cerebellum signal transmission process, cerebellum, brain anatomy, neural function, neural physiology, neural circuit

1. NEURAL CIRCUIT OF
CEREBELLUM
By MEENALI MISHRA
A13156216001
M.Sc. Medical Physiology
(3rd Semester)

2. CEREBELLUM
 Largest part of the hindbrain &
lies behind the Pons & medulla
oblongata.
 Situated in the dorsal aspect of
the brainstem & is connected
to it by three cerebral peduncle
on either side:
• Superior peduncle(brachium
conjunctivum).
• Middle peduncle(brachium
pontis).
• Inferior peduncle(restiform
body).

3. SUBDIVISIONS OF THE CEREBELLUM
• Composed of central vermis &
two cerebral hemispheres on
either side.
A. PHYLOGENIC
DIVISIONS:
 Archicerebellum
 Flocculonodular lobe &
lingula.
 Palleocerebellum
 Anterior lobe except- lingula.
 Posterior lobe- pyramis, uvula.
 Neocerebellum
 Whole posterior lobe except-
pyramis & uvula.

4. B. FUNCTIONAL SUBDIVISIONS:
 Vestibulocerebellum:
 Consists of flocculonodular lobe & lingula.
 Vestibular connections.
 Control body posture & equilibrium.
 Spinocerebellum:
 Includes vermis except nodule & lingula.
 Helps in controlling the activities of distal limb muscles
 Cerebrocerebellum:
 Consists of lateral portions of cerebral hemispheres.
 Helps in planning & programming movements.

6. STRUCTURE OF CEREBELLUM
 Outer Cerebellar Cortex
• Molecular layer.
• Purkinje cell layer.
• Granule cell layer.
 Inner core of White Matter
• Projection fibres.
• Association fibres.
• Commissural fibres.
 Deep Cerebellar Nuclei
• Dentate nucleus.
• Emboliform nucleus.
• Globose nucleus.
• Fastigeal nucleus.

7. LAYERS OF THE CEREBELLAR CORTEX
 Outer Molecular Layer:
• Consists of Stellate cells & Basket cells
• Innumerable synapses present executing a large amount of
integrative work.
 Intermediate layer of Purkinje Cells:
• Have large flask shaped bodies with freely branching
dendrites extending into the molecular layer & one axon
passing to the cerebellar nuclei.
• Contains cell bodies of Purkinje cells.
 Inner Granular Layer:
• Contains small Granule cells & Golgi cells.
• Have multiple short dendrites & one long axon.
• Axon ascends to the molecular layer & bifurcates into the
transverse branches parallel to the surface.

9. NEURONES IN THE
CEREBELLAR CORTEX:
1. Purkinje cells
2. Granule cells
3. Stellate cells
4. Basket cells
5. Golgi cells

11. PURKINJE CELLS:
• Biggest neurons in the body.
• Have extensive dendritic arbors that extend throughout the
molecular layer.
• Cells receive the climbing fibres at the stem of dendritic tree.
• Also receives axons of Stellate cell & basket cells.
• Axons of these cells project to the deep cerebellar nuclei & few to
the vestibular nuclei.
GRANULE CELLS:
• Small, numerous, spherical neurons occupying greater part of the
granular layer.
• Axons go up the molecular layer & bifurcate like letter ‘T’ called
the parallel fibre.
• These fibres connect the Stellate cells, basket cells & Golgi cells.
• Mossy fibres makes glomerular synapse with the dendrites of the
granule cells

12.  STELLATE CELLS:
• Confined to the molecular layer.
• Dendrites synapse with the parallel fibres while the axons synapse
with the dendrites of Purkinje cell(near their origin).
 BASKET CELLS:
• Lie in the deeper part of the molecular layer.
• Axons form networks around the cell bodies of Purkinje cells.
 GOLGI CELLS:
• Large stellate cells lying in the granular layer.
• Dendrites which project into molecular layer receive inputs from
the parallel fibres.
• Golgi cells are responsible for feedback inhibition of granule cells.
 The stellate cells, basket cells & Golgi cells act as
interneurones & are inhibitory

15. CONNECTION OF CEREBELLUM
A. Incoming Fibres
 CLIMBING FIBRES:
• Bring excitatory inputs.
• Bring proprioceptive inputs along with other information.
• Give collaterals to deep cerebellar nuclei & end like creepers
on primary dendrites of Purkinje cells.
 MOSSY FIBRES:
• Carry proprioceptive inputs from all parts of body plus cerebral
cortex via the pontine nuclei to the cerebellar cortex.
• Give collaterals to the deep cerebellar nuclei & end on the
dendrites of the granule cells.
• One mossy fibre communicates with many granule cells

16. Climbing Fibres:
inferior olivary nucleus Cerebellum(Purkinje cells)
Mossy Fibres:
pontine nuclei Cerebellum(Glomerulus)
Climbing Fibres Mossy Fibres
Olivocerebellar Tract Spinocerebellar Tract
Vestibulocerebellar Tract
Reticulocerebellar Tract
Cuneocerebellar Tract
Corticocerebellar tract

17. B. Outgoing Fibres
 Outgoing fibres from cerebellum are axons of the
deep cerebellar nuclei together with some P cell
axons.
 Cells of nuclei get excitatory collaterals from
climbing & mossy fibres but inhibitory influence
from axons of the purkinje cells.
 Excitatory output of cerebellum goes to the
thalamus, red nucleus, reticular formation, olivary
complex, vestibular nuclei etc.
 Cerebellar projection is sent to motor cortex, brain
stem & spinal cord to achieve control of
movements.

19. The Circuit Within The Cerebellum
 Climbing fibres, mossy fibres & granule cells are stimulatory
whereas Purkinje cells, basket cells, Stellate cells & Golgi cells are
inhibitory.
 One climbing synapse with one P cell & stimulates it whereas one
Mossy fibre makes contact with many granule cell which in turn
make contact with many P cell through the parallel fibres &
stimulates these cells.
 One mossy fibres stimulates many Purkinje cells through the
granule cells.
 Parallel fibres makes contact with the basket cell, stellate cells &
Golgi cells.
 Mossy fibres contact with the Golgi cells along with the granule
cells.

20. Stellate & basket cells end on the purkinje cells & Golgi
cells end on the granule cells.
Climbing & mossy fibres send collaterals to the deep
cerebellar nuclei.
Output of the cerebellar nuclei form output of the
cerebellum.
Golgi cells are stimulated by mossy & parallel fibres &
they inhibit granule cells.
Basket cells & stellate cells are excited by parallel fibres
& they inhibit the granule cells.

22. • Processing of information in cerebellum occurs as
follows:
Impulses entering the cerebellum take
courses, one through deep cerebellar nuclei &
other through the circuitry in the cortex.
Result of cortical integration is ultimately
presented in deep cerebellar nuclei. Final
output of the nuclei is the output of the
cerebellum & is distributed to different parts
of CNS

25. CONNECTION OF CEREBELLUM
• The afferent (entering) & efferent(leaving) connecting the
cerebellum with the extra cerebellar regions run through the three
large bundles known as superior, middle & inferior cerebellar
peduncles.
INFERIOR CEREBELLAR PEDUNCLE
(Restiform Body)
 AFFRENTS:
• Dorsal Spinocerebellar tract.
• External Arcuate fibres.
• Vestibulocerebellar tract.
• Olivocerebellar tract.
• Tectocerebellar tract.
 EFFERENTS:
• Fastigiovestibular tract & Fastigiobulbar tract.
• Cerebello-olivary tract.

26. MIDDLE CEREBELLAR PEDUNCLE
(Brachium Pontis)
AFFERENTS:
• Pontocerebellar tract.
• Fibres from cerebellum to cerebellum.
SUPERIOR CEREBELLAR PEDUNCLE
(Brachium Conjunctivum)
AFFERENTS:
• Ventral spinocerebellar tract.
• Tectocerebellar tract
EFFERENTS:
• Dentatothalamocortical tract.
• Dentatorubrothalamic tract.

30. Thank you......