8. Cerebellum

What are the characteristics of fastigial nucleus?

(Input from the vermis (all about balance), and from cerebellar afferents that carry vestibular, proximal somatosensory, auditory and visual info.) -Primarily concerned with balance. -Sends info mainly to vestibular and reticular nuclei. -Efferents pass with superior peduncle in two bundles: 1. The majority loop around the superior peduncle to the unicinate fasciculus (visual recognition) and go to either the thalamus or vestibular nuclei via the juxtarestiform body (vestibular). 2. The second bundle, the fastigiopontine fibers, go to the ipsilateral vestibular nuclei. -Primary concern = 3D orientation in space. -Vestibular nuclei receive info from vestibular apparatus and occulomotor areas for spatial orientation and tracking.

What are the characteristics of vestibular nucleus?

(Nothing but balance. Receive input from the flocculomodular lobe and from the vestibular labyrinth). -Fibers pass from vestibular apparatus to vestibular nuclei. -Major outputs to axial areas for maintenance of balance (Everything axial is all about balance).

What are the characteristics of the emboliform nucleus?

(Remember input from intermediate hemispheres: spinal, proximal somatosensory, auditory and visual info) (where am I in space?) -Projections to the contralateral red nucleus with some to the contralateral thalamus and then onward to the cerebral cortex. -Two decussations. -Primarily concerned with ipsilateral flexor muscle control as messages pass to the spinal cord and feedback somatotopic information to the cerebral areas via the thalamus.

What are the characteristics of the dentate nucleus?

(Remember input from lateral hemispheres cortex and motor planning) -Most fibers pass ventromedially, decussate at the inferior collilculus, enter the red nucleus (big one: feedback to cortex), few terminate there, others pass through to the thalamus where the message is then sent to the coritical areas. -Some fibers feedback into the cerebellum through the reticulotegmental nucleus, while others go to the contralateral inferior peduncle through the reticular nuclei of the medulla.

What are the inputs to the middle cerebellar peduncle?

-Afferents from pontine nuclei in contralateral basilar portion of the pons. -This provides info from peripheral receptors and visual receptors. -It also gives information from the motor and premotor portions of the cerebral cortex.

What are the inputs to the superior cerebellar peduncle?

-Afferents include the anterior spinocerebellar and tectocerebellar tracts. -Anterior spinocerebellar tract fibers originate in Clarke's column of the spinal cord and cross to the lateral funiculus, where they ascend to upper pontine levels before crossing back to enter the cerebellum. -They terminate in the hind limb region of the cerebellar cortex. -Tectocerebellar tracts emerge from the superior and inferior colliculi on both sides, terminating in the intermediate vermis and the lobules simplex. -The tectocerebellar tract is widely believed to mediate visual and auditory relfexes.

How do the anatomical locations of the cerebellar nuclei correspond to the cerebellar cortex?

-Anatomical locations of the cerebellar nuclei correspond to the cerebellar cortex regions from which they receive input. -Thus the medially located fastigial nucleus receives input from the medially located vermis, the slightly lateral interposed nuclei receive input from the slightly lateral intermediate zone...

What is the difference between a simple spike and a complex spike?

-Simple spike: much better control over fine adjustments that need to be made. -CF talks only to Purkinje cells. -MF → granule cell → parallel cells → Golgi cells for feedback and Purkinje cells for output & ...

What are Golgi cells?

1. Cell bodies in granular layer 2. Input is from granule cells via positive synapses in the molecular layer 3. Make inhibitory synapses with granule cells in the glomerulus of the granular layer (negative feedback mechanism)

What are Purkinje cells?

1. Cell bodies in purkinje layer 2. Dendrites in molecular layer where they receive excitatory synapses from granule cell parallel fibers and negative synapses from stellate cells 3. Axons pass through the granular layer and are inhibited by basket cells. 4. THEY ARE THE OUTPUT MECHANISM FOR THE CEREBELLUM.

What are stellate and basket cells?

1. Cells completely in the molecular layer 2. Input is from granule cells which provide positive synapses through parallel fibers 3. Stellate cell has negative synapse with Purkinje cell dendrites, Basket cells negative synapse with Purkinje cell soma

What are the characteristics of the interposed nuclei?

1. Comprise the emboliform nucleus and the globose nucleus. 2. Situated lateral to the fastigial nucleus. 3. Receive input from the intermediate zone and from cerebellar afferents that carry spinal, proximal somatosensory, auditory, and visual information. 4. Project to the contralateral red nucleus (the origin of the rubrospinal tract (upper limb movement).

What are the characteristics of the vestibulocerebellum?

1. Functions in control of balance and head-and-eye movements 2. Has extensive connections to the brainstem vestibular nuclei 3. Receives primary afferent input from semicircular canals (vestibular apparatus in ears) 4. Receives input from and sends output to the vestibular nuclei

What are the characteristics of the spinocerebellum?

1. Functions to adjust ongoing movements especially smoothing their execution 2. Receives extensive somatosensory input from the spinal cord and brainstem and sends output back to the spinal cord via brainstem nuclei 3. Output can also go to the motor cortex via the thalamus

What are the characteristics of the dentate nucleus?

1. Largest of the cerebellar nuclei, located lateral to the interposed nuclei. 2. Receives input from lateral hemisphere and from cerebellar afferents that carry information from the cerebral cortex (via the pontine nuclei). 3. Projects to the contralateral red nucleus and the ventrolateral thalamic nucleus.

What are the characteristics of the vestibular nuclei?

1. Located outside cerebellum, in the medulla (hence, not strictly cerebellar nuclei, but they are considered to be functionally equivalent to the cerebellar nuclei because their connectivity patterns are identical to the cerebellar nuclei). 2. Receive input from flocculonodular lobe and from vestibular labyrinth. 3. Project to various motor nuclei and originate the vestibulospinal tracts (role in balance)

What are the layers of the cerebellum?

1. ML = molecular layer 2. PL = purkinje layer 3. GL = granular layer

What are the characteristics of the fastigial nucleus?

1. Most medially located of the cerebellar nuclei. 2. Receives input from the vermis and from cerebellar afferents that carry vestibular, proximal somatosensory, auditory, and visual information. 3. It projects to the vestibular nuclei and the reticular formation

What are the cells of the cerebellum?

1. PF = parallel fibers 2. PC = purkinje cells 3. GC = Golgi cells 4. BC = basket cells 5. CF = climbing fibers 6. MF = mossy fibers 7. CN = cerebellar nuclei 8. ML = molecular layer 9. PL = purkinje layer 10. GL = granular layer

What are granule cells?

1. Soma in granular layer 2. Input via cerebellar nuclei through mossy fibers that synapse with 6 to 8 dendritic trunks 3. Axons go to molecular layer and send parallel fibers that make excitatory synapses with Purkinje, stellate, golgi and basket cells.

What are the nuclei that make up the cerebellar nuclei?

1. The fastigial nucleus (mainly concerned with balance) 2. The interposed nuclei 3. The dentate nucleus (Dentate and interposed nuclei are concerned more with voluntary movement, and send axons mainly to thalamus and the red nucleus) 4. The vesitubular nuclei

What are the characteristics of the cerebrocerebellum (Neocerebellum)?

1. Thought to coordinate and plan limb movements 2. Receives input from wide areas of the cerebral cortex via the brainstem (pontine nuclei) and sends output via the thalamus to extensive area of the cortex

What are the anatomical divisions of the cerebellum?

1. Three lobes: -Anterior lobe -Posterior lobe -Flocculonodular lobe 2. Three zones: -Vermis -Hemisphere intermediate zone -Hemisphere lateral zone 3. Cerebellar Peduncles (highways → connect cerebellum to pons and midbrain): -Superior cerebellar peduncle: primary output of the cerebellum with mostly fibers carrying information to the midbrain (brainstem) -Middle cerebellar peduncle: carry input fibers from the contralateral cerebral cortex. -Inferior cerebellar peduncle: receives proprioceptive information from the ipsilateral (same side of body) side of the body.

What are the functions of the cerebellum?

1. Timing device 2. Coordination of complex movements 3. Learning and memory 4. Output/feedback comparator 5. Movement smoother

What are the three functional subdivisions of the cerebellum or the cerebellar tracks?

1. Vestibulocerebellum 2. Spinocerebellum 3. Cerebrocerebellum (Neocerebellum)

How is the tracking of people with and without cerebellar injury different?

A: Tracking of people without cerebellar injury. B: Tracking of people with cerebellar injuries.

What is a common input to all cerebellar nuclei?

All cerebellar nuclei and all regions of cerebellum receive input from inferior olive of the medulla (motor coordination and most likely motor learning).

What are the cerebellar nuclei?

All outputs from the cerebellum originate from the cerebellar deep nuclei.

Where is the cerebellum situated?

It is the largest part of metencephalon (hindbrain), which includes the pons + cerebellum. Lies posterior to pons.

What are the inputs to the inferior cerebellar peduncle?

The afferent tracts: -include the olivocerebellar, paraolivocerebellar, vestibulocerebellar, reticulocerebellar, posterior spinocerebellar, cuneocerebellar, and trigeminocerebellar. -Also included arethe anterior external arcuate fibers and the striae medullares.

What are the outputs from the inferior cerebellar peduncle?

The efferent fibers include cerebelloolivary, cerebellovestibular, and cerebelloreticular tracts.

What is the somatotopic map?

The receptive fields of granule cells recorded in the rat cerebellum reveal that there are multiple representations of the same body parts in different locations.