Exam 3 Week 12 PP 1 Basal Ganglia review

Question 1

Two parts of Substantia Nigra

Answer 1

1. Pars compacta- cell rich

2. Pars reticulata- fiber rich

Question 2

Two additional structures to Basal Nuclei

Answer 2

1. Nucleus Accumbens

2. Pedunculopontine nucleus

Question 3

3 geographic points of the Pedunculopontine nucleus

Answer 3

1. Located in brainstem just caudal to substantia nigra.
2. Part of the ascending reticular activating system (ARAS)
3. Part of the Descending connections thru reticulospinal tracts to LMNs

Question 4

Another term for Nucleus Accumbens

Answer 4

ventral striatum

Question 5

What system is Nucleus Accumbens densely connected to?

Answer 5

limbic

Question 6

What pathway is Nucleus Accumbens a part of?

Answer 6

mesolimbic reward pathway

Question 7

What communication loops in the basal ganglia are utilized with diseases such as Parkinson’s disease (PD) or Huntington’s disease?

Answer 7

may affect multiple loops and thus present with a variety of motor, cognitive, and emotional symptoms

Question 8

What is the key to basal nuclei function in motor activities? (1 word)

Answer 8

disinhibition

Question 9

Projections from this nuclei in thalamus to the motor cortex are excitatory

Answer 9

VA/VL

Question 10

Neurotransmitter that tonically inhibits VA/VL of thalamus

Answer 10

GABA

Question 11

What structures of basal ganglia release GABA to tonically inhibit VA/VL?

Answer 11

globus pallidus & substantia nigra pars reticulata

Question 12

What needs to occur for thalamus to excite motor cortex?

Answer 12

basal nuclei must phasically remove this inhibition of the motor nuclei of the thalamus (VA/VL)

Question 13

How does the striatum participate in the direct pathway

Answer 13

removal of inhibition of disinhibition is done by the striatum acting via the globus pallidus internus

For a simplified explanation of the direct pathway go to
https://www.youtube.com/watch?v=noBTt1tsAMs

Question 14

Excitatory and Inhibitory steps of the direct pathway (4)

Answer 14

1. Cerebral cortex using glumate excites the striatum
2. The striatum produces GABAnergic inhibition of globus pallidus internus (Gpi)
3. This inhibits the action of the GPi on the thalamus (inhibition of the inhibition on the thalamus - disinhibition)
4. Disinhibition of the VA/VL thalamus allows a burst of tonic activity which excite the motor cortex to produce a movement.

Question 15

Steps of the indirect pathway

Answer 15

1. Excitatory pathway from cortex to striatum.
2. Striatal inhibitory neurons produces an inhibition of inhibitory GABA output from globus pallidus externus to subthalamus.
3. The now disinhibited Subthalamus excites GPi
4. The now excited GPi inhibits the VA/VL thalamus which can no longer excite the cortex.
5. The unexcited motor cortex will fail to produce movement.

Question 16

What is the overall purpose of the indirect pathway?

Answer 16

inhibit voluntary movement

Question 17

Excitatory neurotransmitter used in the indirect and direct pathways

Answer 17

Glutamate