CEREBELLUM

Involved w/ feedback control of movement.

Key player in motor system is the motor cortex à motor neuron à muscle

The VA and VL have input to the motor cortex

The cerebellum also projects to VA and VL

The Feedback

The cerebellum receives info from the cortico spinal tract informing the cerebellum what the motor commands are

There is feedback info from spino cerebellar, muscle spindles, bones, and joints that go to the cerebellum

The cerebellum will compare and see what’s the command and what’s the feedback

Ex. Command to touch nose and feedback is the arm is moving

If there is an error then the cerebellum can send a correction signal to the motor cortex

Anatomy

Hemisection through cerebellum at midline

Made up of many little gyri

Grey matter on top and white matter beneath

Each gyrus is called a folium

You can distinguish 2 important fissures

Primary fissure: separates ant and post lobe of cerebellum

Posterolateral fissure: separates the foculonodule lobe.

b/c of the 2 fissures you have 3 lobs of the cerebellum:

anterior

posterior: largest

flocculo – nodular (flocullo part is lateral) – small primitive lobe

areas of lobe

vermis (midline) – “looks like a worm”

hemispheres (2 lateral areas)

if you took the cerebellum and squashed it flat: it’ll look like

Divisions of cerebellum based on evolution and function

vestibulo-cerebellum (archicerebellum)

most ancient

deals with balance and positioning in space  – connected to vestibule system

floculonodule lobe

feedback control of positioning

spino-cerebellum (paleocerebellum)

mostly ant lobe and vermis of the post lobe

has to do with feedback control of limb movements

cerebro-cerebellum (neocerebellum)

lateral hemispheres of post lobe

most highly developed in humans

for rapid learned motor activity – no time for feedback

most recent

Histological Structure

white matter

on the surface there’s grey matter with 3 layers

granular layer w/ billions of small neurons and are tightly packed

purkinje cell layer w/ large cells and single cells

most important cell of the cerebellum

very large neuron

extremely large dendritic branches

tremendous number of sub branches

axon goes down

goes to deep cerebellar nuclei which are embedded in the white matter

output of cerebellum come out of the deep cerebellar nuclei

there are 4 of them

you have a very perfuse dendritic tree all in one plane

molecular layer with dendrites and axons meet where you get synaptic interaction