Function and dysfunction of cerebellum and basal ganglia Flashcards
Feedback and feedforward controller
Feedback- using a sensor to control something, but have to wait until passes the threshold to do something about it, so get oscillations and variation in whatever you’re measuring
Feedforward- using cues to predict a future state based on an internal model of the system
Role of the parietal cortex in matching joint position sense with visual coordinates for a reaching motion.
Spatial representation of vision is in parietal lobe
Integrates visual and spacial information (contralateral side of body)
Input-output from pareital and pre-motor cortex is how you plan movements
How does the cerebellum adapt cortical networks to changes in the relationship between joint position sense and visual coordinates
Adaptive controller
Cerebellum does adaptation, so that if you have some change, like muscle atrophy or broken arm, that changes the model of the angles to make a reaching movement for example, you can also change your model for how to preform those movements
With prism example, the cerebellum helps you adjust to that new model and then there’s a post-adaptation time where even without the prisms, you still sue that model and are off again until your cerebellum adapts again back to the old model
How does the inferior olivary nucleus contribute to how the cerebellum can adapt cortical networks to changes in the relationship between joint position sense and visual coordinates
Climbing fiber discharge from ION is a kind of error signal that instructs the cerebellar cortex
Form of synaptic plasticity at purkinje cells dendrites when have simultaneous activity of climbing fiber and parallel fiber interaction
Depresses those synapses and alter output of purkinje cell output to deep cerebellar nucleus
Role that dopaminergic neurons in the VTA/SNc play in conveying reward prediction errors to the striatum
When you get your reward, you get a spike in the dopamine release from the SNc into the striatum.
Enhances the synaptic relationship between the cortico-striatal neurons that were active in producing reward and their striatal counterpart
What was unstructured, gets reinforced as a stereotyped movement that is related to the reward
With iced tea symbol example, eventually the burst of dopamine happens just when see the symbol and not when receive the reward
Describe similarities between the role the ION plays in modifying cerebellar circuitry and the role that VTA/SNc neurons play in modifying corticostriatal circuitry.
Both are comparitors that discharge when there’s a mismatch between expected and observed outcomes
Architecture of striatum is not uniform (striosomes and matrix)
One set of striatal projections in the matrix project through absal ganglia loop
Ones from striosomes receive same inputs but project directly to SNc as a carbon copy (inhibitory)
Comparison between what’s expected and what happens
If unexpected, produce an error signal and update model to make that more expected
How does the ION know there’s an error?
Some early signals are encoded very early in sensory transmission (example from Person’s lecture with picking something up that’s lighter or heavier than expected). ION receives and amplifies those signals.
