bio approach: neural pruning Flashcards
definition of neuroplasticity
the ability of the brain to change throughout the course of life.
changed developed are due to?
the creation of new synaptic connections between neurons and the breakdown of ones no longer in use; in response to biological maturation, genetics, environmental stimulus, learning or brain injury.
brief on neural networks -
one of the ways that our brains change is through the creation of neural networks. this happens because of long-term potentiation - that is, the repeated firing of neurons. this leads to an increase in dendritic branching which leads to an increase in the number of synapses.
intro to neural pruning -
another way that our brain can change is through neural pruning - which is a decrease in the number of synapses as a result of the removal of dendritic branches. if there is no continuous stimulation from our environment, some of the neural networks remain largely unused - therefore the process of synaptic pruning occurs
study connected to this?
Draganski et. al. (2004) which demonstrates how repeated action can lead to the growth of neural networks and then the cessation of that activity can lead to neural pruning.
draganski et al. (2004) aim -
to see whether learning a new skill - in this case, juggling - would affect the brains of participants.
draganski et al. (2004) sample -
24 volunteers (21 females and 3 males) who were between the ages of 20 and 24.
draganski et al. (2004) procedure -
each P had an MRI scan at the start of the study to serve as a base rate for grey matter and brain structure.
juggling condition - taught a three-ball cascade juggling routine. they were asked to practice this routine and to notify the researchers when they had mastered it. at that point, the jugglers had a second MRI scan. after the second scan, they were told not to juggle anymore. then a third and final scan was carried out three months later.
non- jugglers -> control group.
MRI scans: identify the part of the brain involved in the formation of visual memory. to analyze the MRI scans, the researchers used voxel-based morphometry [VBM] to determine if there were significant differences in neural density (grey matter) in the brains of jugglers vs. non-jugglers.
draganski et al. (2004) results -
first, MRI scans of both groups showed no significant regional differences in the grey matter between the two conditions.
However, at the end of the first part of the study (after mastery), the researchers observed a significant bilateral expansion in grey matter in the mid-temporal area (hMT/V5) and the left posterior intraparietal sulcus for the juggler group.
3 months after the participants stopped juggling - when many were no longer able to carry out the routine - the amount of grey matter in these parts of the brain had decreased.
however, the jugglers still had more grey matter in these areas than at the first brain scan (before they started juggling).
no change throughout the study in the non-juggling sample.
conclusion -
grey matter grows in the brain in response to environmental demands (learning) and shrinks in the absence of stimulation (lack of practice), and this shows a causality relationship b/w learning and brain structure.
provides strong evidence for neuroplasticity, the brain’s ability to adapt and change structure in response to new experiences.
P who learned to juggle showed increased grey matter in the mid-temporal area, a region associated with visual memory, compared to the non-juggling control group.
however, after 3 months when participants were told not to practice juggling, this led to reduction in grey matter which is an indicative of a pruning mechanism, where the brain eliminates connections that are no longer deemed essential for the given skill or cognitive function.
these findings suggest that even complex skills like juggling can induce brain plasticity in young adults, challenging the previously held belief that such changes were limited to early development.
