Cerebellum

Lec 12

Purves, 18-5

Functional regions of cerebellum

Cerebrocerebellum (hemispheres): coordination of voluntary movements, cognitive role?

Spinocerebellum &Vestibulocerebellum (midline):posture and balance, eye movements

What kinds of information doesthe cerebellum receive?

somatosensoryvestibular

auditory

visual

proprioceptive

Cerebellar circuit diagram

inputs arrive at the cerebellar cortex

The cerebellum is a fast feedback loop that helps smooth and coordinate all movements

the cortex processes the informationand projects to the deep nuclei

the deep nuclei generate the output.

CEREBELLAR CORTEX

Deep nuclei

Rednucleus

Inferiorolive

Vestibularnuclei

ThalamusVL

CerebralCortex

from Purves, 18-6

Principal OUTPUTS from the cerebellum

Superiorcerebellarpeduncle

Primary motor Cx

Premotor Cx

Thalamus(VL) Superior cereb.

peduncle

Pons

Deepcereb.nuclei

Vestib. nuclei

Inf. olive

The cerebellar microcircuit

Deepcerebellar

nuclei

Inferiorolive All other

inputs

clim

bin

g fi

be

r

mo

ssy

fib

er

parallel fiber

Purkinjeneuron

granule cell

+

+

+

cortex

Golgicell

Basketcell

Stellate cell

+

++

VestibularPonsSpinal cord

+

+

+

CortexRed nucleusSpinal cord

Symptoms:Nausea - vomitingDizzinessVertigoHand shakingImbalanceFallsClumsinessSlurred speechDouble visionDifficulty concentrating

Cerebellar dysfunctionNeurological signs:Ataxia TremorDysdiadochokinesisDysarthria and scanning speechNystagmusHypotoniaCerebellar ataxia (Romberg test)DysmetriaDiplopiaCognitive dysfunction

Summary

1. The cerebellum “balances” motor commands and sensory information to smooth and coordinate movement.

2. Lesions of the cerebellum cause ataxia, tremor, balance and posture problems.

3. Inputs to cerebellum: mossy fibers (pons & spinal cord) & climbing fibers (inferior olive).

4. Purkinje neurons use the neurotransmitter GABA and inhibit their targets in the deep nuclei.

5. Outputs from cerebellum: deep nuclei to red nucleus, thalamus, inferior olive, and vestibular nuclei.

6. Associative forms of motor learning occur in the cerebellum.

7. Think of the cerebellum when you’re in the ER

This is cerebellum!