﺳﺖ ﻣﻲﺁﻳﺪ‬
‫ﺁﻧﻴﻮﻥ ﺑﺎ ﻇﺮﻓﻴﺖ ‪ n‬ﺑﺎﺷﺪ‪ ،‬ﻣﻲﺗﻮﺍﻥ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫‪A n‬‬ ‫ﻇﺮﻓﻴﺖ ‪ m‬ﻭ‬ ‫] ‪V  RT 1 [C‬‬
‫‪‬‬ ‫‪‬‬
‫‪x‬‬ ‫‪zF [C ] x‬‬
‫ﺗﻌــﺎﺩﻝ ﻫــﺮ ﻳــﻮﻥ ﻧﻔــﻮﺫﭘــﺬﻳﺮ ﺭﺍ ﺑــﻪ ﮐﻤــﮏ ﻣﻌﺎﺩﻟــﺔ ﻧﺮﻧﺴــﺖ‪،‬‬ ‫‪V2‬‬ ‫)‪(۹‬‬
‫‪RT [C ]2‬‬
‫‪‬‬
‫‪RT‬‬
‫‪RT [C ]out‬‬ ‫‪dV ‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪V2  V1  ‬‬ ‫‪ln‬‬ ‫‪.‬‬
‫‪ ، Vm ‬ﻧﻮﺷــﺖ ﻭ ﻗﺎﻋــﺪﺓ ﺗﻌــﺎﺩﻝ ﺩُﻧــﺎﻥ ﺭﺍ ﭼﻨـﻴﻦ‬ ‫‪ln‬‬
‫‪V1‬‬
‫‪zF‬‬ ‫‪zF [C ]1‬‬
‫‪zF‬‬ ‫‪[C ]in‬‬
‫ﺑﻪﺩﺳﺖ ﺁﻭﺭﺩ‬ ‫ﺍﮔﺮ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺭﺍ ﺑﻪ ﺻﻮﺭﺕ ‪ Vm  Vin Vout‬ﺗﻌﺮﻳﻒ ﮐﻨـﻴﻢ‪،‬‬
‫‪1‬‬ ‫‪1‬‬ ‫ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﭘﺘﺎﻧﺴﻴﻞ ﺗﻌﺎﺩﻝ ﺩﺍﺭﻳﻢ‪.‬‬
‫‪ C  m  m  A n  n‬‬
‫‪ out‬‬‫‪m‬‬
‫‪]   in  .‬‬
‫‪n‬‬
‫)‪(۱۲‬‬ ‫‪Ei  Vm ( I i  0)  Vin  Vout ‬‬
‫‪RT [C ]out‬‬
‫‪ln‬‬ ‫‪,‬‬ ‫)‪(۱۰‬‬
‫‪ Cin‬‬ ‫‪‬‬ ‫‪ Aout‬‬ ‫‪‬‬ ‫‪zF‬‬ ‫‪[C ]in‬‬
‫ﺍﺯ ﺁﻧﺠﺎ ﮐﻪ ﺗﻌﺪﺍﺩ ﺯﻳﺎﺩﻱ ﺍﺯ ﻣﻮﻟﮑﻮﻝﻫﺎﻳﻲ ﺑﺎ ﺑﺎﺭ ﻣﻨﻔﻲ )ﭘـﺮﻭﺗﺌﻴﻦﻫـﺎﻳﻲ‬ ‫ﺑﻪ ﻳﻮﻥ ﻣﻮﺭﺩ ﻧﻈﺮ ﺍﺷﺎﺭﻩ ﺩﺍﺭﺩ‪ .‬ﺑﻪ ﺳﺎﺩﮔﻲ ﻣﻲﺗـﻮﺍﻥ ﺩﺭ‬ ‫‪i‬‬ ‫ﮐﻪ ﺩﺭ ﺁﻥ‬
‫‪ ( A‬ﺩﺭ ﺳﻴﺘﻮﭘﻼﺳﻢ ﻳﺎﺧﺘﻪ ﻭﺟﻮﺩ ﺩﺍﺭﻧﺪ ﻭ ﻗﺎﺑﻠﻴﺖ ﻋﺒﻮﺭ ﺍﺯ ﻏﺸـﺎﺀ ﺭﺍ‬ ‫‪‬‬
‫ﺩﻣﺎﻱ ‪ T=37 C‬ﻭ ﺑﺮﺍﻱ ﻳﮏ ﻳﻮﻥ ﺗﮏ ﻇﺮﻓﻴﺘﻲ ﭘﺘﺎﻧﺴﻴﻞ ﺗﻌـﺎﺩﻝ ﺭﺍ‬
‫‪o‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۵۶‬‬

‫ﺑﺎﺷﺪ‪ ،‬ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﺴﺘﻘﻞ ﺑﻮﺩﻥ ﺣﺮﮐﺖ ﻳﻮﻥﻫﺎ ﻣﻲﺗﻮﺍﻥ ﺟﺮﻳﺎﻥ ﺧـﺎﺭﺝ‬ ‫ﻧﺪﺍﺭﻧـــــﺪ ﻣـــــﻲ ﺗـــــﻮﺍﻥ ﻧﻮﺷـــــﺖ ‪ [K  ]out  [Cl ]out‬ﻭ‬
‫ﺷﻮﻧﺪﻩ ﺍﺯ ﻳﺎﺧﺘﻪ ﻭ ﻭﺍﺭﺩ ﺷﻮﻧﺪﻩ ﺑﻪ ﺁﻥ ﺭﺍ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﻧﻮﺷﺖ‪:‬‬ ‫‪ . [K + ]in = [Cl- ]in + [A - ]in‬ﺑﺎ ﮐﻤﮏ ﺍﻳﻦ ﺩﻭ ﺭﺍﺑﻄﻪ ﻭ ﻗﺎﻋﺪﻩ ﺩُﻧـﺎﻥ‬

‫‪efflux: Iout  PzF‬‬

‫‪[C ]in‬‬
‫‪.‬‬ ‫)‪ (۱۵‬ﺟﺮﻳﺎﻥ ﺧﺎﺭﺝ ﺷﻮﻧﺪﻩ‬ ‫ﻭ ‪ Cl‬ﻣﻲﺗﻮﺍﻥ ﻧﺸﺎﻥ ﺩﺍﺩ ﮐﻪ ﺣﺘـﻲ ﺑـﺪﻭﻥ ﺍﻧﺘﻘـﺎﻝ ﻓﻌـﺎﻝ‬ ‫‪K‬‬ ‫ﺑﺮﺍﻱ‬
‫‪‬‬
‫‪1 e‬‬
‫ﻳﻮﻧﻲ ﻣﻲﺗﻮﺍﻥ ﺍﺧﺘﻼﻑ ﻏﻠﻈﺖ ﻭ ﺩﺭ ﻧﺘﻴﺠﻪ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺩﺍﺷﺖ‪.‬‬
‫‪[C ]out e‬‬
‫‪influx: Iin   PzF‬‬ ‫‪.‬‬ ‫)‪(۱۶‬ﺟﺮﻳﺎﻥ ﻭﺍﺭﺩ ﺷﻮﻧﺪﻩ‬ ‫‪[K  ]2in  [K  ]2out  [A - ]in [K  ]in‬‬ ‫‪‬‬
‫‪1  e‬‬ ‫)‪(۱۳‬‬
‫ﻣﻌﺎﺩﻟﺔ )‪ (۱۴‬ﺑﻪ ﻣﻌﺎﺩﻟﺔ ﺟﺮﻳﺎﻥ ‪ GHK‬ﻣﻌﺮﻭﻑ ﺍﺳﺖ ﮐﻪ ﺭﺍﺑﻄـﺔ ﺑـﻴﻦ ﺟﺮﻳـﺎﻥ‬ ‫‪[K ]in > [K ]out , [Cl ]out > [Cl - ]in‬‬
‫‪+‬‬ ‫‪+‬‬ ‫‪-‬‬

‫ﻭ ﻭﻟﺘﺎﮊ ﻏﺸﺎﺀ )ﺭﺍﺑﻄﺔ ‪ ( I  V‬ﻳﺎ ﻫﻤﺎﻥ ﺟﺮﻳﺎﻥ ﻳـﻮﻧﻲ ﺭﺍ ﺍﺭﺍﺋـﻪ ﻣـﻲﺩﻫـﺪ‪ .‬ﺍﺯ‬
‫)‪(GHK‬‬ ‫‪ .۴.۳.۲‬ﻣﻌﺎﺩﻟﺔ ﮔﻠﺪﻣﻦ‪ -‬ﻫﺎﺟﮑﻴﻦ‪ -‬ﮐﺘﺰ‬
‫ﺁﻧﺠﺎ ﮐﻪ ﻳﻮﻥﻫﺎﻱ ﺍﺻﻠﻲ ﻋﺒﻮﺭﭘﺬﻳﺮ ﺍﺯ ﻏﺸـﺎﺀ ﻧـﻮﺭﻭﻥﻫـﺎ ‪Cl , Na  , K ‬‬
‫ﻣﻌﺎﺩﻟﺔ ﻧﺮﻧﺴﺖ ‪ -‬ﭘﻼﻧﮏ ﺑﺮﺍﻱ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﺳﺎﺩﺓ ﺭﻗﻴـﻖ ﺁﺑﮑـﻲ‬
‫ﻫﺴﺘﻨﺪ‪ ،‬ﺑﺎ ﻓﺮﺽ ﻋﺪﻡ ﻭﺟﻮﺩ ﭘﻤﭗﻫﺎﻱ ﻳﻮﻧﻲ‪ ،‬ﻣـﻲﺗـﻮﺍﻥ ﺑـﺎ ﻣﺴـﺎﻭﻱ ﺻـﻔﺮ‬
‫)ﺁﺏﺩﺍﺭ( ﺑﻪ ﺧﻮﺑﻲ ﭘﺘﺎﻧﺴﻴﻞ ﺗﻌﺎﺩﻝ ﻳﻮﻧﻲ ﺭﺍ ﻣﺤﺎﺳﺒﻪ ﻣﻲﮐﻨﺪ‪ .‬ﺑـﺮﺍﻱ‬
‫ﻗﺮﺍﺭ ﺩﺍﺩﻥ ﮐﻞ ﺟﺮﻳﺎﻥ ﻋﺒﻮﺭﻱ ﺍﺯ ﻏﺸﺎﺀ ) ‪ ، (I  IK  I Na  ICl‬ﭘﺘﺎﻧﺴـﻴﻞ‬
‫ﺣﺎﻟﺖﻫﺎﻳﻲ ﮐﻪ ﺩﺭ ﺁﻥ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﺑﺎ ﺳﺪﻫﺎﻱ ﺍﻧﺮﮊﻱ ﭘﻴﭽﻴﺪﻩ ﻭ‬
‫ﺍﺳﺘﺮﺍﺣﺖ ﻧﻮﺭﻭﻥ ﺭﺍ ﭼﻨﻴﻦ ﻣﺤﺎﺳﺒﻪ ﮐﺮﺩ‪:‬‬
‫ﻣﺤﻞﻫﺎﻱ ﺑﻨﺪﺁﻭﺭﻧﺪﻩ ﺣﺮﮐﺖ ﻳﻮﻥﻫـﺎ ﻭﺟـﻮﺩ ﺩﺍﺷـﺘﻪ ﺑﺎﺷـﻨﺪ‪ ،‬ﺍﻳـﻦ‬
‫‪‬‬ ‫‪PK [K  ]out  PNa [Na  ]out  PCl [Cl ]in‬‬
‫‪e ‬‬ ‫‪,‬‬ ‫)‪(۱۷‬‬ ‫ﻣﻌﺎﺩﻟﻪ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺭﺍ ﺑﻪ ﺩﺭﺳﺘﻲ ﻣﺤﺎﺳﺒﻪ ﻧﻤﻲﮐﻨﺪ‪ .‬ﺟﻬـﺖ ﺣـﻞ‬
‫‪PK [K  ]in  PNa [Na  ]in  PCl [Cl ]out‬‬
‫ﺍﻳﻦ ﻣﺸﮑﻞ ﻣﺪﻟﻲ ﺗﻮﺳﻂ ﮔُﻠﺪﻣﻦ‪ ،‬ﻫﺎﺟﮑﻴﻦ ﻭ ﮐﺘﺰ ﭘﻴﺸﻨﻬﺎﺩ ﺷﺪ ﮐـﻪ‬
‫‪‬‬ ‫‪‬‬ ‫‪‬‬
‫‪RT PK [K ]out  PNa [Na ]out  PCl [Cl ]in‬‬ ‫ﺑﺮ ﺍﺳﺎﺱ ﺁﻥ ‪ NPE‬ﻫﻢﭼﻨﺎﻥ ﺩﺭ ﺍﻳﻦ ﻏﺸﺎﺀ ﺑﺮﻗﺮﺍﺭ ﺍﺳـﺖ ﻭ ﻣﻴـﺪﺍﻥ‬
‫‪Vrest ‬‬ ‫‪ln‬‬ ‫‪‬‬
‫‪F‬‬ ‫‪PK [K  ]in  PNa [Na  ]in  PCl [Cl ]out‬‬
‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﺁﻥ ﻧﻴﺰ ﺛﺎﺑﺖ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﻣﺪﻝ ﺗﻮﺍﻧﺴﺖ ﺑﻌﻀﻲ ﺍﺯ ﺧﻮﺍﺹ‬
‫‪RT‬‬
‫‪Vrest‬‬ ‫‪‬‬ ‫‪.‬‬ ‫)‪(18‬‬ ‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﻏﺸﺎﻫﺎﻱ ﺗﺤﺮﻳﮏﭘﺬﻳﺮ ﻭ ﺑﺮﺧﻲ ﺍﺯ ﺟﺮﻳﺎﻥ ﻫﺎﻱ ﻳـﻮﻧﻲ ﺭﺍ‬
‫‪F‬‬
‫ﺍﻳﻦ ﻣﻌﺎﺩﻟﻪ ﺑﺴﻴﺎﺭ ﻣﻬـﻢ‪ ،‬ﻣﻌﺎﺩﻟـﺔ ﻭﻟﺘـﺎﮊ ‪ GHK‬ﻧﺎﻣﻴـﺪﻩ ﻣـﻲﺷـﻮﺩ‪ ،‬ﮐـﻪ‬ ‫ﺩﺭﺳﺖ ﻣﺤﺎﺳﺒﻪ ﮐﻨﺪ ﻭﻟـﻲ ﺑـﺮﺍﻱ ﻣﺤﺎﺳـﺒﺔ ﺳـﺎﻳﺮ ﺧـﻮﺍﺹ ﻏﺸـﺎﺀ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﺣﺎﻟﺖ ﭘﺎﻳﺎﻱ )ﺍﺳﺘﺮﺍﺣﺖ( ﻏﺸﺎﺀ ﻧﻮﺭﻭﻥ ﺭﺍ ﻣﺤﺎﺳﺒﻪ ﻣﻲﮐﻨﺪ‪.‬‬ ‫ﻣﻨﺎﺳﺐ ﻧﻴﺴﺖ‪ .‬ﺑﻪ ﺍﻳﻦ ﺩﻟﻴﻞ ﮐﻪ ﻳﺎ ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻮﺟﻮﺩ ﺩﺭ ﺍﻳﻦ‬
‫ﻏﺸﺎﻫﺎ ﺛﺎﺑﺖ ﻧﻴﺴﺖ ﻭ ﻳـﺎ ﺍﻳـﻦ ﮐـﻪ ﻣﻌﺎﺩﻟـﺔ ‪ NPE‬ﺩﺭ ﺁﻧﻬـﺎ ﺑﺮﻗـﺮﺍﺭ‬
‫‪ .۵.۳.۲‬ﺭﺳﺎﻧﺶ ﻏﺸﺎ‬
‫ﻧﻴﺴﺖ‪ .‬ﺳﻪ ﻓﺮﺽ ﺍﺻﻠﻲ ﺑﺮﺍﻱ ﻣـﺪﻝ ‪ GHK‬ﻣﻴـﺪﺍﻥ ﺛﺎﺑـﺖ ﻭﺟـﻮﺩ‬
‫ﺑﺎ ﺗﻮﺟﻪ ﺑـﻪ ﻣـﺪﻝ ﻓﻴﺰﻳﮑـﻲ ﻏﺸـﺎﺀ ﻧـﻮﺭﻭﻥ )ﺷـﮑﻞ ‪ (۷‬ﻭ ﺑـﻪﮐـﺎﺭﮔﻴﺮﻱ‬ ‫ﺩﺍﺭﺩ‪ (۱) :‬ﺣﺮﮐﺖ ﻳﻮﻥ ﺩﺭ ﻋﺮﺽ ﻏﺸﺎﺀ ﺍﺯ ﻣﻌﺎﺩﻟﺔ ﻧﺮﻧﺴﺖ‪-‬ﭘﻼﻧـﮏ‬
‫ﻗﺎﻧﻮﻥﻫﺎﻱ ﮐﻴﺮﺷـﻬُﻒ ﻣـﻲﺗـﻮﺍﻥ ﻣﻌﺎﺩﻟـﺔ ﺩﻳﻔﺮﺍﻧﺴـﻴﻞ ﺟﺮﻳـﺎﻥ ﮐـﻞ ‪Im‬‬
‫ﺗﺒﻌﻴﺖ ﻣﻲﮐﻨﺪ‪ (۲) ،‬ﻳﻮﻥﻫﺎ ﺑﻪ ﻃﻮﺭ ﻣﺴﺘﻘﻞ ﺍﺯ ﻫﻢ ﺍﺯ ﻋﺮﺽ ﻏﺸـﺎﺀ‬
‫‪A‬‬
‫ﻳﮏ ﺗﮑﺔ ﻏﺸﺎ‪١‬ﺭﺍ ﻧﻮﺷﺖ‪ .‬ﺍﮔـﺮ ‪Cm‬‬ ‫ﻋﺒﻮﺭﮐﻨﻨﺪﻩ ﺍﺯ ﻭﺍﺣﺪ ﺳﻄﺢ‬ ‫ﻋﺒﻮﺭ ﻣﻲﮐﻨﻨﺪ )ﺑـﺮﻫﻢﮐـﻨﺶ ﻧﺪﺍﺭﻧـﺪ( ﻭ )‪ (۳‬ﻣﻴـﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺩﺭ‬
‫‪cm2‬‬
‫‪dV‬‬ ‫‪V‬‬
‫( ‪ Rm ،‬ﻣﻘﺎﻭﻣـﺖ ﻭﺍﺣـﺪ ﺳـﻄﺢ‬ ‫‪F‬‬
‫)‬ ‫ﻇﺮﻓﻴﺖ ﻏﺸﺎﺀ ﺩﺭ ﻭﺍﺣﺪ ﺳﻄﺢ‬ ‫‪ . E  ‬ﺑﻪ ﮐﻤﮏ ﺍﻳـﻦ ﺳـﻪ‬ ‫‪‬‬ ‫ﻋﺮﺽ ﻏﺸﺎﺀ ﺛﺎﺑﺖ ﺍﺳﺖ‪،‬‬
‫‪2‬‬ ‫‪dx‬‬ ‫‪l‬‬
‫‪cm‬‬
‫ﻓﺮﺽ ﻭ ﺣﻞ ﻣﻌﺎﺩﻟﺔ ﺩﻳﻔﺮﺍﻧﺴﻴﻞ ﻣﺮﺑﻮﻃﻪ ﻣﻲﺗﻮﺍﻥ ﺟﺮﻳﺎﻥ ﻋﺒﻮﺭﻱ ﺍﺯ‬
‫ﻏﺸــﺎ ) ‪ Gm  1 ، (  cm2‬ﺭﺳــﺎﻧﺶ ﺩﺭ ﻭﺍﺣــﺪ ﺳــﻄﺢ ﻏﺸــﺎﺀ‬
‫‪Rm‬‬
‫ﻋﺮﺽ ﻏﺸﺎﺀ ﺭﺍ ﭼﻨﻴﻦ ﻣﺤﺎﺳﺒﻪ ﮐﺮﺩ ]‪ ۴۲ ،۲‬ﻭ‪:[۴۳‬‬
‫ﻭ ‪ E R‬ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳﺘﺮﺍﺣﺖ ﻏﺸﺎ ) ‪ (V‬ﺑﺎﺷﺪ ﻣـﻲﺗـﻮﺍﻥ ‪ Im‬ﺭﺍ‬ ‫(‬
‫‪S‬‬
‫)‬ ‫‪ zFV‬‬
‫‪cm 2‬‬
‫‪u * z2 FV  [C ]out e RT  [C ]in‬‬
‫ﭼﻨﻴﻦ ﻧﻮﺷﺖ‪:‬‬ ‫‪I‬‬ ‫[‬
‫‪ zFV‬‬
‫‪],‬‬ ‫)‪(۱۴‬‬
‫‪l‬‬
‫) ‪dVm (Vm  Er‬‬ ‫‪e RT  1‬‬
‫‪I m  IC  Ii  Cm‬‬ ‫‪‬‬
‫‪dt‬‬ ‫‪Rm‬‬ ‫‪ ‬ﺩﺭ ﺭﺍﺑﻄــﺔ ‪[C ]x0   [C ]in , [C ]xl   [C ]out‬‬ ‫ﮐــﻪ ﺩﺭ ﺁﻥ‬
‫)‪(۱۹‬‬
‫‪dVm‬‬
‫‪ Cm‬‬ ‫‪ Gm (Vm  Er ) ,‬‬ ‫ﺗﻌﺮﻳـ ـﻒ ﻣـ ـﻲﺷـــﻮﺩ ﻭ *‪ u‬ﺗﺤـــﺮﮎ ﻣـــﻮﻟﻲ ﻳـــﻮﻥ ‪ i‬ﺩﺭ ﻏﺸـــﺎﺀ‬
‫‪dt‬‬
‫‪2‬‬
‫‪zVF‬‬ ‫‪ u* RT‬‬ ‫‪cm‬‬
‫____________________________________________‬ ‫‪‬‬ ‫‪ P‬ﻭ‬ ‫( ﺍﺳـــﺖ‪ .‬ﺍﮔــــﺮ ‪s‬‬ ‫)‬
‫‪RT‬‬ ‫‪lF‬‬ ‫‪V  sec mol‬‬
‫‪1. Patch‬‬
‫‪۳۵۷‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫‪ .۱.۴.۲‬ﻣﺪﻝ ﺭﺳﺎﻧﺶ ﻣﻮﺍﺯﻱ‬

‫ﺩﺭ ﺻﻮﺭﺗﻲ ﮐﻪ ﺭﺳﺎﻧﺶ ﻳﻮﻧﻲ ﺑﺎ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﻭ ﺯﻣﺎﻥ ﺗﻐﻴﻴﺮ ﮐﻨـﺪ‪،‬‬
‫ﻣﻲﺗﻮﺍﻥ ﻣﻄﺎﺑﻖ ﺷﮑﻞ ‪ ۱۰‬ﻣﺪﻝ ﺭﺳﺎﻧﺶ ﻣـﻮﺍﺯﻱ ﺭﺍ ﺑـﺮﺍﻱ ﻣﺤﺎﺳـﺒﺔ‬
‫ﺟﺮﻳﺎﻥ ﻏﺸﺎﯼ ﺁﻥ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺖ‬
‫‪dV‬‬
‫‪I total  IC  ( I K  I Na  I Cl )  C‬‬ ‫‪‬‬
‫‪dt‬‬ ‫)‪(۲۰‬‬
‫‪g K (V  EK )  g Na (V  E Na )  g Cl (V  ECl ).‬‬
‫‪dV‬‬ ‫ﺷﮑﻞ‪ .١٠‬ﻣﺪﺍﺭ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻌﺎﺩﻝ ﻏﺸﺎﺀ ﻧﻮﺭﻭﻥ‪.‬‬
‫ﺑﻮﺩﻩ ﻭ ﺩﺍﺭﻳﻢ‬ ‫‪0‬‬ ‫ﺩﺭ ﺣﺎﻟﺖ ﺍﺳﺘﺮﺍﺣﺖ ﺟﺮﻳﺎﻥ ‪ Itotal 0‬ﻭ‬
‫‪dt‬‬
‫‪gK EK  g Na ENa  gCl ECl‬‬
‫‪V‬‬ ‫‪.‬‬ ‫)‪(۲۱‬‬ ‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ IC‬ﺟﺮﻳﺎﻥ ﺧﺎﺯﻧﻲ‪ Ii ،‬ﺟﺮﻳﺎﻥ ﻳﻮﻧﻲ ﮔﺬﺭﻧـﺪﻩ ﺍﺯ ﮐﺎﻧـﺎﻝﻫـﺎ‪،‬‬
‫‪gK  g Na  gCl‬‬
‫ﺑﻪ ﮐﻤﮏ ﻣﻌﺎﺩﻟﺔ )‪ (۲۰‬ﻣـﻲﺗـﻮﺍﻥ ﺟﺮﻳـﺎﻥ ﮐـﻞ ﻏﺸـﺎﺀ ﺭﺍ ﺑﺮﺣﺴـﺐ‬ ‫‪ Vm‬ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎ‪ Vm  ER ،‬ﻧﻴﺮﻭﻱ ﻣﺤﺮﮐﻪ ﻭ ‪ Rm‬ﻣﻘﺎﻭﻣـﺖ ﮐﺎﻧـﺎﻝ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳﺘﺮﺍﺣﺖ ﻭ ﺑﻪ ﮐﻤﮏ ﻣﻌﺎﺩﻟﺔ )‪ (۲۱‬ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳـﺘﺮﺍﺣﺖ ﺭﺍ‬ ‫ﻣﻲﺑﺎﺷﺪ‪ .‬ﺑﺎ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﻳﻮﻥﻫﺎﻱ ﻣﻬﻢ ﺩﺭ ﻧﻮﺭﻭﻥﻫﺎ ﻣﻲﺗـﻮﺍﻥ ﺟﺮﻳـﺎﻥ‬
‫ﺑﺮ ﺣﺴﺐ ﺭﺳﺎﻧﺶ ﻫﺎﻱ ﻳﻮﻧﻲ ﻣﺤﺎﺳﺒﻪ ﮐﺮﺩ‪ .‬ﺍﻳﻦ ﺩﻭ ﻣﻌﺎﺩﻟﻪ ﮐـﺎﺭﺑﺮﺩ‬ ‫ﻳــــﻮﻧﻲ ﮐــــﻞ ﺭﺍ ﺑــــﻪ ﺻــــﻮﺭﺕ ﻣﺠﻤــــﻮﻉ ﺁﻧﻬــــﺎ ﻧﻮﺷــــﺖ‬
‫ﺯﻳﺎﺩﻱ ﺩﺭ ﻣﺤﺎﺳﺒﺎﺕ ﻓﻴﺰﻳﻮﻟﻮﮊﻱ ﺍﻋﺼﺎﺏ ﺩﺍﺭﻧﺪ ]‪ ۳‬ﻭ ‪.[۷‬‬ ‫)‪ . (I  IK  INa  ICl ...‬ﻫــﺮ ﮐــﺪﺍﻡ ﺍﺯ ﺍﻳ ـﻦ ﺟﺮﻳــﺎﻥﻫــﺎ ﺭﺍ ﻫــﻢ‬
‫ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﺻﻮﺭﺕ ﺣﺎﺻﻞﺿـﺮﺏ ﺿـﺮﻳﺐ ﺭﺳـﺎﻧﺶ ﺑـﺮﺍﻱ ﺁﻥ ﻳـﻮﻥ ﻭ‬
‫‪ .۳‬ﻧﻈﺮﻳﺔ ﮐﺎﺑﻞ ﺧﻄﻲ ﺑﺮﺍﻱ ﺩﻧﺪﺭﻳﺖ ﻭ ﺁﮐﺴﻮﻥ‬ ‫ﺍﺧﺘﻼﻑ ﺑﻴﻦ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ )ﺩﺭ ﻳﮏ ﻟﺤﻈﻪ ﺍﺯ ﺯﻣﺎﻥ( ﻭ ﭘﺘﺎﻧﺴﻴﻞ ﺗﻌـﺎﺩﻝ‬
‫ﺑﻌﻀﻲ ﺍﺯ ﻗﺴﻤﺖﻫـﺎﻱ ﻧـﻮﺭﻭﻥ ﻫﻤﺎﻧﻨـﺪ ﺁﮐﺴـﻮﻥ ﻭ ﻗﺴـﻤﺖﻫـﺎﻳﻲ ﺍﺯ‬ ‫ﺑــﺮﺍﻱ ﺁﻥ ﻳــﻮﻥ ﻧﻮﺷــﺖ‪) .‬ﺑــﻪ ﻋﻨــﻮﺍﻥ ﻣﺜــﺎﻝ ﺑــﺮﺍﻱ ﻳــﻮﻥ ﺳــﺪﻳﻢ‬
‫ﺩﻧﺪﺭﻳﺖﻫﺎ ﺭﺍ ﻣﻲﺗـﻮﺍﻥ ﺑـﺎ ﺍﺳـﺘﻮﺍﻧﻪ ﺗﻘﺮﻳـﺐ ﺯﺩ‪ .‬ﺍﻳـﻦ ﺍﺳـﺘﻮﺍﻧﻪ ﺩﺍﺭﺍﻱ‬ ‫) ‪.( (INa  gNa (Vm  ENa‬ﻣﻌﻤﻮﻻً ﺑﺮﺍﻱ ﻧﻴﺮﻭﻱ ﻣﺤﺮﮐﻪ ﺩﺭ ﻋـﺮﺽ‬
‫ﻫﺴﺘﺔ ﺭﺳﺎﻧﺎ ﺍﺳﺖ ﮐﻪ ﺩﻭﺭ ﺁﻥ ﻳﮏ ﻏﺸﺎﺀ ﺑـﺎ ﺧﺼﻮﺻـﻴﺎﺕ ﺍﻟﮑﺘﺮﻳﮑـﻲ‬ ‫ﻏﺸﺎﺀ ﻧﻮﺭﻭﻥ ﺍﺯ ﭘﺘﺎﻧﺴـﻴﻞ ﻣﻌﮑـﻮﺱ ‪ Vrev‬ﮐـﻞ ﺍﺳـﺘﻔﺎﺩﻩ ﻣـﻲﮐﻨﻨـﺪ‪ ،‬ﮐـﻪ‬
‫ﻣﺨﺘﻠﻒ ﻭﺟـﻮﺩ ﺩﺍﺭﺩ‪ .‬ﺟﻬـﺖ ﺗﺤﻠﻴـﻞ ﺧﺼﻮﺻـﻴﺎﺕ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺍﻳـﻦ‬ ‫ﻋﺒﺎﺭﺕ ﺍﺳﺖ ﺍﺯ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﻳﻲ ﮐﻪ ﺑﻪ ﺍﺯﺍﯼ ﺁﻥ ﻗﻄﺒﺶ ﺟﺮﻳﺎﻥ ﻋـﻮﺽ‬
‫ﺭﺳﺎﻧﺎﻫﺎﻱ ﻫﺴـﺘﻪﺩﺍﺭ ﻣـﻲﺗـﻮﺍﻥ ﺍﺯ ﺭﻳﺎﺿـﻴﺎﺕ ﻣﺮﺑـﻮﻁ ﺑـﻪ ﮐﺎﺑـﻞﻫـﺎﻱ‬ ‫ﻣﻲﺷﻮﺩ‪ .‬ﺭﺳﺎﻧﺶﻫﺎﻱ ﻳﻮﻧﻲ ﻣﻲﺗﻮﺍﻧﻨﺪ ﺑـﺎ ﺗﻐﻴﻴـﺮ ﭘﺘﺎﻧﺴـﻴﻞ ﻏﺸـﺎﺀ ﺛﺎﺑـﺖ‬
‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﮐﻪ ﺳﺎﻝﻫﺎ ﻗﺒﻞ ﺗﻮﺳﻌﻪ ﻳﺎﻓﺘﻪ ﺍﺳـﺖ ﺍﺳـﺘﻔﺎﺩﻩ ﮐـﺮﺩ‪ .‬ﺩﺳـﺘﮕﺎﻩ‬ ‫ﺑﻤﺎﻧﻨﺪ ﻳﺎ ﺗﻐﻴﻴﺮ ﮐﻨﻨﺪ‪ .‬ﻫﻤﭽﻨﻴﻦ ﺭﺳﺎﻧﺶﻫﺎﻱ ﻳﻮﻧﻲ ﻣـﻲﺗﻮﺍﻧﻨـﺪ ﺑـﺎ ﻭﻟﺘـﺎﮊ‬
‫ﺍﻋﺼﺎﺏ ﻣﺮﮐﺰﻱ )‪ (CNS‬ﺩﺍﺭﺍﻱ ﺷﺎﺧﻪﻫﺎﻱ ﺩﻧـﺪﺭﻳﺘﻲ ﻓﺮﺍﻭﺍﻧـﻲ ﺍﺳـﺖ‬ ‫ﻏﺸﺎﺀ ﻭ ﭘﻴﻮﻧﺪﻫﺎﻱ ﺩﺭﻭﻥﻳﺎﺧﺘﻪﺍﯼ ﻭ ﺑﻴﺮﻭﻥﻳﺎﺧﺘﻪﺍﯼ ﺑﻪ ﻃـﻮﺭ ﻧﺎﮔﻬـﺎﻧﻲ ﻭ‬
‫ﮐــﻪ ﻫــﺰﺍﺭﺍﻥ ﻭﺭﻭﺩﻱ ﺳﻴﻨﺎﭘﺴــﻲ ﻭﺍﺩﺍﺭﻧــﺪﻩ‪ ،‬ﺑﺎﺯﺩﺍﺭﻧــﺪﻩ ﻭ ﺗﻠﻔﻴﻘــﻲ ﺭﺍ‬ ‫ﻳﺎ ﺁﺭﺍﻡ )ﻭﺍﺑﺴﺘﻪ ﺑﻪ ﺯﻣﺎﻥ( ﻓﻌﺎﻝ ﺷﻮﻧﺪ ]‪.[۳‬‬
‫ﺩﺭﻳﺎﻓﺖ ﻣﻲﮐﻨﻨﺪ‪ .‬ﺑﻪ ﻓﺮﺁﻳﻨﺪﻱ ﺩﻳﻨﺎﻣﻴﮑﻲ ﮐﻪ ﻃﻲ ﺁﻥ ﺩﻧﺪﺭﻳﺖﻫـﺎ ﻫﻤـﻪ‬
‫ﺍﻳﻦ ﻭﺭﻭﺩﻱﻫﺎ ﺭﺍ ﺑﺎ ﻫﻢ ﺟﻤﻊ ﮐﺮﺩﻩ ﻭ ﺩﺭ ﻧﻬﺎﻳﺖ ﺳﺒﺐ ﺗﻐﻴﻴﺮ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫‪ .۴.۲‬ﻏﺸﺎﯼ ﺧﻄﻲ ﻭ ﻏﻴﺮﺧﻄﻲ‬

‫ﻣﺸﺨﺼﻲ ﺩﺭ ﻧﻮﺭﻭﻥ ﻣﻲﺷﻮﻧﺪ ﺍﺩﻏﺎﻡ ﺳﻴﻨﺎﭘﺴﻲ‪ ١‬ﮔﻔﺘﻪ ﻣﻲﺷـﻮﺩ‪ .‬ﺑـﺮﺍﻱ‬ ‫ﺭﺍﺑﻄﺔ ﺑﻴﻦ ﺟﺮﻳﺎﻥ ﻳﻮﻧﻲ ﻏﺸﺎﯼ ‪ Ii‬ﻭ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ‪ Vm‬ﻣﻲﺗﻮﺍﻧـﺪ‬

‫ﻃﺮﺡﺭﻳﺰﻱ ﻳﮏ ﻧﻈﺮﻳﺔ ﻣﻨﺎﺳﺐ ﺑﺮﺍﻱ ﺗﻮﺻﻴﻒ ﻳﮏ ﻧﻮﺭﻭﻥ ﮐﺎﻣﻞ‪ ،‬ﺍﺑﺘـﺪﺍ‬ ‫ﺧﻄﻲ ﻳﺎ ﻏﻴﺮﺧﻄﻲ ﺑﺎﺷﺪ‪ .‬ﺑﺮﺍﻱ ﻏﺸﺎﺀ ﺧﻄﻲ ﺭﺍﺑﻄﺔ ‪ I  V‬ﻳﮏ ﺗﺎﺑﻊ‬

‫ﺑﺎﻳﺪ ﺳﺎﺩﻩﺳﺎﺯﻱﻫﺎﻳﻲ ﺍﻧﺠﺎﻡ ﺩﺍﺩ‪ .‬ﺍﺯ ﺟﻤﻠﻪ ﻓـﺮﺽ ﻣـﻲﮐﻨـﻴﻢ ﮐـﻪ ﻳـﮏ‬ ‫ﺧﻄـﻲ ﺍﺳـﺖ ﻭ ﺑـﺮﺍﻱ ﻏﺸـﺎﯼ ﻏﻴﺮﺧﻄـﻲ ﺍﻳـﻦ ﺭﺍﺑﻄـﻪ ﻳـﮏ ﺗــﺎﺑﻊ‬

‫ﻧـﻮﺭﻭﻥ ﺩﺍﺭﺍﻱ ﻳـﮏ ﺑﺪﻧـﺔ ﻳﺎﺧﺘـﻪ ﮐـﺮﻭﻱ ﻫـﻢﭘﺘﺎﻧﺴـﻴﻞ ﺍﺳـﺖ‪ ،‬ﻫﻤـﻪ‬ ‫ﻏﻴﺮﺧﻄﻲ ﺍﺳﺖ‪ .‬ﺍﮔﺮ ‪ Gm‬ﺭﺳﺎﻧﺶ ﮐﻞ ﻏﺸﺎﺀ ﻳـﮏ ﻧـﻮﺭﻭﻥ ﺑﺎﺷـﺪ‪،‬‬

‫ﺩﻧﺪﺭﻳﺖﻫﺎ ﺭﺍ ﻣﻲﺗﻮﺍﻥ ﺑـﻪ ﺻـﻮﺭﺕ ﻳـﮏ ﺍﺳـﺘﻮﺍﻧﺔ ﻭ ﺁﮐﺴـﻮﻥ ﺭﺍ ﻧﻴـﺰ‬ ‫ﺑﺮﺍﻱ ﻏﺸﺎﻱ ﺧﻄﻲ ﻣﻲﺗﻮﺍﻥ ﻧﻮﺷﺖ ) ‪ ، Ii  Gm (Vm  Ei‬ﮐﻪ ‪Gm‬‬

‫ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﺻﻮﺭﺕ ﻳﮏ ﺍﺳﺘﻮﺍﻧﺔ ﺩﻳﮕﺮ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓـﺖ‪ .‬ﺩﺭ ﺯﻳـﺮ ﻣـﺪﻝ‬ ‫ﻳﮏ ﻣﻘﺪﺍﺭ ﺛﺎﺑﺖ ﺍﺳﺖ‪ .‬ﺑﺮﺍﻱ ﻏﺸﺎﯼ ﻏﻴﺮﺧﻄﻲ ‪ Ii‬ﻣـﻲﺗﻮﺍﻧـﺪ ﻓﻘـﻂ‬
‫ﻓﻴﺰﻳﮑﻲ ﺳﺎﺩﻩﺍﻱ ﺑﺮﺍﻱ ﺍﻳﻦ ﺩﻭ ﻗﺴﻤﺖ ﺍﺭﺍﺋﻪ ﻣﻲﮐﻨﻴﻢ‪.‬‬ ‫ﺗﺎﺑﻊ ﭘﺘﺎﻧﺴﻴﻞ )‪ Ii  f (V‬ﻭ ﻳﺎ ﺗﺎﺑﻌﻲ ﺍﺯ ﻫـﺮ ﺩﻭ ﻣﺘﻐﻴـﺮ ﭘﺘﺎﻧﺴـﻴﻞ ﻭ‬
‫____________________________________________‬ ‫ﺯﻣﺎﻥ ﺑﺎﺷﺪ ) ‪. Ii  f (V , t‬‬
‫‪1. Synaptic integration‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۵۸‬‬

‫ﺷﮑﻞ‪.۱۱‬ﺳﻤﺖ ﭼﭗ‪ :‬ﺷﮑﻞ ﺳﺎﺩﺓ ﻳﮏ ﻧﻮﺭﻭﻥ ﮐﺮﻭﻱ ﻫﻤـﺮﺍﻩ ﺑـﺎ ﺗﺰﺭﻳـﻖ‬

‫ﺷﮑﻞ ‪ .۱۲‬ﻣﺪﻝ ﺍﺳﺘﻮﺍﻧﻪﺍﯼ ﺑﺮﺍﻱ ﺁﮐﺴﻮﻥ ﻭ ﺩﻧﺪﺭﻳﺖ‪.‬‬
‫ﺟﺮﻳﺎﻥ ‪ I0‬ﻭ ﺟﺮﻳﺎﻥ ﻏﺸﺎﺀ ‪ . Im‬ﺳﻤﺖ ﺭﺍﺳﺖ‪ :‬ﻧﻤﻮﺩﺍﺭ ﺟﺮﻳـﺎﻥ ﻭ ﻭﻟﺘـﺎﮊ‬
‫ﻏﺸﺎﺀ ﺑﺮ ﺣﺴﺐ ﺯﻣﺎﻥ‪.‬‬

‫ﭘﺘﺎﻧﺴﻴﻞ ﺑﻪ ﻣﻘﺪﺍﺭ ﺣﺎﻟﺖ ﭘﺎﻳﺎﻱ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺑﺮﺍﻱ ﺟﺮﻳﺎﻥ ﭘﻠـﻪﺍﻱ‬ ‫‪ .۱.۳‬ﻣﺪﻝ ﻳﺎﺧﺘﻪ ﮐﺮﻭﻱ ﻫﻢﭘﺘﺎﻧﺴﻴﻞ‬
‫ﻣﻌﺮﻭﻑ ﺍﺳﺖ‪ .‬ﺩﺭ ﺗﺤﻘﻴﻘﺎﺕ ﺁﺯﻣﺎﻳﺸﮕﺎﻫﻲ ﻧﻴـﺰ ﺩﺭ ﺍﮐﺜـﺮ ﻣـﻮﺍﺭﺩ ﺍﺯ‬ ‫ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺳﺎﺩﻩﺳﺎﺯﻱﻫﺎﻱ ﻓﻮﻕ ﻣﻘﺎﻭﻣﺖ ﻏﺸﺎﺀ ﻳﮏ ﻣﻘـﺪﺍﺭ ﺛﺎﺑـﺖ‬
‫ﺟﺮﻳﺎﻥ ﭘﻠﻪﺍﻱ ﺑﺮﺍﻱ ﺗﺤﺮﻳﮏ ﻧﻮﺭﻭﻥ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲﺷﻮﺩ‪ .‬ﺑﻨﺎ ﺑـﻪ ﻗـﺎﻧﻮﻥ‬ ‫)‪ (Rm‬ﻭ ﻣﺴﺘﻘﻞ ﺍﺯ ﻭﻟﺘﺎﮊ ﻓﺮﺽ ﻣﻲﺷﻮﺩ‪ .‬ﺑﻪ ﻋﺒـﺎﺭﺕ ﺩﻳﮕـﺮ ﻳـﮏ‬
‫ﺟﺮﻳﺎﻥ ﮐﻴﺮﺷﻬُﻒ ﻣﻲﺗﻮﺍﻥ ﻣﻘﺪﺍﺭ ﺟﺮﻳـﺎﻥ ﺩﺭ ﻭﺍﺣـﺪ ﺳـﻄﺢ ﻏﺸـﺎﺀ‬ ‫ﻳﺎﺧﺘﻪ ﺍُﻫﻤﻲ ﺍﺳﺖ‪ .‬ﻫﻤﭽﻨﻴﻦ ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳـﺘﺮﺍﺣﺖ ﻧـﻮﺭﻭﻥ ﺭﺍ ﺑﺮﺍﺑـﺮ‬
‫ﮐﺮﻭﻱ ﺭﺍ ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ‬ ‫ﺻﻔﺮ ﺩﺭ ﻧﻈﺮ ﻣﻲﮔﻴﺮﻳﻢ ﺗﺎ ﻫﻤﺔ ﭘﺘﺎﻧﺴﻴﻞﻫﺎ ﺑﺎ ﻣﺮﺟﻊ ﺻـﻔﺮ ﻣﻘﺎﻳﺴـﻪ‬
‫‪I0‬‬
‫‪Im ‬‬ ‫‪,‬‬ ‫)‪(۲۵‬‬ ‫ﺷﻮﻧﺪ‪ .‬ﺍﮔﺮ ﺗﺤﺮﻳـﮏ ﺭﺍ ﺑـﻪ ﺻـﻮﺭﺕ ﺗﺰﺭﻳـﻖ ﺟﺮﻳـﺎﻥ ‪ I0‬ﺩﺭ ﻧﻈـﺮ‬
‫‪4 a2‬‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ a‬ﺷﻌﺎﻉ ﻳﺎﺧﺘـﻪ ﺍﺳـﺖ‪ .‬ﻣﻘﺎﻭﻣـﺖ ﻭﺭﻭﺩﻱ ﻳـﮏ ﻳﺎﺧﺘـﻪ‬ ‫ﺑﮕﻴﺮﻳﻢ‪ ،‬ﺑﻪ ﺩﻟﻴﻞ ﻫﻢﭘﺘﺎﻧﺴﻴﻞ ﺑﻮﺩﻥ ﻏﺸﺎ‪ ،‬ﺟﺮﻳﺎﻥ ﺑﻪ ﻃﻮﺭ ﻳﮑﻨﻮﺍﺧـﺖ‬
‫)ﺑﺪﻭﻥ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﻫﻨﺪﺳﺔ ﻳﺎﺧﺘـﻪ( ﻳﮑـﻲ ﺍﺯ ﭘﺎﺭﺍﻣﺘﺮﻫـﺎﻱ ﻣﻬـﻢ‬ ‫ﺩﺭ ﻏﺸﺎﺀ ﺗﻮﺯﻳﻊ ﻣﻲﺷﻮﺩ )ﺷﮑﻞ ‪.(۱۱‬‬
‫ﺍﺳﺖ‪ .‬ﻣﻘﺎﻭﻣﺖ ﻭﺭﻭﺩﻱ ﻳﮏ ﻳﺎﺧﺘﻪ ﮐﺮﻭﻱ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﻣﺤﺎﺳﺒﻪ‬ ‫ﻣﺠﺪﺩﺍً ﺟﺮﻳﺎﻥ ﮔﺬﺭﻧﺪﻩ ﺍﺯ ﻭﺍﺣﺪ ﺳﻄﺢ ﻏﺸﺎﺀ ﺭﺍ ﻣﻲﺗـﻮﺍﻥ ﺑـﻪ‬
‫ﻣﻲﺷﻮﺩ‪:‬‬ ‫ﺻﻮﺭﺕ ﻣﺠﻤﻮﻉ ﺟﺮﻳﺎﻥﻫﺎﻱ ﺧﺎﺯﻧﻲ ﻭ ﻣﻘﺎﻭﻣﺘﻲ ﻧﻮﺷﺖ‪:‬‬
‫‪dVm Vm‬‬
‫‪RN ‬‬
‫‪Vm‬‬ ‫‪I R‬‬
‫‪ m m  m ,‬‬
‫‪R‬‬
‫)‪(۲۶‬‬ ‫‪I m  Cm‬‬ ‫‪‬‬ ‫‪.‬‬ ‫)‪(۲۲‬‬
‫‪I0 I m (4 a ) 4 a2‬‬
‫‪2‬‬ ‫‪dt‬‬ ‫‪Rm‬‬

‫ﮐﻪ ﻧﺸﺎﻥ ﻣﻲﺩﻫـﺪ ﺑـﺮﺍﻱ ﻫـﺮ ﻣﻘﺎﻭﻣـﺖ ﻏﺸـﺎﺀ ‪ ، Rm‬ﻳﺎﺧﺘـﻪﻫـﺎﻱ‬ ‫ﺟﺮﻳﺎﻥ ﺗﺰﺭﻳﻖﺷﺪﻩ ﺑﻴـﺮﻭﻥﺭﻭﻧـﺪﻩ ﺳـﺒﺐ ﻭﺍﻗﻄﺒﻴـﺪﮔﻲ )ﻣﺜﺒـﺖﺗـﺮ(‬

‫ﺑﺰﺭﮒﺗﺮ ﺩﺍﺭﺍﻱ ﻣﻘﺎﻭﻣﺖﻫﺎﻱ ﻭﺭﻭﺩﻱ ﮐﻮﭼﮏﺗﺮ ﻫﺴﺘﻨﺪ ﻭ ﺑﺮﻋﮑﺲ‬ ‫ﻣﻲﺷﻮﺩ ﻭ ﺑﺮﻋﮑﺲ‪ .‬ﺍﮔﺮ ﺟﺮﻳﺎﻥ ﺗﺰﺭﻳﻖﺷﺪﻩ ﺭﺍ ﻳﮏ ﺟﺮﻳـﺎﻥ ﭘﻠـﻪﺍﻱ‬

‫]‪.[۳‬‬ ‫ﺩﺭ ﻧﻈــﺮ ﺑﮕﻴــﺮﻳﻢ‪ ،‬ﺟــﻮﺍﺏ ﻣﻌﺎﺩﻟــﺔ‬ ‫‪T‬‬ ‫ﺑــﺎ ﺩﺍﻣﻨــﺔ ‪ I0‬ﺩﺭ ﻣــﺪﺕ‬
‫ﺩﻳﻔﺮﺍﻧﺴﻴﻞ ﺑﺎﻻ ﺭﺍ ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﺳﺎﺩﮔﻲ ﻫﻤﺎﻧﻨﺪ ﻣﻌﺎﺩﻟﺔ ﺷـﺎﺭﮊ ﺧـﺎﺯﻥ‬
‫ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ‬
‫‪ .۲.۳‬ﭘﺘﺎﻧﺴﻴﻞ ﻳﺎﺧﺘﺔ ﻏﻴﺮﻫﻢﭘﺘﺎﻧﺴﻴﻞ )ﺍﺳﺘﻮﺍﻧﻪﺍﯼ(‬
‫‪t‬‬
‫ﻫﻤﺎﻥ ﻃﻮﺭ ﮐﻪ ﺩﺭ ﺑﺎﻻ ﺍﺷﺎﺭﻩ ﺷﺪ ﺑﻬﺘﺮﻳﻦ ﻭ ﺳﺎﺩﻩﺗـﺮﻳﻦ ﻣـﺪﻟﻲ ﮐـﻪ‬ ‫‪Vm (t )  I m Rm (1  e  m ),‬‬ ‫‪0 t T‬‬ ‫)‪(۲۳‬‬
‫ﺑﺮﺍﻱ ﺁﮐﺴﻮﻥ ﻭ ﻗﺴﻤﺖﻫـﺎﻳﻲ ﺍﺯ ﺩﻧـﺪﺭﻳﺖ ﻣـﻲﺗـﻮﺍﻥ ﺗﻘﺮﻳـﺐ ﺯﺩ‬ ‫ﮐﻪ ﺛﺎﺑﺖ ﺯﻣﺎﻧﻲ ﻏﺸﺎﺀ ﺩﺭ ﺁﻥ ﺑﺮﺍﺑﺮ ‪ m  RmCm‬ﺍﺳﺖ‪ .‬ﻫﻤﭽﻨـﻴﻦ‬
‫ﺍﺳﺘﻮﺍﻧﻪ ﺍﺳﺖ‪ .‬ﺷـﮑﻞ ‪ ۱۲‬ﻣـﺪﻝ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﭼﻨـﻴﻦ ﺍﺳـﺘﻮﺍﻧﻪﺍﯼ ﺭﺍ‬ ‫ﻣـﻲﺗـﻮﺍﻥ ﺟـﻮﺍﺏ ﻣﻌﺎﺩﻟـﻪ ﺭﺍ‬ ‫‪T‬‬ ‫ﺑﻌﺪ ﺍﺯ ﻗﻄﻊ ﺟﺮﻳﺎﻥ ﺑﻌﺪ ﺍﺯ ﺯﻣـﺎﻥ‬
‫ﻧﺸﺎﻥ ﻣﻲﺩﻫﺪ‪ .‬ﺟﺮﻳﺎﻥ ﻭﺍﺭﺩ ﺷﺪﻩ ﺑﻪ ﺍﻳـﻦ ﺍﺳـﺘﻮﺍﻧﻪ ﺑﻨـﺎ ﺑـﻪ ﻗـﺎﻧﻮﻥ‬ ‫ﻫﻤﺎﻧﻨﺪ ﺗﺨﻠﻴﺔ ﺧﺎﺯﻥ ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ‬
‫‪t‬‬
‫ﺟﺮﻳﺎﻥ ﮐﻴﺮﺷﻬﻒ ﺑﻪ ﺟﺮﻳﺎﻥﻫﺎﻱ ﻏﺸﺎﻳﻲ ‪ im‬ﻭ ﺩﺍﺧﻠﻲ ‪ ii‬ﺗﻘﺴـﻴﻢ‬ ‫‪Vm (t )  I m Rm e  m .‬‬ ‫‪T t‬‬ ‫)‪(۲۴‬‬
‫ﻣﻲﺷﻮﺩ‪ x .‬ﻓﺎﺻـﻠﻪ ﺩﺭ ﻃـﻮﻝ ﺍﺳـﺘﻮﺍﻧﻪ‪ a ،‬ﺷـﻌﺎﻉ ﺍﺳـﺘﻮﺍﻧﻪ‪ri ،‬‬
‫ﺑﻪ ﺳﺎﺩﮔﻲ ﻣﻲﺗﻮﺍﻥ ﺩﻳﺪ ﮐﻪ ﺍﮔﺮ ﺟﺮﻳﺎﻥ ﺑﺮﺍﻱ ﻣﺪﺕ ﻃﻮﻻﻧﻲ ﺍﻋﻤـﺎﻝ‬
‫ﻣﻘﺎﻭﻣـﺖ ﺩﺍﺧﻠـﻲ )ﺳﻴﺘﻮﭘﻼﺳــﻢ( ﻭ ‪ r0‬ﻣﻘﺎﻭﻣـﺖ ﻓﻀـﺎﻱ ﺑﻴــﺮﻭﻥ‬ ‫ﺷــﻮﺩ‪ ،‬ﭘﺘﺎﻧﺴ ـﻴﻞ ﻏﺸــﺎﺀ ﺑﺮﺍﺑــﺮ ‪ Vm ()  ImRm‬ﻣ ـﻲﺷــﻮﺩ‪ .‬ﺍﻳ ـﻦ‬
‫‪۳۵۹‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫) ‪1 2Vm ( x, t‬‬ ‫‪V‬‬ ‫‪V‬‬

‫‪2‬‬
‫‪ cm m  m .‬‬ ‫)‪(۳۰‬‬
‫‪ri‬‬ ‫‪x‬‬ ‫‪t‬‬ ‫‪rm‬‬
‫ﻣﻌﺎﺩﻟﺔ )‪ (۳۰‬ﻣﻌﺎﺩﻟﺔ ﮐﺎﺑﻞ ﻧﺎﻡ ﺩﺍﺭﺩ‪ .‬ﻣﻌﺎﺩﻟﺔ ﮐﺎﺑﻞ ﺑﺴﻴﺎﺭ ﺭﺍﺑﻄﺔ ﻣﻬﻤﻲ‬
‫ﺍﺳﺖ ﮐﻪ ﺩﺭ ﻣﻮﺍﺭﺩ ﺯﻳﺎﺩﻱ‪ ،‬ﺍﺯ ﺟﻤﻠﻪ ﮐﺎﺑﻞ ﺑـﻲﻧﻬﺎﻳـﺖ ﺑﻠﻨـﺪ‪ ،‬ﮐﺎﺑـﻞ‬
‫ﻣﺤﺪﻭﺩ‪ ،‬ﻭ ﮐﺎﺑﻞ ﻣﺤﺪﻭﺩ ﺑﺎ ﺑﺪﻧﺔ ﮐﺮﻭﻱ ﻳﺎﺧﺘﻪ ﮐـﺎﺭﺑﺮﺩ ﺩﺍﺭﺩ‪ .‬ﺛﺎﺑـﺖ‬
‫ﺯﻣﺎﻧﻲ ﻏﺸﺎﺀ ﺑﺮﺍﺑﺮ ﺍﺳﺖ ﺑﺎ‪:‬‬
‫‪ m  rmcm  RmCm ,‬‬ ‫)‪(۳۱‬‬ ‫ﺷﮑﻞ ‪ .۱۳‬ﻣﺪﻝ ﺁﺏ ﻧﺒﺎﺕ ﭼﻮﺑﻲ ﻧﻮﺭﻭﻥ ﻫﻤﺮﺍﻩ ﺑﺎ ﻣﺪﺍﺭ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻌﺎﺩﻝ ﺁﻥ‪.‬‬
‫ﻣﻲﺗﻮﺍﻥ ﺍﻳﻦ ﻣﻌﺎﺩﻟﻪ ﺭﺍ ﺑﻪ ﺻﻮﺭﺗﻲ ﺩﻳﮕﺮ ﻧﻮﺷـﺖ ﺗـﺎ ﺛﺎﺑـﺖ ﻣﮑـﺎﻧﻲ‬
‫ﻳﺎﺧﺘﻪﺍﯼ ﺍﺳﺖ‪.‬‬
‫ﮐﺎﺑﻞ ﻧﻴﺰ ﻣﺤﺎﺳﺒﻪ ﺷﻮﺩ‬
‫ﺑﺮﺍﻱ ﺳﺎﺩﮔﻲ ﺑﻴﺸﺘﺮ ﭼﻨﺪ ﻓﺮﺽ ﺭﺍ ﺍﻧﺠﺎﻡ ﻣﻲﺩﻫـﻴﻢ‪ .‬ﺍﻭﻝ ﺍﻳـﻦ‬
‫‪2‬‬ ‫) ‪2Vm ( x, t‬‬ ‫‪V‬‬
‫‪‬‬ ‫‪  m m  Vm ,‬‬ ‫)‪(۳۲‬‬ ‫ﮐﻪ ﻓﻀﺎﻱ ﺑﻴﺮﻭﻥ ﻳﺎﺧﺘﻪ ﻫﻢ ﭘﺘﺎﻧﺴﻴﻞ ﺍﺳﺖ‪ .‬ﺑﻪ ﻋﺒﺎﺭﺕ ﺩﻳﮕﺮ ‪r0 0‬‬
‫‪x2‬‬ ‫‪t‬‬
‫‪rm‬‬ ‫ﺍﺳﺖ‪ .‬ﺍﻣﺎ ‪ r0‬ﻣﻲﺗﻮﺍﻧﺪ ﺩﺭ ﻣﻮﺍﺭﺩﻱ ﻣﺎﻧﻨﺪ ﺣﺎﻟﺘﻲ ﮐﻪ ﺁﮐﺴـﻮﻥﻫـﺎ ﺩﺭ‬
‫‪  ‬ﺍﺳـﺖ‪ .‬ﺩﺭ ﺻـﻮﺭﺗﻲ ﮐـﻪ ﻣﻘﺎﻭﻣـﺖ ﻓﻀـﺎﻱ‬ ‫ﮐﻪ ﺩﺭ ﺁﻥ‬
‫‪ri‬‬
‫ﻳﮏ ﺧﺮﻃﻮﻣﻲ ﻋﺼﺒﻲ ﺑﻪ ﺻﻮﺭﺕ ﻓﺸﺮﺩﻩ ﺣﻀﻮﺭ ﺩﺍﺷـﺘﻪ ﺑﺎﺷـﻨﺪ‪ ،‬ﻭ‬
‫ﺑـﻪ ﺻـﻮﺭﺕ‬ ‫‪‬‬ ‫ﺑﻴﺮﻭﻥ ﻳﺎﺧﺘﻪﺍﯼ ﻫﻢ ﺩﺭ ﻧﻈـﺮ ﮔﺮﻓﺘـﻪ ﺷـﻮﺩ‪ ،‬ﺗﻨﻬـﺎ‬
‫ﻳﺎ ﺩﺭ ﻧﻮﺭﻭﻥﻫﺎﻱ ‪ CNS‬ﮐﻪ ﺟﺮﻳﺎﻥ ﺟﺎﺭﻱ ﺷﺪﻩ ﺩﺭ ﻓﻀـﺎﻱ ﺑﻴـﺮﻭﻥ‬
‫‪rm‬‬
‫‪  ‬ﺗﻐﻴﻴﺮ ﻣﻲﮐﻨـﺪ ﮐـﻪ ‪ ro‬ﻣﻘﺎﻭﻣـﺖ ﺩﺭ ﻭﺍﺣـﺪ ﻃـﻮﻝ‬ ‫ﻳﺎﺧﺘﻪﺍﯼ ﺯﻳﺎﺩ ﺑﺎﺷﺪ ﻣﻬﻢ ﺍﺳﺖ ﻭ ﺑﺎﻳﺪ ﺩﺭ ﻣﺪﻝ ﮔﻨﺠﺎﻧﺪﻩ ﺷـﻮﺩ‪ .‬ﺩﻭﻡ‬
‫‪ri  ro‬‬
‫‪‬‬ ‫ﺍﻳﻦ ﮐﻪ ﭘﺎﺭﺍﻣﺘﺮﻫﺎﻱ ﻏﺸﺎﺀ ﺧﻄﻲ ﻭ ﻳﮑﻨﻮﺍﺧﺖ ﻫﺴـﺘﻨﺪ‪ .‬ﺑـﻪ ﻋﺒـﺎﺭﺕ‬
‫) ( ﺍﺳﺖ‪ .‬ﺍﮔﺮ ﺩﻭ ﭘﺎﺭﻣﺘﺮ ﺑﺪﻭﻥ ﺑﻌﺪ ﺛﺎﺑﺖ ﻃﻮﻝ ‪ X  x / ‬ﻭ‬
‫‪cm‬‬ ‫ﺩﻳﮕﺮ ‪ ri , rm‬ﻭ ‪ Cm‬ﺛﺎﺑﺖ ﻫﺴﺘﻨﺪ‪ .‬ﺍﻧﺪﺍﺯﺓ ﺁﻧﻬﺎ ﺩﺭ ﻫﻤﺔ ﻧﻘﺎﻁ ﻧﻮﺭﻭﻥ‬
‫ﺛﺎﺑﺖ ﺯﻣﺎﻥ ‪ T  t / m‬ﺭﺍ ﺟﻬﺖ ﻫﻨﺠﺎﺭﺵ ﻣﻌﺎﺩﻟـﺔ ﮐﺎﺑـﻞ ﻣﻌﺮﻓـﻲ‬
‫ﻳﮑﺴﺎﻥ ﺑﻮﺩﻩ ﻭ ﺗﺎﺑﻊ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﻧﻴﺴﺘﻨﺪ‪ .‬ﺳﻮﻡ ﻓـﺮﺽ ﻣـﻲﮐﻨـﻴﻢ‬
‫ﮐﻨﻴﻢ‪ ،‬ﻣﻌﺎﺩﻟﺔ ﮐﺎﺑﻞ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﻧﻮﺷﺘﻪ ﻣﻲﺷﻮﺩ‪:‬‬
‫ﺟﺮﻳﺎﻥ ﺑﻪ ﻃﻮﺭ ﻳﮏﺑﻌﺪﻱ ﺩﺭ ﺭﺍﺳﺘﺎﻱ ﻃﻮﻝ ﮐﺎﺑﻞ ﺟﺮﻳـﺎﻥ ﺩﺍﺭﺩ ﻭ ﺍﺯ‬
‫‪2Vm‬‬ ‫‪V‬‬
‫‪ m  Vm  0 .‬‬ ‫)‪(۳۳‬‬ ‫ﺍﻳﻦﺭﻭ ﺟﺮﻳﺎﻥ ﺷﻌﺎﻋﻲ ﺭﺍ ﺑﺮﺍﺑﺮ ﺻﻔﺮ ﻓﺮﺽ ﻣﻲﮐﻨﻴﻢ‪ .‬ﺍﮔﺮ ﺟﺮﻳﺎﻥ ﺩﺭ‬
‫‪X 2‬‬ ‫‪T‬‬
‫ﺟﻮﺍﺏ ﺍﻳـﻦ ﻣﻌﺎﺩﻟـﻪ ﺗﻮﺳـﻂ ﮔـﺮﻭﻩﻫـﺎﻱ ﻣﺨﺘﻠـﻒ ﺑـﺮﺍﻱ ﺷـﺮﺍﻳﻂ‬ ‫ﻧﻘﻄﻪﺍﻱ ﺩﺭ ﻃﻮﻝ ﺍﺳﺘﻮﺍﻧﻪ ﺗﺰﺭﻳﻖ ﺷﻮﺩ‪ ،‬ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﯼ ﺍﺳﺘﻮﺍﻧﻪ ‪Vm‬‬

‫ﻣﺸﺨﺺ ﺍﺭﺍﺋﻪ ﺷﺪﻩ ﺍﺳﺖ ]‪ .[۳‬ﺑﻪ ﻋﻨﻮﺍﻥ ﻣﺜﺎﻝ ﺑﺮﺍﻱ ﮐﺎﺑﻞ ﺑﻲﻧﻬﺎﻳﺖ‬ ‫ﺗﺎﺑﻌﻲ ﺍﺯ ﺯﻣﺎﻥ ﻭ ﻓﺎﺻﻠﻪ ﺍﺯ ﻣﺤﻞ ﺗﺰﺭﻳﻖ ﺧﻮﺍﻫﺪ ﺑﻮﺩ‬
‫) ‪Vm ( x, t‬‬
‫ﺑﻠﻨﺪ ﻭ ﺟﺮﻳﺎﻥ ﭘﻠﻪﺍﻱ‪ ،‬ﺟﻮﺍﺏ ﻋﻤﻮﻣﻲ ﻣﻌﺎﺩﻟﺔ ﮐﺎﺑﻞ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳـﺮ‬ ‫‪  ri ii .‬‬ ‫)‪(۲۷‬‬
‫‪x‬‬
‫ﺍﺳﺖ‪:‬‬ ‫ﺍﻳﻦ ﻫﻤﺎﻥ ﻗﺎﻧﻮﻥ ﺍُﻫﻢ ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺍﺳﺘﻮﺍﻧﻪ ﻣﻲﺗﻮﺍﻧﺪ ﺩﺍﺭﺍﻱ ﻧﺸﺖ ﻫـﻢ‬
‫‪ri I0   X‬‬ ‫‪X‬‬ ‫ﺑﺎﺷﺪ‪ .‬ﻣﻘﺪﺍﺭ ﻧﺸﺘﻲ ﺟﺮﻳﺎﻥ )ﻣﺎﻧﻨﺪ ﻳﮏ ﺷﻴﻠﻨﮓ ﺳـﻮﺭﺍﺥﺩﺍﺭ( ﮐـﻪ ﺩﺭ‬
‫‪Vm (T , X ) ‬‬ ‫(‪e erfc‬‬ ‫)‪ T‬‬
‫‪4 ‬‬ ‫‪2 T‬‬
‫)‪(۳۴‬‬ ‫ﺟﻬﺖ ﺷﻌﺎﻋﻲ ﺍﺳﺘﻮﺍﻧﻪ ﺧﺎﺭﺝ ﻣﻲﺷﻮﺩ‪ ،‬ﺑﺮﺍﺑﺮ ﺍﺳﺖ ﺑﺎ ﻣﻘﺪﺍﺭ ﮐﺎﻫﺶ‬
‫‪X‬‬‫‪‬‬
‫(‪e erfc‬‬ ‫‪X‬‬
‫‪ T ) ,‬‬ ‫ﺟﺮﻳﺎﻥ ﺩﺭ ﻃﻮﻝ ﮐﺎﺑﻞ ﻳﻌﻨﻲ‪:‬‬
‫‪2 T‬‬ ‫‪‬‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ) ‪ erfc ( X‬ﺗﺎﺑﻊ ﺧﻄﺎﻱ ﺍﻟﺤﺎﻗﻲ ﻭ ) ‪ erf ( X‬ﺗﺎﺑﻊ ﺧﻄـﺎ‬ ‫‪ii‬‬
‫‪ im ,‬‬ ‫)‪(۲۸‬‬
‫‪x‬‬
‫ﺍﺳﺖ‪ .‬ﻣﻌﻤﻮﻻً ﺟﻮﺍﺏﻫﺎﻱ ﺣﺎﻟﺖ ﭘﺎﻳـﺎ )‪ Vm(, x‬ﻭ ﮔـﺬﺭﺍﻱ ﺁﻥ‬ ‫ﺑﻨﺎﺑﺮﺍﻳﻦ ﻣﻲﺗﻮﺍﻥ ﻧﻮﺷﺖ‬
‫)‪ Vm (t, x‬ﻣﻮﺭﺩ ﺑﺤﺚ ﻗﺮﺍﺭ ﻣﻲﮔﻴﺮﺩ‪ .‬ﺑﺎ ﺭﺳﻢ ﻧﻤـﻮﺩﺍﺭ )‪Vm (t, x‬‬
‫) ‪2Vm ( x, t‬‬ ‫‪ii‬‬
‫‪  ri‬‬ ‫‪ ri im .‬‬ ‫)‪(۲۹‬‬
‫ﻣﻲﺗﻮﺍﻥ ﺗﻐﻴﻴﺮﺍﺕ ﭘﺘﺎﻧﺴﻴﻞ ﺩﺭ ﻧﻘـﺎﻁ ﻣﺨﺘﻠـﻒ‬ ‫‪t‬‬ ‫ﻧﺴﺒﺖ ﺑﻪ ﺯﻣﺎﻥ‬ ‫‪x‬‬ ‫‪2‬‬ ‫‪x‬‬
‫‪.[۴۵‬‬ ‫ﮐﺎﺑﻞ ﺭﺍ ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﺩ ]‪ ۴۴ ،۳‬ﻭ‬ ‫ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺍﻳﻦ ﮐﻪ ﺟﺮﻳﺎﻥ ﻏﺸﺎﺀ ﺑﺮﺍﺑﺮ ﺍﺳﺖ ﺑـﺎ ﺟﺮﻳـﺎﻥ ﺧـﺎﺯﻧﻲ ﻭ‬
‫ﺑﺮﺍﻱ ﺗﺤﻠﻴﻞ ﻧﻮﺭﻭﻥ ﺑﻬﺘﺮ ﺍﺳﺖ ﻣﻌﺎﺩﻟﺔ ﮐﺎﺑﻞ ﺭﺍ ﺑﺮﺍﻱ ﮐﺎﺑـﻞ ﺑـﺎ‬ ‫ﺟﺮﻳــﺎﻥ ﻳــﻮﻧﻲ ) ‪ ، (Im  IC  Ii‬ﻣﻌﺎﺩﻟــﺔ )‪ (۲۹‬ﺭﺍ ﻣــﻲﺗــﻮﺍﻥ ﺑــﻪ‬
‫ﺻﻮﺭﺕ ﺯﻳﺮ ﺑﺎﺯﻧﻮﻳﺴﻲ ﮐﺮﺩ‪:‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۶۰‬‬

‫ﺑﺎﺷﺪ )ﺯﻣـﺎﻧﻲ‬
‫‪[C ]out‬‬
‫‪1‬‬ ‫ﮐﺎﺗﻴﻮﻧﻲ‪ ،‬ﺩﻳﺪﻩ ﻣﻲﺷﻮﺩ ﺩﺭ ﺻﻮﺭﺗﻲ ﮐﻪ‬ ‫ﻃﻮﻝ ﻣﺤﺪﻭﺩ ﻭ ﺟﺮﻳﺎﻥ ﭘﻠﻪﺍﻱ ﺣﻞ ﮐﻨﻴﻢ‪ .‬ﺑﺎ ﺍﻋﻤﺎﻝ ﺷﺮﺍﻳﻂ ﻣـﺮﺯﻱ‬
‫‪[C ]in‬‬
‫ﻣﻲﺗﻮﺍﻥ ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎﺀ ﺭﺍ ﺑﺮﺣﺴﺐ ﺯﻣﺎﻥ ﻭ ﻣﮑﺎﻥ ﺑﻪ ﺩﺳـﺖ ﺁﻭﺭﺩ‪.‬‬
‫ﮐﻪ ‪ E r‬ﻣﺜﺒﺖ ﺑﺎﺷﺪ( ﺟﺮﻳﺎﻥ ﻳﻮﻧﻲ ﺗﮏﺳﻮﻳﻪ ﺩﺭﻭﻥﺭﻭﻧـﺪﻩ ﺑـﻮﺩﻩ‪ ٢‬ﻭ‬
‫ﺳﭙﺲ ﺑﺎ ﺗﺮﮐﻴﺐ ﻳﮏ ﺍﺳﺘﻮﺍﻧﺔ ﻣﺤﺪﻭﺩ ﺑﺎ ﻳﮏ ﻳﺎﺧﺘﻪ ﮐﺮﻭﻱ ﮐﻪ ﺑـﻪ‬
‫‪[C ]out‬‬
‫ﺑﺎﺷﺪ )ﺯﻣﺎﻧﻲ ﮐـﻪ ‪ E r‬ﻣﻨﻔـﻲ ﺑﺎﺷـﺪ(‬ ‫‪1‬‬ ‫ﺩﺭ ﺻﻮﺭﺗﻲ ﮐﻪ‬
‫‪[C ]in‬‬ ‫ﺍﻧﺘﻬﺎﻱ ﺁﻥ ﭼﺴﺒﻴﺪﻩ ﺍﺳـﺖ )ﻣـﺪﻝ ﺁﺏ ﻧﺒـﺎﺕ ﭼـﻮﺑﻲ(‪ ،‬ﻣـﻲﺗـﻮﺍﻥ‬
‫‪٣‬‬
‫ﺟﺮﻳﺎﻥ ﻳﻮﻧﻲ ﺗﮏﺳﻮﻳﻪ ﺑﻴﺮﻭﻥﺭﻭﻧﺪﻩ ﺍﺗﻔﺎﻕ ﻣﻲﺍﻓﺘـﺪ‪ .‬ﻫﺮﭼﻨـﺪ ﺍﻳـﻦ‬ ‫ﺳﺎﺩﻩﺗﺮﻳﻦ ﻣﺪﻝ ﺭﺍ ﺑﺮﺍﻱ ﻧﻮﺭﻭﻥ ﺣﻞ ﮐﺮﺩ‪ .‬ﺷﮑﻞ ‪ ۱۳‬ﺳﺎﺧﺘﺎﺭ ﺍﻳـﻦ‬
‫ﻣﺪﻝ ﺑﺮﺍﻱ ﺗﻮﺻﻴﻒ ﻣﻮﺭﺩﻫﺎﻳﻲ ﻣﺎﻧﻨﺪ ﺭﺳﺎﻧﺶ ﮐﻠﺮﺍﻳﺪ ﺩﺭ ﻋﻀـﻼﺕ‬ ‫ﻧﻮﺭﻭﻥ ﺳﺎﺩﻩ ﺭﺍ ﻫﻤﺮﺍﻩ ﺑﺎ ﻣﺪﺍﺭ ﻣﻌﺎﺩﻝ ﺁﻥ ﻧﺸﺎﻥ ﻣﻲﺩﻫﺪ‪ .‬ﺍﮔـﺮ ﻳـﮏ‬
‫ﺍﺳﺘﺨﻮﺍﻧﻲ ﻭ ﻫﻤﭽﻨﻴﻦ ﺑﺮﺍﻱ ﺭﺍﺑﻄﺔ ‪ I  V‬ﺁﻧـﻲ ﮐﺎﻧـﺎﻝﻫـﺎﻱ ‪ Na ‬ﻭ‬ ‫ﻧﻮﺭﻭﻥ ﺩﺍﺭﺍﻱ ﺗﻌﺪﺍﺩ ﺑﻴﺸﺘﺮﻱ ﺩﻧـﺪﺭﻳﺖ ﻭ ﻳـﺎ ﺁﮐﺴـﻮﻥ ﺑـﻪ ﻫﻤـﺮﺍﻩ‬

‫‪ K‬ﺩﺭ ﺍﻋﺼﺎﺏ ﺩﺍﺭﺍﻱ ﭘﻴﻪ ﻏﻼﻑ‪ ٤‬ﻣﻨﺎﺳـﺐ ﺍﺳـﺖ‪ ،‬ﻭﻟـﻲ ﻣـﻮﺍﺭﺩ‬ ‫ﺩﻧﺪﺭﻳﺖﻫﺎ ﺑﺎﺷﺪ ﻣـﻲﺗـﻮﺍﻥ ﺑـﻪ ﮐﻤـﮏ ﻣـﺪﻝ ﺭﺍﻝ‪ ١‬ﻃـﻮﻝ ﻣﻌـﺎﺩﻝ‬

‫ﻓﺮﺍﻭﺍﻧﻲ ﻭﺟﻮﺩ ﺩﺍﺭﻧﺪ ﮐﻪ ﺍﻳﻦ ﻣﺪﻝ ﻗﺎﺩﺭ ﺑـﻪ ﺗﻮﺻـﻴﻒ ﺁﻧﻬـﺎ ﻧﻴﺴـﺖ‬ ‫ﺍﻟﮑﺘﺮﻭﻧﻴﮑﻲ ﻫﺮ ﮐﺪﺍﻡ ﺍﺯ ﺩﻧﺪﺭﻳﺖﻫﺎ ﻭ ﺁﮐﺴﻮﻥ ﺭﺍ ﺑـﻪ ﺩﺳـﺖ ﺁﻭﺭﺩ‬

‫]‪.[۳‬‬ ‫ﻭ ﺳﭙﺲ ﻫﻤﺔ ﺍﻳﻦ ﺍﺳﺘﻮﺍﻧﻪﻫﺎ ﺭﺍ ﺑﺎ ﻳﮏ ﺍﺳﺘﻮﺍﻧﺔ ﺗﻨﻬﺎ ﺑـﻪ ﻃـﻮﻝ ‪ L‬ﻭ‬
‫ﺗﻘﺮﻳﺐ ﺯﺩ‪.‬‬ ‫‪d‬‬ ‫ﻗﻄﺮ‬

‫‪ .۲.۳.۳‬ﻣﺪﻝ ﺳﺪ ﺍﻧﺮﮊﻱ )ﻧﻈﺮﻳﺔ ﻧﺮﺥ ﺍﻳﺮﻳﻨﮓ‪(٥‬‬

‫‪...۳.۳‬ﺧﺼﻮﺻﻴﺎﺕ ﻏﻴﺮﺧﻄﻲ ﻏﺸﺎﻫﺎﻱ ﺗﺤﺮﻳﮏﭘﺬﻳﺮ‬
‫ﺭﺍ ﺑــﺎ ﺍﺳــﺘﻔﺎﺩﻩ ﺍﺯ ﺭﺍﻫﮑــﺎﺭ‬ ‫‪I V‬‬ ‫ﺍﻳ ـﻦ ﺭﻭﺵ ﺭﺍﺑﻄ ـﺔ ﻏﻴ ـﺮﺧﻄ ـﻲ‬
‫ﺗﺎ ﺍﻳﻨﺠﺎ ﺭﺳﺎﻧﺶ ﻏﺸﺎﻫﺎ ﺭﺍ ﺛﺎﺑﺖ ﺩﺭ ﻧﻈﺮ ﮔـﺮﻓﺘﻴﻢ‪ ،‬ﻳﻌﻨـﻲ ﺭﺍﺑﻄـﺔ‬
‫ﺗﺮﻣﻮﺩﻳﻨﺎﻣﻴﮑﻲ ﻣﺪﻝ ﻣﻲﮐﻨـﺪ‪ .‬ﺑـﻪ ﺍﻳـﻦ ﺗﺮﺗﻴـﺐ ﮐـﻪ ﺿـﺮﺍﻳﺐ ﻧـﺮﺥ‬
‫ﻭﻟﺘﺎﮊ‪ -‬ﺟﺮﻳﺎﻥ ﺭﺍ ﺧﻄﻲ ﻓﺮﺽ ﮐﺮﺩﻳﻢ‪ .‬ﻭﻟـﻲ ﺩﺭ ﻭﺍﻗـﻊ ﻣﺤـﺪﻭﺩﺓ‬
‫ﺑﺮﻫﻢﮐﻨﺶﻫـﺎﻱ ﺷـﻴﻤﻴﺎﻳﻲ ﺑـﻪ ﮐﻤـﮏ ﺳـﺪﻫﺎﻱ ﺍﻧـﺮﮊﻱ ﮐـﻪ ﻣـﻮﺍﺩ‬
‫ﺧﻄﻲ ﺍﺳﺖ ﺑﺴﻴﺎﺭ ﻣﺤﺪﻭﺩ ﺑـﻮﺩﻩ‬ ‫‪I V‬‬ ‫ﻭﻟﺘﺎﮊﻱ ﮐﻪ ﺩﺭ ﺁﻥ ﺭﺍﺑﻄﺔ‬
‫ﺑﺮﻫﻢﮐﻨﺶﮐﻨﻨﺪﻩ ﺑﺎﻳـﺪ ﺍﺯ ﺁﻥ ﻋﺒـﻮﺭ ﮐﻨﻨـﺪ ﺑﻴـﺎﻥ ﻣـﻲﺷـﻮﻧﺪ‪ .‬ﺑـﺮﺍﻱ‬
‫ﺩﺍﺭﻧـﺪ‪ .‬ﻣﻌﻤـﻮﻻً‬ ‫‪I V‬‬ ‫ﻭ ﺍﮐﺜﺮ ﻏﺸﺎﻫﺎﻱ ﺯﻳﺴﺘﻲ ﺭﺍﺑﻄﺔ ﻏﻴﺮﺧﻄﻲ‬
‫ﺟﺮﻳﺎﻥ ﻫﺎﻱ ﻳﻮﻧﻲ‪ ،‬ﺍﻳﻦ ﻣﺪﻝ ﻓﺮﺽ ﻣﻲﮐﻨﺪ ﮐﻪ ﻫﺮ ﻳﻮﻥ ﻋﺒﻮﺭﮐﻨﻨـﺪﻩ‬
‫ﺧﺼﻮﺻﻴﺎﺕ ﻏﻴﺮﺧﻄﻲ ﻏﺸﺎﺀ ﺍﺯ ﻭﺍﺑﺴﺘﮕﻲ ﺑﻪ ﻭﻟﺘـﺎﮊ ﻭ ﺯﻣـﺎﻥ ﺑـﻪ‬
‫ﺍﺯ ﻏﺸﺎﺀ ﺑﺎﻳﺪ ﺍﺯ ﻳﮏ ﺳﺪ ﺍﻧﺮﮊﻱ ﺑﮕﺬﺭﺩ )ﻣﺪﻝ ﺳﺪ ﺗـﮏ‪ -‬ﺍﻧـﺮﮊﻱ(‪.‬‬
‫ﻭﺟﻮﺩ ﻣﻲﺁﻳﺪ‪ .‬ﺟﻬﺖ ﻣﺪﻝﺳﺎﺯﻱ ﺧﺼﻮﺻﻴﺎﺕ ﻏﻴﺮﺧﻄـﻲ ﻏﺸـﺎﺀ‬
‫ﺑﺮﺍﻱ ﻣﺪﻝﻫﺎﻱ ﭘﻴﭽﻴﺪﻩﺗﺮ ﻣﻲﺗﻮﺍﻥ ﭼﻨﺪﻳﻦ ﺳﺪ ﺍﻧـﺮﮊﻱ )ﻣـﺪﻝ ﺳـﺪ‬
‫ﻣﺪﻝﻫﺎﻱ ﻣﺨﺘﻠﻔﻲ ﺍﺭﺍﺋﻪ ﺷﺪﻩ ﺍﺳﺖ ﮐﻪ ﺩﺭ ﺯﻳﺮ ﺑﻪ ﺳـﻪ ﻣـﻮﺭﺩ ﺁﻥ‬
‫ﭼﻨﺪ‪ -‬ﺍﻧﺮﮊﻱ( ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺖ‪ .‬ﺑﻨﺎ ﺑـﻪ ﻗـﺎﻧﻮﻥ ﮐـﻨﺶ ﺟﺮﻣـﻲ ﺑـﺮﺍﻱ‬
‫ﺍﺷﺎﺭﻩ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﻣﺪﻝﻫـﺎ ﻧـﻪ ﺗﻨﻬـﺎ ﺑـﻪ ﺧـﻮﺩﻱ ﺧـﻮﺩ ﺑﺴـﻴﺎﺭ‬
‫ﺑﺮﻫﻢﮐﻨﺶﻫﺎﻱ ﺷﻴﻤﻴﺎﻳﻲ‪ ،‬ﺷﺎﺭ ﻳﮏ ﮐﻨﺶﮐﻨﻨﺪﻩ ﻣﺘﻨﺎﺳﺐ ﺑـﺎ ﻏﻠﻈـﺖ‬
‫ﺁﻣﻮﺯﻧﺪﻩ ﻫﺴﺘﻨﺪ‪ ،‬ﺑﻠﮑﻪ ﻣﻲﺗﻮﺍﻧﻨﺪ ﺑﻪ ﻋﻨـﻮﺍﻥ ﭘﺎﻳـﻪﺍﻱ ﺑـﺮﺍﻱ ﺍﺭﺍﺋـﺔ‬
‫ﻧﺎﻣﻴﺪﻩ ﻣـﻲﺷـﻮﺩ‪.‬‬ ‫‪k‬‬ ‫ﺁﻥ ﺍﺳﺖ‪ ،‬ﻭ ﺿﺮﻳﺐ ﺗﻨﺎﺳﺐ ﺁﻥ ﺿﺮﻳﺐ ﻧﺮﺥ‬
‫ﻣﺪﻝﻫﺎﻱ ﺑﻬﺘﺮ ﻭ ﭘﻴﭽﻴﺪﻩﺗﺮ ﺑﺮﺍﻱ ﺷﺮﺍﻳﻂ ﻣﺨﺘﻠﻒ ﺑﺎﺷﻨﺪ‪.‬‬
‫ﺑﻨﺎﺑﺮﺍﻳﻦ ﺑﺮﺍﻱ ﺷﺎﺭ ﻳـﻮﻧﻲ ﻋﺒﻮﺭﮐﻨﻨـﺪﻩ ﺍﺯ ﻳـﮏ ﺳـﺪ ﺗـﮏ‪ -‬ﺍﻧـﺮﮊﻱ‬
‫ﻣﻲﺗﻮﺍﻥ ﺷﺎﺭ ﻭﺭﻭﺩﻱ ﻭ ﺷﺎﺭ ﺧﺮﻭﺟﻲ ﺭﺍ ﭼﻨﻴﻦ ﻧﻮﺷﺖ‪:‬‬ ‫)‪(GHK‬‬ ‫‪ .۱.۳.۳‬ﻣﺪﻝ ﻣﻴﺪﺍﻥ ﺛﺎﺑﺖ‬
‫‪Jinward  k1[C]out ,‬‬ ‫ﺍﻳﻦ ﻣﺪﻝ ﻫﻤﺎﻥ ﻃﻮﺭ ﮐﻪ ﺩﺭ ﺑﺨﺶ ‪ ۴-۳-۲‬ﺍﺷﺎﺭﻩ ﺷـﺪ‪ ،‬ﺑـﻪ ﮐﻤـﮏ‬
‫‪Joutward  k 2[C]in ,‬‬ ‫)‪(۳۶‬‬ ‫ﻣﻌﺎﺩﻟﺔ ﻧﺮﻧﺴﺖ‪-‬ﭘﻼﻧﮏ ﻭ ﺑﺎ ﻓﺮﺽ ﻣﻴﺪﺍﻥ ﺛﺎﺑﺖ ﺩﺭ ﻋﺮﺽ ﻏﺸـﺎﺀ ﻭ‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ J‬ﺷـﺎﺭ ﻳـﻮﻧﻲ ﺗـﮏﺳـﻮﻳﻪ‪ k1 ،‬ﻭ ‪ k2‬ﺿـﺮﺍﻳﺐ ﻧـﺮﺥ‪ ،‬ﻭ ‪‬‬
‫ﺭﺍ ﺑـﻪ‬ ‫‪I V‬‬ ‫ﻣﺴﺘﻘﻞ ﺍﺯ ﻫﻢ ﺑﻮﺩﻥ ﺣﺮﮐﺖ ﻳﻮﻥﻫﺎ‪ ،‬ﺭﺍﺑﻄﺔ ﻏﻴﺮﺧﻄـﻲ‬
‫ﺿﺮﻳﺐ ﺟﺪﺍﻳﻲ ﻏﺸﺎ‪ -‬ﺁﺏ ﺑﺮﺍﻱ ﻳﻮﻥ ﺍﺳﺖ‪ .‬ﺩﺭ ﺗﻌـﺎﺩﻝ ﺗﺮﻣﻮﺩﻳﻨـﺎﻣﻴﮑﻲ‪،‬‬ ‫ﺻﻮﺭﺕ ﺯﻳﺮ ﺗﻮﺟﻴﻪ ﻣﻲﮐﻨﺪ‪:‬‬
‫ﺿـﺮﺍﻳﺐ ﻧـﺮﺥ ﺑـﻪ ﮐﻤـﮏ ﺛﺎﺑـﺖ ﺑـﻮﻟﺘﺰﻣﻦ ﺑـﻪ ﺍﻧـﺮﮊﻱ ﺁﺯﺍﺩ ﺍﺳـﺘﺎﻧﺪﺍﺭﺩ‬ ‫‪ zVF‬‬
‫‪2 2‬‬
‫‪z F‬‬ ‫‪[C ]  [C ]out‬‬ ‫‪e RT‬‬
‫____________________________________________‬ ‫‪IP‬‬ ‫‪V ( in‬‬
‫‪ zVF‬‬
‫)‬ ‫)‪(۳۵‬‬
‫‪2. Inward rectify‬‬ ‫‪RT‬‬
‫‪1  e RT‬‬
‫‪3. Outward rectify‬‬ ‫ﺑﻪ ﮐﻤﮏ ﺍﻳﻦ ﻣﺪﻝ ﺑـﺮﺍﻱ ﺟﺮﻳـﺎﻥ ﻫـﺎﻱ‬ ‫‪I V‬‬ ‫ﺑﺎ ﺭﺳﻢ ﻧﻤﻮﺩﺍﺭﻫﺎﻱ‬
‫‪4. Myelinated nerves‬‬ ‫____________________________________________‬
‫‪5. Ring rate theory‬‬ ‫‪1. Rall‬‬
‫‪۳۶۱‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﻏﻴﺮﺧﻄﻲ ﺑﻮﺩﻥ ﻏﺸﺎﺀ ﻳﻌﻨﻲ ﻭﺍﺑﺴﺘﮕﻲ ﺭﺳﺎﻧﺶ ﻳﻮﻧﻲ ﺑـﻪ ﺯﻣـﺎﻥ ﺭﺍ ﺩﺭ‬ ‫ﻓﻌــــﺎﻝﺳــــﺎﺯﻱ ‪ G0‬ﻋﺒﻮﺭﮐﻨﻨــــﺪﻩ ﺍﺯ ﻏﺸــــﺎﺀ ﺑــــﻪ ﺻــــﻮﺭﺕ‬
‫ﻣﺪﻝ ﺑﮕﻨﺠﺎﻧﻨﺪ‪ .‬ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴﻠﻲ ﺟﻬﺖ ﺩﺭ ﻧﻈﺮ ﮔـﺮﻓﺘﻦ ﻫـﺮ ﺩﻭ‬ ‫‪ k1  k2  AeG0 / RT‬ﻣﺮﺑﻮﻁ ﻣﻲﺷﻮﻧﺪ‪.‬‬
‫ﻋﺎﻣﻞ ﻭﻟﺘﺎﮊ ﻭ ﺯﻣﺎﻥ ﺩﺭ ﺭﺳﺎﻧﺶﻫﺎﻱ ﻳـﻮﻧﻲ ﺁﮐﺴـﻮﻥ ﺍﺳـﮑﻮﺋﻴﺪ ﻣـﺪﻝ‬ ‫ﺍﮔﺮ ﻳﮏ ﻣﻴﺪﺍﻥ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑﻪ ﻏﺸﺎﺀ ﺍﻋﻤﺎﻝ ﺷﻮﺩ‪ ،‬ﺳـﺪ ﺍﻧـﺮﮊﻱ ﺑـﺮﺍﻱ‬
‫ﺩﺭﻭﺍﺯﻩﺍﻱ ﺭﺍ ﺍﺭﺍﺋﻪ ﮐﺮﺩﻧﺪ‪ .‬ﺍﻳﻦ ﺩﺭﻭﺍﺯﻩﻫﺎ ﺩﺭ ﺩﺍﺧﻞ ﮐﺎﻧﺎﻝﻫـﺎﻱ ﻳـﻮﻧﻲ‬ ‫ﻳﻮﻥﻫﺎﻱ ﻧﻔﻮﺫﭘﺬﻳﺮ ﺑﺎ ﻋﺎﻣﻞ ‪  z F V‬ﺗﺤﺖ ﺗﺄﺛﻴﺮ ﻗـﺮﺍﺭ ﻣـﻲﮔﻴـﺮﺩ‪ ،‬ﮐـﻪ‬
‫)ﭘﺮﻭﺗﺌﻴﻦ( ﻋﺒﻮﺭ ﻳﻮﻥﻫﺎ ﺭﺍ ﮐﻨﺘـﺮﻝ ﻣـﻲﮐﻨﻨـﺪ‪ .‬ﻋﺎﻣـﻞ ﺍﻳـﻦ ﺩﺭﻭﺍﺯﻩﻫـﺎ‬ ‫ﺭﺍ‬ ‫‪G‬‬ ‫ﺑـﺮ‬ ‫‪V‬‬ ‫ﻳﮏ ﻋﺎﻣﻞ ﻋـﺪﻡ ﺗﻘـﺎﺭﻥ ﺍﺳـﺖ ﮐـﻪ ﺗـﺄﺛﻴﺮ ﺟﺰﺋـﻲ‬ ‫‪‬‬
‫ﺑﺎﺭﻫﺎﻱ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺣﺴﺎﺱ ﺑـﻪ ﻭﻟﺘـﺎﮊ‪ ،‬ﻳـﺎ ﺫﺭﺍﺕ ﺩﺭﺑـﺎﻥ ﻫﺴـﺘﻨﺪ‪ .‬ﺩﺭ‬ ‫ﺑﺎﺷﺪ ﻭ ﺍﮔﺮ ﺳـﺪ‬ ‫ﻏﺸﺎ ‪  1‬‬ ‫ﻣﻲﺩﻫﺪ‪ .‬ﺍﮔﺮ ﺳﺪ ﺍﻧﺮﮊﻱ ﺩﺭ ﺑﻴﺮﻭﻥ ﺣﺎﺷﻴﺔ‬
‫ﺣﻘﻴﻘﺖ ﺍﻳﻦ ﻣﺪﻝ ﻳﮏ ﺳﺪ ﺍﻧـﺮﮊﻱ ﺑـﺮﺍﻱ ﺫﺭﺍﺕ ﺩﺭﺑـﺎﻥ ﻣﺤـﺪﻭﺩ ﺩﺭ‬ ‫ﺍﺳــﺖ‪ ،‬ﺑﻨــﺎﺑﺮﺍﻳﻦ‬ ‫‪ 0‬‬ ‫ﺍﻧــﺮﮊﻱ ﺩﺭ ﺩﺭﻭﻥ ﻣﺤــﺪﻭﺩﺓ ﻏﺸــﺎﺀ ﺑﺎﺷــﺪ‬
‫ﭘﺮﻭﺗﺌﻴﻦ ﮐﺎﻧﺎﻝ ﺩﺭ ﻧﻈﺮ ﻣﻲﮔﻴﺮﺩ‪ ،‬ﺩﺭ ﺣﺎﻟﻲ ﮐﻪ ﺩﺭ ﻣـﺪﻝ ﺳـﺪ ﺍﻧـﺮﮊﻱ‬ ‫‪ . 0  ‬ﺩﺭ ﺍﻳﻦ ﺷﺮﺍﻳﻂ ﺍﻧﺮﮊﻱ ﺁﺯﺍﺩ ﻓﻌﺎﻝﺳﺎﺯﻱ ﺩﻳﮕﺮ ﻣﺘﻘﺎﺭﻥ ﻧﺒـﻮﺩﻩ‬ ‫‪1‬‬
‫ﺍﻳﻦ ﺳﺪ ﺑﺮﺍﻳﻴﻮﻥﻫﺎﻱ ﻋﺒﻮﺭﮐﻨﻨﺪﻩ ﺍﺯ ﻏﺸﺎﺀ ﺑﻮﺩ‪ .‬ﺑﻪ ﺩﻟﻴﻞ ﺍﻫﻤﻴـﺖ ﺍﻳـﻦ‬ ‫ﻭ ﺿﺮﺍﻳﺐ ﻧﺮﺥ ﺑﺮﺍﺑﺮ ﻧﻴﺴﺘﻨﺪ ) ‪ ( k1  k2‬ﺑﻠﮑﻪ ﺑﻪ ﺻـﻮﺭﺕ ﺯﻳـﺮ ﺗﻐﻴﻴـﺮ‬
‫ﻣﺪﻝ ﻭ ﻭﺳﻌﺖ ﮐﺎﺭﺑﺮﺩ ﺁﻥ ﺑﺮﺍﻱ ﻣﺤﻘﻘﻴﻦ ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ ﺍﻳﻦ ﻣـﺪﻝ ﺭﺍ‬ ‫ﻣﻲﮐﻨﻨﺪ‪:‬‬
‫ﺩﺭ ﺯﻳﺮ ﺑﻪ ﻃﻮﺭ ﺩﻗﻴﻖﺗﺮ ﻣﻮﺭﺩ ﺑﺮﺭﺳﻲ ﻗﺮﺍﺭ ﻣﻲﺩﻫﻴﻢ ]‪.[۳‬‬ ‫‪k1  k0e  (1 ) zFV / RT ,‬‬
‫)‪(۳۷‬‬
‫‪k2  k0e zFV / RT ,‬‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ‪ k0  Ae   G0 / RT‬ﺍﺳـﺖ‪ .‬ﺍﺯ ﺍﻳـﻦ ﺭﻭ ﺟﺮﻳـﺎﻥ ﺧـﺎﻟﺺ‬
‫‪ .۴‬ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ ‪ -‬ﻫﺎﮐﺴﻠﻲ ﺑﺮﺍﻱ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‬
‫ﮔﺬﺭﻧﺪﻩ ﺍﺯ ﻋﺮﺽ ﻏﺸﺎﺀ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﻣﺤﺎﺳﺒﻪ ﻣﻲﺷﻮﺩ‬
‫ﺍﺯ ﺩﻳـﺪﮔﺎﻩ ﺑﻴﻮﻓﻴﺰﻳـﮏ‪ ،‬ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤــﻞ ﻧﺘﻴﺠـﺔ ﻋﺒــﻮﺭ ﺟﺮﻳـﺎﻥ ﺍﺯ‬
‫‪I  zF ( Joutward  Jinward ) ‬‬
‫ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳـﻮﻧﻲ ﺍﺳـﺖ‪ .‬ﺩﻳﻨﺎﻣﻴـﮏ ﺗﻮﻟﻴـﺪ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺑـﺮﺍﻱ‬ ‫)‪(۳۸‬‬
‫] ‪zF  k0[[C]in e zFV / RT  [C]out e(1 ) zFV / RT‬‬
‫ﭼﻨﺪﻳﻦ ﺩﻫﻪ ﺫﻫﻦ ﺩﺍﻧﺸﻤﻨﺪﺍﻥ ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ ﺭﺍ ﺑﻪ ﺧـﻮﺩ ﻣﺸـﻐﻮﻝ‬ ‫ﻣﺪﻝ ﺳﺪ ﺗﮏﺍﻧﺮﮊﻱ ﺑﻴﺸﺘﺮ ﺍﺯ ﻣﺪﻝ ﻣﻴﺪﺍﻥ ﺛﺎﺑﺖ ﮐـﺎﺭﺑﺮﺩ ﺩﺍﺭﺩ ]‪.[۳‬‬
‫ﮐــﺮﺩﻩ ﺑــﻮﺩ‪ .‬ﺑــﺮﺍﻱ ﺍﻭﻟـﻴﻦ ﺑــﺎﺭ ﻫــﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴــﻠﻲ ﺍﻗــﺪﺍﻡ ﺑــﻪ‬ ‫ﺑﺎ ﺟﺮﻳﺎﻥﻫﺎﻱ ﻳﻮﻧﻲ ﺗـﮏﺳـﻮﻳﻪ‬ ‫‪I V‬‬ ‫ﺍﻳﻦ ﻣﺪﻝ ﻣﻲﺗﻮﺍﻧﺪ ﺭﻭﺍﺑﻂ‬
‫ﺍﻧﺪﺍﺯﻩﮔﻴﺮﻱ ﻋﻤﻠﻲ ﺍﻳﻦ ﺟﺮﻳﺎﻥﻫﺎ ﮐﺮﺩﻩ ﻭ ﺳﭙﺲ ﺑـﺮﺍﻱ ﺍﻭﻟـﻴﻦ ﺑـﺎﺭ‬ ‫ﺑﻴﺮﻭﻥﺭﻭﻧﺪﻩ ﻳﺎ ﺩﺭﻭﻥﺭﻭﻧﺪﻩ ﺭﺍ ﺑﺎ ﭘﺘﺎﻧﺴﻴﻞﻫﺎﻱ ﻣﻌﮑﻮﺱ ﻣﺜﺒـﺖ ﻳـﺎ‬
‫ﻣﺪﻝ ﭘﺪﻳﺪﻩﺷﻨﺎﺳﻲ ﺟـﺎﻟﺒﻲ ﺭﺍ ﺑـﺮﺍﻱ ﺗﻮﺿـﻴﺢ ﺩﻳﻨﺎﻣﻴـﮏ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫ﻣﻨﻔـﻲ ﺗﻮﺻـﻴﻒ ﮐﻨــﺪ‪ .‬ﺩﺭ ﺣــﺎﻟﻲ ﮐــﻪ ﻣــﺪﻝ ﻣﻴـﺪﺍﻥ ﺛﺎﺑــﺖ ﻓﻘــﻂ‬
‫ﻋﻤﻞ ﺍﺭﺍﺋﻪ ﺩﺍﺩﻧﺪ‪ .‬ﺑﻪ ﺩﻟﻴﻞ ﻓﻘﺪﺍﻥ ﻭﺳـﺎﻳﻞ ﺍﻧـﺪﺍﺯﻩﮔﻴـﺮﻱ ﺩﻗﻴـﻖ ﺩﺭ‬ ‫ﻣﻲﺗﻮﺍﻧﺴﺖ ﺟﺮﻳﺎﻥ ﺑﻴﺮﻭﻥﺭﻭﻧﺪﻩ ﺭﺍ ﺑﺎ ﭘﺘﺎﻧﺴﻴﻞ ﻣﻌﮑﻮﺱ ‪ E r‬ﻣﻨﻔﻲ‬
‫ﺁﻥ ﺯﻣﺎﻥ‪ ،‬ﺁﻧﻬﺎ ﺍﺯ ﻳﮏ ﺣﻴﻮﺍﻥ ﺩﺭﻳﺎﻳﻲ ﺑﻪ ﻧـﺎﻡ ﺍﺳـﮑﻮﺋﻴﺪ ﮐـﻪ ﺩﺍﺭﺍﻱ‬ ‫ﻭ ﺟﺮﻳﺎﻥ ﺩﺭﻭﻥﺭﻭﻧﺪﻩ ﺭﺍ ﺑـﺎ ﭘﺘﺎﻧﺴـﻴﻞ ﻣﻌﮑـﻮﺱ ﻣﺜﺒـﺖ ﺗﻮﺻـﻴﻒ‬
‫ﺁﮐﺴﻮﻥ ﺑﺰﺭﮔـﻲ ﺍﺳـﺖ ﺍﺳـﺘﻔﺎﺩﻩ ﮐﺮﺩﻧـﺪ‪ .‬ﺁﻧﻬـﺎ ﺣﺘـﻲ ﺑـﻪ ﮐﻤـﮏ‬ ‫ﮐﻨﺪ‪ .‬ﺩﺭ ﺩﺳﺘﮕﺎﻩﻫﺎﻱ ﺑﻴﻮﻟﻮﮊﻳﮑﻲ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺘﻦ ﺳﺪ ﺗﮏ‪-‬ﺍﻧـﺮﮊﻱ‬
‫ﻣﺎﺷﻴﻦﺣﺴﺎﺏﻫﺎﻱ ﻣﻮﺟﻮﺩ ﺩﺭ ﺁﻥ ﺯﻣﺎﻥ ﺷﺒﻴﻪﺳﺎﺯﻱ ﻭ ﻣﺤﺎﺳـﺒﺎﺕ‬ ‫ﺑﺮﺍﻱ ﻋﺒﻮﺭ ﻫﻤﻪ ﻳﻮﻥﻫـﺎ ﺍﺯ ﻋـﺮﺽ ﻏﺸـﺎﺀ ﺑـﺎ ﺿـﺨﺎﻣﺖ ﺣـﺪﻭﺩ‬
‫ﻋﺪﺩﻱ ﺭﺍ ﺑﺮﺍﻱ ﻣﺪﻝ ﺧﻮﺩ ﺍﻧﺠﺎﻡ ﺩﺍﺩﻧﺪ‪ .‬ﺍﻳﻦ ﻣـﺪﻝ ﺩﺭ ﺳـﺎﻝ ‪۱۹۵۲‬‬
‫‪ 100 A‬ﺧﻴﻠﻲ ﻭﺍﻗﻊﮔﺮﺍﻳﺎﻧﻪ ﺑﻪ ﻧﻈﺮ ﻧﻤﻲﺭﺳﺪ‪ .‬ﺍﮔﺮ ﻳﮑﻲ ﺍﺯ ﺳـﺪﻫﺎﻱ‬
‫‪o‬‬

‫ﺍﺭﺍﺋﻪ ﺷﺪ ﻭ ﺑﻪ ﺩﻟﻴﻞ ﺍﻫﻤﻴﺖ ﺍﻳﻦ ﮐـﺎﺭ ﻣﻮﻓـﻖ ﺑـﻪ ﺩﺭﻳﺎﻓـﺖ ﺟـﺎﻳﺰﻩ‬

‫ﺍﻧﺮﮊﻱ ﺑﺴﻴﺎﺭ ﺑﺰﺭﮔﺘﺮ ﺍﺯ ﺑﻘﻴﻪ ﺑﺎﺷﺪ‪ ،‬ﺍﻳﻦ ﻣﺪﻝ ﻗﺎﺑـﻞ ﮐـﺎﺭﺑﺮﺩ ﺍﺳـﺖ‬
‫ﻧﻮﺑــﻞ ﻓﻴﺰﻳﻮﻟــﻮﮊﻱ ﻳــﺎ ﭘﺰﺷــﮑﻲ ﺩﺭ ﺳــﺎﻝ ‪ ۱۹۶۳‬ﺷــﺪﻧﺪ‪ .‬ﺭﻭﺵ‬
‫ﻭﻟﻲ ﺍﮔﺮ ﺳﺪﻫﺎﻱ ﺍﻧﺮﮊﻱ ﺗﻘﺮﻳﺒﺎً ﻫﻢ ﺍﺭﺗﻔﺎﻉ ﺑﺎﺷـﻨﺪ‪ ،‬ﺑﺎﻳـﺪ ﺍﺯ ﻣـﺪﻝ‬
‫ﺷﺒﻴﻪﺳـﺎﺯﻱ ﻫـﺎﺟﮑﻴﻦ ‪ -‬ﻫﺎﮐﺴـﻠﻲ ﺍﺳـﺎﺱ ﮐـﺎﺭ ﺗﺤﻘﻴﻘـﺎﺕ ﺭﻭﺯ‬
‫ﺳﺪ ﺍﻧﺮﮊﻱ ﭼﻨﺪ‪-‬ﮔﺎﻧﻪ ﺍﺳﺘﻔﺎﺩﻩ ﮐﺮﺩ ]‪.[۴۶‬‬
‫ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ ﺍﺳﺖ ]‪ ۹‬ﻭ ‪.[۴۷‬‬

‫‪ .۳.۳.۳‬ﻣﺪﻝ ﺩﺭﻭﺍﺯﻩﺍﻱ )ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴﻠﻲ(‬

‫‪ .۱.۴‬ﺧﻼﺻﺔ ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴﻠﻲ‬ ‫ﺩﻭ ﻣﺪﻝ ﻣﻴﺪﺍﻥ ﺛﺎﺑﺖ ﻭ ﺳﺪ ﺍﻧﺮﮊﻱ ﮐﻪ ﺩﺭ ﺑﺎﻻ ﺑﺤﺚ ﺷﺪ‪ ،‬ﻣـﻲﺗﻮﺍﻧﻨـﺪ‬
‫ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴـﻠﻲ ﺟﺮﻳـﺎﻥ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺭﺍ ﺑـﻪ ﺁﮐﺴـﻮﻥ ﺩﺭﺷـﺖ‬ ‫ﺭﺍ‪ ،‬ﻭﻗﺘﻲ ﺭﺳﺎﻧﺶ ﻏﺸﺎﺀ ﻓﻘـﻂ ﺑـﻪ ﭘﺘﺎﻧﺴـﻴﻞ‬ ‫‪I V‬‬ ‫ﺭﻭﺍﺑﻂ ﻏﻴﺮﺧﻄﻲ‬
‫ﺍﺳﮑﻮﺋﻴﺪ ﺍﻋﻤﺎﻝ ﮐﺮﺩﻩ ﻭ ﺗﻐﻴﻴﺮﺍﺕ ﭘﺘﺎﻧﺴـﻴﻞ ﺭﺍ ﺩﺭ ﻏﺸـﺎﺀ ﺁﻥ ﺍﻧـﺪﺍﺯﻩ‬ ‫ﺑﺴﺘﮕﻲ ﺩﺍﺷﺘﻪ ﺑﺎﺷﺪ‪ ،‬ﺗﻮﺻﻴﻒ ﮐﻨﻨﺪ‪ .‬ﻭﻟﻲ ﻧﻤﻲﺗﻮﺍﻧﻨﺪ ﺍﺛـﺮ ﻋﺎﻣـﻞ ﺩﻭﻡ‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۶۲‬‬

‫ﺷﮑﻞ ‪ .۱۴‬ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﻭ ﻣﺪﺍﺭ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﻌﺎﺩﻝ ﺁﻧﻬﺎ ﺩﺭ ﻧﻮﺭﻭﻥ‪.‬‬

‫ﺭﺳﺎﻧﺎﻳﻲ ﮐﺎﻧـﺎﻝ ﻣﺮﺑﻮﻃـﻪ ﻭ ﺿـﺮﻳﺒﻲ ﺟﻬـﺖ ﺍﻋﻤـﺎﻝ ﺩﺭﻭﺍﺯﺓ ﮐﻨﺘـﺮﻝ ﺁﻥ‬ ‫ﮔﺮﻓﺘﻨﺪ‪ .‬ﺍﮔﺮ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ﻣﻮﺟﻮﺩ ﺩﺭ ﻏﺸـﺎﯼ ﺁﮐﺴـﻮﻥ ﺭﺍ ‪ K ‬ﻭ‬
‫ﮐﺎﻧﺎﻝ ﺍﺳـﺖ‪ .‬ﺿـﺮﻳﺐ ‪ i‬ﻫﺮﭼﻨـﺪ ﺑـﺎﺯ ﻭ ﺑﺴـﺘﻪ ﺷـﺪﻥ ﮐﺎﻧـﺎﻝ ﺭﺍ ﻭﺍﺭﺩ‬ ‫‪ Na ‬ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﻢ ﻭ ﺑﻘﻴﻪ ﺭﺍ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻧﺸﺖ ﺑﻨﺎﻣﻴﻢ‪ ،‬ﻣﻲﺗﻮﺍﻧﻴﻢ‬
‫ﻣﺤﺎﺳﺒﺎﺕ ﻣﻲﮐﻨﺪ ﻭﻟﻲ ﺗﺄﺧﻴﺮ ﺩﺭ ﺍﻳﻦ ﻋﻤﻞ ﺭﺍ ﺑﻪ ﺣﺴـﺎﺏ ﻧﻤـﻲﺁﻭﺭﺩ‪ .‬ﺍﺯ‬ ‫ﻣﺪﺍﺭ ﻣﻌﺎﺩﻝ ﺷﮑﻞ ‪ ۱۴‬ﺭﺍ ﺑﺮﺍﻱ ﺁﻥ ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﻢ‪ .‬ﺩﺭ ﺍﻳـﻦ ﺷـﮑﻞ‬
‫ﺍﻳﻦ ﺭﻭ ﺍﻳﻦ ﺿﺮﺍﻳﺐ ﺭﺍ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﻭﺍﺭﺩ ﻣﻌﺎﺩﻟﻪ ﮐﺮﺩﻧﺪ‬ ‫ﺟﺮﻳـﺎﻥ ﺗﺰﺭﻳـﻖ ﺷـﺪﻩ ﺑـﻪ ﺁﮐﺴـﻮﻥ‪ E K ،‬ﻭ‬ ‫‪I‬‬ ‫‪ u‬ﭘﺘﺎﻧﺴﻴﻞ ﻏﺸﺎ‪،‬‬
‫‪C‬‬
‫‪du‬‬
‫) ‪ I (t )  g K n 4 (u  E K‬‬ ‫‪ ENa‬ﭘﺘﺎﻧﺴﻴﻞ ﻣﻌﮑـﻮﺱ ﮐﺎﻧـﺎﻝ ﭘﺘﺎﺳـﻴﻢ ﻭ ﺳـﺪﻳﻢ‪ RK ،‬ﻭ ‪RNa‬‬
‫‪dt‬‬ ‫)‪(۴۱‬‬
‫‪ g Na m 3 (u  E Na )  g L (u  E L ),‬‬ ‫‪RL‬‬ ‫ﻇﺮﻓﻴـﺖ ﺧـﺎﺯﻧﻲ ﻏﺸـﺎ‪،‬‬ ‫‪C‬‬ ‫ﻣﻘﺎﻭﻣﺖ ﻣﺘﻐﻴـﺮ ﺍﻳـﻦ ﮐﺎﻧـﺎﻝﻫـﺎ‪،‬‬

‫ﺍﺳﺖ‪ .‬ﺑﺮﺍﻱ ﮐﺎﻧﺎﻝ‬

‫‪1‬‬
‫‪ g Na m3 h‬‬ ‫ﻭ‬
‫‪1‬‬
‫ﺁﻥ ‪ g K n4‬‬ ‫ﮐﻪ ﺩﺭ‬ ‫ﻣﻘﺎﻭﻣﺖ ﺛﺎﺑﺖ ﺳﺎﻳﺮ ﮐﺎﻧﺎﻝﻫـﺎ )ﻧﺸـﺖ( ﻭ ‪ E L‬ﭘﺘﺎﻧﺴـﻴﻞ ﻣﻌﮑـﻮﺱ‬
‫‪RNa‬‬ ‫‪RK‬‬
‫ﮐﺎﻧﺎﻝ ﻧﺸﺖ ﺍﺳﺖ‪ .‬ﺑﻨﺎ ﺑﻪ ﻗﺎﻧﻮﻥ ﺟﺮﻳﺎﻥ ﮐﻴﺮﺷٌـﻬﻒ‪ ،‬ﺟﺮﻳـﺎﻥ ﺍﻋﻤـﺎﻝ‬
‫ﺳﺪﻳﻢ‪ ،‬ﻫﻢ ﻧﻴﺎﺯ ﺑﻪ ﻳﮏ ﻣﺘﻐﻴﺮ ﺑﺮﺍﻱ ﻓﻌﺎﻝﺷﺪﻥ ﺁﻥ ‪ m3‬ﻣـﻲﺑﺎﺷـﺪ ﻭ‬
‫ﺷﺪﻩ ﺭﺍ ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﺻﻮﺭﺕ ﻣﺠﻤﻮﻉ ﺟﺮﻳﺎﻥﻫﺎ ﻧﻮﺷﺖ‪:‬‬
‫ﻫﻢ ﻳـﮏ ﻣﺘﻐﻴـﺮ ﺑـﺮﺍﻱ ﻏﻴـﺮﻓﻌـﺎﻝ ﺷـﺪﻥ ﺁﻥ ) ‪ . ( h‬ﺗﻐﻴﻴـﺮ ﺯﻣـﺎﻧﻲ‬
‫‪I (t)  IC (t)  IK  INa  IL .‬‬
‫ﻣﺘﻐﻴﺮﻫﺎﻱ ﺩﺭﻭﺍﺯﻩﺍﻱ ﻣﻄﺎﺑﻖ ﻣﻌﺎﺩﻟﺔ ﺩﻳﻔﺮﺍﻧﺴﻴﻠﻲ ﺑﻪ ﺷﮑﻞ ﺯﻳﺮ ﺍﻧﺠﺎﻡ‬ ‫‪du‬‬
‫‪ IC (t )  C‬ﺍﺳﺘﻔﺎﺩﻩ‬ ‫ﺑﺮﺍﻱ ﺧﺎﺯﻥ ﻣﻲﺗﻮﺍﻥ ﺑﻪﺟﺎﻱ ‪ IC‬ﺍﺯ ﻣﻌﺎﺩﻟﺔ‬
‫ﻣﻲﮔﻴﺮﺩ‬ ‫‪dt‬‬
‫‪‬‬
‫‪1‬‬
‫ﮐﺮﺩ ]‪[۴۷ ،۳‬‬
‫‪x‬‬ ‫‪[ x  x0. (u )],‬‬ ‫)‪(۴۲‬‬
‫) ‪ x (u‬‬ ‫‪du‬‬
‫)‪(۳۹‬‬
‫‪C‬‬ ‫‪ I (t )  I K  I Na  I L .‬‬
‫‪dx‬‬ ‫‪dt‬‬
‫‪ x ‬ﺍﺳﺖ ﻭ ‪ x‬ﺑﻪ ﺟﺎﻱ ‪ n ، m‬ﻭ ‪ h‬ﻣـﻲ ﻧﺸـﻴﻨﺪ‪ .‬ﻣﻌﺎﺩﻟـﺔ‬ ‫ﮐﻪ‬ ‫ﺑﻪ ﮐﻤﮏ ﻗﺎﻧﻮﻥ ﺍُﻫﻢ ﻣﻲﺗﻮﺍﻥ ﺟﺮﻳﺎﻥﻫﺎ ﺭﺍ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﻧﻮﺷﺖ‪:‬‬
‫‪dt‬‬
‫)‪ (۳۰‬ﺭﺍ ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﺍﻳﻦ ﺻﻮﺭﺕ ﺗﻔﺴﻴﺮ ﮐﺮﺩ ﮐﻪ ﺑـﺮﺍﻱ ﻳـﮏ ﻭﻟﺘـﺎﮊ‬
‫‪du‬‬ ‫‪u  E K u  E Na u  E L‬‬
‫‪C‬‬ ‫‪ I (t ) ‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪.‬‬ ‫)‪(۴۰‬‬
‫ﺛﺎﺑﺖ ‪ ، u‬ﻣﺘﻐﻴﺮ ‪ x‬ﺑﻪ ﻳﮏ ﻣﻘـﺪﺍﺭ ﻫـﺪﻑ )‪ x0(u‬ﺑـﺎ ﻳـﮏ ﺛﺎﺑـﺖ‬ ‫‪dt‬‬ ‫‪RK‬‬ ‫‪RNa‬‬ ‫‪RL‬‬

‫ﺯﻣﺎﻧﻲ )‪  x (u‬ﻧﺰﺩﻳﮏ ﻣﻲﺷﻮﺩ‪ .‬ﻭﺍﺑﺴـﺘﮕﻲ ﺛﺎﺑـﺖ ﺯﻣـﺎﻧﻲ ﻭ ﻣﻘـﺪﺍﺭ‬ ‫ﻣﺸﮑﻞ ﺍﺻﻠﻲ ﺑﺮﺍﻱ ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴـﻠﻲ ﺍﻳـﻦ ﺑـﻮﺩ ﮐـﻪ ‪ R‬ﻫـﺎ ﺛﺎﺑـﺖ‬
‫ﺑﻴﺸﻴﻨﺔ ‪ x‬ﺑـﻪ ﻭﻟﺘـﺎﮊ ﺩﺭ ﺷـﮑﻞ ‪ ۱۵‬ﺭﺳـﻢ ﺷـﺪﻩ ﺍﺳـﺖ‪ .‬ﻣﻬﻤﺘـﺮﻳﻦ‬ ‫ﻧﺒﻮﺩﻧﺪ ﺑﻠﮑﻪ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻣﺤﻴﻂ‪ ،‬ﭘﺘﺎﻧﺴـﻴﻞ ﻭ ﺗﺎﺭﻳﺨﭽـﻪ ﻓﻌﺎﻟﻴـﺖ ﻧـﻮﺭﻭﻥ‬
‫ﺧﺎﺻﻴﺖ ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴﻠﻲ ﺗﻮﺍﻧﺎﻳﻲ ﺁﻥ ﺩﺭ ﺗﻮﻟﻴﺪ ﻫـﺎﺟﮑﻴﻦ‬ ‫ﺗﻐﻴﻴﺮ ﻣﻲﮐﺮﺩﻧﺪ‪ .‬ﺑﻨﺎﺑﺮﺍﻳﻦ ﻣﻲﺑﺎﻳﺴﺖ ﺳـﺎﺯ ﻭ ﮐـﺎﺭﻱ ﺑـﺮﺍﻱ ﺑـﺎﺯ ﻭ ﺑﺴـﺘﻪ‬

‫‪n‬‬ ‫ﻭ ﻫﺎﮐﺴﻠﻲ ﺍﻳﻦ ﻧﻤﻮﺩﺍﺭﻫﺎﻱ ﺗﻮﺍﺑﻊ ﺗﻌﺎﺩﻝ ﺑﺮﺍﻱ ﻣﺘﻐﻴﺮﻫــﺎﻱ ‪، m‬‬ ‫ﺷﺪﻥ ﮐﺎﻧﺎﻝﻫﺎ ﺩﺭ ﻣﺪﻝ ﺩﺭ ﻧﻈﺮ ﻣـﻲﮔﺮﻓﺘﻨـﺪ‪ .‬ﻳـﮏ ﮐﺎﻧـﺎﻝ ﻣـﻲﺗﻮﺍﻧـﺪ ﺩﺭ‬
‫ﻭ ﻫﻤﭽﻨﻴﻦ ﻣﻘﺎﺩﻳﺮ ﺑﻴﺸﻴﻨﺔ ﺭﺳﺎﻧﺶ ﻭ ﭘﺘﺎﻧﺴﻴﻞﻫـﺎﻱ ﻣﻌﮑـﻮﺱ‬ ‫‪h‬‬ ‫ﻭ‬ ‫ﻣﺪﺕ ﺯﻣﺎﻥ ﻣﺸﺨﺼﻲ ﺍﺯ ﺣﺎﻟـﺖ ﺑـﺎﺯ )‪ (۱‬ﺑـﻪ ﺣﺎﻟـﺖ ﺑﺴـﺘﻪ )‪ (۰‬ﺗﻐﻴﻴـﺮ‬
‫ﺭﺍ ﺑﺎ ﺍﻧﺪﺍﺯﻩﮔﻴﺮﻱﻫﺎﻱ ﺁﺯﻣﺎﻳﺸـﮕﺎﻫﻲ ﺑـﻪﺩﺳـﺖ ﺁﻭﺭﺩﻧـﺪ‪ .‬ﺩﺍﺩﻩﻫـﺎﻱ‬ ‫ﺣﺎﻟﺖ ﺩﻫﺪ ﻭ ﺩﺭ ﺣﺎﻟﺖ ﺑﻴﻦ ‪ ۰‬ﻭ ‪ ۱‬ﻧﻴﺰ ﺭﺳﺎﻧﺎﻳﻲ ﺧـﺎﺹ ﺧـﻮﺩ ﺭﺍ ﺩﺍﺭﺩ‪.‬‬
‫ﺗﺠﺮﺑﻲ ﺍﺻﻠﻲ ﻭ ﻣﻬﻢﺗﺮﻳﻦ ﺧﺎﺻـﻴﺖ ﻣـﺪﻝ ﻫـﺎﺟﮑﻴﻦ ﻭ ﻫﺎﮐﺴـﻠﻲ‬ ‫ﻟﺬﺍ ﺑﻪ ﺟﺎﻱ ) ‪ ( 1‬ﻣﻲﺗـﻮﺍﻥ ‪ gii‬ﺭﺍ ﺟـﺎﻳﮕﺰﻳﻦ ﮐـﺮﺩ ﮐـﻪ ﺩﺭ ﺁﻥ ‪gi‬‬
‫‪Ri‬‬
‫‪۳۶۳‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﺷﮑﻞ ‪ .۱۵‬ﻭﺍﺑﺴﺘﮕﻲ ﺛﺎﺑﺖ ﺯﻣﺎﻧﻲ ﻭ ﻣﻘﺪﺍﺭ ﺑﻴﺸﻴﻨﺔ ‪ x‬ﺑﻪ ﻭﻟﺘﺎﮊ ﺩﺭ ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ‪ -‬ﻫﺎﮐﺴﻠﻲ‪.‬‬

‫ﺷﮑﻞ ‪ .١٧‬ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﻣﺤﺎﺳﺒﻪ ﺷﺪﻩ ﺗﻮﺳﻂ ﻳﮏ ﺟﺮﻳﺎﻥ ﭘﻠﻪﺍﻱ ﮐﻮﺗـﺎﻩ‬ ‫ﺷﮑﻞ ‪ .١٦‬ﺩﺍﺩﻩ ﻫﺎﻱ ﺗﺠﺮﺑﻲ ﺍﺻﻠﻲ ﻭ ﻧﻤﻮﺩﺍﺭ ﺑﺮﺍﺯﺵ ﺷـﺪﻩ ﺗﻮﺳـﻂ ﻫـﺎﺟﮑﻴﻦ ﻭ‬
‫ﺩﺭ ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ‪ -‬ﻫﺎﮐﺴﻠﻲ‪.‬‬ ‫ﻫﺎﮐﺴﻠﻲ‪.‬‬

‫ﺑﻄﻮﺭﻱ ﮐﻪ ﻧﻮﺭﻭﻥ ﺗﻮﻟﻴـﺪ ﻳـﮏ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﮐﻨـﺪ‪ ،‬ﺑـﺎ ﺍﻋﻤـﺎﻝ‬ ‫ﺗﻮﺍﻧﺎﻳﻲ ﺁﻥ ﺩﺭ ﺗﻮﻟﻴﺪ ﭘﺘﺎﻧﺴﻴﻞﻫﺎﻱ ﻋﻤﻞ ﺍﺳﺖ‪ .‬ﺑﺎ ﺍﻋﻤﺎﻝ ﺟﺮﻳﺎﻥﻫﺎﻱ‬
‫ﻣﺠﺪﺩ ﺍﻳﻦ ﺟﺮﻳﺎﻥ ﻟﺰﻭﻣﺎً ﻧﻮﺭﻭﻥ ﺗﻮﻟﻴـﺪ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺑﻌـﺪﻱ ﺭﺍ‬ ‫ﻣﺨﺘﻠﻒ ﻭﺭﻭﺩﻱ ) ‪ I (t‬ﻣﻲﺗـﻮﺍﻥ ﺑـﺎ ﺣـﻞ ﭼﻬـﺎﺭ ﻣﻌﺎﺩﻟـﺔ ﻏﻴﺮﺧﻄـﻲ‬
‫ﻧﺨﻮﺍﻫﺪ ﮐﺮﺩ‪ .‬ﺍﻭﻝ ﺍﻳـﻦ ﮐـﻪ ﺍﮔـﺮ ﺟﺮﻳـﺎﻥ ﻣـﻮﺭﺩ ﻧﻈـﺮ ﺩﺭ ﻓﺎﺻـﻠﺔ‬ ‫ﻫﻢﺑﺴﺘﻪ ) ‪ m(t ) ، n(t ) ، u (t‬ﻭ ) ‪ h(t‬ﺩﻳﻨﺎﻣﻴـﮏ ﻏﺸـﺎﺀ ﺭﺍ ﺗﺤﻠﻴـﻞ‬
‫ﺯﻣﺎﻧﻲ ﮐﻤﺘﺮ ﺍﺯ ﻣﺪﺕ ﻣﺮﺩﮔﻲ ﻏﺸـﺎﺀ ﻭﺍﺭﺩ ﺷـﻮﺩ ﺑـﻪ ﻫـﻴﭻ ﻋﻨـﻮﺍﻥ‬ ‫ﮐﺮﺩ ﻭ ﺗﺎﺑﻊ ) ‪ u (t‬ﺭﺍ ﺑﺮ ﺣﺴﺐ ﺯﻣـﺎﻥ ﺭﺳـﻢ ﮐـﺮﺩ‪ .‬ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ‬
‫ﻧﻮﺭﻭﻥ ﻗﺎﺩﺭ ﺑﻪ ﺗﻮﻟﻴـﺪ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺑﻌـﺪﻱ ﻧﻴﺴـﺖ‪ .‬ﺩﺭ ﻋﻠـﻮﻡ‬ ‫ﻣﺤﺎﺳﺒﻪ ﺷﺪﻩ ﺑﻪ ﻭﺳﻴﻠﺔ ﺍﻳﻦ ﻣﺪﻝ ﮐﻪ ﺗﻮﺳﻂ ﻳﮏ ﺟﺮﻳﺎﻥ ﺍﻟﮑﺘﺮﻳﮑـﻲ‬
‫ﺍﻋﺼﺎﺏ ﺍﻳﻦ ﻣﺪﺕ ﺯﻣﺎﻥ ﺩﻭﺭﺓ ﻣﻘﺎﻭﻣﺖ ﻧﺎﻡ ﺩﺍﺭﺩ‪ .‬ﺩﺭ ﺍﻳـﻦ ﻣـﺪﺕ‪،‬‬ ‫ﭘﻠﻪﺍﻱ ﮐﻮﺗﺎﻩ ﺩﺭ ﺷﮑﻞ‪ ۱۷‬ﻧﺸﺎﻥ ﺩﺍﺩﻩ ﺷﺪﻩ ﺍﺳﺖ‪.‬‬
‫ﻏﺸﺎﺀ ﺩﺭ ﺣﺎﻝ ﺑﺮﮔﺸﺖ ﺑﻪ ﺣﺎﻟﺖ ﺍﺳﺘﺮﺍﺣﺖ ﺧﻮﺩ ﺑـﻮﺩﻩ ﻭ ﺍﻣﮑـﺎﻥ‬
‫‪١‬‬
‫ﺑﺮﮔﺸﺖ ﺑﻪ ﺷﺮﺍﻳﻂ ﺻﺪﻭﺭ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺭﺍ ﻧـﺪﺍﺭﺩ‪ .‬ﺩﻭﻡ ﺍﻳـﻦ ﮐـﻪ‬ ‫‪ .۱.۱.۴‬ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﻭ ﻣﺪﺕ ﻣﺮﺩﮔﻲ ﻏﺸﺎ‬
‫ﺣﺘﻲ ﺍﮔﺮ ﺟﺮﻳﺎﻥ ﺗﺤﺮﻳـﮏﮐﻨﻨـﺪﻩ ﺑﻌـﺪ ﺍﺯ ﺩﻭﺭﺓ ﻣﻘﺎﻭﻣـﺖ ﺍﻋﻤـﺎﻝ‬ ‫ﺷﺮﻁ ﺗﻮﻟﻴﺪ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤـﻞ ﻭﺍﻗﻄﺒﻴـﺪﮔﻲ ﮐـﺎﻓﻲ ﺩﺭ ﻏﺸـﺎﺀ ﻧـﻮﺭﻭﻥ‬
‫ﺷﻮﺩ ﺍﺣﺘﻤﺎﻝ ﺻـﺪﻭﺭ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺑﻌـﺪﻱ ﮐـﺎﻣﻼً ﺍﺣﺘﻤـﺎﻻﺗﻲ‬ ‫ﺍﺳﺖ‪ .‬ﺑﻪ ﻋﺒﺎﺭﺕ ﺩﻳﮕﺮ ﺍﮔـﺮ ﺟﺮﻳـﺎﻧﻲ ﺑـﻪ ﻧـﻮﺭﻭﻥ ﺍﻋﻤـﺎﻝ ﺷـﻮﺩ ﻭ‬
‫ﺍﺳﺖ‪ .‬ﻫﺮﭼﻨﺪ ﻣﻤﮑﻦ ﺍﺳﺖ ﺍﻳﻦ ﺟﺮﻳﺎﻥﻫﺎ ﻣﻨﺠﺮ ﺑﻪ ﺗﺤﺮﻳـﮏﻫـﺎﻱ‬ ‫ﺍﺧﺘﻼﻑ ﭘﺘﺎﻧﺴﻴﻞ ﻧﺎﺷـﻲ ﺍﺯ ﺁﻥ ﺍﺯ ﺳـﺪ ﭘﺘﺎﻧﺴـﻴﻞ ﺧﺎﺻـﻲ ﺑﮕـﺬﺭﺩ‪،‬‬
‫ﺯﻳﺮﺁﺳﺘﺎﻧﻪﺍﻱ ﺷﻮﻧﺪ ﻭﻟـﻲ ﻫﻤﻴﺸـﻪ ﻧﻤـﻲﺗﻮﺍﻧﻨـﺪ ﻣﻨﺠـﺮ ﺑـﻪ ﺗﻮﻟﻴـﺪ‬ ‫ﻧﺎﮔﻬﺎﻥ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺗﻮﻟﻴﺪ ﻣﻲﺷﻮﺩ‪ .‬ﺟﺰﺋﻴﺎﺕ ﺷﺮﻁ ﺗﻮﻟﻴﺪ ﭘﺘﺎﻧﺴﻴﻞ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺷﻮﻧﺪ‪ .‬ﻧﻤﻮﻧـﻪﺍﻱ ﺍﺯ ﺍﻳـﻦ ﺍﺣﺘﻤـﺎﻝ ﺭﺍ ﻣـﻲﺗـﻮﺍﻥ ﺩﺭ‬ ‫ﻋﻤﻞ )ﻫﻤﺎﻧﻨﺪ ﺷﮑﻞ ﭘﻴﺎﻡ‪ ،‬ﻃـﻮﻝ ﺯﻣـﺎﻧﻲ ﭘﻴـﺎﻡ ﻭ ﺁﺳـﺘﺎﻧﺔ ﻣـﺆﺛﺮ( ﺭﺍ‬
‫ﻣﻮﺭﺩ ﻧﻮﺭﻭﻥﻫﺎﻱ ﺗﺸـﺨﻴﺺﺩﻫﻨـﺪﺓ ﺣﺮﮐـﺖ ﺍﺟﺴـﺎﻡ ﺩﺭ ﻗﺴـﻤﺖ‬ ‫ﻣﻲﺗﻮﺍﻥ ﺩﺭ ﻣﺮﺍﺟﻊ ]‪ ۳‬ﻭ‪ [۴۷‬ﻳﺎﻓﺖ‪.‬‬
‫ﺗﮑﺘﻮﻡ ﻧﻮﺭﻱ ﻣﻐﺰ ﺟﻮﺟﻪ ﻣﺸـﺎﻫﺪﻩ ﮐـﺮﺩ‪ .‬ﻣﺤﺎﺳـﺒﺎﺕ ﻣﺮﺑـﻮﻁ ﺑـﻪ‬ ‫ﻭﻟﻲ ﻧﮑﺘﺔ ﻣﻬﻢ ﺩﺭ ﻭﺟﻮﺩ ﻣﺪﺕ ﺯﻣﺎﻥ ﻣﺮﺩﮔﻲ ﻏﺸـﺎﺀ ﻫﻤﺎﻧﻨـﺪ‬
‫ﺍﺣﺘﻤﺎﻝ ﺗﻮﻟﻴﺪ ﻣﺠﺪﺩ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞﻫـﺎﻱ ﺑﻌـﺪﻱ ﺩﺭ ﻣﺮﺟـﻊ ]‪[۱۸‬‬ ‫ﺯﻣﺎﻥ ﻣﺮﮒ ﺁﺷﮑﺎﺭﺳﺎﺯ ﮔﺎﻳﮕﺮ‪ -‬ﻣـﻮﻟﺮ ﺑـﺮﺍﻱ ﺁﺷﮑﺎﺭﺳـﺎﺯﻱ ﺫﺭﺍﺕ‬
‫ﺁﻣﺪﻩ ﺍﺳـﺖ )ﺍﻳـﻦ ﺁﺯﻣﺎﻳﺸـﺎﺕ ﺗﻮﺳـﻂ ﺩﮐﺘـﺮ ﺭﺿـﺎ ﺧـﺎﻥﺑﺎﺑـﺎﻳﻲ‪،‬‬ ‫ﻫﺴﺘﻪﺍﻱ ﺍﺳﺖ ]‪ .[۴۸‬ﺍﮔﺮ ﺟﺮﻳـﺎﻥ ﺑـﻪ ﺍﻧـﺪﺍﺯﺓ ﮐـﺎﻓﻲ ﻗـﻮﻱ ﺑﺎﺷـﺪ‬
‫ﻧﻮﻳﺴــﻨﺪﺓ ﺍﻳــﻦ ﻣﻘﺎﻟــﻪ ﺍﻧﺠــﺎﻡ ﺷــﺪﻩ ﺍﺳــﺖ ﻭ ﺩﺭ ﻣﺠﻠــﺔ ﻧﻴﭽــﺮ‬
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‫ﻧﺮﻭﺳﺎﻳﻨﺲ ﭼﺎﭖ ﺷﺪﻩ ﺍﺳﺖ( ]‪.[24‬‬ ‫‪1.Refractory period‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۶۴‬‬

‫ﻭ ‪Kv3‬‬ ‫ﺍﻭﻟـﻴﻦ ﺯﻳﺮﮐﺎﻧـﺎﻝ‬ ‫ﻳـﻮﻧﻲ ‪Kv1‬‬ ‫ﺑﻪ ﻋﻨـﻮﺍﻥ ﻣﺜـﺎﻝ ﮐﺎﻧـﺎﻝ‬

‫ﺍﺯ ﺧﺎﻧﻮﺍﺩﺓ ﭘﺘﺎﺳﻴﻢ‬ ‫ﻭﻟﺘﺎﮊ ‪Kv‬‬ ‫ﺩﻭﻣﻴﻦ ﺯﻳﺮﮐﺎﻧﺎﻝ ﺍﺯ ﮐﺎﻧﺎﻝ ﺣﺴﺎﺱ ﺑﻪ‬
‫ﺍﺳﺖ‪ .‬ﺍﮔﺮ ﺩﺭ ﻳﮏ ﺁﺯﻣﺎﻳﺶ ﺍﻃﻼﻋﺎﺕ ﮐﺎﻧـﺎﻝﻫـﺎﻱ ﻳـﻮﻧﻲ ﺑـﻪ ﺍﻳـﻦ‬
‫ﺻﻮﺭﺕ ﺑﻪ ﺩﺳﺖ ﺁﻣﺪﻩ ﺑﺎﺷﻨﺪ‪ ،‬ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﮐﻤﮏ ﺭﺍﻫﮑﺎﺭ ﻫـﺎﺟﮑﻴﻦ‬
‫ﻭ ﻫﺎﮐﺴﻠﻲ ﺑﻪ ﺻﻮﺭﺕ ﺯﻳﺮ ﺍﻳﻦ ﺩﺳﺘﮕﺎﻩ ﺭﺍ ﻣﺪﻝ ﮐﺮﺩ‬
‫‪du‬‬
‫‪C‬‬ ‫) ‪  g Na m 3 h(u  E Na‬‬
‫‪dt‬‬
‫‪4‬‬
‫‪ g Kv1nKv‬‬‫) ‪1 (u  E K‬‬ ‫)‪(۴۳‬‬
‫ﺷﮑﻞ ‪ .١٨‬ﻣﺪﺍﺭ ﻣﻌﺎﺩﻝ ﻧﻮﺭﻭﻥ ﺑﺎ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳﻮﻧﻲ ‪ Kv3 ، Kv1‬ﻭ ‪. Na‬‬
‫) ‪ g Kv 3 n2Kv 3 (u  EK )  g L (u  EL‬‬
‫ﺗﻮﺟﻪ ﺷﻮﺩ ﮐﻪ ﺗﻮﺍﻥﻫﺎﻱ ‪ n Kv1‬ﻭ ‪ nKv 3‬ﺑﺎ ﻫﻢ ﻳﮑﺴﺎﻥ ﻧﻴﺴـﺘﻨﺪ‪ .‬ﺍﻳـﻦ‬
‫‪ .۲.۴‬ﻣﺪﻝﺳﺎﺯﻱ ﻧﻮﺭﻭﻥﻫﺎ‬
‫ﺗﻮﺁﻧﻬﺎ ﻧﻴﺰ ﺑﺎ ﺍﻧﺪﺍﺯﻩﮔﻴﺮﻱ ﭼﮕﺎﻟﻲ ﮐﺎﻧﺎﻝﻫﺎ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﻣﻲﺷﻮﺩ‪.‬‬
‫ﻫﺮﭼﻨﺪ ﻣﺪﻝ ﻫﺎﺟﮑﻴﻦ‪ -‬ﻫﺎﮐﺴﻠﻲ ﺑﺮﺍﻱ ﺁﮐﺴﻮﻥ ﺍﺳﮑﻮﺋﻴﺪ ﻭ ﺑـﺮﺍﻱ‬

‫‪ .۵‬ﺳﻴﻨﺎﭘﺲ ﻭ ﺣﺎﻓﻈﻪ‬ ‫ﺳﻪ ﻧﻮﻉ ﮐﺎﻧﺎﻝ ﻳﻮﻧﻲ ﺑﻪ ﺩﺳـﺖ ﺁﻣـﺪ ﻭﻟـﻲ ﻳـﮏ ﻣﺴـﻴﺮ ﻣﺸـﺨﺺ‬
‫ﻧﻈﺮﻱ‪ -‬ﺗﺠﺮﺑﻲ ﺭﺍ ﺑﺮﺍﻱ ﺗﺤﻠﻴﻞ ﻫـﺮ ﻧـﻮﻉ ﻏﺸـﺎﺋﻲ ﺗﺮﺳـﻴﻢ ﮐـﺮﺩﻩ‬
‫ﺑﻪ ﻣﺤﻞ ﺍﺗﺼﺎﻝ ﻧﻮﺭﻭﻥﻫﺎ ﺑـﻪ ﻳﮑـﺪﻳﮕﺮ ﺳـﻴﻨﺎﭘﺲ ﮔﻔﺘـﻪ ﻣـﻲﺷـﻮﺩ‪.‬‬
‫ﺍﺳﺖ‪ .‬ﻫﻢ ﺍﮐﻨﻮﻥ ﻣﻲﺩﺍﻧﻴﻢ ﮐﻪ ﺑﻌﻀـﻲ ﺍﺯ ﻏﺸـﺎﻫﺎ ﻫﻤﺎﻧﻨـﺪ ﻏﺸـﺎﯼ‬
‫ﺳﻴﻨﺎﭘﺲﻫﺎ ﻣﺤﻞ ﺍﺻﻠﻲ ﺍﺭﺗﺒﺎﻁ ﻧﻮﺭﻭﻥﻫﺎ ﺑﺎ ﻳﮑﺪﻳﮕﺮ ﻫﺴـﺘﻨﺪ‪ .‬ﻣﻐـﺰ‬
‫ﻧﻮﺭﻭﻥﻫﺎﻱ ﮐﻮﺭﺗﮑﺲ‪ ١‬ﺩﺍﺭﺍﻱ ﺍﻧﻮﺍﻉ ﺑﺴﻴﺎﺭ ﺑﻴﺸﺘﺮﻱ ﺍﺯ ﮐﺎﻧـﺎﻝﻫـﺎﻱ‬
‫ﺍﻧﺴﺎﻥ ﺣـﺪﻭﺩ ‪ ۱۰۱۵‬ﺳـﻴﻨﺎﭘﺲ ﺩﺍﺭﺩ ]‪ .[۳‬ﺳـﻴﻨﺎﭘﺲﻫـﺎ ﺑـﻪ ﺩﻭ ﻧـﻮﻉ‬
‫ﻳﻮﻧﻲ ﻫﺴﺘﻨﺪ‪ ،‬ﻭﻟﻲ ﻋﻤﻠﮑﺮﺩ ﻫﻤﺔ ﺁﻧﻬﺎ ﺩﺭ ﻫﻤﻴﻦ ﭼﺎﺭﭼﻮﺏ ﺍﺳـﺖ‪.‬‬
‫ﺍﻟﮑﺘﺮﻳﮑﻲ ﻭ ﺷﻴﻤﻴﺎﻳﻲ ﺩﺳﺘﻪﺑﻨﺪﻱ ﻣﻲﺷﻮﻧﺪ‪ .‬ﺳﻴﻨﺎﭘﺲ ﺍﻟﮑﺘﺮﻳﮑﻲ ﺑـﻪ‬
‫ﺍﻳﻦ ﻣﺪﻝ‪ ،‬ﺑﻪ ﺩﻟﻴـﻞ ﻋـﺪﻡ ﻭﺟـﻮﺩ ﺍﻣﮑﺎﻧـﺎﺕ ﺁﺯﻣﺎﻳﺸـﮕﺎﻫﻲ ﺩﺭ ﺁﻥ‬
‫ﺗﻮﻧﻞﻫﺎﻳﻲ ﮐﻪ ﺩﺭﻭﻥ ﺩﻭ ﻧﻮﺭﻭﻥ ﺭﺍ ﺑﻪ ﻫﻢ ﺍﺭﺗﺒﺎﻁ ﻣﻲﺩﻫﻨﺪ ﻭ ﺍﺟـﺎﺯﺓ‬
‫ﺯﻣﺎﻥ ﺑﺮﺍﻱ ﺗﻌﺪﺍﺩ ﺑﻲﻧﻬﺎﻳﺖ ﺯﻳﺎﺩ ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳـﻮﻧﻲ )ﻧـﻪ ﺍﻧـﻮﺍﻉ ﺁﻥ(‬
‫ﻋﺒﻮﺭ ﺟﺮﻳﺎﻥ ﺑﻴﻦ ﺁﻥ ﺩﻭ ﺭﺍ ﻣﻲﺩﻫﻨﺪ ﮔﻔﺘﻪ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﺳﻴﻨﺎﭘﺲﻫـﺎ‬
‫ﺑﻪﺩﺳﺖ ﺁﻣﺪ‪ .‬ﺩﺭ ﺣﺎﻝ ﺣﺎﺿﺮ ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﮐﻤـﮏ ﺁﺯﻣﺎﻳﺸـﮕﺎﻩﻫـﺎﻱ‬
‫ﻣﻌﻤﻮﻻً ﺩﺭ ﻗﺴﻤﺖ ﮔﺎﻑ ﺍﺗﺼﺎﻝ )ﻣﺤﻞ ﺍﺗﺼﺎﻝ ﻋﺼﺐ ﺑـﻪ ﻋﻀـﻠﻪ(‬
‫ﮊﻧﺘﻴﮑﻲ ﻣﻌﻴﻦ ﮐﺮﺩ ﮐﻪ ﭼﻪ ﻧﻮﻉ ﮐﺎﻧﺎﻝﻫﺎﻳﻲ ﺣﻀﻮﺭ ﺩﺍﺭﻧﺪ ﻭ ﺳـﭙﺲ‬
‫ﻳﺎﻓﺖ ﻣﻲﺷﻮﻧﺪ ﻭﻟﻲ ﺩﺭ ‪ CNS‬ﺍﻧﺴﺎﻥﻫـﺎﻱ ﺑـﺰﺭﮒﺳـﺎﻝ ﺑﺴـﻴﺎﺭ ﺑـﻪ‬
‫ﺍﻗﺪﺍﻡ ﺑﻪ ﺷﺒﻴﻪﺳﺎﺯﻱ ﺁﻧﻬﺎ ﮐﺮﺩ‪ .‬ﺟﻬﺖ ﺗﺸﺨﻴﺺ ﻧـﻮﻉ ﮐﺎﻧـﺎﻝﻫـﺎﻱ‬
‫ﻧﺪﺭﺕ ﻳﺎﻓﺖ ﻣﻲﺷﻮﻧﺪ‪ .‬ﻧـﻮﻉ ﺩﻳﮕـﺮ ﺳـﻴﻨﺎﭘﺲ‪ ،‬ﺳـﻴﻨﺎﭘﺲ ﺷـﻴﻤﻴﺎﻳﻲ‬
‫ﻣﻮﺟﻮﺩ ﻣﻲﺗﻮﺍﻥ ﻗﻄﺮﻩﺍﻱ ﺍﺯ ﺁﻥ ﻏﺸﺎﺀ ﺭﺍ ﺟﻬﺖ ﺗﺸﺨﻴﺺ ﺗﺮﮐﻴـﺐ‬
‫ﺍﺳﺖ ﮐﻪ ﺑﻪ ﺗﻌﺪﺍﺩ ﺑﺴﻴﺎﺭ ﺯﻳﺎﺩ ﺩﺭ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﻣﺮﮐـﺰﻱ ﺍﻧﺴـﺎﻥ‬
‫ﭘﻴﺎﻡﺭﺳﺎﻥ ‪ RNA‬ﻧـﻮﺭﻭﻥ ﺗﺤـﺖ ﺁﺯﻣـﺎﻳﺶ ﻗـﺮﺍﺭ ﺩﺍﺩ‪ .‬ﮐﺎﻧـﺎﻝﻫـﺎﻱ‬
‫ﻳﺎﻓﺖ ﻣﻲﺷﻮﻧﺪ‪ .‬ﺳﻴﻨﺎﭘﺲﻫﺎﻱ ﺷﻴﻤﻴﺎﻳﻲ ﺑﺎ ﺁﺯﺍﺩ ﮐﺮﺩﻥ ﭘﻴﺎﻡﺭﺳﺎﻥﻫﺎﯼ‬
‫ﻳــﻮﻧﻲ ﺍﺯ ﭘــﺮﻭﺗﺌﻴﻦﻫــﺎﻱ ﭘﻴﭽﻴ ـﺪﻩﺍﻱ ﺗﺸــﮑﻴﻞ ﺷــﺪﻩﺍﻧــﺪ ﮐــﻪ ﺑــﻪ‬
‫ﺷﻴﻤﻴﺎﻳﻲ ﻳﺎ ﭘﻴﺎﻡﺭﺳﺎﻥ ﻋﺼﺒﻲ‪ ٢‬ﭘﻴﺎﻡﻫﺎ ﺭﺍ ﺍﺯ ﻧﻮﺭﻭﻥ ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﺑﻪ‬
‫ﺻﻮﺭﺕﻫﺎﻱ ﻣﺨﺘﻠﻒ ﻭﺟﻮﺩ ﺩﺍﺭﻧﺪ‪ .‬ﮐﺎﻧﺎﻝﻫﺎﻱ ﻳـﻮﻧﻲ ﺭﺍ ﻣـﻲﺗـﻮﺍﻥ‬
‫ﻧﻮﺭﻭﻥ ﭘﺲﺳﻴﻨﺎﭘﺴﻲ ﻣﻨﺘﻘﻞ ﻣﻲﮐﻨﻨﺪ ‪.‬ﭘﻴﺎﻡ ﺭﺳﺎﻥ ﻫﺎﯼ ﻋﺼﺒﻲ ﻣﻌﻤﻮﻻً‬
‫ﺑﻪ ﮐﻤﮏ ﺷﻨﺎﺳﻪﻫﺎﻱ ﺧﺎﺻﻲ ﻣﺎﻧﻨﺪ ﺗﺴﻠﺴﻞ ﮊﻧﺘﻴﮑـﻲ‪ ،‬ﻧـﻮﻉ ﻳـﻮﻧﻲ‬
‫ﺩﺭ ﮐﻴﺴﻪﻫﺎﻱ ﺧﺎﺻﻲ )ﻭِﺳﻴﮑﻞ‪ (٣‬ﺩﺭ ﻧﻮﺭﻭﻥ ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﺫﺧﻴـﺮﻩ‬
‫ﮐﻪ ﺍﺯ ﮐﺎﻧﺎﻝ ﻣﻲﮔﺬﺭﺩ )ﺳﺪﻳﻢ‪ ،‬ﭘﺘﺎﺳﻴﻢ‪ ،‬ﮐﻠﺴﻴﻢ ﻭ‪ ،(...‬ﻭﺍﺑﺴﺘﮕﻲ ﺑـﻪ‬
‫ﺷﺪﻩ ﺍﻧﺪ ﻭ ﺑﺎ ﺗﻐﻴﻴﺮﺍﺕ ﭘﺘﺎﻧﺴﻴﻞ ﺩﺭ ﺍﻧﺘﻬﺎﻱ ﺁﮐﺴﻮﻥ ﺍﻳﻦ ﭘﻴﺎﻡﺭﺳﺎﻥﻫـﺎ‬
‫ﻭﻟﺘﺎﮊ ﮐﺎﻧﺎﻝ‪ ،‬ﺣﺴﺎﺳﻴﺖ ﺁﻥ ﺑﻪ ﭘﻴﺎﻡﺭﺳﺎﻥﻫـﺎﯼ ﺩﻭﻡ ﻣﺎﻧﻨـﺪ ﮐﻠﺴـﻴﻢ‬
‫ﺁﺯﺍﺩ ﺷﺪﻩ ﻭ ﺑـﻪ ﻣﺤﻮﻃـﻪ ﻓﻌـﺎﻝ ﺑـﻴﻦ ﺍﻳـﻦ ﺩﻭ ﻧـﻮﺭﻭﻥ ﻣـﻲﺭﻭﻧـﺪ‪.‬‬
‫ﺩﺭﻭﻥﻳﺎﺧﺘﻪﺍﯼ‪ ،‬ﻋﻤﻠﮑﺮﺩ ﺍﺣﺘﻤـﺎﻟﻲ ﺁﻥ ﻭ ﭘﺎﺳـﺦ ﺁﻥ ﺑـﻪ ﺩﺍﺭﻭﻫـﺎﻱ‬
‫ﺍﺗﺼﺎﻻﺕ ﺳﻴﻨﺎﭘﺴﻲ ﺩﺭ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﺑﺴﻴﺎﺭ ﭘﻴﭽﻴﺪﻩ ﺍﺳﺖ‪.‬‬
‫ﺷـﻴﻤﻴﺎﻳﻲ ﻭ ﺗﻐﻴﻴـﺮ ﺩﻫﻨــﺪﻩﻫــﺎﻱ ﻋﺼــﺒﻲ ﻣﺎﻧﻨــﺪ ﺍﺳــﺘﻴﻞﮐــﻮﻟﻴﻦ ﻭ‬
‫ﺑﻌﻀﻲ ﺍﺯ ﻧﻮﺭﻭﻥﻫـﺎ ﺑـﺎ ﻧـﻮﺭﻭﻥﻫـﺎﻱ ﻫﻤﺴـﺎﻳﻪ ﺍﺗﺼـﺎﻝ ﺑﺮﻗـﺮﺍﺭ‬
‫ﺩﻭﭘﺎﻣﻴﻦ ﻣﺸﺨﺺ ﮐﺮﺩ‪ .‬ﺍﻣﺮﻭﺯﻩ ﺑﻴﺶ ﺍﺯ ‪ ۲۰۰‬ﻧﻮﻉ ﮐﺎﻧـﺎﻝ ﺷـﻨﺎﺧﺘﻪ‬
‫ﻣﻲﮐﻨﻨﺪ ﻭﻟﻲ ﺑﻌﻀﻲ ﺩﻳﮕﺮ ﺁﮐﺴﻮﻥﻫﺎﻳﻲ ﺑﺴﻴﺎﺭ ﻃﻮﻻﻧﻲ ﺍﻳﺠﺎﺩ ﮐﺮﺩﻩ ﻭ‬
‫____________________________________________‬
‫ﺷﺪﻩ ﺍﺳﺖ ]‪ ۴۹ ،۴۷‬ﻭ‪.[۵۰‬‬
‫‪2. Neurotransmitter‬‬ ‫____________________________________________‬
‫‪3. Vesicle‬‬ ‫‪1. Cortex‬‬
‫‪۳۶۵‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﺷﮑﻞ ‪ .٢٠‬ﻣﺪﺍﺭ ﻣﻌﺎﺩﻝ ﺩﺭ ﺻﻮﺭﺕ ﻋﺪﻡ ﻭﺟﻮﺩ ﺳﻴﻨﺎﭘﺲ ﺑﻴﻦ ﺩﻭ ﻧـﻮﺭﻭﻥ‬ ‫ﺷﮑﻞ‪ .١٩‬ﺷﮑﻞ ﺳﺎﺩﻩﺍﻱ ﺍﺯ ﺳﻴﻨﺎﭘﺲ ﻭ ﺍﻧﺘﻘﺎﻝ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺍﺯ ﻧـﻮﺭﻭﻥ‬
‫ﺍﻓﺖ ﭘﺘﺎﻧﺴﻴﻞ ﺩﺭ ﺻﻮﺭﺕ ﻋﺪﻡ ﻭﺟﻮﺩ ﺳﻴﻨﺎﭘﺲ ﺑﺴﻴﺎﺭ ﺯﻳﺎﺩ ﺧﻮﺍﻫﺪ ﺑﻮﺩ‪.‬‬ ‫ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﺑﻪ ﻧﻮﺭﻭﻥ ﭘﺲﺳﻴﻨﺎﭘﺴﻲ‪.‬‬

‫ﺑﺮﺍﺑﺮ ‪ 1 M‬ﺑﺎﺷﺪ‪ .‬ﺗﺤﻠﻴﻞ ﺍﻳﻦ ﻣﺪﺍﺭ ﺳﺎﺩﻩ ﻧﺸﺎﻥ ﻣﻲﺩﻫﺪ ﭘﺘﺎﻧﺴـﻴﻠﻲ‬ ‫ﺗﺎ ﻓﻮﺍﺻﻞ ﺣﺪﻭﺩ ﻳﮏ ﻣﺘﺮ ﺑﺎ ﺳﺎﻳﺮ ﻧﻮﺭﻭﻥﻫﺎ ﺍﺗﺼﺎﻝ ﺑﺮﻗﺮﺍﺭ ﻣﻲﮐﻨﻨﺪ‪.‬‬
‫ﮐﻪ ﺍﺯ ﺍﻧﺘﻬﺎﻱ ﺁﮐﺴﻮﻥ ﻧﻮﺭﻭﻥ ﭘﻴﺶﺳﻴﻨﺎﭘﺴـﻲ ﺑـﻪ ﺍﺑﺘـﺪﺍﻱ ﺩﻧـﺪﺭﻳﺖ‬ ‫ﺗﻌﺪﺍﺩ ﺍﺗﺼﺎﻻﺕ ﺳﻴﻨﺎﭘﺴﻲ ﺩﺭ ﺩﺳﺘﮕﺎﻩ ﺍﻋﺼﺎﺏ ﺑﺴـﻴﺎﺭ ﺑﺴـﻴﺎﺭ ﺯﻳـﺎﺩ‬

‫ﻣﻲﺷﻮﺩ‪ .‬ﺣﺘـﻲ‬
‫‪1‬‬
‫ﭘﺲﺳﻴﻨﺎﭘﺴﻲ ﻣﻲﺭﺳﺪ ﺩﭼﺎﺭ ﺍﻓﺘﻲ ﺑﻪ ﺍﻧﺪﺍﺯﺓ‬ ‫ﺍﺳﺖ‪ .‬ﺳﻴﻨﺎﭘﺲﻫﺎ ﻣﻌﻤﻮﻻً ﻳﮏﻃﺮﻓﻪ ﻧﻴﺴﺘﻨﺪ )ﻓﻘﻂ ﺑﻪ ﺟﻠﻮ ﻧﻴﺴـﺘﻨﺪ(‬
‫‪10000‬‬
‫ﺑﻠﮑﻪ ﺑﻪ ﻃﻮﺭ ﺑﺎﺯﺧﻮﺭﺩﻱ )ﻓﻴﺪﺑﮏ( ﻧﻴﺰ ﺍﺗﺼﺎﻝ ﺑﺮﻗﺮﺍﺭ ﻣﻲﮐﻨﻨـﺪ‪ .‬ﺑـﻪ‬
‫ﺍﮔﺮ ﻓﻀﺎﻱ ﺑﻴﻦ ﺩﻭ ﻧـﻮﺭﻭﻥ ﺑﺴـﻴﺎﺭ ﻓﺸـﺮﺩﻩ ﻭ ﻧﺰﺩﻳـﮏ ﻫـﻢ ﺑﺎﺷـﺪ‪،‬‬
‫ﺍﻳﻦ ﻣﻌﻨﻲ ﮐﻪ ﻓﻘﻂ ﺍﺯ ﻧﻮﺭﻭﻥ ﺍﻭﻝ ﺑﻪ ﻧﻮﺭﻭﻥ ﺩﻭﻡ ﺳﻴﻨﺎﭘﺲ ﻧﻤﻲﺯﻧﻨﺪ‬
‫ﻃﻮﺭﻱ ﮐﻪ ﺩﺍﺭﺍﻱ ﻣﻘﺎﻭﻣﺖ ‪ 10 M ‬ﺑﺎﺷﺪ ﺑﺎﺯ ﻫﻢ ﺍﻓﺘـﻲ ﺑـﻪ ﺍﻧـﺪﺍﺯﺓ‬
‫‪1‬‬
‫ﺑﻠﮑﻪ ﻣﻲﺗﻮﺍﻧﻨﺪ ﺳﻴﻨﺎﭘﺲﻫﺎﻳﻲ ﺍﺯ ﻧـﻮﺭﻭﻥ ﺩﻭﻡ ﺑـﻪ ﺍﻭﻝ ﻫـﻢ ﻭﺟـﻮﺩ‬
‫ﺭﺍ ﺗﺠﺮﺑﻪ ﺧﻮﺍﻫﺪ ﮐﺮﺩ‪ ،‬ﺑﻪ ﺍﻳﻦ ﻣﻌﻨﻲ ﮐﻪ ﺑـﻪ ﺍﺯﺍﯼ ‪100 mV‬‬
‫‪10000‬‬ ‫ﺩﺍﺷﺘﻪ ﺑﺎﺷﺪ‪ .‬ﻋﻼﻭﻩ ﺑﺮ ﺍﻳﻦ ﺑﺴﻴﺎﺭﻱ ﺍﺯ ﻧﻮﺭﻭﻥﻫﺎ ﺳﻴﻨﺎﭘﺲﻫـﺎﻳﻲ ﺑـﻪ‬
‫ﭘﺘﺎﻧﺴﻴﻞ ﻧﻮﺭﻭﻥ ﺍﻭﻝ ﻓﻘﻂ ‪ 100  V‬ﺑﻪ ﻧﻮﺭﻭﻥ ﺩﻭﻡ ﻣﻨﺘﻘﻞ ﻣﻲﺷـﻮﺩ‪.‬‬
‫ﺍﻃﺮﺍﻑ ﺧﻮﺩ ﻧﻴﺰ ﻣﻲﺯﻧﻨﺪ )ﺑﻪ ﻃﻮﺭ ﺟﺎﻧﺒﻲ ﻧﻴﺰ ﺑﺎ ﻧﻮﺭﻭﻥﻫـﺎﻱ ﺩﻳﮕـﺮ‬
‫ﻣﺸﺎﻫﺪﻩ ﻣﻲﺷﻮﺩ ﮐﻪ ﺑﺪﻭﻥ ﺳﺎﺯ ﻭ ﮐﺎﺭ ﺧﺎﺹ ﺍﻧﺘﻘﺎﻝ ﭘﻴﺎﻡﻫـﺎ ﺑﺴـﻴﺎﺭ‬
‫ﺍﺭﺗﺒﺎﻁ ﺑﺮﻗﺮﺍﺭ ﻣﻲﮐﻨﻨﺪ(‪ .‬ﻧﻮﺭﻭﻥﻫﺎ ﺑﺎ ﺑﺮﻗﺮﺍﺭﻱ ﺍﺗﺼﺎﻻﺕ ﭘﻲ ﺩﺭﭘﻲ ﻭ‬
‫ﻣﺸﮑﻞ ﺧﻮﺍﻫﺪ ﺑﻮﺩ‪ .‬ﻟﺬﺍ ﺑﺮﺍﻱ ﺳﻴﻨﺎﭘﺲﻫﺎﻱ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺗﻮﻧـﻞﻫـﺎﻳﻲ‬
‫ﻣﺤﻠﻲ ﺑﻴﻦ ﻳﮑﺪﻳﮕﺮ ﺣﻠﻘﻪﻫﺎﻱ ﻧﻮﺭﻭﻧﻲ ﺍﻳﺠﺎﺩ ﻣﻲﮐﻨﻨﺪ‪ .‬ﺩﺭ ﻗﺴـﻤﺖ‬
‫ﺑﻴﻦ ﺩﻭ ﻧﻮﺭﻭﻥ ﺍﻳﺠﺎﺩ ﻣﻲﺷﻮﺩ ﻭ ﺍﺗﺼﺎﻝ ﺍﻟﮑﺘﺮﻳﮑﻲ ﻣﺴـﺘﻘﻴﻢ ﺑﺮﻗـﺮﺍﺭ‬
‫ﺑﻌﺪﻱ ﺍﺷـﺎﺭﻩ ﻣـﻲﺷـﻮﺩ ﮐـﻪ ﺍﻳـﻦ ﺣﻠﻘـﻪﻫـﺎﻱ ﺳﻴﻨﺎﭘﺴـﻲ ﻧـﻮﺭﻭﻧﻲ‬
‫ﻣﻲﮔﺮﺩﺩ‪ .‬ﺷﮑﻞﻫﺎﻱ ﺳﺎﺩﺓ ﺯﻳـﺮ ﻣﺤﺎﺳـﺒﺎﺕ ﻣﺮﺑﻮﻃـﻪ ﺭﺍ ﺭﻭﺷـﻦﺗـﺮ‬
‫ﻣﺤﺘﻤﻞﺗﺮﻳﻦ ﻣﺤﻞ ﺑﺮﺍﻱ ﻧﮕﻬـﺪﺍﺭﻱ ﺍﻃﻼﻋـﺎﺕ ﻳـﺎ ﺣﺎﻓﻈـﻪ ﺍﺳـﺖ‪.‬‬
‫ﻣﻲﮐﻨﺪ ]‪ .[۱۰‬ﺑﻪ ﻃﻮﺭ ﮐﻠﻲ ﺳﻴﻨﺎﭘﺲﻫـﺎﻱ ﺍﻟﮑﺘﺮﻳﮑـﻲ ﺑـﺮﺍﻱ ﺍﻧﺘﻘـﺎﻝ‬
‫ﺗﺤﻘﻴﻘﺎﺕ ﻓﺮﺍﻭﺍﻧﻲ ﺑﺮﺍﻱ ﺩﺭﮎ ﺑﻴﺸﺘﺮ ﻋﻤﻠﮑﺮﺩ ﺳﻴﻨﺎﭘﺲ ﻫﻢﺍﮐﻨﻮﻥ ﺩﺭ‬
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‫ﺳــﺮﻳﻊ ﺍﻃﻼﻋــﺎﺕ ﻭ ﻫﻤﭽﻨــﻴﻦ ﺑــﺮﺍﻱ ﻫــﻢﺯﻣــﺎﻧﻲ ﻳﺎﺧﺘــﻪﻫــﺎ‬
‫ﺩﻧﻴﺎ ﺩﺭ ﺣﺎﻝ ﺍﻧﺠﺎﻡ ﺍﺳﺖ‪ .‬ﻣﺎ ﺩﺭ ﺍﻳﻦﺟﺎ ﺑﻪ ﻃﻮﺭ ﺧﻼﺻﻪ ﺑـﻪ ﺍﺻـﻮﻝ‬
‫ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﺳﻴﻨﺎﭘﺲﻫﺎ ﺑﺮﺍﻱ ﺗﺤﻠﻴﻞ ﻋﻼﻣﺖﻫﺎ ﺩﺭ ﺷﺒﮑﻴﺔ‬
‫ﺍﻭﻟﻴﺔ ﻓﻴﺰﻳﮑﻲ ﺳﻴﻨﺎﭘﺲ ﺍﺷﺎﺭﻩ ﻣﻲﮐﻨـﻴﻢ ﻭ ﺑـﺮﺍﻱ ﻣﻄﺎﻟﻌـﺔ ﺟﺰﺋﻴـﺎﺕ‬
‫ﭼﺸﻢ ﻧﻴﺰ ﺑﺴﻴﺎﺭ ﻣﻬـﻢ ﻫﺴـﺘﻨﺪ ]‪ ۵۱،3‬ﻭ‪ .[۵۲‬ﺍﻣـﺎ ﻫﻤـﺎﻥ ﻃـﻮﺭ ﮐـﻪ‬
‫ﻋﻤﻠﮑﺮﺩ ﺳﻴﻨﺎﭘﺲ ﺑﻪ ﻣﺮﺍﺟﻊ ﺍﺭﺟﺎﻉ ﺩﺍﺩﻩ ﻣﻲﺷﻮﺩ ]‪ ۳‬ﻭ ‪.[۱۵‬‬
‫ﺍﺷﺎﺭﻩ ﺷﺪ ﺍﮐﺜﺮ ﺳﻴﻨﺎﭘﺲﻫﺎﻱ ‪ CNS‬ﺷـﻴﻤﻴﺎﻳﻲ ﻫﺴـﺘﻨﺪ ﻭ ﺳـﺎﺯﻭﮐﺎﺭ‬
‫ﺳﻮﺍﻝ ﺍﻭﻝ ﺍﻳﻦ ﺍﺳﺖ ﮐـﻪ ﭼـﺮﺍ ﻧـﻮﺭﻭﻥﻫـﺎ ﺑـﺮﺍﻱ ﺍﺭﺗﺒـﺎﻁ ﺑـﺎ‬
‫ﺁﻧﻬﺎ ﺑﺎ ﺁﺯﺍﺩﺳـﺎﺯﻱ ﭘﻴﺎﻡﺭﺳﺎﻥﻫﺎﻱ ﻋﺼﺒﻲ ﻣﻲﺑﺎﺷﺪ )ﺷﮑﻞ ‪.(۲۲‬‬
‫ﻧﻮﺭﻭﻥﻫﺎﻱ ﻫـﻢﺟـﻮﺍﺭ ﺍﺯ ﺳـﻴﻨﺎﭘﺲ ﺍﺳـﺘﻔﺎﺩﻩ ﻣـﻲﮐﻨﻨـﺪ ﻭ ﭘﻴـﺎﻡ ﺑـﻪ‬
‫ﺍﻳﻦ ﺳﺎﺯ ﻭ ﮐﺎﺭ ﺭﺍ ﻣﻲﺗﻮﺍﻥ ﺑﻪ ﻃﻮﺭ ﺧﻼﺻﻪ ﭼﻨﻴﻦ ﺑﻴـﺎﻥ ﮐـﺮﺩ‪:‬‬
‫ﺳﺎﺩﮔﻲ ﺑﻪ ﻃﻮﺭ ﻣﺴﺘﻘﻴﻢ ﺍﺯ ﻳﮏ ﻧـﻮﺭﻭﻥ ﺑـﻪ ﻧـﻮﺭﻭﻥ ﺩﻳﮕـﺮ ﻣﻨﺘﻘـﻞ‬
‫ﺍﺑﺘﺪﺍ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺍﺯ ﻧﻮﺭﻭﻥ ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﻭﺍﺭﺩ ﺁﮐﺴﻮﻥ ﺁﻥ ﺷـﺪﻩ‬
‫ﻧﻤﻲﺷﻮﺩ؟ ﻣﻲﺗﻮﺍﻥ ﺍﻳﻦ ﻣﺴﺌﻠﻪ ﺭﺍ ﺑﻪ ﻃﻮﺭ ﻓﻴﺰﻳﮑﻲ ﺗﺤﻠﻴـﻞ ﮐـﺮﺩﻩ ﻭ‬
‫ﻭ ﭘﺎﻳﺎﻧﺔ ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﺭﺍ ﺍﺷﻐﺎﻝ ﻣﻲﮐﻨﺪ‪ .‬ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺩﺭ ﺁﮐﺴﻮﻥ‬
‫ﭘﺎﺳﺦ ﺁﻥ ﺭﺍ ﻳﺎﻓﺖ‪ .‬ﻓﺮﺽ ﮐﻨﻴﺪ ﻣﻘﺎﻭﻣﺖ ﻏﺸـﺎﯼ ﭘﺎﻳﺎﻧـﻪﻫـﺎﻱ ﺑـﻴﻦ‬
‫‪‬‬ ‫‪‬‬
‫ﺑﻪ ﻃﻮﺭ ﻋﻤﺪﻩ ﻭﺍﺑﺴﺘﻪ ﺑﻪ ﮐﺎﻧﺎﻝﻫـﺎﻱ ‪ Na‬ﻭ ‪ K‬ﺍﺳـﺖ‪ .‬ﺑـﺎ ﻭﺭﻭﺩ‬ ‫ﻧﻮﺭﻭﻥ ﺍﻭﻝ ﻭ ﺩﻭﻡ ‪ ۱۰۰۰ M ‬ﺑﺎﺷـﺪ‪ ،‬ﻣﻘﺎﻭﻣـﺖ ﻭﺭﻭﺩﻱ ﻧـﻮﺭﻭﻥ‬

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‫‪ ۱۰۰‬ﻭ ﻣﻘﺎﻭﻣﺖ ﻓﻀﺎﻱ ﺑﻴﻦ ﺁﮐﺴـﻮﻥ ﻭ ﺩﻧـﺪﺭﻳﺖ‬ ‫ﺑﺮﺍﺑﺮ ‪M ‬‬ ‫ﺩﻭﻡ‬
‫‪1. Synchronization‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۶۶‬‬

‫ﺷﮑﻞ ‪ .٢٢‬ﺷﮑﻞ ﻧﻤﺎﺩﻳﻦ ﻳﮏ ﺳﻴﻨﺎﭘﺲ ﺷﻴﻤﻴﺎﻳﻲ‪.‬‬ ‫ﺷﮑﻞ ‪ .٢١‬ﻣﺪﺍﺭ ﻣﻌﺎﺩﻝ ﺑﺮﺍﻱ ﺣﻀﻮﺭ ﺳﻴﻨﺎﭘﺲ ﺑﻴﻦ ﺩﻭ ﻧﻮﺭﻭﻥ ﺑـﺎ ﻭﺟـﻮﺩ‬
‫ﺳﻴﻨﺎﭘﺲ ﺍﻧﺘﻘﺎﻝ ﭘﻴﺎﻡ ﺑﺴﻴﺎﺭ ﺁﺳﺎﻥ ﺗﺮ ﺧﻮﺍﻫﺪ ﺑﻮﺩ‪.‬‬

‫ﺁﻣﺎﺭﻱ ﻣﻮﺭﺩ ﺑﺮﺭﺳﻲ ﻗﺮﺍﺭ ﻣﻲﺩﻫﻴﻢ‪.‬‬ ‫ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺑﻪ ﺗﺮﻣﻴﻨﺎﻝ ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﺗﻌﺪﺍﺩ ﺯﻳﺎﺩﻱ ﺍﺯ ﮐﺎﻧﺎﻝﻫﺎﻱ‬
‫ﺣﺴﺎﺱ ﺑـﻪ ﻭﻟﺘـﺎﮊ ﻓﻌـﺎﻝ ﻣـﻲﺷـﻮﻧﺪ‪ .‬ﺍﻃﻼﻋـﺎﺕ ﺩﻗﻴﻘـﻲ ﺍﺯ ﺍﻧـﻮﺍﻉ‬
‫ﮐﺎﻧــﺎﻝﻫــﺎﻱ ﻣﻮﺟــﻮﺩ ﺩﺭ ﺍﻳ ـﻦ ﺗﺮﻣﻴﻨــﺎﻝﻫــﺎ ﺩﺭ ﺩﺳــﺖ ﻧﻴﺴــﺖ ]‪،۳‬‬
‫‪ ۱ -۵‬ﻓﺮﺿﻴﺔ ﮐﻮﺍﻧﺘﺎﻳﻲ )ﮔﺴﺴﺘﻪ( ﺁﺯﺍﺩﺳـﺎﺯﻱ ﭘﻴـﺎﻡ ﺭﺳـﺎﻥﻫـﺎﯼ‬
‫‪۱۵‬ﻭ‪ .[۴۷‬ﮐﺎﻫﺶ ﭘﺘﺎﻧﺴﻴﻞ ﺗﺮﻣﻴﻨﺎﻝ ﺑﻪ ﻭﺳﻴﻠﺔ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ‪ ،‬ﺣﺪﺍﻗﻞ‬
‫ﻋﺼﺒﻲ‬
‫ﮐﺎﻧﺎﻝﻫﺎﻱ ﮐﻠﺴﻴﻢ ﺑﺎ ﺩﺭﻭﺍﺯﺓ ﺣﺴـﺎﺱ ﺑـﻪ ﻭﻟﺘـﺎﮊ ﺭﺍ ﻓﻌـﺎﻝ ﮐـﺮﺩﻩ ﻭ‬
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‫ﺩﺭ ﺳـﻴﻨﺎﭘﺲ ﺑـﻴﻦ ﻧـﻮﺭﻭﻥﻫـﺎﻱ ﺣﺮﮐﺘـﻲ ﻭ ﻳﺎﺧﺘـﻪﻫـﺎﻱ ﻋﻀـﻼﻧﻲ‬
‫ﺍﺟﺎﺯﺓ ﻭﺭﻭﺩ ﻳﻮﻥﻫﺎﻱ ‪ Ca2‬ﺭﺍ ﻣﻲﺩﻫﺪ‪ .‬ﻭﺭﻭﺩ ﺍﻳﻦ ﻳـﻮﻥﻫـﺎ ﺳـﺒﺐ‬
‫ﻣﻨﻄﻘﻪﺍﻱ ﻓﻌﺎﻝ ﻭﺟﻮﺩ ﺩﺍﺭﺩ ﮐﻪ ﺩﺭ ﺁﻥ ﺁﮐﺴﻮﻥ ﻧﻮﺭﻭﻥ ﺣﺮﮐﺘﻲ ﻏـﻼﻑ‬
‫ﺑﺮﻭﺯ ﺭﺧﺪﺍﺩﻫﺎﻱ ﺩﻳﮕﺮﻱ ﻣﻲﮔﺮﺩﺩ ﮐﻪ ﺩﺭ ﻧﻬﺎﻳﺖ ﻣﻨﺠﺮ ﺑﻪ ﺗﺮﮐﻴـﺐ‬
‫ﭼﺮﺑﻲ ﺧـﻮﺩ ﺭﺍ ﺩﺭ ﻃـﻮﻟﻲ ﺣـﺪﻭﺩ ‪ 30 nm‬ﻗﺒـﻞ ﺍﺯ ﻏﺸـﺎﯼ ﻳﺎﺧﺘـﺔ‬
‫ﭘﻼﺳﻤﺎﻱ ﻏﺸﺎﻱ ﺳﻴﻨﺎﭘﺲ ﮐﻴﺴﻪﻫﺎﻱ ﺣﺎﻭﻱ ﭘﻴﺎﻡﺭﺳـﺎﻥﻫـﺎ ﻋﺼـﺒﻲ‬
‫ﻋﻀﻠﻪ ﺍﺯ ﺩﺳﺖ ﻣﻲﺩﻫﺪ‪ .‬ﺍﻳﻦ ﻣﻨﻄﻘﻪ ﻫﻤﺎﻥ ﺷﮑﺎﻑ ﺳﻴﻨﺎﭘﺴـﻲ ﺍﺳـﺖ‬
‫ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﺧﻮﺩ ﺳﺒﺐ ﺁﺯﺍﺩﺳﺎﺯﻱ ﻳﮏ ﻳﺎ ﺑﻴﺸـﺘﺮ ﻣـﻮﺍﺩ ﺷـﻴﻤﻴﺎﻳﻲ‬
‫ﮐﻪ ﺩﺭ ﺁﻥ ﻣﻮﻟﮑﻮﻝﻫﺎﻱ ﭘﻴﺎﻡﺳﺎﺯ ﺁﺯﺍﺩ ﻣﻲﺷﻮﻧﺪ‪ .‬ﺟﻬﺖ ﺍﻓﺰﺍﻳﺶ ﺳﻄﺢ‬
‫ﺩﺭ ﺷﮑﺎﻑ ﺳﻴﻨﺎﭘﺴﻲ ﻣـﻲﺷـﻮﺩ‪ .‬ﺑـﻪ ﺍﻳـﻦ ﻋﻤـﻞ ﺑـﺮﻭﻥﺭﺍﻧـﻲ ﮔﻔﺘـﻪ‬
‫ﺗﻤﺎﺱ ﻏﺸﺎﯼ ﻳﺎﺧﺘﺔ ﻋﻀﻼﻧﻲ ﺑﺎ ﺷﮑﺎﻑ ﺳﻴﻨﺎﭘﺴﻲ‪ ،‬ﻓﺮﻭ ﺭﻓﺘﮕﻲﻫﺎﻳﻲ‬
‫ﻣﻲﺷﻮﺩ‪.‬‬
‫ﺩﺭ ﻏﺸﺎﯼ ﻳﺎﺧﺘﺔ ﻋﻀﻼﻧﻲ ﺍﻳﺠﺎﺩ ﻣﻲﺷﻮﺩ ﮐﻪ ﺑـﻪ ﺻـﻔﺤﺎﺕ ﺍﻧﺘﻬـﺎﻳﻲ‬
‫ﺣﺮﮐﺘﻲ ﻣﻌﺮﻭﻑ ﺍﺳﺖ‪ .‬ﺩﺭ ﻓﻴﺒﺮﻫﺎﻱ ﻧﺰﺩﻳﮏ ﺍﻳـﻦ ﺻـﻔﺤﺎﺕ ﮐـﺎﻫﺶ‬ ‫ﭘﻴﺎﻡﺭﺳﺎﻥﻫﺎ ﻋﺼﺒﻲ ﺩﺭ ﺷﮑﺎﻑ ﺳﻴﻨﺎﭘﺴﻲ ﭘﺨﺶ ﺷﺪﻩ ﻭ ﺑﺎ ﻏﺸﺎﺀ‬
‫ﻗﻄﺒﺶﻫﺎﻱ ﺧﻮﺩ ﺑﻪﺧﻮﺩﻱ ﻭﺟﻮﺩ ﺩﺍﺭﺩ ﺷﮑﻞ ‪ ۲۳‬ﮐﻪ ﺑﻪ ﭘﺘﺎﻧﺴﻴﻞﻫﺎﻱ‬ ‫ﭘﺲﺳﻴﻨﺎﭘﺴﻲ ﺗﻤﺎﺱ ﺑﺮﻗﺮﺍﺭ ﻣﻲﮐﻨﺪ‪ .‬ﺍﻳﻦ ﭘﻴﺎﻡﺭﺳﺂﻥﻫﺎ ﺑـﻪ ﺩﺭﻳﺎﻓـﺖ‬
‫ﮐﻮﺗﺎﻩ ﺻﻔﺤﺔ ﺍﻧﺘﻬﺎﻳﻲ‪ ٢‬ﻣﻌﺮﻭﻑ ﺷﺪﻩ ﺍﺳﺖ ‪ MEPP‬ﻫﺎ ﺑﺎ ﻓﺎﺻﻠﻪﻫـﺎﻱ‬ ‫ﮐﻨﻨﺪﻩﻫـﺎﻱ ﻣﺨﺼﻮﺻـﻲ ﺩﺭ ﻏﺸـﺎﯼ ﭘـﺲﺳﻴﻨﺎﭘﺴـﻲ ﻣـﻲﭼﺴـﺒﻨﺪ‪.‬‬
‫ﺯﻣﺎﻧﻲ ﺗﺼﺎﺩﻓﻲ ﺭﺥ ﺩﺍﺩﻩ ﻭ ﺩﺍﺭﺍﻱ ﺑﺴﺎﻣﺪﻱ ﺣﺪﻭﺩ ‪ 1 HZ‬ﺍﺳﺖ‪ .‬ﻳﮏ‬ ‫ﭼﺴﺒﻴﺪﻥ ﺍﻳﻦ ﻣﻮﻟﮑﻮﻝﻫﺎ ﺳﺒﺐ ﺑﺎﺯﺷﺪﻥ ﺳـﺮﻳﻊ ﮐﺎﻧـﺎﻝﻫـﺎﻱ ﻳـﻮﻧﻲ‬
‫‪ MEPP‬ﺑﺎ ﺁﺯﺍﺩ ﺷﺪﻥ ﻳـﮏ ﮐﻴﺴـﺔ ﻫﻴﺴـﺘﻮﮔﺮﺍﻡ ﺩﺍﻣﻨـﻪﻫـﺎﻱ ﺣـﺎﻭﻱ‬ ‫ﻣﻲﺷﻮﻧﺪ‪ .‬ﺑﺎﺯ ﺷﺪﻥ ﺍﻳﻦ ﮐﺎﻧﺎﻝﻫﺎ ﺳﺒﺐ ﺗﻐﻴﻴـﺮ ﺩﺭ ﭘﺘﺎﻧﺴـﻴﻞ ﻏﺸـﺎﯼ‬
‫ﭘﻴﺎﻡﺭﺳﺎﻥﻫﺎﻱ ﻋﺼﺒﻲ ﺍﻳﺠﺎﺩ ﻣﻲﺷﻮﺩ ]‪.[۳‬‬ ‫ﻧﻮﺭﻭﻥ ﭘﺲﺳﻴﻨﺎﭘﺴﻲ ﻣﻲﺷﻮﺩ‪ .‬ﺍﻳﻦ ﻣﺮﺍﺣﻞ ﺩﺭ ﮐﻤﺘﺮ ﺍﺯ ‪ 1 ms‬ﺍﺗﻔﺎﻕ‬
‫‪ MEPP‬ﻫﺎ ﻳﮏ ﺗﻮﺯﻳﻊ ﺑﺎ ﻳﮏ ﺑﻴﺸﻴﻨﻪ ﺭﺍ ﻧﺸﺎﻥ ﻣﻲﺩﻫﺪ )ﺷـﮑﻞ‬ ‫ﻣﻲﺍﻓﺘﻨﺪ‪.‬‬
‫‪ .(۲۴‬ﻭﺍﺭﻳﺎﻧﺲ ﺍﻳﻦ ﻫﻴﺴﺘﻮﮔﺮﺍﻡ ﻣﻲﺗﻮﺍﻧﺪ ﺍﺯ ﻣﻨﺎﺑﻊ ﻣﺨﺘﻠﻔـﻲ ﻫﻤﺎﻧﻨـﺪ‬ ‫ﺑﻌﺪ ﺍﺯ ﺍﺗﻤﺎﻡ ﻣﺮﺣﻠﺔ ﺑـﺮﻭﻥﺭﺍﻧـﻲ‪ ،‬ﻏﺸـﺎﯼ ﮐﻴﺴـﻪﻫـﺎ ﺍﺯ ﻏﺸـﺎﯼ‬
‫ﺗﻌﺪﺍﺩ ﭘﻴﺎﻡﺭﺳﺂﻧﻬﺎﻱ ﻋﺼـﺒﻲ ﺩﺭ ﻫـﺮ ﮐﻴﺴـﻪ‪ ،‬ﺗﻌـﺪﺍﺩ ﻣﻮﻟﮑـﻮﻝﻫـﺎﻱ‬ ‫ﭘﻼﺳﻤﺎﯼ ﺳﻴﻨﺎﭘﺲ ﺟﺪﺍ ﺷﺪﻩ ﻭ ﻃﻲ ﻓﺮﺁﻳﻨﺪ ﺩﺭﻭﻥﺭﺍﻧﻲ‪ ،‬ﮐﻴﺴﻪﻫـﺎﻱ‬
‫ﭼﺴــﺒﻴﺪﻩ ﺑــﻪ ﺩﺭﻳﺎﻓــﺖﮐﻨﻨــﺪﻩﻫــﺎ‪ ،‬ﺗﻌــﺪﺍﺩ ﺩﺭﻳﺎﻓــﺖﮐﻨﻨــﺪﻩﻫــﺎﻱ‬ ‫ﺣﺎﻭﻱ ﭘﻴﺎﻡ ﺭﺳﺎﻥ ﻫﺎ ﻋﺼـﺒﻲ ﺭﺍ ﺑـﺮﺍﻱ ﻓﻌﺎﻟﻴـﺖﻫـﺎﻱ ﺑﻌـﺪﻱ ﺁﻣـﺎﺩﻩ‬
‫ﭘﺲﺳﻴﻨﺎﭘﺴﻲ‪ ،‬ﻭ ﺍﺣﺘﻤﺎﻝ ﺑﺎﺯﺷﺪﻥ ﮐﺎﻧﺎﻝ ﻏﺸﺎﯼ ﭘﺲﺳﻴﻨﺎﭘﺴـﻲ ﺑﻌـﺪ‬ ‫ﻣﻲﮐﻨﻨﺪ‪.‬‬
‫ﺍﺯ ﭼﺴﺒﻴﺪﻥ ﻣﻮﻟﮑﻮﻝ ﭘﻴﺎﻡﺭﺳﺎﻥ ﺑﺎﺷﺪ‪.‬‬
‫ﻣﻄﺎﻟﻌﺎﺕ ﺍﺗﺼﺎﻝ ﻋﺼﺒﻲ‪ -‬ﻋﻀﻼﻧﻲ ﻣﻬﺮﻩﺩﺍﺭﺍﻥ ﻣﻨﺠﺮ ﺑـﻪ ﻧﻈﺮﻳـﺔ‬
‫____________________________________________‬ ‫ﮐﻮﺍﻧﺘﺎﻳﻲ )ﮔﺴﺴﺘﻪ( ﺁﺯﺍﺩﺳﺎﺯﻱ ﭘﻴﺎﻡﺭﺳـﺎﻥﻫـﺎ ﻋﺼـﺒﻲ ﺷـﺪ‪ .‬ﺟﻬـﺖ‬
‫‪1. Neuromuscular junction‬‬ ‫ﺭﻭﺷﻦﺗﺮ ﺷﺪﻥ ﺑﻴﺸﺘﺮ ﺍﻳﻦ ﻧﻈﺮﻳﺔ ﺩﺭ ﻗﺴﻤﺖ ﺑﻌﺪﻱ ﺁﻥ ﺭﺍ ﺍﺯ ﺩﻳﺪﮔﺎﻩ‬
‫)‪2. Miniature End-Plate Potential (MEPP‬‬
‫‪۳۶۷‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫ﺷﮑﻞ ‪ .٢٤‬ﻫﻴﺴﺘﻮﮔﺮﺍﻡ ﭘﺘﺎﻧﺴﻴﻞ ﻫﺎﻱ ﮐﻮﺗﺎﻩ ﺻـﻔﺤﺔ ﺍﻧﺘﻬـﺎﻳﻲ ﺩﺭ ﻣﺤـﻞ‬ ‫ﺷﮑﻞ ‪ .۲۳‬ﮐﺎﻫﺶ ﻗﻄـﺒﺶ ﻫـﺎﻱ ﺧـﻮﺩﺑـﻪ ﺧـﻮﺩﻱ ﺻـﻔﺤﺎﺕ ﺍﻧﺘﻬـﺎﻳﻲ‬
‫ﺳﻴﻨﺎﭘﺲ ﻋﺼﺐ ﺑﻪ ﻋﻀﻠﻪ‪.‬‬ ‫ﺣﺮﮐﺘﻲ‪.‬‬

‫‪‬‬ ‫ﺟﺎﻟﺐ ﺍﻳﻨﺠﺎﺳﺖ ﮐﻪ ﺍﮔﺮ ﺑﺎ ﺗﺰﺭﻳﻖ ﻳﻮﻥﻫﺎﻱ ﻣﺨﺘﻠﻒ ﺳـﻌﻲ ﺩﺭ‬

‫ﻫﻤﺔ ﺟﺎﻳﮕﺎﻩﻫﺎﻱ ﺁﺯﺍﺩﺳﺎﺯﻱ ﻳﮑﺴﺎﻥ ﻭ ﺩﺍﺭﺍﻱ ﻣﺘﻮﺳﻂ ‪ P‬ﺑـﻪ ﺍﺯﺍﯼ‬
‫ﺗﻐﻴﻴﺮ ﻗﺪﺭﺕ ﻣﺨﺎﺑﺮﺓ ﺳﻴﻨﺎﭘﺲ ﻋﺼﺒﻲ‪ -‬ﻋﻀﻼﻧﻲ ﮐﻨﻴﻢ‪ ،‬ﺩﺭ ﻣﺘﻮﺳـﻂ‬
‫ﻫﺮ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺑﺎﺷﺪ‪ .‬ﻫﻤﭽﻨﻴﻦ ﺍﻳﻦ ﺍﺣﺘﻤﺎﻝ ﻳﮑﻨﻮﺍﺧـﺖ ﺩﺭ ﻧﻈـﺮ‬
‫‪‬‬
‫ﺩﺍﻣﻨﻪﻫﺎ ﺗﻐﻴﻴﺮﻱ ﺍﻳﺠـﺎﺩ ﻧﻤـﻲﺷـﻮﺩ )ﺣـﺪﻭﺩ ‪ .( 0/ 4 mV‬ﺍﺯ ﺍﻳـﻦ ﺭﻭ‬
‫ﮔﺮﻓﺘﻪ ﻣﻲﺷﻮﺩ )‪ . (P  P‬ﺍﺯ ﺍﻳﻦ ﺭﻭ ﺗﻌﺪﺍﺩ ﻣﺘﻮﺳﻂ ﻭﺍﺣﺪﻫﺎﻳﻲ ﮐـﻪ‬ ‫ﮐﺎﺳﺘﻴﻠﻮ‪ ١‬ﻭ ﮐﺘﺰ‪ ٢‬ﺑﻪ ﺍﻳﻦ ﻧﺘﻴﺠﻪ ﺭﺳﻴﺪﻧﺪ ﮐﻪ ﺗﻐﻴﻴـﺮ ﭘﺘﺎﻧﺴـﻴﻞ ﻧﻬـﺎﻳﻲ‬
‫‪‬‬
‫ﺑﻪ ﺍﺯﺍﯼ ﻫﺮ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺁﺯﺍﺩﺳﺎﺯﻱ ﮐﺮﺩﻩﺍﻧﺪ ﺑﺮﺍﺑﺮ ‪ m  n P‬ﺍﺳﺖ‪.‬‬ ‫ﺍﻳﻦ ﺳﻴﻨﺎﭘﺲ ﻧﺎﺷﻲ ﺍﺯ ﺗﺮﮐﻴﺐ ﺗـﮏﺗـﮏ ‪MEPP‬ﻫﺎﺳـﺖ ﺑﻨـﺎﺑﺮﺍﻳﻦ‬
‫)ﺝ( ﻓﺮﺽ ﻣﻲﮐﻨﻴﻢ ﺗﻌﺪﺍﺩ ﺩﺭﻳﺎﻓﺖﮐﻨﻨﺪﻩﻫﺎﻱ ﻣﻮﺟﻮﺩ ﺑﺴﻴﺎﺭ ﺑﻴﺸـﺘﺮ‬ ‫ﭘﻴﺸﻨﻬﺎﺩ ﮐﺮﺩﻧﺪ ﮐﻪ ﺍﻓﺖﻭﺧﻴﺰ ﺩﺭ ﺩﺍﻣﻨﺔ ﺍﻳﻦ ﺗﻐﻴﻴﺮ ﭘﺘﺎﻧﺴﻴﻞﻫﺎ ﻧﺎﺷـﻲ‬
‫ﺍﺯ ﺗﻌﺪﺍﺩ ﭘﻴﺎﻡﺭﺳﺎﻥﻫﺎﯼ ﺁﺯﺍﺩﺷﺪﻩ ﺍﺯ ﻫﺮ ﻭﺍﺣﺪ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺍﺳﺖ‪ .‬ﺍﻳﻦ‬ ‫ﺍﺯ ﺗﻐﻴﻴﺮ ﺩﺭ ﺗﻌﺪﺍﺩ ‪ MEPP‬ﻫﺎ ﻳﺎ ﮐﻮﺍﻧﺘﺎﻫﺎﻱ ﺁﺯﺍﺩ ﺷـﺪﻩ ﺍﺳـﺖ‪ .‬ﺍﻳـﻦ‬
‫ﻣﻨﺠﺮ ﺑﻪ ﺍﻳﻦ ﻓﺮﺽ ﻣﻲﺷﻮﺩ ﮐﻪ ﺗﻌﺪﺍﺩ ﻣﻮﻟﮑﻮﻝﻫﺎﻱ ﻣﻮﺟﻮﺩ ﺩﺭ ﻫﺮ‬ ‫ﻓﺮﺿﻴﻪ ﺑﻪ ﻓﺮﺿﻴﺔ ﮐﻮﺍﻧﺘـﺎﻳﻲ ﻣﻌـﺮﻭﻑ ﺷـﺪﻩ ﻭ ﻳﮑـﻲ ﺍﺯ ﭘﺎﻳـﻪﻫـﺎﻱ‬
‫ﺟﺎﻳﮕﺎﻩ ﺑﺎ ﻫﻢ ﻳﮑﺴﺎﻥ ﻧﻴﺴﺘﻨﺪ ﻭ ﻫﻤﻴﻦ ﺳﺒﺐ ﺍﻓﺖ ﻭ ﺧﻴﺰ ﺩﺭ ﺩﺍﻣﻨـﺔ‬ ‫ﺍﺳﺎﺳﻲ ﻓﻴﺰﻳﮏ ﺍﻧﺘﻘﺎﻝ ﺳﻴﻨﺎﭘﺴﻲ ﺭﺍ ﺗﺸﮑﻴﻞ ﻣﻲﺩﻫﺪ ]‪.[۵۳‬‬
‫‪ MEPP‬ﻣﻲﺷﻮﺩ‪.‬‬
‫)ﺩ( ﻓﺮﺽ ﻣﻲﮐﻨـﻴﻢ ‪ n‬ﺑـﺰﺭﮒ ﺍﺳـﺖ ﻭ ﺁﺯﺍﺩﺳـﺎﺯﻱ ﻫـﺮ ﺟﺎﻳﮕـﺎﻩ‬ ‫‪ .۱.۱.۵‬ﺑﺮﺭﺳــﻲ ﺁﻣـــﺎﺭﻱ ﻓﺮﺿــﻴﺔ ﮐﻮﺍﻧﺘـــﺎﻳﻲ ﺁﺯﺍﺩﺳـــﺎﺯﻱ‬

‫ﻣﺴﺘﻘﻞ ﺍﺯ ﺳﺎﻳﺮﻳﻦ ﺑﺎﺷﺪ )ﺭﺧﺪﺍﺩﻫﺎﻱ ﻣﺴﺘﻘﻞ(‪.‬‬ ‫ﭘﻴﺎﻡﺭﺳﺎﻥﻫﺎﻱ ﻋﺼﺒﻲ‬

‫)ﻩ( ﺁﺯﺍﺩﺳﺎﺯﻱ ﻫـﺮ ﻭﺍﺣـﺪ )ﮐﻴﺴـﻪ( ﻳـﮏ ﮐـﻮﺍﻧﺘﻢ ﺩﺭ ﻧﻈـﺮ ﮔﺮﻓﺘـﻪ‬ ‫ﺍﺑﺘﺪﺍ ﺑﻪ ﻣﻌﺎﺩﻻﺕ ﺭﻳﺎﺿﻲ ﻓﺮﺿﻴﺔ ﮐﻮﺍﻧﺘﺎﻳﻲ ﺍﺷﺎﺭﻩ ﮐﺮﺩﻩ ﻭ ﺳﭙﺲ ﺑـﻪ‬
‫ﻣﻲﺷﻮﺩ‪.‬‬ ‫ﺍﻧﺘﻘﺎﻝ ﻳـﮏ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺍﺯ ﻳـﮏ ﺳـﻴﻨﺎﭘﺲ ﻣـﻲﭘـﺮﺩﺍﺯﻳﻢ‪ .‬ﺍﮐﺜـﺮ‬
‫‪r‬‬ ‫ﻓﻴﺰﻳﮏﭘﻴﺸﮕﺎﻥ ﺑﺎ ﻧﻈﺮﻳﺔ ﺁﻣﺎﺭﻱ ﺁﺷﻨﺎ ﺑﻮﺩﻩ ﻭ ﻟﺬﺍ ﻣﺎ ﻓﻘﻂ ﺑﻪ ﮐﻠﻴـﺎﺕ‬
‫ﺑﺎﺷﺪ‪ ،‬ﻭ‬ ‫ﺍﮔﺮ ﻓﺮﺽ ﮐﻨﻴﻢ ﻣﺘﻮﺳﻂ ﺁﺯﺍﺩﺳﺎﺯﻱ‪ MEPP‬ﺑﺮﺍﺑﺮ‬
‫‪sec‬‬
‫ﺷﺮﺍﻳﻂ ﺣﺎﮐﻢ ﺑﺮ ﺍﻳﻦ ﭘﺪﻳﺪﻩ ﺍﺷﺎﺭﻩ ﻣﻲﮐﻨﻴﻢ‪ .‬ﻓﺮﺽ ﻣﻲﮐﻨﻴﻢ‪:‬‬
‫ﺍﺗﻔﺎﻕ ﺑﻴﺎﻓﺘﺪ‪ ،‬ﻣﻲﺧﻮﺍﻫﻴﻢ ﻣﻌﺎﺩﻟـﺔ‬ ‫‪t 0‬‬ ‫ﺍﻭﻟﻴﻦ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺩﺭ ﺯﻣﺎﻥ‬
‫)ﺍﻟﻒ( ﺗﻌﺪﺍﺩ ‪ n‬ﻭﺍﺣﺪ )ﻳﺎ ﺟﺎﻳﮕﺎﻩ( ﺑﺮﺍﻱ ﺁﺯﺍﺩﺳﺎﺯﻱ ﭘﻴﺎﻡﺭﺳﺎﻥﻫـﺎﯼ‬
‫ﺍﺣﺘﻤﺎﻝ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺑﻌﺪﻱ ﺭﺍ ﺑﺮﺣﺴﺐ ﺯﻣﺎﻥ ﺑﻪ ﺩﺳﺖ ﺁﻭﺭﻳـﻢ‪ .‬ﺍﻳـﻦ‬
‫ﻋﺼﺒﻲ ﺩﺭ ﺩﺳﺘﺮﺱ ﻫﺴﺘﻨﺪ ﻭ ﻫﺮ ﻭﺍﺣﺪ ﻓﻘﻂ ﻳﮏ ﺁﺯﺍﺩﺳﺎﺯﻱ )ﻳـﮏ‬
‫ﻣﻌﺎﺩﻟﺔ ﺗﻮﺯﻳﻊ ﻓﺎﺻﻠﻪﻫﺎﻱ ﺯﻣـﺎﻧﻲ ﺑـﻴﻦ ‪ MEPP‬ﻫـﺎﻱ ﭘـﻲﺩﺭﭘـﻲ ﺭﺍ‬
‫ﮐﻴﺴﻪ( ﺍﻧﺠﺎﻡ ﻣﻲﺩﻫﺪ‪.‬‬
‫ﻭ ﺍﺣﺘﻤﺎﻝ ﻋـﺪﻡ‬ ‫‪ t‬ﺑﺮﺍﺑﺮ ‪r t‬‬ ‫ﻣﻲﺩﻫﺪ‪ .‬ﺍﺣﺘﻤﺎﻝ ﻳﮏ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺩﺭ‬
‫)ﺏ( ﺩﺭ ﻏﻴ ـﺎﺏ ﭘﺘﺎﻧﺴ ـﻴﻞ ﻋﻤــﻞ‪ ،‬ﺍﺣﺘﻤــﺎﻝ ﻣﺤــﺪﻭﺩ ﻭﻟ ـﻲ ﺑﺴ ـﻴﺎﺭ‬
‫ﺍﺳﺖ‪ .‬ﻟﺬﺍ ﺍﺣﺘﻤﺎﻝ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺻﻔﺮ ﮐﻮﺍﻧﺘـﺎ‬ ‫ﺑﺮﺍﺑﺮ ‪1  r  t‬‬ ‫ﺁﺯﺍﺩﺳﺎﺯﻱ‬
‫ﮐﻮﭼﮑﻲ ﺑﺮﺍﻱ ﺁﺯﺍﺩﺳﺎﺯﻱ ﻭﺟﻮﺩ ﺩﺍﺭﺩ‪ .‬ﺍﻳﻦ ﺍﺣﺘﻤﺎﻝ ﺑﺴﻴﺎﺭ ﮐﻮﭼـﮏ‬
‫ﺑﺮﺍﺑﺮ ﺍﺳﺖ ﺑﺎ )ﺷﮑﻞ ‪(۲۵‬‬ ‫‪t  t‬‬ ‫ﺩﺭ‬
‫ﻣﻨﺠﺮ ﺑﻪ ﻇﻬﻮﺭ ‪ MEPP‬ﻏﻴﺮﺗﮑﺮﺍﺭﻱ ﻣﻲﺷـﻮﺩ‪ .‬ﺍﮔـﺮ ﻳـﮏ ﭘﺘﺎﻧﺴـﻴﻞ‬
‫‪P (0, t  t )  P (0, t ).(1  r t ) ,‬‬ ‫)‪(۴۴‬‬
‫ﻋﻤﻞ ﺑﻪ ﺍﻧﺘﻬﺎﻱ ﺁﮐﺴﻮﻥ ﺑﺮﺳـﺪ‪ ،‬ﺍﺣﺘﻤـﺎﻝ ﺁﺯﺍﺩﺳـﺎﺯﻱ ﺑـﺮﺍﻱ ﻣـﺪﺕ‬
‫ﻣﻲﺗﻮﺍﻥ ﺑﺎ ﺣﻞ ﻣﻌﺎﺩﻟﺔ ﺩﻳﻔﺮﺍﻧﺴﻴﻞ ﺳﺎﺩﺓ ﻣﺮﺗﺒﺔ ﺍﻭﻝ‬ ‫‪t  0‬‬ ‫ﺍﮔﺮ‬
‫ﮐﻮﺗﺎﻫﻲ ﺑﻪ ﺷﺪﺕ ﺯﻳﺎﺩ ﻣﻲﺷﻮﺩ‪ .‬ﻓﺮﺽ ﻣﻲﺷﻮﺩ ﺍﻳﻦ ﺍﺣﺘﻤﺎﻝ ﺑـﺮﺍﻱ‬
‫ﺑﻪ ﺭﺍﺑﻄﺔ ﺯﻳﺮ ﺭﺳﻴﺪ‪:‬‬
‫‪P(0, t )  ert .‬‬ ‫)‪(۴۵‬‬
‫____________________________________________‬
‫ﻣﺤﺎﺳﺒﺔ ﻓﻮﻕ ﺑﺮﺍﻱ ﮐﻤﮏ ﺑـﻪ ﻣﺤﺎﺳـﺒﺔ ﺍﺻـﻠﻲ ﻳﻌﻨـﻲ ﺍﺣﺘﻤـﺎﻝ‬ ‫‪1. Castillo‬‬
‫‪2. Ketz‬‬
‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ‫‪۳۶۸‬‬

‫ﮐﻮﺗﺎﻩ ) ‪ ( k‬ﻋﻼﻗﻪﻣﻨﺪ ﻫﺴﺘﻴﻢ‪ .‬ﺑﺮﺍﻱ ﻣﺤﺎﺳﺒﻪ ﺁﻥ ﻣﻲﺗﻮﺍﻥ ﻣﺪﻝﻫـﺎﻱ‬

‫ﺁﻣﺎﺭﻱ ﻣﺨﺘﻠﻔﻲ ﺭﺍ ﺩﺭ ﻧﻈﺮ ﮔﺮﻓﺖ‪ .‬ﻣـﺪﻝ ﭘﻮﺁﺳـﻮﻥ‪ ١‬ﺍﻭﻟـﻴﻦ ﻣـﺪﻟﻲ‬
‫ﺍﺳــﺖ ﮐــﻪ ﻣــﺎ ﺩﺭ ﻧﻈــﺮ ﻣـﻲﮔﻴـﺮﻳﻢ‪ .‬ﺍﮔــﺮ ‪ m‬ﺭﺍ ﻣﻴـﺎﻧﮕﻴﻦ ﺗﻌــﺪﺍﺩ‬
‫ﮐﻮﺍﻧﺘﺎﻫﺎﻱ ﺁﺯﺍﺩﺷﺪﻩ ﺑﻌﺪ ﺍﺯ ﻳﮏ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﺑﻌﺪ ﺍﺯ ﺗﮑـﺮﺍﺭ ﺯﻳـﺎﺩ‬ ‫ﺷﮑﻞ ‪ .٢٥‬ﺗﻮﺯﻳﻊ ﻓﺎﺻﻠﻪﻫﺎﻱ ﺯﻣﺎﻧﻲ ﺑﻴﻦ ‪ MEPP‬ﻫﺎﻱ ﭘﻲﺩﺭﭘﻲ‪.‬‬
‫ﺯﻣﺎﻥ ﺑﻌـﺪ ﺍﺯ ﻳـﮏ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ‬ ‫‪t‬‬ ‫ﺗﻌﺮﻳﻒ ﮐﻨﻴﻢ‪ ، m  rt ،‬ﮐﻪ‬
‫ﺍﺳﺖ‪ .‬ﺍﺣﺘﻤﺎﻝ ﺁﺯﺍﺩ ﺷﺪﻥ ‪ k‬ﮐﻮﺍﻧﺘﺎ ) ‪ P ( k‬ﻋﺒﺎﺭﺕ ﺍﺳﺖ ﺍﺯ‪:‬‬ ‫ﺣﺎﻟﻲﮐﻪ ‪t  0‬‬ ‫ﺍﺳﺖ ﺩﺭ‬ ‫‪t  t‬‬ ‫ﺁﺯﺍﺩﺳﺎﺯﻱ ﻳﮏ ﮐﻮﺍﻧﺘﻢ ﺩﺭ‬
‫‪t‬‬ ‫‪P (1 , t  t )  P (1 , t )  P (0 , t ).(1  r t ),‬‬ ‫)‪(۴۶‬‬
‫‪r k t k 1e m‬‬ ‫‪r k t k e m‬‬
‫‪P(k ) ‬‬ ‫‪‬‬ ‫!)‪(k  1‬‬
‫‪dt ‬‬
‫!‪k‬‬
‫‪.‬‬ ‫)‪(۵۱‬‬
‫ﺗﺎﺑﻊ ﭼﮕﺎﻟﻲ ﺍﺣﺘﻤﺎﻝ ﻋﺒﺎﺭﺕ ﺍﺳﺖ ﺍﺯ‪:‬‬
‫‪0‬‬
‫ﺍﺯ ﺁﻧﺠﺎﻳﻲ ﮐﻪ ﺑﻼﻓﺎﺻﻠﻪ ﺑﻌﺪ ﺍﺯ ﭘﺘﺎﻧﺴﻴﻞ ﻋﻤﻞ ﻣﺘﻮﺳﻂ ﻧـﺮﺥ ﺁﺯﺍﺩﺳـﺎﺯﻱ‬ ‫) ‪d[ P(1, t )] lim P(1, t  t )  P(1, t‬‬
‫‪ t 0‬‬
‫‪dt‬‬ ‫‪t‬‬
‫‪ r‬ﺑﺴﻴﺎﺭ ﺑﺎﻻﺳﺖ‪ p ( k ) ،‬ﺑﻪ ﺗﺎﺑﻊ ﭘﻮﺁﺳﻮﻥ ﻣﻨﺘﻬﻲ ﺧﻮﺍﻫﺪ ﺷﺪ‬ ‫)‪(۴۷‬‬
‫) ‪P(1, t‬‬
‫) ‪ P(0, t‬‬ ‫) ‪ r ert  f1 (t‬‬
‫‪t‬‬
‫‪mk em‬‬
‫‪P(k ) ‬‬ ‫‪,‬‬ ‫)‪(۵۲‬‬ ‫ﺗﺎﺑﻊ )‪ f1(t‬ﺑﺮﺍﺑﺮ ﺍﺳﺖ ﺑﺎ ﺗﺎﺑﻊ ﭼﮕـﺎﻟﻲ ﺍﺣﺘﻤـﺎﻝ ﺑـﺮﺍﻱ ﺑـﺎﺯﻩﻫـﺎﻱ‬
‫!‪k‬‬
‫ﺯﻣﺎﻧﻲ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺑﺮﺍﻱ ﻣﺤﺎﺳﺒﺔ ﺗﺎﺑﻊ ﭼﮕﺎﻟﻲ ﺍﺣﺘﻤـﺎﻝ ﺑـﺮﺍﻱ ﺯﻣـﺎﻥ‬
‫ﮐﻪ ﺑﺮﺍﻱ ﺁﻥ ﻭﺍﺭﻳﺎﻧﺲ ﺑﺮﺍﺑﺮ ﻣﻴﺎﻧﮕﻴﻦ ﺍﺳﺖ‪ ،‬ﺑﻪ ﻋﺒﺎﺭﺕ ﺩﻳﮕـﺮ ‪،  2  m‬‬
‫ﺁﺯﺍﺩﺳــﺎﺯﻱ ﺩﻭﻡ ﺑﺎﻳــﺪ ﻫﻤــﺔ ﻣﻘــﺎﺩﻳﺮ ﻣﻤﮑــﻦ ﺑــﺮﺍﻱ ﺯﻣــﺎﻥ ﺑــﻴﻦ‬
‫ﻭ ﺑﻪ ‪ m‬ﺣﺠﻢ ﮐﻮﺍﻧﺘﺎﻳﻲ ﮔﻔﺘﻪ ﻣﻲﺷـﻮﺩ‪ .‬ﺩﺭ ﺣـﺎﻟﺘﻲ ﮐـﻪ ﺗﻌـﺪﺍﺩ ﺑﺴـﻴﺎﺭ‬
‫ﺁﺯﺍﺩﺳــﺎﺯﻱﻫــﺎﻱ ﭘـﻲﺩﺭﭘـﻲ ) ‪ u ( t‬ﺭﺍ ﺩﺭ ﻧﻈــﺮ ﺑﮕﻴـﺮﻳﻢ‪ .‬ﺍﮔــﺮ ﻳـﮏ‬
‫ﺯﻳﺎﺩﻱ ﮐﻮﺍﻧﺘﺎ ﺑﺮﺍﻱ ﺁﺯﺍﺩ ﺷـﺪﻥ ﻣﻮﺟـﻮﺩ ﻧﺒﺎﺷـﺪ ) ‪ n‬ﮐﻮﭼـﮏ ﺑﺎﺷـﺪ(‪ ،‬ﻭ‬
‫ﺁﺯﺍﺩﺳــﺎﺯﻱ ﺩﺭ ﺯﻣــﺎﻥ ‪ u‬ﺑــﺎ ﺍﺣﺘﻤــﺎﻝ )‪ f1(u‬ﻭ ﺩﻳﮕــﺮﻱ ﺩﺭ ﺯﻣــﺎﻥ‬
‫ﻫﺮﮐﺪﺍﻡ ﺍﺣﺘﻤﺎﻝ ﺑﺰﺭﮔﺘﺮﻱ ﺑﺮﺍﻱ ﺁﺯﺍﺩ ﺷﺪﻥ ﺩﺍﺷـﺘﻪ ﺑﺎﺷـﻨﺪ ) ‪ p‬ﮐﻮﭼـﮏ‬
‫ﺑﺎ ﺍﺣﺘﻤﺎﻝ ) ‪ f (t  u‬ﺑﻪ ﻃﻮﺭ ﻣﺴﺘﻘﻞ ﺭﺥ ﺩﻫﺪ‪ .‬ﺩﺍﺭﻳﻢ‬ ‫‪t u‬‬
‫ﻧﺒﺎﺷـﺪ(‪ ،‬ﻧﻤـﻲﺗــﻮﺍﻧﻴﻢ ﺍﺯ ﺗﻮﺯﻳـﻊ ﭘﻮﺁﺳــﻮﻥ ﺑــﺮﺍﻱ ﺗﻮﺻـﻴﻒ ﺁﺯﺍﺩﺳــﺎﺯﻱ‬
‫‪t‬‬
‫ﭘﻴﺎﻡﺭﺳﺎﻥ ﺍﺳـﺘﻔﺎﺩﻩ ﮐﻨـﻴﻢ‪ .‬ﺩﺭ ﺍﻳـﻦ ﺻـﻮﺭﺕ ﻣـﻲﺗـﻮﺍﻧﻴﻢ ﺍﺯ ﺗﻮﺯﻳـﻊ ﺩﻭ‪-‬‬ ‫‪f2 (t ) ‬‬ ‫‪ f1(t  u) f1(u)du ,‬‬ ‫)‪(۴۸‬‬
‫ﺟﻤﻠﻪﺍﻱ ﺍﺳﺘﻔﺎﺩﻩ ﮐﻨﻴﻢ‪ .‬ﺍﮔﺮ ﺗﻌﺪﺍﺩ ﻭﺍﺣﺪﻫﺎﻱ ﺁﺯﺍﺩﮐﻨﻨـﺪﻩ ﺑﺮﺍﺑـﺮ ‪ n‬ﺑﺎﺷـﺪ‬ ‫‪0‬‬
‫ﺍﻡ ﻣﻲﺗﻮﺍﻥ ﺗﺎﺑﻊ ﭼﮕﺎﻟﻲ ﺍﺣﺘﻤـﺎﻝ‬ ‫‪k‬‬ ‫ﻭ ﻫﻤﻴﻦ ﻃﻮﺭ ﺑﺮﺍﻱ ﺁﺯﺍﺩﺳﺎﺯﻱ‬
‫ﻭ ‪ P‬ﻣﺘﻮﺳﻂ ﺍﺣﺘﻤﺎﻝ ﺁﺯﺍﺩﺳﺎﺯﻱ ﻳﮏ ﮐﻮﺍﻧﺘﻢ ﺍﺯ ﻫـﺮ ﺟﺎﻳﮕـﺎﻩ ﺑﺎﺷـﺪ‪ ،‬ﻭ‬
‫ﺭﺍ ﭼﻨﻴﻦ ﻧﻮﺷﺖ‪:‬‬
‫‪ P‬ﺑﺮﺍﻱ ﻫﻤﻪ ﺟﺎﻳﮕﺎﻩﻫﺎ ﻳﮑﺴﺎﻥ ﺑﺎﺷﺪ ) ‪ n‬ﻭ ‪ P‬ﺑﺎ ﺯﻣﺎﻥ ﺗﻐﻴﻴﺮ ﻧﮑﻨﻨـﺪ(‪،‬‬
‫‪t‬‬
‫ﺍﺣﺘﻤﺎﻝ ﺍﻳﻦ ﮐﻪ ‪ k‬ﮐﻮﺍﻧﺘﺎ ﺁﺯﺍﺩ ﺷﻮﺩ ﻋﺒﺎﺭﺕ ﺍﺳﺖ ﺍﺯ‪:‬‬ ‫‪f k (t ) ‬‬ ‫‪ f1 (t  u ) fk 1 (u ) du‬‬ ‫)‪(۴۹‬‬
‫‪0‬‬
‫!‪n‬‬
‫‪Pn (k ) ‬‬ ‫‪. pk (1  P)nk ,‬‬ ‫)‪(۵۳‬‬ ‫ﺑﺎ ﺣﻞ ﻣﻌﺎﺩﻟﺔ ﺍﻧﺘﮕﺮﺍﻟﻲ ﻫﻤﮕﺸﺖ ﻓﻮﻕ ﺑﻪ ﮐﻤـﮏ ﺗﺒـﺪﻳﻞ ﻻﭘـﻼﺱ‬
‫) ‪k !(n  k‬‬
‫ﻭ‬ ‫ﻣﻲﺗﻮﺍﻧﻴﻢ ﺗﺎﺑﻊ ﭼﮕﺎﻟﻲ ﺍﺣﺘﻤﺎﻝ ﺁﺯﺍﺩﺳﺎﺯﻱ ‪ k‬ﺍﻡ ﺭﺍ ﺑﻪ ﺻـﻮﺭﺕ ﺯﻳـﺮ‬
‫ﺁﻥ ‪m  nP‬‬ ‫ﮐـــﻪ ﺍﻳـــﻦ ﺗﻮﺯﻳـــﻊ ﺩﻭﺟﻤﻠـــﻪﺍﻱ ﺍﺳـــﺖ ﻭ ﺩﺭ‬
‫ﺑﻪﺩﺳﺖ ﺁﻭﺭﻳﻢ‪:‬‬
‫)‪ .  2  m(1  P‬ﻣﺪﻝ ﺩﻭﺟﻤﻠﻪﺍﻱ ﺑﻪ ﺍﺯﺍﯼ )‪ n   ( P  0‬ﺑـﻪ‬
‫‪r k t k 1e  rt‬‬
‫ﻣﺪﻝ ﭘﻮﺁﺳـﻮﻥ ﺗﻘﻠﻴـﻞ ﻣـﻲﻳﺎﺑـﺪ‪ .‬ﺑﺎﻳـﺪ ﺗﻮﺟـﻪ ﺩﺍﺷـﺖ ﮐـﻪ ﻓـﺮﺽ‬ ‫‪f k (t ) ‬‬
‫!)‪( k  1‬‬
‫)‪(۵۰‬‬
‫ﻳﮑﻨﻮﺍﺧﺖ ﺑﻮﺩﻥ ﺍﺣﺘﻤﺎﻝ ﺁﺯﺍﺩﺳﺎﺯﻱ ﺑﺮﺍﻱ ﻫـﺮ ﺟﺎﻳﮕـﺎﻩ ﺁﺯﺍﺩﮐﻨﻨـﺪﻩ‪،‬‬
‫ﺍﺯ ﺁﻧﺠﺎﻳﻲ ﮐﻪ !)‪ ( k  1‬ﺩﺭ ﻣﺨﺮﺝ ﺗﺎﺑﻊ ﮔﺎﻣﺎﻱ ‪ k‬ﻳﺎ ) ‪  ( k‬ﺍﺳﺖ‪ ،‬ﺑـﻪ‬
‫ﻣﺤﺪﻭﺩﻳﺖ ﺷﺪﻳﺪﻱ ﺍﺳـﺖ ﻭ ﺑﻌﻀـﻲ ﺍﻭﻗـﺎﺕ ﺧﻄـﺎﻱ ﺑﺰﺭﮔـﻲ ﺩﺭ‬
‫)‪ fk (t‬ﻳﮏ ﺗﻮﺯﻳﻊ ﮔﺎﻣﺎ ﮔﻔﺘﻪ ﻣﻲﺷﻮﺩ ]‪.[۵۴‬‬
‫ﻣﺤﺎﺳﺒﺎﺕ ﻭﺍﺭﺩ ﻣﻲﮐﻨﺪ‪ .‬ﺩﺭ ﺍﻳﻦ ﺣﺎﻟﺖ ﺑﺎﻳـﺪ ﺍﺯ ﻣـﺪﻝ ﺩﻭﺟﻤﻠـﻪﺍﻱ‬
‫ﺗﻔــﺎﻭﺕ ﺍﺻــﻠﻲ ﺁﺯﺍﺩﺳــﺎﺯﻱ ﻫﻨﮕــﺎﻡ ﺗﺤﺮﻳــﮏ ﺑــﺎ ﺁﺯﺍﺩﺳــﺎﺯﻱ‬
‫ﺗﺮﮐﻴﺒﻲ ﺍﺳﺘﻔﺎﺩﻩ ﺷﻮﺩ‪ ،‬ﺑﻪ ﻃﻮﺭﻱ ﮐﻪ ﺑﺮﺍﻱ ﻫـﺮ ﮐـﺪﺍﻡ ﺍﺯ ‪ n‬ﺟﺎﻳﮕـﺎﻩ‬
‫ﺧﻮﺩﺑﻪﺧﻮﺩﻱ ﺍﻳﻦ ﺍﺳـﺖ ﮐـﻪ ﻫﻨﮕـﺎﻡ ﺗﺤﺮﻳـﮏ‪ ،‬ﭼﻨـﺪﻳﻦ ﮐﻮﺍﻧﺘـﺎﻱ‬
‫ﺁﺯﺍﺩﮐﻨﻨﺪﺓ ﻣﻘﺪﺍﺭ ﺧﺎﺹ ‪ P‬ﺭﺍ ﺩﺭ ﻧﻈﺮ ﺑﮕﻴﺮﻳﻢ ]‪ ۳‬ﻭ ‪.[۴۷‬‬
‫ﭘﻴﺎﻡﺭﺳﺎﻥ ﺩﺭ ﻳﮏ ﺑﺎﺯﺓ ﺯﻣﺎﻧﻲ ﮐﻮﺗﺎﻩ ﺑﻪ ﺩﻧﺒـﺎﻝ ﭘﺘﺎﻧﺴـﻴﻞ ﻋﻤـﻞ ﺁﺯﺍﺩ‬
‫____________________________________________‬
‫‪1. Poisson‬‬ ‫ﻣﻲﺷﻮﻧﺪ‪ .‬ﺩﺭ ﺍﻳﻦ ﺣﺎﻟﺖ ﻣﺎ ﺑﻪ ﺗﻌﺪﺍﺩ ﮐﻮﺍﻧﺘﺎﻫﺎﻱ ﺁﺯﺍﺩﺷﺪﻩ ﺩﺭ ﻣـﺪﺕ‬
‫‪۳۶۹‬‬ ‫ﻓﯿﺰﯾﮏ ﮐﺎرﺑﺮدي‪ :1 -‬ﻣﻘﺪﻣﻪاي ﺑﺮ ﻓﯿﺰﯾﮏ اﻋﺼﺎب‬ ‫ﺟﻠﺪ ‪ ،۱۵‬ﺷﻤﺎﺭﺓ ‪۴‬‬

‫‪LTP‬‬ ‫ﮐﻪ ﺳﺒﺐ ﺗﻐﻴﻴﺮ ﺩﺭ ﺁﻥ ﻣﻲﺷﻮﻧﺪ‪ .‬ﻧﺤﻮﺓ ﺗﺄﺛﻴﺮ ﺍﻳـﻦ ﻋﻮﺍﻣـﻞ ﺑـﺮ‬ ‫‪.۲.۵‬ﺗﻐﻴﻴﺮﺍﺕ ﺳﻴﻨﺎﭘﺴﻲ ﻭ ﻓﺮﺿﻴﺔ ﻳﺎﺩﮔﻴﺮﻱ ﻭ ﺣﺎﻓﻈﻪ‬
‫ﻫﻨﻮﺯ ﺷﻨﺎﺧﺘﻪ ﺷﺪﻩ ﻧﻴﺴﺖ‪ ،‬ﻭﻟﻲ ﺍﺣﺘﻤﺎﻝ ﺩﺧﺎﻟـﺖ ﭘﻴـﺎﻡﺭﺳـﺎﻥﻫـﺎﯼ‬ ‫ﻗﺪﺭﺕ ﺍﺗﺼﺎﻝ ﺳﻴﻨﺎﭘﺴﻲ ﻣﻲﺗﻮﺍﻧﺪ ﺑﻪ ﺩﻻﻳـﻞ ﻣﺨﺘﻠـﻒ ﺗﻐﻴﻴـﺮ ﮐﻨـﺪ‪.‬‬
‫ﺛﺎﻧﻮﻳ ـﻪ ﻭﺟ ـﻮﺩ ﺩﺍﺭﺩ ]‪ .[۵۹-۵۵‬ﺑﻬﺘــﺮﻳﻦ ﮔﺰﻳﻨــﻪ ﺑــﺮﺍﻱ ﻧﮕﻬــﺪﺍﺭﻱ‬ ‫ﻳﮑﻲ ﺍﺯ ﺩﻻﻳﻞ ﺍﻳﻦ ﺗﻐﻴﻴﺮ ﻓﻌﺎﻟﻴﺖ ﺳﻴﻨﺎﭘﺴﻲ ﻳﺎ ﺍﺳـﺘﻔﺎﺩﻩ ﺍﺯ ﺳـﻴﻨﺎﭘﺲ‬
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‫ﺍﻃﻼﻋﺎﺕ ‪ LTP‬ﺍﺳﺖ‪ .‬ﺑﺎ ﺗﻮﺟﻪ ﺑـﻪ ﺗﻌـﺪﺍﺩ ﺑﺴـﻴﺎﺭ ﺯﻳـﺎﺩ ﺍﺗﺼـﺎﻻﺕ‬ ‫ﺍﺳﺖ‪ .‬ﺍﻳﻦ ﺗﻐﻴﻴﺮﺍﺕ ﺑﻪ ﺩﻭ ﺩﺳﺘﺔ ﺍﺻﻠﻲ ﮐﻮﺗﺎﻩﻣﺪﺕ‪ ١‬ﻭ ﺑﻠﻨـﺪﻣـﺪﺕ‬
‫ﺳﻴﻨﺎﭘﺴﻲ‪ ،‬ﻣﻲ ﺗﻮﺍﻥ ﺣﺠﻢ ﺑﺴـﻴﺎﺭ ﺑـﺎﻻﻱ ﻗﺎﺑـﻞ ﺩﺳـﺖﻳـﺎﺑﻲ ﺑـﺮﺍﻱ‬ ‫ﺗﻘﺴﻴﻢ ﻣﻲﺷﻮﻧﺪ‪ .‬ﺗﻐﻴﻴﺮﺍﺕ ﺳﻴﻨﺎﭘﺴﻲ ﮐﻮﺗﺎﻩﻣﺪﺕ )ﺍﺯ ﭼﻨﺪ ﺩﻗﻴﻘﻪ ﺗـﺎ‬
‫ﺣﺎﻓﻈﺔ ﻣﻐﺰ ﺭﺍ ﺑﻪ ﻃﻮﺭ ﻓﻴﺰﻳﮑﻲ ﺩﺭﮎ ﮐﺮﺩ‪.‬‬ ‫ﻧﻴﻢ ﺳﺎﻋﺖ( ﺧﻮﺩ ﺑـﻪ ﺳـﻪ ﺩﺳـﺘﻪ ﺗﻘﻮﻳـﺖﮐﻨﻨـﺪﻩ‪ ،‬ﺍﻓـﺰﺍﻳﺶﺩﻫﻨـﺪﻩ‬
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‫ﺩﺭ ﺳﺎﻝ ‪ ۱۹۴۹‬ﺩﺍﻧﺎﻟﺪ ﻫﺐ ﻗﺎﻋﺪﻩﺍﻱ ﺭﺍ ﺑﺮﺍﻱ ﺗﻐﻴﻴـﺮ ﺳﻴﻨﺎﭘﺴـﻲ‬ ‫)‪ (PTP٣‬ﻫﻨﮕﺎﻡ ﺗﮑﺮﺍﺭ ﺗﺤﺮﻳﮏ ﻭ ﺗﻀﻌﻴﻒﮐﻨﻨﺪﻩ ﺗﻘﺴﻴﻢ ﻣـﻲﺷـﻮﺩ‪.‬‬
‫ﭘﻴﺸﻨﻬﺎﺩ ﮐﺮﺩ ﮐﻪ ﺛﺎﺑﺖ ﺷﺪ ﺑﺮﺍﻱ ﺩﺭﮎ ﻳـﺎﺩﮔﻴﺮﻱ ﻣﻐـﺰ ﺑﺴـﻴﺎﺭ ﻣﻬـﻢ‬ ‫ﺯﻣﺎﻧﻲﮐﻪ ﺩﻭ ﻋﻼﻣﺖ ﺗﺤﺮﻳﮑﻲ ﺭﺍ ﺑﺎ ﻓﺎﺻﻠﺔ ﺯﻣﺎﻧﻲ ﺧﺎﺻﻲ ﺑـﻪ ﻳـﮏ‬
‫ﺍﺳﺖ‪ .‬ﺍﻭ ﭘﻴﺸـﻨﻬﺎﺩ ﮐـﺮﺩ ﮐـﻪ ﻓﻌﺎﻟﻴـﺖ ﻫـﻢﺯﻣـﺎﻥ ﺩﺭ ﻗﺴـﻤﺖﻫـﺎﻱ‬ ‫ﺳﻴﻨﺎﭘﺲ ﻭﺍﺭﺩ ﮐﻨﻴﻢ ﻭ ﺍﺭﺗﻔﺎﻉ ﭘﺎﺳﺦ ﺩﻭﻡ ﺭﺍ ﻧﺴﺒﺖ ﺑﻪ ﭘﺎﺳﺦ ﺍﻭﻝ ﺑـﺎ‬
‫ﭘﻴﺶﺳﻴﻨﺎﭘﺴﻲ ﻭ ﭘﺲﺳﻴﻨﺎﭘﺴﻲ ﺳـﺒﺐ ﺍﻓـﺰﺍﻳﺶ ﺑـﺎﺯﺩﻫﻲ ﺳـﻴﻨﺎﭘﺲ‬ ‫ﻫـﻢ ﻣﻘﺎﻳﺴـﻪ ﮐﻨـﻴﻢ‪ ،‬ﺍﮔـﺮ ﺍﻓﺰﺍﻳﺸـﻲ ﺩﺭ ﺍﺭﺗﻔـﺎﻉ ﻧﺴـﺒﻲ ﭘــﺎﻟﺲ ﺩﻭﻡ‬
‫ﻣﻲﺷـﻮﺩ‪ .‬ﺑﻌـﺪ ﺍﺯ ﺍﻳـﻦ ﭘﻴﺸـﻨﻬﺎﺩ ﭘـﮋﻭﻫﺶﻫـﺎﻱ ﺯﻳـﺎﺩﻱ ﺑـﺮ ﺭﻭﻱ‬ ‫ﻣﺸﺎﻫﺪﻩ ﺷﻮﺩ ﺑﻪ ﺁﻥ ﺗﻐﻴﻴﺮ ﺗﻘﻮﻳﺖ ﮐﻨﻨﺪﺓ ﻭ ﺍﮔﺮ ﮐﺎﻫﺶ ﻧﺴﺒﻲ ﺩﺍﺷﺘﻪ‬
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‫ﻓﻌﺎﻟﻴﺖﻫﺎﻱ ﻫﻢ ﺯﻣﺎﻥ ﺍﻧﺠﺎﻡ ﮔﺮﻓﺘﻪ ﻭ ﻫﻢ ﭼﻨـﺎﻥ ﺍﺩﺍﻣـﻪ ﺩﺍﺭﺩ ]‪-۶۰‬‬ ‫ﺑﺎﺷﺪ‪ ،‬ﺑﻪ ﺁﻥ ﺗﻐﻴﻴﺮ ﺳﻴﻨﺎﭘﺴﻲ ﺗﻀﻌﻴﻒﮐﻨﻨﺪﻩ ﻣﻲﮔﻮﻳﻨﺪ‪ .‬ﺩﺭ ﺻـﻮﺭﺗﻲ‬
‫‪ .[۶۲‬ﺟﻬﺖ ﻣﺪﻝﺳﺎﺯﻱ ﻣﺤﺎﺳﺒﺎﺗﻲ ﺣﺎﻓﻈﻪ ﻧﻴﺰ ﻣﺎﺗﺮﻳﺲ ﻫﻢﺑﺴـﺘﮕﻲ‬ ‫ﮐﻪ ﺑﺎ ﺗﮑﺮﺍﺭ ﺗﺤﺮﻳﮏ ﺳﻴﻨﺎﭘﺲ‪ ،‬ﺍﻓﺰﺍﻳﺸـﻲ ﺩﺭ ﺗﻘﻮﻳـﺖ ﻳـﺎ ﺗﻀـﻌﻴﻒ‬
‫ﺑﻪ ﻋﻨﻮﺍﻥ ﻣﺤﻞ ﻧﮕﻬﺪﺍﺭﻱ ﺣﺎﻓﻈﻪ ﻣﻌﺮﻓﻲ ﺷﺪﻩ ﺍﺳﺖ ]‪ .[۶۳‬ﺑﻪ ﻧﻈـﺮ‬ ‫ﺷﺪﻥ ﺁﻥ ﺍﻳﺠﺎﺩ ﺷﻮﺩ ﺑﻪ ﺁﻥ ﺗﻐﻴﻴﺮ ﺍﻓﺰﺍﻳﺶﺩﻫﻨﺪﺓ ﺗﮑﺮﺍﺭﻱ ﻣﻲﮔﻮﻳﻨﺪ‪.‬‬
‫ﻣﻲﺭﺳﺪ ﮐﺸﻒ ﺍﺳﺎﺱ ﻓﻴﺰﻳﮑﻲ‪ -‬ﺷـﻴﻤﻴﺎﻳﻲ ﺳـﺎﺯ ﻭ ﮐـﺎﺭ ﺗﻐﻴﻴـﺮﺍﺕ‬ ‫ﺗﻐﻴﻴﺮ ﺳﻴﻨﺎﭘﺴﻲ ﺩﺭﺍﺯ‪ -‬ﻣﺪﺕ )ﭼﻨﺪﻳﻦ ﺳﺎﻋﺖ ﺗﺎ ﻣﺎﻩﻫـﺎ( ﺑـﻪ ﺩﻭ‬
‫ﺩﺭﺍﺯ ﻣﺪﺕ ﺳﻴﻨﺎﭘﺴﻲ ﺭﺍﺯ ﻳﺎﺩﮔﻴﺮﻱ ﻭ ﺣﺎﻓﻈﻪ ﺭﺍ ﺧﻮﺍﻫـﺪ ﮔﺸـﻮﺩ‪ .‬ﺍﺯ‬ ‫ﺩﺳﺘﺔ ﺍﺻﻠﻲ ﺗﻘﻮﻳﺖﮐﻨﻨـﺪﻩ ﺩﺭﺍﺯ ﻣـﺪﺕ )‪ (LTP٤‬ﻭ ﺗﻀـﻌﻴﻒﮐﻨﻨـﺪﻩ‬
‫ﺍﻳﻦ ﻧﮕﺎﻩ‪ ،‬ﺣﺎﻓﻈﻪ ﻋﺒﺎﺭﺕ ﺍﺯ ﺗﻐﻴﻴـﺮ ﺩﺭﺍﺯ ﻣـﺪﺕ ﺳـﻴﻨﺎﭘﺲ ﺍﺳـﺖ ﻭ‬ ‫ﺩﺭﺍﺯ ﻣﺪﺕ )‪ (LTD٥‬ﺗﻘﺴﻴﻢ ﻣﻲﺷﻮﺩ‪ LTP .‬ﻳﮏ ﺗﻐﻴﻴﺮ ﺩﺭﺍﺯ ﻣـﺪﺕ‬
‫ﮐﻨﺘﺮﻝ ﺗﻐﻴﻴﺮﺍﺕ ﺳﻴﻨﺎﭘﺴﻲ ﻣﻨﺠﺮ ﺑﻪ ﻳﺎﺩﮔﻴﺮﻱ ﻣﻲﺷﻮﺩ‪ .‬ﺍﮔـﺮ ﺑﺘـﻮﺍﻧﻴﻢ‬ ‫ﺩﺭ ﺩﺍﻣﻨﺔ ﭘﺎﺳﺦ ﺳﻴﻨﺎﭘﺴﻲ ﺑﻌﺪ ﺍﺯ ﺍﻋﻤﺎﻝ ﻳﮏ ﺗﺤﺮﻳﮏ ﺳﻴﻨﺎﭘﺴـﻲ ﺑـﺎ‬
‫ﺑﻪ ﺩﺭﮎ ﻓﻴﺰﻳﮑﻲ ﮐﺎﻣﻞ ﺣﺎﻓﻈﻪ ﺩﺳﺖ ﻳﺎﺑﻴﻢ ﭼﻪ ﺑﺴﺎ ﺑﺘﻮﺍﻧﻴﻢ ﺑﻪ ﻃﻮﺭ‬ ‫ﺑﺴﺎﻣﺪ ﺯﻳﺎﺩ ﺍﺳﺖ‪ LTP .‬ﺩﺭ ﺍﻏﻠﺐ ﺳﻴﻨﺎﭘﺲﻫﺎﻱ ﻭﺍﺩﺍﺭﻧـﺪﺓ ﺩﺳـﺘﮕﺎﻩ‬
‫ﻣﺼﻨﻮﻋﻲ ﺍﻃﻼﻋﺎﺗﻲ ﺩﺭ ﻣﻐﺰ ﺑﮕﻨﺠﺎﻧﻴﻢ ﻭ ﻳﺎ ﺍﻳﻦ ﮐـﻪ ﺍﻃﻼﻋـﺎﺗﻲ ﮐـﻪ‬ ‫ﺍﻋﺼﺎﺏ ﻣﺮﮐﺰﻱ ﻣﺸﺎﻫﺪﻩ ﺷﺪﻩ ﺍﺳﺖ ﻭ ﺩﺭ ﺩﻭ ﻓﺎﺯ ﺍﻟﻘﺎ ﻭ ﻧﮕﻬـﺪﺍﺭﻱ‬
‫ﻣﻨﺠﺮ ﺑﻪ ﺑﻴﻤﺎﺭﻱ ﻫﺎﻱ ﺭﻭﺍﻧﻲ ﻣﻲﺷﻮﺩ ﺭﺍ ﺍﺯ ﺣﺎﻓﻈﻪ ﻣﻐﺰ ﭘﺎﮎ ﮐﻨـﻴﻢ‪.‬‬ ‫ﺍﺗﻔﺎﻕ ﻣﻲﺍﻓﺘﺪ‪ ،‬ﻓﺎﺯ ﺍﻟﻘﺎ ﺍﻧﺪﮐﻲ ﺑﻌﺪ ﺍﺯ ﺗﺤﺮﻳﮏ ﺑﺴـﺎﻣﺪ ﺑـﺎﻻ ﺷـﺮﻭﻉ‬
‫ﺭﺳﻴﺪﻥ ﺑﻪ ﺍﻳﻦ ﺍﻫﺪﺍﻑ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﭘﻴﺸﺮﻓﺖﻫﺎﻱ ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ ﺑـﻪ‬ ‫ﻣﻲﺷﻮﺩ ﺩﺭ ﺣﺎﻟﻲ ﮐﻪ ﻓﺎﺯ ﻧﮕﻬﺪﺍﺭﻱ ﻣﺪﺕ ﺯﻣﺎﻧﻲ ﺑﻌﺪ ﺍﺯ ﺍﻟﻘﺎ ﺍﺳـﺖ‬
‫ﻫﻴﭻ ﻋﻨﻮﺍﻥ ﺭﻭﻳﺎ ﻣﺤﺴﻮﺏ ﻧﻤﻲﺷﻮﺩ‪.‬‬ ‫‪LTP‬‬ ‫ﮐﻪ ﺗﺄﺛﻴﺮ ﺳﻴﻨﺎﭘﺴﻲ ﺁﻥ ﻧﻤﺎﻳﺎﻥ ﻣﻲﺷـﻮﺩ‪ .‬ﺳـﺎﺯ ﻭ ﮐـﺎﺭ ﺷـﺮﻭﻉ‬
‫ﻫﻨﻮﺯ ﺷﻨﺎﺧﺘﻪ ﺷﺪﻩ ﻧﻴﺴﺖ‪ .‬ﻫﻤﭽﻨﻴﻦ ﻣﺪﺕ ﺯﻣـﺎﻥ ﺣﻀـﻮﺭ ﺁﻥ ﻫـﻢ‬
‫‪ .۶‬ﺑﺤﺚ ﻭ ﻧﺘﻴﺠﻪﮔﻴﺮﻱ‬ ‫ﺷﻨﺎﺧﺘﻪ ﺷﺪﻩ ﻧﻴﺴﺖ‪ ،‬ﻭﻟﻲ ﺷﻮﺍﻫﺪ ﺑﺮ ﻋﺪﻡ ﺩﺍﺋﻤﻲ ﺑـﻮﺩﻥ ﺁﻥ ﺩﻻﻟـﺖ‬
‫ﮐﺎﺭﺑﺮﺩ ﻓﻴﺰﻳﮏ ﺩﺭ ﺗﺤﻠﻴـﻞ ﻣﺴـﺎﺋﻞ ﻣﺨﺘﻠـﻒ ﺑـﺮ ﮐﺴـﻲ ﭘﻮﺷـﻴﺪﻩ‬ ‫ﺩﺍﺭﺩ‪ LTP .‬ﺩﺭ ﻃﻮﻝ ﺭﻭﺯﻫﺎ ﻳﺎ ﻫﻔﺘﻪﻫﺎ ﻭ ﺩﺭ ﺑﻌﻀﻲ ﺷﺮﺍﻳﻂ ﻣـﺎﻩﻫـﺎ‬
‫ﻧﻴﺴﺖ‪ .‬ﻣﻐﺰ ﭘﻴﭽﻴﺪﻩﺗـﺮﻳﻦ ﺩﺳـﺘﮕﺎﻩ ﻧﺎﺷـﻨﺎﺧﺘﻪ ﻓﻴﺰﻳﮑـﻲ ﺩﺭ ﺣـﺎﻝ‬ ‫ﻭﺍﭘﺎﺷﻲ ﻣـﻲﮐﻨـﺪ‪ .‬ﺍﺣﺘﻤـﺎﻝ ﻣﺨﺘﻠـﻒ ﺑـﻮﺩﻥ ﺳـﺎﺯ ﻭ ﮐـﺎﺭ ‪ LTP‬ﺩﺭ‬
‫ﺣﺎﺿـﺮ ﺑـﻮﺩﻩ ﻭ ﻋﻠـﻮﻡ ﺍﻋﺼـﺎﺏ ﺗﺒــﺪﻳﻞ ﺑـﻪ ﻭﺳـﻴﻊﺗـﺮﻳﻦ ﺭﺷــﺘﺔ‬ ‫ﺳﻴﻨﺎﭘﺲﻫﺎﻱ ﻣﺨﺘﻠﻒ ﻧﻴﺰ ﻭﺟﻮﺩ ﺩﺍﺭﺩ‪ .‬ﻋﻮﺍﻣﻠﻲ ﻫﻢ ﺷﻨﺎﺧﺘﻪ ﺷﺪﻩﺍﻧﺪ‬
‫ﺑﻴﻦﺭﺷﺘﻪﺍﻱ ﺷﺪﻩ ﺍﺳﺖ ]‪ ۶۴‬ﻭ ‪ .[۶۵‬ﺩﺭ ﺍﻳﻦ ﻣﻘﺎﻟﻪ ﻣـﺮﻭﺭﻱ ﺳـﻌﻲ‬
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‫ﺷﺪﻩ ﺍﺳﺖ ﺑﻪ ﻃﻮﺭ ﺧﻼﺻﻪ ﺑﻪ ﻓﻴﺰﻳﮏ ﺍﻋﺼﺎﺏ ﮐـﻪ ﻫﻤـﺎﻥ ﻧﺤـﻮﺓ‬ ‫‪1. Short-term‬‬
‫ﺑﻪﮐﺎﺭﮔﻴﺮﻱ ﻗﻮﺍﻧﻴﻦ ﻓﻴﺰﻳﮏ ﺩﺭ ﺗﺤﻠﻴﻞ ﻋﻤﻠﮑـﺮﺩ ﻣﻐـﺰ ﻭ ﺍﻋﺼـﺎﺏ‬ ‫‪2. Long-term‬‬

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‫‪3. Post-tetanic potentiation‬‬
‫‪6. Donald O Hebb‬‬ ‫‪4. Long-term potentiation‬‬
‫‪7. Synchrony‬‬ ‫‪5. Long-term depression‬‬
۴ ‫ ﺷﻤﺎﺭﺓ‬،۱۵ ‫ﺟﻠﺪ‬ ‫رﺿﺎ ﺧﺎﻧﺒﺎﺑﺎﺋﯽ و ﻣﻬﺴﺎ ﺗﺎﺑﺶ‬ ۳۷۰

‫ﻗﺪﺭﺩﺍﻧﯽ‬ ‫ ﮐﺸﻒ ﺍﺳـﺮﺍﺭ ﻣﻐـﺰ ﻭ ﺍﻋﺼـﺎﺏ ﻧﻴـﺎﺯ ﺑـﻪ ﻭﺭﻭﺩ‬.‫ﺍﺳﺖ ﺍﺷﺎﺭﻩ ﺷﻮﺩ‬

‫ﺩﺭ ﺍﻳﻨﺠﺎ ﺑﺎﻳﺪ ﺍﺯ ﻫﻤﺔ ﺍﺳـﺎﺗﻴﺪﻱ ﮐـﻪ ﺩﺭ ﻫـﺪﺍﻳﺖ ﺑﻨـﺪﻩ ﺑـﻪ ﺳـﻤﺖ‬ ‫ ﻫـﻢﺍﮐﻨـﻮﻥ ﻓﻴﺰﻳـﮏ‬.‫ﺍﻓﺮﺍﺩ ﺯﻳﺎﺩﻱ ﺑﺎ ﺗﺨﺼﺺﻫﺎﻱ ﮔﻮﻧﺎﮔﻮﻥ ﺩﺍﺭﺩ‬

‫ ﺍﺯ‬.‫ﻳﺎﺩﮔﻴﺮﻱ ﺍﻳﻦ ﺷﺎﺧﻪ ﺟﺪﻳﺪ ﻓﻴﺰﻳﮏ ﻧﻘـﺶ ﺩﺍﺷـﺘﻨﺪ ﺗﺸـﮑﺮ ﮐـﻨﻢ‬ ،‫ ﻣﻬﻨﺪﺳـﻲ ﺍﻋﺼـﺎﺏ‬،‫ ﺭﻳﺎﺿﻲ ﺍﻋﺼـﺎﺏ‬،‫ ﺷﻴﻤﻲ ﺍﻋﺼﺎﺏ‬،‫ﺍﻋﺼﺎﺏ‬

‫ ﺩﮐﺘﺮ ﻋﻠﻲ ﭘﺬﻳﺮﻧﺪﻩ ﻭ ﺩﮐﺘـﺮ‬،‫ﺟﻤﻠﻪ ﺍﻳﻦ ﺍﺳﺎﺗﻴﺪ ﺩﮐﺘﺮ ﻣﺠﻴﺪ ﻣﺪﺭﺱ‬ ‫ ﺍﻗﺘﺼـﺎﺩ ﺑـﺮ‬،‫ ﺁﻣﻮﺯﺵ ﺑـﺮ ﺍﺳـﺎﺱ ﻋﻠـﻮﻡ ﺍﻋﺼـﺎﺏ‬،‫ﺁﻣﺎﺭ ﺍﻋﺼﺎﺏ‬

‫ ﻫﻤﭽﻨﻴﻦ ﺍﺯ ﺩﻭﺳﺘﺎﻥ ﻭ ﻫﻤﮑﺎﺭﺍﻧﻲ ﮐﻪ ﻣﻮﺟـﺐ‬.‫ﻓﻴﺮﻭﺯ ﺁﺭﺵ ﻫﺴﺘﻨﺪ‬ ‫ ﺑﺎﺯﺍﺭﻳﺎﺑﻲ ﺑﺮ ﺍﺳﺎﺱ ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ ﻭ ﻏﻴـﺮﻩ‬،‫ﺍﺳﺎﺱ ﻋﻠﻮﻡ ﺍﻋﺼﺎﺏ‬

‫ﺁﺷﻨﺎﻳﻲ ﺑﻨﺪﻩ ﺑﺎ ﭘﮋﻭﻫﺸﮕﺮﺍﻥ ﺟـﻮﺍﻥ ﻓﻴﺰﻳـﮏ ﻭ ﺭﻳﺎﺿـﻲ ﺩﺭ ﻣﺮﺍﮐـﺰ‬ ۶۶ ،۴۷] ‫ﮔﺮﺍﻳﺶ ﺗﺤﻘﻴﻘـﺎﺗﻲ ﺍﻓـﺮﺍﺩ ﺯﻳـﺎﺩﻱ ﺭﺍ ﺗﺸـﮑﻴﻞ ﻣـﻲﺩﻫـﺪ‬

‫ ﺍﺯ ﺟﻤﻠﺔ ﺍﻳﻦ ﺩﻭﺳـﺘﺎﻥ‬.‫ﻣﺨﺘﻠﻒ ﭘﮋﻭﻫﺸﻲ ﺷﺪﻧﺪ ﻗﺪﺭﺩﺍﻧﻲ ﻣﻲﻧﻤﺎﻳﻢ‬ ‫ ﺑـﺎ‬،‫ ﺑﻪ ﻧﻈﺮ ﻣﻲﺭﺳﺪ ﺑﺎﻳﺪ ﺩﺍﻧﺸـﺠﻮﻳﺎﻥ ﮐﻮﺷـﺎﻱ ﻓﻴﺰﻳـﮏ ﺭﺍ‬.[۶۷‫ﻭ‬

،‫ ﺩﮐﺘﺮ ﺣﺴـﻴﻦ ﻓﻀـﻠﻲ‬،‫ ﺩﮐﺘﺮ ﺭﺿﺎ ﺍﺑﺮﺍﻫﻴﻢﭘﻮﺭ‬،‫ﺩﮐﺘﺮ ﺣﺴﻴﻦ ﺍﺳﺘﮑﻲ‬ ‫ﺍﺭﺍﺋﻪ ﻧﻤـﻮﺩﻥ ﺩﺭﺱ ﻓﻴﺰﻳـﮏ ﺍﻋﺼـﺎﺏ ﺩﺭ ﺩﻭﺭﺓ ﮐﺎﺭﺷﻨﺎﺳـﻲ ﻭ ﻳـﺎ‬

‫ ﺩﮐﺘﺮ ﺣﺴﻴﻦ ﻣﻬـﺮﻱ‬،‫ ﺩﮐﺘﺮ ﭘﻴﻤﺎﻥ ﺻﺎﺣﺐﺳﺮﺍ‬،‫ﺩﮐﺘﺮ ﺭﺿﺎ ﺍﺟﺘﻬﺎﺩﻱ‬ ‫ ﺑﺎ ﺍﻳﻦ ﭘﮋﻭﻫﺶﻫﺎ ﺁﺷﻨﺎ ﮐﺮﺩ ﺗﺎ ﺑﺘـﻮﺍﻧﻴﻢ ﺩﺭ ﺍﻳـﻦ‬،‫ﮐﺎﺭﺷﻨﺎﺳﻲ ﺍﺭﺷﺪ‬

‫ﺩﻫﻨﻮﻱ ﻭ ﺳﺎﻳﺮ ﺍﻋﻀﺎﻱ ﮔﺮﻭﻩ ﻓﻴﺰﻳﮏ ﺩﺍﻧﺸﮕﺎﻩ ﺻﻨﻌﺘﻲ ﻧﻮﺷـﻴﺮﻭﺍﻧﻲ‬ ‫ﺯﻣﻴﻨﻪ ﻫﻤﺮﺍﻩ ﺑﺎ ﺳﺎﻳﺮ ﭘﮋﻭﻫﺶﮔـﺮﺍﻥ ﺟﻬـﺎﻥ ﺑـﻪ ﮐﺸـﻔﻴﺎﺗﻲ ﺩﺳـﺖ‬

.‫ﺑﺎﺑﻞ ﻫﺴﺘﻨﺪ‬ ‫ ﺍﺯ ﺁﻧﺠـﺎ ﮐـﻪ ﻳـﺎﺩﮔﻴﺮﻱ ﻭ ﺣﺎﻓﻈـﻪ ﺩﺭ ﻧﻬﺎﻳـﺖ ﻳـﮏ ﭘﺪﻳـﺪﻩ‬.‫ﻳﺎﺑﻴﻢ‬

‫ﻓﻴﺰﻳﮑﻲ ﺍﺳﺖ ﺍﻧﺘﻈـﺎﺭ ﻣـﻲﺭﻭﺩ ﺩﺭ ﺍﻳـﻦ ﻗـﺮﻥ ﻳـﮏ ﻣـﺪﻝ ﺟـﺎﻣﻊ‬
.‫ﻓﻴﺰﻳﮑﻲ ﺑﺮﺍﻱ ﺁﻥ ﺍﺭﺍﺋﻪ ﺷﻮﺩ‬

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