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Lecture 9

BIO SCI N110 Lecture 9: 9 Cortical Plasticity in Adults


Department
Biological Sciences
Course Code
BIO SCI N110
Professor
Parker
Lecture
9

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Mon | 5.13.19 Cortical Plasticity in Adults
The old dogma regarding cortical plasticity in adults
"After developmental plasticity is completed (i.e., after critical periods are over), the functional
organization of the adult cortex is static and unchangeable"
Effects of "enriched" environments on adult cortex
The adult cortex shows substantial plasticity
Sensory cortex becomes thicker
Neurons exhibit larger dendritic and axonal trees
Larger amount of synapses and more complex capillary patterns
Notably, such animals are typically better in problem solving tasks (e.g., mazes) than control
animals
Clearly, the cortex can change a lot, even in adults
Effects of peripheral damage on adult somatosensory cortex organization
Cortex organization: digit removal or nerve damage
Experiments demonstrating plasticity of hand representation
After a finger was removed, the regions of other fingers took over cortical somatosensory area
The cortical representation of the face is next to that of the hands
Severing the input from the arm and hand at the level of the shoulder
In the control monkey, this area of the somatosensory cortex represents the arm and face
In the deafferented monkey, the area of the somatosensory cortex that formerly
represented the arm has been taken over by the expansion of the face area
The remapping involves a few cm of cortex, so it's a major functional change
General rule for adult plasticity following peripheral damage
The inputs to the cortex are in a constant state of "territorial competition," and the inputs
with an advantage will gain cortical territory
In our examples, the inputs with an advantage were originating from the
neighboring areas in the cortical body map
Similar experiments were performed in other sensory systems with similar
results, thus generalizing the findings from the somatosensory cortex
Effects of preferential use on adult somatosensory cortex organization
Cortex organization (no surgical damage)
Finger-specific training on a difficult texture discrimination task
Only middle three digits (2-4) were trained in the task
Before training (control)
Normal representation of the 5 digits
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