| Term | Definition |
|---|
| Stage #1 | initial conceptualization of movement plan - parietal association cortex |
| Stage #2 | corticopontine tract conveys this to Pons (PN); synapses in Pons and enters cerebellum through middle peduncle, as "mossy fibers" |
| Stage #3 | mossy fibers ascend to cerebellar cortex, sunapse with granule cells that synapse with Purkinje cells in middle layer of cerebellar cortex; Purkinse axons descend into deep nuclei, e.g., dentate where they exert inhibitory effects on dentate neurons (IPSPs) via GABA-mediated synapses |
| Stage #4 | dentate axons then leave cerebellum through superior peduncle and synapse in VL nucleus of thalamus |
| Stage #5 | VL neurons then ascend to motor cortex regions of cerebral cortex to drive Pyramidal tract motorneurons |
| Stage #6 | Corticospinal tract activation: Golgi I (giant Betz cell) signals traveling down to cross at medulla, enter spinal cord and exit ventral roots to innervate muscles for contraction and movement |
| Stage #7 | collateral branch off of descendin axon of corticospinal tract enters pons where it synapses with neuron in pons |
| Stage #8 | continuation (pontine-cerebellar tract) of above goes into intermediate zone as the "efferent copy" (through middle cerebellar peduncle) |
| Stage #9 | while this occurs, the efferent signal arrives at spinal cord and activates muscles for movement. Afferent signals from these activated muscles ascends to intermediate zone (spinal-cerebellar tract): intermediate zone is somatopically represented) |
| Stage #10 | results of comparison sent to IP - interpositus nucleus from Purkinje cells in intermediate zone. Output of IP neurons exits cerebellum through superior peduncle and goes to VL nucleus in thalamus, and red nucleus in midbrain |
| Stage #11 | descending rubrospinal tract (part of extrapyramidal tract) goes to spinal cord and executes changes in motor signals as needed; VL projection drive pyramidal tract motoneurons and changes made at cerebral level for eventual corticospinal (or corticobulbar) signals to be enacted for corrections |
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