Exam 3-basal ganglia

Question 1

What is the main function the basal ganglia is responsible for?

Answer 1

ADJUSTS activity 1. Selection of right motor program 2. Initiation of movement program 3. Simultaneously prevent non-desired motor programs

Question 2

What in the brain provides input to the basal ganglia?

Answer 2

1. Caudate and putamen (striatum) 2. Subthalmic nucleus 3. Cortical- inputs are all excitatory (glutamate)

Question 3

Damage to basal ganglia generally does what?

Answer 3

Hypokinetic (Parkinson’s) or hyperkinetic

Question 4

Damage caudate does what symptom wise?

Answer 4

Impair executive function and planning

Question 5

What does basal ganglia have to compensate for the excitatory information received from cortex?

Answer 5

90% of striatal cells are GABAergic medium spiny neurons (MSN), inhibitory

Question 6

2 pathways basal ganglia output

Answer 6

Direct: selection/initiation movement, fewer synaptic relays, Indirect: inhibits movement, more synaptic relays

Question 7

The direct pathway does what to cerebral cortex

Answer 7

Increase excitation of cortex

Question 8

The indirect pathway does what to cerebral cortex?

Answer 8

Decrease excitation of cerebral cortex (inhibits through GABA disinhibit subthalamic nucleus tonic activity, so enhance tonic activity of globus pallidus, continue suppress motor thalamus and cortex)

Question 9

All outputs of basal ganglia are…

Answer 9

Inhibitory (GABA)

Question 10

Does the basal ganglia directly connect with LMNs?

Answer 10

NO

Question 11

Name a major output area of the basal ganglia and where the info goes

Answer 11

Thalamus (VA/VL) -> cortex

Question 12

Tonically active

Answer 12

Neuron that fires rapidly all the time (globus pallidus firing GABA even at rest to thalamus, so inhibit activity), thalamus (VA/VL) downstream inhibited by tonic activity

Question 13

Disinhibition

Answer 13

Neuron upstream of globus pallidus fires, releasing GABA, surpressing tonic activity so motor information can reach VA/VL thalamus (disinhibits thalamus)

Question 14

Basal ganglia circuit from Substantia nigra represents motor from …

Answer 14

Head and neck

Question 15

Basal ganglia circuit from globus pallidus represents motor from…

Answer 15

Body

Question 16

In Parkinson’s disease what pathway is damaged and how does it impair motor function?

Answer 16

Damaged nigrostriatal pathway- dopaminergic projection originating from substantia nigra from midbrain dopamine aids in or facilitates the initiation of voluntary movement, so impairment= hypokinetic disorder with impair movement initiation

Question 17

Activation of the direct pathway does what to globus pallidus cells?

Answer 17

• suppress tonical activity, which free up motor thalamus to excite motor cortex
• selection and initiation of motor function

Question 18

Activation of the indirect pathway does what to the globus pallidus cells?

Answer 18

• Tighten grip on globus pallidus inhibitory neurons on motor thalamus, so inhibit motor cortical
• Suppresion of undesired motor function

Question 19

What mediates indirect pathway control?

Answer 19

subthalamic nucleus

Question 20

What facilitates direct pathway activity?

Answer 20

substantia nigra (first thing damaged parkinson’s disease)