Plasticity Flashcards
4 traits of normal hand map in 3b
- Individual variations
- Medio-lateral topography of body parts
- Distal to proximal shift of RF as electrode moves caudally
- Interpolated islands representing hairy skin
If medial nerve is transected
Ulnar and and radial take over cortex
Unmasking is
immediate map changes
2 things implied by progressive changes to somatosensory cortex
- Axonal sprouting
2. Synaptic reorganization
Progressive topographic reorganization does what to RF size?
decreases in size
Example of visual plasticity?
Perceptual fill in of scotomas
Example of auditory plasticity?
Tinnitus
3 subcortical regions that reorganize after amputation
1 that doesn’t
Spinal cord dorsal horn
Cuneate nucleus
Cortico-cortical connections
Doesn’t: thalamo-cortical connections
When axon is cut (like in Pons study) atrophy is seen in 2 regions
Expansion in 1`
Cuneate nucleus
Thalamic VPL nucleus
Expansion of face in VPM thalamic nucleus
Hypothesis behind finger amputation repurposing
Hebbian plasticity:temporal coincidence of inputs
What developed with 3 finger bar training
2-3 digit receptive fields
Supports Hebbian plasticity
Transplanting skin, nerves and blood supply is called
Neurovascular pedical flap transplant
3 good things about crushed nerve regeneration
- RFs are small
- Topographic map is conserved
- More correct localization
3 bad things about crushed nerve regeneration
- Imperfect and haphazard
- Not all original territory is recaptured
- RFs are scattered and representations of skin are fractured
Vibration training on skin caused 2 things
- Expanded representation of S1 3b for trained skin region
2. Enlarged RFs for whole finger
Moving stimuli training on skin caused 2 things
- Expanded representations of stimulated skin region
2. Shrinkage of RFs (maybe greater acuity)
Vibration vs moved stimuli training implies
they are very different physiological processes
3 examples of somatosensory or motor reorganization of topographical maps
- Braille- reading finger
- Musicians with string instruments
- Motor maps after amputation
2 traits of reorganization after scotoma
- Blind spot persists in LGN but is filled in in V1
2. Increased cortico-cortical connections
3 major categories of mechanisms of neural plasticity
- Sprouting
- Substitution
- Synaptic changes
3 types of sprouting
- Regenerative: to replace lost axon (only in PNS)
- Collateral: intact axons help neighbors
- Compensatory: in reponse to printing axonal tree
Recruitment means
intact neural tissue to perform novel functions (like crosstraining)
2 types of synaptic changes
- Unmasking latent synapses
2. Hebbian plasticity
2 neurogenic zones
- Subventricular zone of the lateral ventricles
2. Subgranular zone
What promotes hippocampal neurogenesis?
Aerobic exercise
