International Symposium on Collaborative Technologies and Systems (CTS'06), 2006
ABSTRACT Team formation is a challenging problem in many large organizations in which it is entir... more ABSTRACT Team formation is a challenging problem in many large organizations in which it is entirely possible for two individuals to work on similar projects without realizing it. By applying social network analysis to mappings of co-authors and to mappings of related research paper keywords, we are able to help generate teams of diverse individuals with similar interests and aptitudes.
This report describes response patterns recorded in inner and outer hair cells in the apical thre... more This report describes response patterns recorded in inner and outer hair cells in the apical three turns of the guinea pig cochlea. Characteristic frequencies (CF) in these regions are approximately 270 Hz in turn four, 1000 Hz in turn three and 4000 Hz in turn two. Although the two receptor types exhibit differences in resting membrane potentials and in response phase at low stimulus frequencies, they both produce ac and dc receptor potentials in response to sound. When measured around CF, both cell types produce a depolarizing dc response at low and moderate levels. This contrasts with results published for basal-turn outer hair cells (Russell and Sellick, 1983; Cody and Russell, 1987) whose responses become asymmetrical only at very high levels.
A simple transzygomatic approach to the middle fossa centered on the inferior retraction of the t... more A simple transzygomatic approach to the middle fossa centered on the inferior retraction of the temporal muscle after transection of the zygomatic arch is described. This approach allows a very low basal exposure of the middle and temporal fossa, minimizing the amount of temporal lobe retraction needed to approach intradural and extradural lesion in this location. This approach is simple, easily performed, does not require extensive skull base removal, and still offers excellent visualization of the middle fossa and of the region of the tentorial incisura.
2010 International Symposium on Collaborative Technologies and Systems, 2010
We examine the ontology mapping problem with three different groups of readers in mind: system de... more We examine the ontology mapping problem with three different groups of readers in mind: system designers, who need to know what is and isn't possible given the current state of alignment algorithms and what pitfalls to watch out for when someone suggests the use of ontologies in a project; system developers, who require knowledge of specific algorithms and useful software
... and Its Solution Lateral Approach to Tumors of the Craniovertebral Junction Rinaldo F. Canali... more ... and Its Solution Lateral Approach to Tumors of the Craniovertebral Junction Rinaldo F. Canalis, MD; Neil Martin, MD; Keith Black, MD ... Surgery, Department of Surgery, University of California School of Medicine, Los Angeles, and Harbor-UCLA Medical Center, Torrance, Calif. ...
The Journal of the Acoustical Society of America, 1998
Hair cell responses are recorded from third turn of the guinea pig cochlea in order to define the... more Hair cell responses are recorded from third turn of the guinea pig cochlea in order to define the relationship between hair cell depolarization and position of the basilar membrane. Because the latter is determined locally, using the cochlear microphonic recorded in the organ of Corti (OC) fluid space, no corrections are required to compensate traveling wave and/or synaptic delays. At low levels, inner hair cells (IHC) depolarize near basilar membrane velocity to scala vestibuli reflecting the free standing nature of their stereocilia. At high levels, the time of depolarization changes rapidly from velocity to scala vestibuli to the scala tympani phase of the basilar membrane response. This change in response phase, recorded in the fundamental component of the IHC response, is associated with a decrease in response magnitude. The absence of this behavior in OC and outer hair cell responses implies that basilar membrane mechanics may not be responsible for these response patterns. Because these features are reminiscent of the magnitude notches and the large phase shifts observed in single unit responses at high stimulus levels, they provide the IHC correlates of these phenomena.
Two-tone suppression was studied in both ac and dc receptor potentials recorded from inner hair c... more Two-tone suppression was studied in both ac and dc receptor potentials recorded from inner hair cells in the third turn of the guinea pig cochlea. Frequency response functions for the ac component obtained at moderate intensities indicate that frequency selectivity is enhanced when a high-side suppressor is added to the stimulus. This occurs because the largest reductions in magnitude take place well above and below the characteristic frequency (CF) of the cell. Changes near CF are relatively small. In contrast, frequency response functions for the dc receptor potential become broader in the presence of an excitatory suppressor. The significance of these findings for the processing of complex stimuli is considered.
Inner hair cell (IHC) recordings were made from second turn of the guinea pig cochlea where chara... more Inner hair cell (IHC) recordings were made from second turn of the guinea pig cochlea where characteristic frequencies are approximately 4000 Hz. In order to compare IHC responses with rate suppression measured in the auditory nerve, suppressors were introduced that produced little or no response in the hair cell. The effects of a variable-frequency suppressor on a constant-frequency probe, placed near characteristic frequency, were also investigated since this paradigm is commonly used in single unit experiments. Resulting magnitude changes were measured in the fundamental component of the ac receptor potential and/or in the total dc produced in the region of temporal overlap between the two stimulus inputs. This latter component is especially important when considering how changes in IHC responses relate to decreases in discharge rate in single auditory nerve fibers. Since the ac receptor potential is filtered by the hair cell's basolateral membrane, the dc component probably controls transmitter release at the characteristic frequency of these second-turn IHCs. Based on results from these and previous experiments, a proposal is advanced to explain the evolution of two-tone suppression in the peripheral auditory system. The paper also discusses the use of excitatory versus non-excitatory suppressors and includes a description of two-tone suppression areas at the mechanical, IHC and single unit levels. The explanation of low-side suppression areas is of special interest since hitherto they have been difficult to model (Kim, 1985).
Two methods were used to extract frequency specific information from the gross d.c. cochlear pote... more Two methods were used to extract frequency specific information from the gross d.c. cochlear potential, the summating potential (SP). The first approach was to derive SP tuning curves using a two-tone simultaneous masking procedure; the second to obtain SP iso-response functions. The influence of various parameter changes on the configuration of these functions was also investigated. While SP tuning curves measured using the two-tone paradigm have higher Q10 dB values than SP iso-response functions in the base of the cochlea, the latter have the advantage of avoiding contamination by various nonlinear phenomena which are inherent in the simultaneous tone-on-tone masking procedure. Since SP tuning curves are similar to those for basilar membrane motion (Sellick, P.M., Patuzzi, R. and Johnstone, B.M. (1982): J. Acoust. Soc. Am. 72, 131-141) and the whole nerve action potential (AP) (Cheatham, M.A. and Dallos, P. (1979): J. Acoust. Soc. Am. 65, S13), nearly the same degree of tuning may be reflected at these peripheral recording locations.
Low-frequency tones are used to study changes in responsiveness as a function of phase in inner h... more Low-frequency tones are used to study changes in responsiveness as a function of phase in inner hair cell (IHC) and organ of Corti (OC) responses recorded from second turn of the guinea pig cochlea. In these experiments a 40 Hz stimulus is combined with a variable frequency probe to determine the degree to which tones at and below best frequency (BF) are modulated. Changes in responsiveness produced by the low-frequency input are quantified and related to position of the basilar membrane which is estimated using the phase of the cochlear microphonic measured in the OC fluid space. Results obtained when 40 Hz is presented at its lowest effective level demonstrate that ac responses to low-level BF probes are reduced for basilar membrane displacements to scala tympani while probe tones well below BF are modulated in the opposite direction. The transition between these two response patterns occurs when the overall DC produced in the OC by the two-tone input changes from positive to negative. Because of this association, the frequency dependence exhibited in the bias results may be linked to mechanisms responsible for generating the two polarities of the summating potential and the DC receptor potentials that it reflects. An attempt is also made to relate bias-induced changes in hair cell receptor potentials to modulations in single-unit rate responses. In other words, to address variations in the temporal relationships between excitation and suppression measured in the auditory nerve.
International Symposium on Collaborative Technologies and Systems (CTS'06), 2006
ABSTRACT Team formation is a challenging problem in many large organizations in which it is entir... more ABSTRACT Team formation is a challenging problem in many large organizations in which it is entirely possible for two individuals to work on similar projects without realizing it. By applying social network analysis to mappings of co-authors and to mappings of related research paper keywords, we are able to help generate teams of diverse individuals with similar interests and aptitudes.
This report describes response patterns recorded in inner and outer hair cells in the apical thre... more This report describes response patterns recorded in inner and outer hair cells in the apical three turns of the guinea pig cochlea. Characteristic frequencies (CF) in these regions are approximately 270 Hz in turn four, 1000 Hz in turn three and 4000 Hz in turn two. Although the two receptor types exhibit differences in resting membrane potentials and in response phase at low stimulus frequencies, they both produce ac and dc receptor potentials in response to sound. When measured around CF, both cell types produce a depolarizing dc response at low and moderate levels. This contrasts with results published for basal-turn outer hair cells (Russell and Sellick, 1983; Cody and Russell, 1987) whose responses become asymmetrical only at very high levels.
A simple transzygomatic approach to the middle fossa centered on the inferior retraction of the t... more A simple transzygomatic approach to the middle fossa centered on the inferior retraction of the temporal muscle after transection of the zygomatic arch is described. This approach allows a very low basal exposure of the middle and temporal fossa, minimizing the amount of temporal lobe retraction needed to approach intradural and extradural lesion in this location. This approach is simple, easily performed, does not require extensive skull base removal, and still offers excellent visualization of the middle fossa and of the region of the tentorial incisura.
2010 International Symposium on Collaborative Technologies and Systems, 2010
We examine the ontology mapping problem with three different groups of readers in mind: system de... more We examine the ontology mapping problem with three different groups of readers in mind: system designers, who need to know what is and isn't possible given the current state of alignment algorithms and what pitfalls to watch out for when someone suggests the use of ontologies in a project; system developers, who require knowledge of specific algorithms and useful software
... and Its Solution Lateral Approach to Tumors of the Craniovertebral Junction Rinaldo F. Canali... more ... and Its Solution Lateral Approach to Tumors of the Craniovertebral Junction Rinaldo F. Canalis, MD; Neil Martin, MD; Keith Black, MD ... Surgery, Department of Surgery, University of California School of Medicine, Los Angeles, and Harbor-UCLA Medical Center, Torrance, Calif. ...
The Journal of the Acoustical Society of America, 1998
Hair cell responses are recorded from third turn of the guinea pig cochlea in order to define the... more Hair cell responses are recorded from third turn of the guinea pig cochlea in order to define the relationship between hair cell depolarization and position of the basilar membrane. Because the latter is determined locally, using the cochlear microphonic recorded in the organ of Corti (OC) fluid space, no corrections are required to compensate traveling wave and/or synaptic delays. At low levels, inner hair cells (IHC) depolarize near basilar membrane velocity to scala vestibuli reflecting the free standing nature of their stereocilia. At high levels, the time of depolarization changes rapidly from velocity to scala vestibuli to the scala tympani phase of the basilar membrane response. This change in response phase, recorded in the fundamental component of the IHC response, is associated with a decrease in response magnitude. The absence of this behavior in OC and outer hair cell responses implies that basilar membrane mechanics may not be responsible for these response patterns. Because these features are reminiscent of the magnitude notches and the large phase shifts observed in single unit responses at high stimulus levels, they provide the IHC correlates of these phenomena.
Two-tone suppression was studied in both ac and dc receptor potentials recorded from inner hair c... more Two-tone suppression was studied in both ac and dc receptor potentials recorded from inner hair cells in the third turn of the guinea pig cochlea. Frequency response functions for the ac component obtained at moderate intensities indicate that frequency selectivity is enhanced when a high-side suppressor is added to the stimulus. This occurs because the largest reductions in magnitude take place well above and below the characteristic frequency (CF) of the cell. Changes near CF are relatively small. In contrast, frequency response functions for the dc receptor potential become broader in the presence of an excitatory suppressor. The significance of these findings for the processing of complex stimuli is considered.
Inner hair cell (IHC) recordings were made from second turn of the guinea pig cochlea where chara... more Inner hair cell (IHC) recordings were made from second turn of the guinea pig cochlea where characteristic frequencies are approximately 4000 Hz. In order to compare IHC responses with rate suppression measured in the auditory nerve, suppressors were introduced that produced little or no response in the hair cell. The effects of a variable-frequency suppressor on a constant-frequency probe, placed near characteristic frequency, were also investigated since this paradigm is commonly used in single unit experiments. Resulting magnitude changes were measured in the fundamental component of the ac receptor potential and/or in the total dc produced in the region of temporal overlap between the two stimulus inputs. This latter component is especially important when considering how changes in IHC responses relate to decreases in discharge rate in single auditory nerve fibers. Since the ac receptor potential is filtered by the hair cell's basolateral membrane, the dc component probably controls transmitter release at the characteristic frequency of these second-turn IHCs. Based on results from these and previous experiments, a proposal is advanced to explain the evolution of two-tone suppression in the peripheral auditory system. The paper also discusses the use of excitatory versus non-excitatory suppressors and includes a description of two-tone suppression areas at the mechanical, IHC and single unit levels. The explanation of low-side suppression areas is of special interest since hitherto they have been difficult to model (Kim, 1985).
Two methods were used to extract frequency specific information from the gross d.c. cochlear pote... more Two methods were used to extract frequency specific information from the gross d.c. cochlear potential, the summating potential (SP). The first approach was to derive SP tuning curves using a two-tone simultaneous masking procedure; the second to obtain SP iso-response functions. The influence of various parameter changes on the configuration of these functions was also investigated. While SP tuning curves measured using the two-tone paradigm have higher Q10 dB values than SP iso-response functions in the base of the cochlea, the latter have the advantage of avoiding contamination by various nonlinear phenomena which are inherent in the simultaneous tone-on-tone masking procedure. Since SP tuning curves are similar to those for basilar membrane motion (Sellick, P.M., Patuzzi, R. and Johnstone, B.M. (1982): J. Acoust. Soc. Am. 72, 131-141) and the whole nerve action potential (AP) (Cheatham, M.A. and Dallos, P. (1979): J. Acoust. Soc. Am. 65, S13), nearly the same degree of tuning may be reflected at these peripheral recording locations.
Low-frequency tones are used to study changes in responsiveness as a function of phase in inner h... more Low-frequency tones are used to study changes in responsiveness as a function of phase in inner hair cell (IHC) and organ of Corti (OC) responses recorded from second turn of the guinea pig cochlea. In these experiments a 40 Hz stimulus is combined with a variable frequency probe to determine the degree to which tones at and below best frequency (BF) are modulated. Changes in responsiveness produced by the low-frequency input are quantified and related to position of the basilar membrane which is estimated using the phase of the cochlear microphonic measured in the OC fluid space. Results obtained when 40 Hz is presented at its lowest effective level demonstrate that ac responses to low-level BF probes are reduced for basilar membrane displacements to scala tympani while probe tones well below BF are modulated in the opposite direction. The transition between these two response patterns occurs when the overall DC produced in the OC by the two-tone input changes from positive to negative. Because of this association, the frequency dependence exhibited in the bias results may be linked to mechanisms responsible for generating the two polarities of the summating potential and the DC receptor potentials that it reflects. An attempt is also made to relate bias-induced changes in hair cell receptor potentials to modulations in single-unit rate responses. In other words, to address variations in the temporal relationships between excitation and suppression measured in the auditory nerve.
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Papers by M. Cheatham