9. Motor Systems - Basal Ganglia

Question 1

coordination of neural and muscular activity in motor systems is largely controlled by:

Answer 1

the basal ganglia and cerebellum

Question 2

what are the eight major components of the basal ganglia?

Answer 2

• caudate nucleus
• putamen
• globus pallidus (interior and exterior)
• substantia nigra
• subthalamic nucleus
• nucleus accumbens
• olfactory tubercle
• ventral pallidum

Question 3

what two parts of the basal ganglia make up the dorsal striatum?

Answer 3

the caudate nucleus and putamen

Question 4

what two parts of the basal ganglia make up the ventral striatum?

Answer 4

the nucleus accumbens and olfactory tubercle

Question 5

connected with the limbic system (involved in reward)

Answer 5

ventral striatum

Question 6

the basal ganglia modulates cortical activity through the ______ thereby influencing ______

Answer 6

ventral thalamus, corticospinal tracts

Question 7

where does the input to the basal ganglia come from?

Answer 7

• corticostriate fibers arise from MI, MII, and SI and target the dorsal striatum (caudate, putamen)
• there is a major projection from the substantia nigra to the caudate and putamen

Question 8

what are the major intrinsic connections of the basal ganglia?

Answer 8

the caudate and putamen both influence the global pallidus (internal and external)

Question 9

what are the four major outpus of the basal ganglia?

Answer 9

• the internal global pallidus (GPint) has heavy output to the ventral thalamus
• the ventral thalamus provides feedback to the SMA and PFC (motor planning)
• the external pallidus projects to the subthalamic nucleus (STN)
• STN projects to GPint

Question 10

how many basal ganglia circuits are there?

Answer 10

> 20 000

Question 11

true or false: each circuit relays signals from the neocortex to the basal ganglia to the ventral thalamus to the frontal cortex

Answer 11

true

Question 12

what are the main types of basal ganglia loops?

Answer 12

• sensory motor loops
• “associative” loops
• limbic loop

Question 13

each basal ganglia circuit has ____ and ____ components

Answer 13

closed, open

Question 14

info from a cortical area feeds back to the original source

Answer 14

closed loop

Question 15

info from one cortical region is relayed to a different cortical region via the basal ganglia

Answer 15

open circuit

Question 16

go review slide 599

Answer 16

that’s actually a really good one to go over

Question 17

list the major steps in the generic basal ganglia loops

Answer 17

cortical areas –input–> striatum (caudate/putamen) –intrinsic–> global pallidus and substantia nigra –output–> ventral thalamus –feedback–> frontal cortex

Question 18

list the major steps in the sensorimotor loop

Answer 18

MI, SI, PMC, SMA –input–> caudate/putamen –intrinsic–> ventrolateral GPint and caudolateral SN –output–> ventrolateral thalamus –feedback–> SMA

Question 19

input from MI, SI, PMC, and the SMA to the caudate/putamen in the sensorimotor loop is:

Answer 19

excitatory (glutamate)

Question 20

intrinsic input from the caudate/putamen to the ventrolateral GPint and caudolateral SN in the sensorimotor loop is:

Answer 20

inhibitory (GABA)

Question 21

output from the ventrolateral GPint and caudolateral SN to the ventrolateral thalamus in the sensorimotor loop is:

Answer 21

inhibitory (GABA)

Question 22

feedback from the ventrolateral thalamus to the SMA in the sensorimotor loop is:

Answer 22

excitatory (glutamate)

Question 23

what are the major steps to the direct (GO) pathway in the sensorimotor loop?

Answer 23

striatum —inhibits—> GPint and SN —inhibits—> thalamus (causes net excitation of the thalamocortical fibers through disinhibition)

Question 24

what are the major steps to the indirect (NO-GO) pathway in the sensorimotor loop?

Answer 24

striatum —inhibits—> GPext —inhibits—> STN —excites—> GPint —inhibits—> thalamus (net inhibition of thalamocortical fibers through dis-disinhibition)

Question 25

dopaminergic neurons in the substantia nigra excite the _____ and inhibits the _____

Answer 25

direct pathway, indirect pathway

Question 26

go review slides 603-604

Answer 26

all the fucking loops

Question 27

the second most common neurodegenerative disorder that impairs motor skills including speech

Answer 27

Parkinson's disease

Question 28

what is the life expectancy of a person with Parkinson's disease post-diagnosis?

Answer 28

7-15 years

Question 29

what are the risk factors of developing Parkinson's disease?

Answer 29

age, sex, pesticide exposure, rural living/working, lack of exercise

Question 30

what are the four most common symptoms of Parkinson's disease?

Answer 30

- muscle rigidity - resting tremor - slowing of movement - impaired balance and coordination

Question 31

what causes Parkinson's disease?

Answer 31

neurons in the substantia nigra do not produce enough dopamine and/or die

Question 32

there is a large amount of ______ in the dopaminergic neurons of the substantia nigra, making them appear _______

Answer 32

melanin, black

Question 33

with less dopamine, there is less excitation of the _____ and less inhibition of the _____, leading to more inhibition of ______

Answer 33

direct pathway, indirect pathway, thalamocortical fibers

Question 34

an autosomal dominant mutation of Huntintin where the abnormal protein leads to cell death

Answer 34

Huntington's disease

Question 35

dance-like, involuntary movements often associated with Huntington's

Answer 35

chorea

Question 36

what are some symptoms of Huntington's diseaes?

Answer 36

muscle rigidity, abnormal posture, abnormal face expression, difficulties swallowing/speaking

Question 37

which areas of the brain are the most affected by Huntington's disease?

Answer 37

the caudate and putamen (especially connections with the globus pallidus)