Neuro 3.3

Cortico-Ponto-Cerebellar Pathway (simple version) What type of pathway? What structures does info come in through? What structures does info go out through?

-Afferent & Efferent pathways -Information comes in thru cerebellum & goes out thru cerebellum (loop) Info comes in thru: 1. Cerebral Cortex 2. Pons 3. Cerebellum Info goes out thru: 1. Cerebellum 2. Thalamus 3. Cerebral Cortex

What are the 3 Functional Anatomy areas of Cerebellum?

1. Cerebrocerebellum 2. Spinocerebellum 3. Vestibulocerebellum -named for function -no clear physical borders

Cerebellum Function (dart example, no dysfunction)

1. Person throws dart at the target not very good at first, but gets better eventually 2. Prism goggles shift image, so even though target is still in the middle, it looks like its on the left at beginning, person just throws dart to the left hand side when person realizes they aren't hitting the target, the cerebellum helps to correct the movement eventually you know that even though the target looks like it is on the left, I need to throw to the middle Cerebellum learns the ~30° shift and person masters hitting the target 3. Remove prism goggles person overcompensates: continues to throw target with a 30° shift, even though the goggles have been removed Cerebellum then corrects your movement again to hit the target

Cerebellum Anatomy

3 Lobes Anterior Posterior Flocculonodular (covers Flocculus & Nodulus) Cerebellar Hemispheres 2 Lateral hemispheres Vermis Between 2 lateral hemispheres Flocculus Nodulus Cerebellar Peduncles Superior Middle Inferior Deep Cerebellar Nuclei

Cerebellum in Motor Control (afferent pathway)

Afferent Pathway: *Motor Plan info from SMA & PMC is ALSO sent to Cerebellum as an Efference Copy (Internal Copy) -Then your Cerebellum can know what the movement is probably going to be (predicted behavior)

Cortico-Ponto-Cerebellar Pathway (afferent pathway - Spinocerebellum & Vestibulocerebellum)

Cerebellum also receives info from: Spinal Cord (Spinocerebellum) Vestibular Nuclei (Vestibulocerebellum)

Where is the Cerebrocerebellum located? Where does it receive input from? What are the main functions?

Cerebrocerebellum -btwn cerebellum & cerebrum -mostly on lateral part of cerebellum hemishpere -receives input from cerebrum/cerebral cortex MAIN FUNCTION: coordinate highly skilled movement/complex sequential movement

How does the Cerebellum help with accurate & smooth movement coordination?

Efferent Copy, Comparison, & Feedback information work constantly during movements

Cerebellum in Motor Control (efferent pathway - motor area to skeletal muscle) 4 steps

Efferent Pathway Motor Area to Skeletal Muscle: 1. Desired behavior is sent to motor planning area: SMA: Supplementary Motor Area PMC: Premotor Cortex 2. SMA & PMC come up with a plan about how to actually put the cookie into your mouth (flex elbow 90°) 3. The motor plan is then sent to Primary Motor Cortex to be executed 4. Motor plan info is sent down thru the spinal cord & into skeletal muscle

Cerebellum in Motor Control (efferent pathway: Cerebellum to Cerebral Cortex) Comparison

Efferent Pathway: Cerebellum to Cerebral Cortex -Since the Cerebellum also receives info via Spinocerebellum & Vestibulocerebellum, it can compare the actual behavior to the predicted behavior -Cerebellum sends comparison information back to Cerebral Cortex -If actual behavior & predicted behavior don't match, Cerebellum will send the information back to Premotor Cortex or Primary Motor Cortex to tell them to fix the plan

Cerebellum Dysfunction (dart example)

Even with the goggles on, the person won't be able to learn to correct where they should aim the darts They will always just throw to the left, even though they know they aren't reaching the target After removing goggles: They do not have the overcompensation behavior since their Cerebellum never learned to correct aim

Gait Ataxia

Gait Ataxia ~swing hips out to form a wide base for walking to avoid falling & maintain balance

Dysmetria Definition

Inability to accurately move to a specific distance Person usually overshoots or undershoots Ex: During finger-nose test, poking eye instead of touching nose

Dysdiadochokinesia definition

Inability to rapidly alternate movement Ex: unable to rapidly switch from Pronation to Supination

Cortico-Ponto-Cerebellar Pathway (afferent pathway - Cerebrocerebellum)

Info comes in thru: 1. Cerebral Cortex Motor planning info comes from Frontal Cortex Primary Somatosensory info comes from Parietal Cortex 2. Pons (ipsilateral) axon crosses midline thru Middle Cerebellar Peduncle to get to..... 3. Cerebroerebellum (contralateral) Since this info is coming from the Cerebrum to the Cerebellum, it travels to a specific area of the cerebellum (Cerebrocerebellum)

Cortico-Ponto-Cerebellar Pathway (efferent pathway) What structures does info go out through?

Info get processed in cerebellum and then sent back to cerebral cortex Info goes out thru: 1. Cerebellum 2. Deep Cerebellar Nuclei (ipsilateral) axon crosses mideline thru Superior Cerebellar Peduncle to get to... 3. Thalamus (contralateral) 4. Cerebral Cortex ~primary motor cortex: execution ~premotor cortex: planning

Limb Ataxia

Limb Ataxia ~Jerky, inaccurate movements with hands

Intention (Action) Tremor

No tremor while still Tremors are present when person tries to move their limb

Where does the Spinocerebellum receive input from? What are the main functions?

Spinocerebellum -btwn the spinal cord & the cerebellum -receives input from the spinal cord MAIN FUNCTION: coordinate limb movement -more lateral part is responsible for distal movement -more medial part is responsible for proximal movement (just like in the spinal cord)

What are the pathways for each Cerebellar Peduncle?

Superior Cerebellar Peduncle -efferent pathways Middle Cerebellar Peduncle -afferent pathways -largest because it receives a lot of info from many places to help coordinate movement Inferior Cerebellar Peduncle -BOTH efferent & afferent pathways

Truncal Ataxia

Truncal Ataxia ~trouble with trunk control and balance ~jerky, shaky movements

What is the Vestibulocerebellum responsible for?

Vestibulocerebellum -responsible for the cerebellar system -helps to understand & coordinate postural movement/balance

What is the main function of the cerebellum?

coordination of movements

Ataxia definition & types

impaired movement coordination 1. Truncal Ataxia 2. Gait Ataxia 3. Limb Ataxia

What is the main function of the efferent Cortico-Ponto-Cerebellar Pathway?

to send feedback to your motor cortex or premotor cortex for the execution or planning of movements