Cortical Plasticity Representational plasticity - induction - mechanisms Hyperacuity - intramodal effects - intermodal effects Clinical relevance Cross-modal plasticity
Representational plasticity
Amputation, deafferentation
- after 2 years Effect of amputation on the cortical representation in SI
Deafferentation of the glabrous part of D1 and D2 by nerve transection dorsal, hairy silent Area 3b
Reorganization of the thalamic representation
Deafferentation of the cortical representation by thalamic lesion
Experience dependent plasticity Training and learning
Extensive multidigit stimulation
Reversibility and dynamics
Return of esthesia Effect of anesthesia on the size of the RF of an SI neuron
Effect of amputaion on the RF size in SI
Mechanisms
Convergence, divergence
Relationship of intrinsic cortical connections and peripheral innervation
Divergence in the major somatosensory pathway
A possible role for the thalamocortical circuitry in regulating cortical plasticity
Microstructure of the somatosensory RF
Unmasking A role for lateral inhibition
Effect of disruption of local inhibition on the RF size in SI
Forward masking increases lateral inhibition
Rapid unmasking by decreasing tonic inhibition
Synaptic plasticity LTP/LTD
Upper layer horizontal connections play pivotal role in representational plasticity
Hyperacuity
Intramodal effects Amputation, reversible inactivation
Sensitivity differences between fingers in normal cases
AMPUTATION Increased representation, better performance?
Reversible inactivation: callosal interactions Behavior
Reversible inactivation: callosal interactions Brain activation (EEG)
Map reorganization Clinical relevance
Phantom feelings, Phantom pain
Focal hand dystonia:Writer’s-, Musician’s Cramp
Aberrant, increased plasticity
Neuronal basis of map reorganization: unresolved issues
Cross-modal plasticity Blindness
Intermodal effects
Blindness induced somatosensory changes
Increased tactile sensitivity
Cross-modal effects
Axonal rerouting
Tactile functions of the visual cortex
Rewiring Subcortical pathways
Uni- and heteromodal connections Cortical pathways
Speech processing in the visual cortex