“Explain NeuroPlasticity”

-11-
Cause /reasons
12- Outline the function of neural pruning on behavior
13- Explain how neural networks works

Neuroplasticity is the ability of the brain to change throughout the course of life.
Every time we gain knowledge through experience, the neurons connect to create a new
network in the brain. This procedure is called dendritic branching because the
dendrites of the neurons grow in numbers and connect with other neurons. Neural
networks in the brain develop by the making and breaking of synaptic connections
between neurons. The reasons for such changes can be both genetic as well as
environmental. Of course, synapses that are not used often are weakened and
eventually are lost through neural pruning. In that way the brain gets rid of synapses
that are no longer needed, thus making the functioning of the neural networks more
efficient. Furthermore, an individual’s neuroplasticity may be affected by a variety of
factors other than experience, like hormones, psychoactive drugs, ageing, stress, diet,
electrical stimulation as well as brain damage. One effect of neuroplasticity that has
been studied experimentally is the effect of practising a new skill on brain structure.
Neuroplasticity is the brain's ability to reorganize itself by forming new neural
connections. Neuroplasticity allows neurons in the brain to compensate for injury or to
respond to changes in the environment. When neurons fire continually as a result of
stimulation in the environment, the neurons sprout new dendrites – known as dendritic
branching. This increases the number of synapses available for the behaviour. Dendritic
branching as a result of stimulation in the environment is seen in a study by Maguire.
A specific example is of Draganski et al (2004), where they carried out an
independent measures design experiment, aiming to investigate structural changes in
the brain in response to practicing a new skill; juggling. The participants consisted of 23
female and 3 male volunteers, who were later randomly divided in the two conditions of
the independent variable. Namely, the “juggling condition” and the “non-juggling
condition”. Participants of the “juggling condition” initially received an MRI scan before
the start of the experiment and were then taught and practiced a simple juggling routine
for 3 months. Afterwards, they received a second MRI scan and were instructed to stop
practicing. A third MRI scan was performed after another 3 months from the ceasing of
practicing the routine. Participants of the “non-juggling condition” never practiced
juggling and also received three MRI brain scans; one before the start of the experiment,
one after 3 months and a final one after another 3 months.
The results showed that although at the beginning of the experiments no
differences regarding brain structure were detected between participants of the two
conditions, this changed significantly after 3 months. Specifically, participants of the
juggling condition were found to have significantly more grey matter in the mid-
temporal area of the cortex in both hemispheres. This area is responsible for
coordination of movement and depends on visual memory, thus showing that practising
juggling leads to neural network development to this area of the brain. These findings
were reversed after the participants of the “juggling condition” stopped practising as
shown in the final MRI scan, where the differences between the two groups decreased,
indicating that ceasing the routine leads to neural pruning in this specific brain area.
The conclusion drawn from this study is that grey matter grows in response to
learning and shrinks in the absence of stimulation. Since the study was an experiment, it
highlighted the cause-effect relationship between learning and brain structure.
Maguire argued that this demonstrates the plasticity of the hippocampus in response to
environmental demands. She argued that the posterior hippocampus stores a spatial
representation of the environment and that in the London taxi drivers the volume of the
posterior hippocampus expanded because of their high reliance on navigation skills and
spatial memories.
EXCELLENT WORK
The ability of brain neurons to adapt their connections and behavior in response to
added information is known as neuroplasticity. The brain adapts by rearranging its
structure and functions due to ongoing changes brought on by experience. In order to
improve the person's impairments and functional challenges after brain loss, the brain
will reassign lost functions to other brain areas. To determine the number of synapses,
dendritic field length and spine density can be used. The process of creating new
dendrites by utilizing a particular brain region is known as dendritic branching. By
making and breaking synaptic connections between neurons, neural networks in the
brain develop. Neural pruning is the function of removing neurons from the brain that
are no longer needed. Brain plasticity can be influenced by many factors and some of
them are stress, diet, brain damage, aging, and more. The following study, by Draganski
et al, 2004, is a study of neuroplasticity that demonstrates how a repeated action can
lead to the growth of neural networks - and then the cessation of that activity can lead
to neural pruning.
Researchers wanted to determine if acquiring a new motor ability, in this case, juggling
would result in structural alterations in the adult human brain. 24 willing volunteers—
21 women and 3 men—participated in this study. Each participant underwent an MRI
scan at the beginning of the study to create a model for grey matter and brain structure.
The sample was randomly split into two groups: jugglers and non-jugglers. The juggling
group was instructed to practice this routine and let the researchers know when they
were skilled. However, the non-jugglers in the control group were instructed to never
engage in any juggling. The jugglers then underwent a second MRI scan. After the scan,
they were instructed to stop juggling, and three months later, a third and final scan was
performed. For the duration of the trial, the non-juggling group was used as a control
group. The researchers compared the neuronal density (grey matter) in the brains of
jugglers and non-jugglers using voxel-based morphometry (VBM), which they utilized
to analyze the MRI images. Prior to the study's start, baseline scans revealed no
appreciable regional variations in the grey matter between the two conditions. The mid-
temporal region, which is connected to visual memory, was shown to have more grey
matter in the jugglers' brains, at the conclusion of the first measurement. The quantity
of grey matter in these regions of the brain had diminished three months after the
participants' last juggling session when many were no longer able to do the routine. The
non-juggling sample did not change during the investigation.
The results of this experiment are interesting as they suggest that juggling depends
more on visual memory than on "procedural memory," which is more likely to alter the
cerebellum or basal ganglia. Thus, grey matter grows in response to learning and
shrinks in the absence of stimulation (lack of practice). There is a cause-effect
relationship between learning and brain structure. Practicing watching balls move and
learning to move in response to them strengthens neural pathways and forms new
neural networks, resulting in the brain adapting to a different shape. When they
stopped juggling in the following 3 months, the area was no longer used, so neural
pruning underwent to get rid of the unnecessary pathways.