Basal Ganglia

Question 1

what is the BG

Answer 1

a collection of highly intercollated nuclei inclluding: the striatum (the putamen and caudate nucleus) the globus Pallidus (GPi and GPe) substantia nigra (SNr and SNc) and subthamalmic nucleus

Question 2

Describe the Striatum

Answer 2

receives input from the whole cortex (bar auditory and primary visual cortex) connections are monosynaptic and excitatory

Question 3

describe the globus pallidus

Answer 3

consists of the GP internal and GP external, both of which have anatomically different connections and therefor different function

Question 4

Describe the substantia nigra

Answer 4

consists of the SN pars compata which supplies dopaminergic input to the striatum and SN pars reticular which is structuarly and functionally like the GPi

Question 5

what is the motor loop

Answer 5

Cortex; putamen; SNr Gpi; Thalamus; cortex

Question 6

explain the input into BG

Answer 6

Big cortical output neurons send colaterals to BG. these then sunaps onto medium spiny neurons. these MSN thenproject to the striatum. MSN make up 95% of cells in striatum, D1 and D2 types.

Question 7

Give the inhibitory outputs from the in/direct pathways

Answer 7

striatum to GPe (indirect)
GPe to STN
Striatum to GPi/SNr (direct)
GPi/SNr to thalamus

Question 8

Give the excitatory outputs from the in/direct pathways

Answer 8

MC to striatum
MC to STN (hyperdirect)
STN to Gpi/SNr
Thalamus to MC

Question 9

what role does the BG play in learning?

Answer 9

incremntally aquiring stimulus respons associations habbits and skills through reward processing.

Question 10

what do reward based measures produce?

Answer 10

induce the learning of behavioural responses to reward related stimuli, S-R relationships, habbit formation, simple motor behaviours. motor skills and complex mootor behaviours.

Question 11

what are the three different learning systems?

Answer 11

Cortex: utilises different learning systems
BG: reinforcement learning
CB: error correction.

Question 12

whatis response inhibition?

Answer 12

Rapid cancelation of a pre-programmed response wwhen an external cue renders it unnecessary or inappropriate

Question 13

what are laboratory tasks that test response inhibition?

Answer 13

Go/No-Go tasks, externally cued, go stimulus replaced by stop stimulus, measures ability to withold a response
Stop Signal : externally cued, go stimulus followed by stop stimulus, measures ability to inhibit a response that has already been initiated
Slater-Hamel: internally generated, aim to stop the cursor on a target, sometimes a stop apears before target, other times not.