M3 L4 Flashcards
What does the cerebellum have a lot of?
Neurons
- lots of granular cells that play roles in processing sensory and motor information.
What does the cerebellum receive a lot of?
Sensory information to help learning and skilled movements.
- lots of info about goals, commands, and feedback signals associated with programming and execution of movement.
What does the cerebellum do?
While it doesn’t directly initiate movement, it fine-tunes signals from other parts of the brain to make actions more accurate.
- basically contributes to the movement following the initial one (checks if initial was done right- if not it corrects it)
Brief explanation of this circuit
Cortex sends commands to brain stem who relays the signals to the spinal cord to transmit motor commands to the muscles to execute movement.
Modulatory structures:
* cerebellum adjusts for accuracy
* basal ganglia imitates and regulates movement
* thalamus acts as a relay center to process signals before sending to cortex
Explain this feedback loop with the cortex, brain stem, cerebellum, and thalamus
Loop is for fine tuning movement:
Cortex → Brain Stem
The motor cortex sends movement signals down to the brainstem, which helps relay them to the spinal cord and muscles.
Brain Stem → Cerebellum
The cerebellum receives a copy of the motor command from the brainstem. It also gets sensory feedback from the body about movement and balance.
Cerebellum → Thalamus
The cerebellum compares the intended movement with the actual movement and makes corrections. It then sends refined motor adjustments to the thalamus.
Thalamus → Cortex
The thalamus acts as a relay station, sending the cerebellum’s corrections back to the motor cortex so it can adjust future commands.
Anatomy of the Cerebellum
* Vermis
– Speech, gait, posture, and eye movement
Anatomy of the Cerebellum
* Paravermis
– Appendicular movement (reaching and grabbing)
Anatomy of the Cerebellum
* Lateral parts of the hemispheres
– Eye-hand coordination
– Learning new movements
Anatomy of the Cerebellum
* Base of the cerebellum
– VOR (vestibulo-ocular reflex) - keeps us not dizzy
– Equilibrium
What is the spinocerebellum made up of?
vermis and paravermis
What is the cerebrocerebellum made up of?
Lateral hemisphere
Whats the vestibulocerebellum made up of
base of cerebellum (nodulus and flocculus)
Information sent to the cerebellum
- cerebral cortex (area 4/6)
- proprioception information
- balance
- visual and auditory information
- learning and memory information
What kind of control does the cerebellum have on the body
The cerebellum is ipsilateral, meaning it controls movement on the same side of the body.
The Cerebellum: Inputs -> Process -> Output
1) receives information from three main sources: Spinal Cord, Vestibular System, Cerebral Cortex
2) The cerebellum compares intended movement (from the cortex) with actual movement (from sensory feedback).
3) Sends corrected signals to the thalamus, which relays them to the motor cortex for future movement adjustments.
Where does the Vestibulocerebellum receives input from?
the vestibular nucleus
Where does the spinocerebellum receives input from?
spinal cord
Where does the cerebrocerebellum receives input from?
many areas of the cerebral cortex
Why does the cerebellum receive info from area 4 and 6, somatosensory areas, and posterior parietal areas?
These inputs help the cerebellum compare what the brain wants to do with actual movement feedback from the body.
- Area 4 (Primary Motor Cortex) → Sends signals about voluntary movement commands.
- Area 6 (Premotor & Supplementary Motor Cortex) → Provides movement planning information.
- Somatosensory areas (S1, S2) → Sends sensory feedback about body position and movement.
- Posterior parietal areas (PPC) → Sends spatial awareness and coordination data.
Through what pathway does the cerebellum receive info?
Motor and sensory signals from the cortex travel down to the pons. he pontine nuclei relay this information to the cerebellar cortex via the corticopontocerebellar tract.
This allows the cerebellum to receive a “copy” of the motor plan before the movement happens.
What does the cerebellum do with the info it receives from the cortex/pons? where send it to after
The cerebellar cortex processes the input and detects any errors in movement. Adjustments are then made and sent to the deep cerebellar nuclei (like the dentate nucleus), which generate corrected motor commands.
What does the deep cerebellar nuclei do with the corrections made by the cerebellum?
The deep cerebellar nuclei send corrections to the ventrolateral (VL) nucleus of the thalamus.
The VLC relays this refined info back to the motor cortex (Areas 4 & 6).
The corrected motor plan is then executed properly through the spinal cord to the muscles.
VLO (Ventral Lateral Oralis - Basal Ganglia Pathway)
* input
* output
* role
Input: From the basal ganglia (which is involved in movement initiation and selection).
Output: To Area 6 (Premotor Cortex), which helps plan movements before execution.
Role: Involved in motor planning and initiation, ensuring smooth and voluntary movements.
VLC (Ventral Lateral Caudalis - Cerebellar Pathway)
* input
* output
* role
Input: From the cerebellum (which processes movement coordination and correction).
Output: To Areas 4 & 6 (Primary Motor & Premotor Cortex), refining movement execution.
Role: Involved in movement coordination and error correction, ensuring smooth, precise motion.
Gray matter of cerebellum is what?
Cerebellar cortex
White matter of cerebellum is what?
Deep cerebellar nuceli
Cells of the Cerebellum
- Granular cells
- Purkinje cells
- Basket cells
- Stellate cells
- Golgi cells
Cellular Circuit: Mossy fibers
* what do? Who connect to?
Bring sensory & motor information from the pons to the cerebellum.
Excite granule cells and deep cerebellar nuclei.
Cellular Circuit: Granule cells
* receive info from who?
* send info to who?
Receive input from mossy fibers and send signals via parallel fibers.
Parallel fibers excite Purkinje cells, basket cells, stellate cells, and Golgi cells.
Cellular Circuit: Purkinje Cells (Main Output Neurons of the Cerebellar Cortex)
* what do
Inhibit deep cerebellar nuclei (which send motor corrections).
Cellular Circuit: Climbing Fibers (from Inferior Olive)
* what do?
* firing speed?
Have a strong influence on Purkinje cells, helping with motor learning. (very powerful, only 1 climbing fiber per purkinje cell but she packs a punch and helps excite purkinje even more)
Fire at a much lower rate than parallel fibers (1-2 Hz vs. 30-100 Hz).
Cellular Circuit: Basket & Stellate Cells
* what are they
* what do
Inhibitory Interneurons
Modulate Purkinje cell activity and help refine motor output by adjusting Purkinje cell firing. (Prevent Over-Inhibition of Deep Cerebellar Nuclei)
Cellular Circuit: Golgi Cells (Inhibitory)
* what do
Regulate granule cell activity, preventing excessive firing and excessive excitation of Purkinje cells.
Cellular Circuit: Deep Cerebellar Nuclei (Main Output of Cerebellum)
* where receive what type of input from who
* where send output to
- Receive inhibitory input from Purkinje cells.
- Send excitatory output to thalamus → motor cortex (M1) to adjust movements.
1 parallel fiber inputs onto 10k _____ cells
1 parallel fiber inputs onto 10k purkinje cells
1 purkinje cells receive inputs from 200k ____
1 purkinje cells receive inputs from 200k parallel fibers
what rate do parallel fibers of granule cells fire at
30-100 hz (fast)
what rate do climbing fibers from inferior olive fire at?
1-2 hz (slow)
What deep cerebellar nuclei are associated with each cerebellar division?
* Cerebrocerebellum
* Spinocerebellum
* Vestibulocerebellum
Cerebrocerebellum → Dentate nucleus
Spinocerebellum → Interposed nuclei & Fastigial nucleus
Vestibulocerebellum → No deep cerebellar nuclei
What role does the ventral nuclear complex in the thalamus play?
Receives input from the dentate nucleus and interposed nuclei
Sends motor coordination signals to the primary motor and premotor cortex
What is the relationship between the cerebellum and the red nucleus?
The red nucleus influences the inferior olive, which sends climbing fibers back to the cerebellum for motor learning
function of the cerebellum
to make sure that the movement we intend to make is equal to the movement we actually made
What is the efferent copy?
Movement we intend to make. It tells the cerebellum what movement was supposed to happen.
- A copy of the command that was sent to the alpha motor neuron (the neurons that activate muscles).
What happens with sensory feedback ?(What Actually Happened)
The body sends signals back to the cerebellum about the actual movement.
This feedback comes from:
* Ia afferents (from muscle spindles) → Tells how much the muscle stretched.
* Ib afferents (from Golgi tendon organs) → Tells how much force the muscle produced.
* Skin receptors → Detect pressure and touch, helping refine movement.
Where does all the info come from (both intended and actual)?
mossy fibers
What happens when there is a lesion in the cerebellum?
Movements become jerky and imprecise, a condition called ataxia.
What is the main problem in ataxia?
The cerebellum fails to correct errors in ongoing movements.
