Most afferents terminate in external granular and internal granular o Most efferents arise from external granular, external pyramidal, and internal pyramidal o Multiform projects to thalamus Vertical columnar: Cytoarchitecture/”chunks”, functional organization (homunculus) o Divergent pathways o Good for parallel processing o Column size is experience dependent; changes with injury and learning Implications: Projections classifications: ( page 244&245) Subcortical (projection fibers) impulses to and fro subcortical areas (thalamus, brain stem, spinal cord) Association : connect neurons within a hemisphere o Ex: synergist share “rich” connections. 4 muscles in quad—they share the rich connection
Commissural: connect neurons to the contralateral hemisphere o Ex: corpus collosm and commissures
Development Cell migration: In to out (layer 6/VI migrate first) o Works from inner most layer to the outer most layer Thalamic sensory neurons attach to cortical neurons o Sensory + motor = sensorimotor integration o Dependent on genetic factors Complete before birth Neural Exuberance: “all over the place”; projections to many areas Pro: redundancy Con: lacks precision Critical periods: an immature state of neural areas or projections transformation: Regressive Events Cell death—we lose about 50% of neurons during development Axonal retraction Synptaic retraction = pruning – effective synapses ***Activity***
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- Spring '14
- Pyramidal cell, pyramidal neurons, large pyramidal neurons, pack granular neurons