week 9 the cerebellum Flashcards
LABEL
CEREBELLUM
Organization and subdivisions of the cerebellum
peducle is
a major fiber bundle or tract
all input and outputs to cerebellum go through these three synaptic relay stations
- fastigial nucleus
- interposed nuclei
- dentate nucleus
how did the cerebellum likely evolve?
as a massive expansion of the brainstem vestibular nucleus, which in all vertebrates integrate vestibular information into core motor control to reflexively maintain balance
outputs of the cerebellum
- motor and premotor cortices (motor planning)
- lateral descending systems (motor execution)
- medial descending systems (motor execution)
- vestibular nuclei ( balance and eye movement)
Cerebellar cortex is organized by somatotopic map(s) but differs from cerebral cortex in that it maps the _________ side rather than the ___________ side of the body.
ipsilateral ; contralateral
_____________ is another example of collateral projections (copies of commands) from the motor pathways.
Cerebellum
Copies of _________ ________ _________ are sent into cerebellum also ___________ __________ __________ from the spinal cord are also sent into the cerebellum.
descending motor commands ; ascending proprioceptive feedback
Cerebellar outputs from Deep Cerebellar Nuclei (DCN) project onto motor pathways at multiple places, including …
- Motor cortex
- Midbrain (e.g. superior colliculus)
- Descending motor pathways
(these outputs modulate ongoing motor activity)
The cerebellum has ____ main inputs and ____ output.
two ; one
It is hypothesized that the cerebellum’s main function is ….
to compare intended movements (motor commands) to actual movements (proprioceptive feedback) and generate a corrective modulatory output. In this way the cerebellum helps to produce smooth & precise movements.
what is the equation for how the cerebellum calculates correction? where does this take place?
Intended - Actual = Correction
(input 1) - (input 2) = (output 1)
this takes place in cerebellar cortex
In this context, it is possible to interpret the functional organization of the cerebellar neural circuits.
Purkinje cell dendrites compare inputs from _________ ________ and _________ _______and sends an output to deep cerebellar nuclei.
climbing fibers ; mossy fibers (granule cells)
Purkinje cell dendrites receive and integrate the _____ types of inputs.
two
Purkinje cell output represents the _________ _________ _______
calculated corrective action
Mossy fibers deliver sensory feedback through _________ ________, which send ________ _______ (axons) across many Purkinje cell dendrites.
granule cells ; parallel fibers
__________ _________deliver motor commands directly to Purkinje cell dendrites.
Climbing fibers
Purkinje cell output is always
GABAergic
Purkinje cell output is delivered….
to deep cerebellar nuclei from which it is sent into descending motor pathways.
Purkinje cells are organized in a __________ manner along the surface of the cerebellar cortex, so that neighboring groups of motor fields can be smoothly coordinated.
somatotopic
________ _____ and _______ _____ are local interneurons that participate in the comparison of ongoing movement and sensory feedback in complicated ways.
Basket cells ; Stellate cells
THE ONLY OUTPUT FROM CEREBELLAR CORTEX IS
INHIBITORY GABA SYNAPSE
Output from DCN is excitatory to ____, but normally inhibited by ________ _______
M1 ; PURKINJE CELLS
LABEL
“complex spike” evoked in Purkinje cell by climbing fiber
how do climbing fibers lead to excitation of the motor cortex.
Climbing Fiber inputs temporarily suppress tonic Purkinje Cell output, which “disinhibits” (allows) output from deep cerebellar nuclei, sending excitation to motor cortex
When the cerebellum is damaged (or removed) movement can still happen, but
they are unsteady and inaccurate.
