Basal Ganglia

Question 1

do the basal ganglia have a direct connection to the LMN pool?

Answer 1

no, they provide and regulate info coming out of UMNs

Question 2

what is the result of that basal ganglia having no direct connection to the LMN pool?

Answer 2

lesions don’t affect strength of muscles but will effect inhibition of movement and suppression of movement

Question 3

what behaviors do the basal ganglia control?

Answer 3

goal-directed behavior, social behavior, and some emotional responses

Question 4

what are the structures of the basal ganglia

Answer 4

caudate, putamen, globus pallidus, subthalamic nucleus, and substantia nigra

Question 5

what structures make up the striatum?

Answer 5

caudate and putamen

Question 6

what structures make up the lenticular nucleus?

Answer 6

putamen and globus pallidus

Question 7

what structure of the basal ganglia is not in the cerebrum, but rather in the midbrain?

Answer 7

the substantia nigra

Question 8

what are the two parts of the GP?

Answer 8

GPi (globus pallidus internal) and GPe (globus pallidus external)

Question 9

what are the two parts of the SN?

Answer 9

SNpc (substantias nigra pars compacta) and SNr (substantia nigra reticulata)

Question 10

what is the area surrounding the 4th ventricle and what does it do?

Answer 10

PEG (periaqueductal grey)

it plays a big role in pain modulation (suppresses pain by releasing endogenous opioids)

Question 11

what are the 5 cortico-BG-thalamic circuits?

Answer 11

2 motor:
- motor
- oculomotor

3 non-motor:
- goal-directed behavior
- emotion/motivation
- social behavior

Question 12

what structures are involved in the motor basal ganglia circuit? what is the function of the circuit?

Answer 12

putamen and GP

skeletal muscle contraction, muscle force, multi joint movement, movement sequencing, motor planning

Question 13

what structures are involved in the oculomotor BG circuit? what is the function of the circuit?

Answer 13

caudate body and SNr

spatial awareness and eye movement

Question 14

what structures are involved in the goal-directed behavior BG circuit? what is the function of the circuit?

Answer 14

caudate head and GP

decision-making, information evaluation, planning, choosing actions in context

Question 15

what structures are involved in the emotion/motivation BG circuit? what is the function of the circuit?

Answer 15

ventral striatum and ventral pallidum

regulates emotional expression, reward-seeking behavior

Question 16

what structures are involved in the social behavior BG circuit? what is the function of the circuit?

Answer 16

caudate head and SNr

recognizes social cues, self-control, attention to social disapproval, and selective attention

Question 17

what 3 things are involved in all BG circuits?

Answer 17

BG, cortical structure, and thalamic nuclei

Question 18

what 3 things are involved in the 3 non-motor and 2 motor BG circuits?

Answer 18

prefrontal cerebral cortex

BG

thalamic nuclei

Question 19

what are the BG afferents?

Answer 19

all areas of the cerebral cortex

PPN

dorsal raphe nuclei

Question 20

what is the NT of the cerebral cortex?

Answer 20

glutamate

excitatory

always excitatotry input from the cortex

Question 21

what are the 2 NTs of the PPN?

Answer 21

ACh (excitatory or inhibitory)

glutamate (excitatory)

Question 22

what is the PPN responsible for?

Answer 22

attention, reward, voluntary movement, etc.

Question 23

what is the NT of the dorsal raphe nuclei?

Answer 23

serotonin (usually inhibitory)

Question 24

inputs enter the BG through what strucures?

Answer 24

striatum (caudate and putament)

subthalamic nucleus (STN)

Question 25

what are the 3 main sources of input?

Answer 25

PPN, dorsal raphe nuclei, and cerebral cortex

Question 26

what is the intrinsic circuitry of the BG?

Answer 26

SNpc to striatum (dopamine=excitatory or inhibitory) striatum to GP and SN (GABA=inhibitory) GPe to STN (GABA=inhibitory) STN to GPi and SNr (glutamate=excitatory) - only soley excitatory pathway

Question 27

what are the efferents of the BG?

Answer 27

GPi (globus pallidus interna) to thalamus (VL and VA) and SNr (substantia nigra reticulata) to superior colliculus

Question 28

tracts in the GPi to thalamus of BG

Answer 28

corticospinal corticopontine corticobrainstem

Question 29

efferent info from GPi to thalamus

Answer 29

provide info for descending system from cerebral cortex

Question 30

efferent info from SNr to superior colliculus

Answer 30

contributes to directing visual attention to the stimulus superior colliculus inhibited by SNr midbrain locomotor region inhibited

Question 31

what are the 3 movement control pathways?

Answer 31

Go (direct) No-Go (indirect) Stop (hyperdirect) normal movement requires all pathways

Question 32

how does the BG control movement?

Answer 32

the BG controls movement by controlling what's happening in these circuits

Question 33

the SN to putamen will activate which 2 pathways depending on the signal?

Answer 33

go or no-go

Question 34

what is disinhibition?

Answer 34

double inhibition=activation silent inhibitory neuron activated and inhibits another inhibitory neuron which always excitation

Question 35

stop (hyperdirect) pathway

Answer 35

inhibition of the motor thalamus goal: inhibit ongoing, irrelevant movement motor cortex activates STN STN excites GPI GPi inhibits motor thalamus

Question 36

go (direct) pathway

Answer 36

goal: getting info from SNpc; facilitate movement disinhibition of motor thalamus motor cortex activates D1 receptor of putamen D1 inhibits GPi (inhibiting inhibitory nucleus) motor thalamus is disinhibited (activated)

Question 37

no-go (indirect) pathway

Answer 37

goal: inhibit/suppress unnecessary movements inhibition of motor thalamus suppress competing movements motor cortex excites D2 receptor of putamen putamen inhibits GPe GPe disinhibits STN STN excites GPi GPi inhibits motor thalamus

Question 38

Control of movement from the GPi

Answer 38

voluntary movement postural control walking

Question 39

LMN: control of voluntary movement

Answer 39

GPi inhibits the motor thalamus motor thalamus excites motor cortex motor cortex excites corticospinal tracts corticospinal tracts contribute to voluntary movements

Question 40

LMN: postural and girdle muscles

Answer 40

GPi inhibits the PPN PNN inhibits reticulospinal tracts disinhibition of postural and girdle muscles

Question 41

stepping pattern generators/LMN for walking

Answer 41

GPi inhibits midbrain locomotor region midbrain locomotor region has cholinergic effects on reticulospinal tracts reticulospinal tracts activate SPG/LMN for walking

Question 42

movement disorders of the BG

Answer 42

affect balance of the function of the 3 pathways

Question 43

hypokinetic disorders

Answer 43

less movement down regulation of go pathways, up regulation of no-go pathway Parkinson's disease: postural instability

Question 44

hyperkinetic disorders

Answer 44

too much movement up regulation of go pathway, down regulation of no-go pathway Huntington's disease Tourette's syndrome