Cerebellar Function pp Flashcards
Main functions of cerebellum
Coordination of motor acts, planning sequential movements Regulation of posture Control of muscle tone Motor Learning Some cognitive function
High Fidelity Tracts
Carry info for unconscious proprioception from receptors in the muscles, tendons & joints
Internal Feedback Tracts
Monitor activity of spinal interneurons & descending motor signals from the cerebral cortex & brainstem
Cognitive function problem
Verb generation produced a pronounced increase in activity w/in right lateral cerbellum
Input to the Cerebellar Cortex
Mossy Fibers - from SC & brainstem
Climbing Fibers - from inferior olivary nuclei
Nonlaminar Afferents - Aminergic fibers - release monamines serotonin from raphe nuclei, NE from locus ceruleus or HA from hypothalamus
- widely distributed brain stem neuron fibers release aCH
Cerebellar layers
Molecular Layer
Purkinje Cell Layer
Granule Cell Layer
Mossy Fibers
Most entering Cerebellum
2 branches, one deep nucleus one to cerebellar cortex to glomerulus.
Make excitatory synapses onto granule and Golgi cell dendrites
Golgi cell axons make inhibitory connections to glomerulus
Granule Cells
Excited by mossy fibers
Axons ascend to the molecular layer where they bifurcate & become the parallel
parallel fiber makes excitatory synapses on the order of tens of thousands of Purkinje cells
Golgi Cells
Axon make inhibitory synapses onto cell dendrites in the glomerulus
Golgi cell dendrites in the molecular layer are excited by parallel fibers from granule cells
Inhibit Purkinje Cells
Stellate Cells - make inhibitory synapses to dendrites
Basket Cells - to purkinje soma, axon hillock and dendrites
Both these cells excited by parallel fibers
Climbing Fibers
From Inferior Olivary Nuclei & divide into two branches in cerebellum
Deep branch terminates in Deep nuclei & cortical branch collaterals into several cerebellar lobes
Purkinje cell receives only one climbing fiber but that fiber makes numerous excitatory synapses
Purkinje Cell Output Cell of the Cerebellar Cortex
Only cell whose axon leaves the cerebellar cortex
Terminate in a deep cerebellar nucleus
Some from vermis & flocculonodular lobe terminate in the vestibular nuclei
INHIBITORY
Cerebellar Cortex - Deep cerebellar nuclei interactions
Input from outside excites deep cerebellar nuclei
Same fibers also excite cell in cereberllar cortex
OUTPUT from cerebellar cortex inhibits deep nuclei
Vestibulocerebellum functions
Regulate equilibrium
Regulate gait & posture (reflexes)
Control eye movements & coordinate head & eyes
ROLE: visual guidance
Lesion of Vestibulocerebellum
Ataxic gait - wide stance
Cerebellar nystagmus
Deficits in smooth pursuit eye movements
