Cerebellum Lec 12

Functional regions of cerebellum Cerebrocerebellum (hemispheres): coordination of voluntary movements, cognitive role? Spinocerebellum & Vestibulocerebellum (midline): posture and balance, eye movements Purves, 18-5

What kinds of information does the cerebellum receive? auditory proprioceptive somatosensory visual vestibular

Cerebellar circuit diagram The cerebellum is a fast feedback loop that helps smooth and coordinate all movements inputs arrive at the cerebellar cortex the cortex processes the information and projects to the deep nuclei the deep nuclei generate the output.

Principal OUTPUTS from the cerebellum Premotor Cx Cerebral Cortex Primary motor Cx Thalamus VL Red nucleus Vestibular nuclei Inferior olive Thalamus (VL) Superior cereb. peduncle Superior cerebellar peduncle Deep nuclei Pons Vestib. nuclei CEREBELLAR CORTEX Deep cereb. nuclei Inf. olive from Purves, 18-6

The cerebellar microcircuit Stellate cell cortex + + + parallel fiber Basket cell + + Purkinje neuron Golgi cell granule cell + + Deep cerebellar nuclei climbing fiber + + mossy fiber Cortex Red nucleus Spinal cord Inferior olive Vestibular Pons Spinal cord All other inputs

Cerebellar dysfunction Neurological signs: Ataxia Tremor Dysdiadochokinesis Dysarthria and scanning speech Nystagmus Hypotonia Cerebellar ataxia (Romberg test) Dysmetria Diplopia Cognitive dysfunction Symptoms: Nausea - vomiting Dizziness Vertigo Hand shaking Imbalance Falls Clumsiness Slurred speech Double vision Difficulty concentrating

VARNISHED

Summary The cerebellum “balances” motor commands and sensory information to smooth and coordinate movement. Lesions of the cerebellum cause ataxia, tremor, balance and posture problems. Inputs to cerebellum: mossy fibers (pons & spinal cord) & climbing fibers (inferior olive). Purkinje neurons use the neurotransmitter GABA and inhibit their targets in the deep nuclei. Outputs from cerebellum: deep nuclei to red nucleus, thalamus, inferior olive, and vestibular nuclei. Associative forms of motor learning occur in the cerebellum. Think of the cerebellum when you’re in the ER

This is cerebellum!