MODULE 10- Modulation of Movement by the Basal Ganglia

Question 1

projections to the basal ganglia come from the ____

Answer 1

cerebral cortex

Question 2

**striatum includes what 2 things

Answer 2

-caudate
-putamen

Question 3

striatum includes what 3 things

Answer 3

-caudate + putamen (motor)
-nucleus accumbens (non-motor)

Question 4

medium spiny neurons of the striatum receive input from what 3 structures

Answer 4

-cortex
-thalamus
-brainstem structures

Question 5

striatum -> ____

Answer 5

pallidum

(globus pallidus (GP) and substantia nigra pars reticulata (SNpr))

Question 6

subregions of stratium + pallidum have what

Answer 6

bilateral parts (R/L)

Question 7

subregions of stratium

Answer 7

-caudate
-putamen

Question 8

subregions of pallidum

Answer 8

-globus pallidus, external + internal segments
-midbrain
-substantia nigra pars compacta
-substantia nigra pars reticulata

Question 9

**motor components of the basal ganglia

Answer 9

stratium:
-caudate
-putamen

pallidum:
-globus pallidus, external + internal segments
-midbrain
-substantia nigra pars compacta
-substantia nigra pars reticulata

Question 10

caudate + putamen are what

Answer 10

the “input zone” or starting point of the basal ganglia

Question 11

sources of input of basal ganglia (2)

Answer 11

-corticostriatal pathways (from nearly all regions of the cerebral cortex)
-brainstem inputs from the substantia nigra pars compacta

Question 12

striatum =

Answer 12

caudate + putament

Question 13

**GABA is excitatory/inhibitory

Answer 13

inhibitory

Question 14

glutamate is excitatory/inhibitory

Answer 14

excitatory

Question 15

____ is found in the stratium

Answer 15

GABAergic medium spiny neurons

Question 16

**striatum + pallidum are GABAergic/glutamate

Answer 16

GABAergic
-aka inhibitory

Question 17

major outputs structures of the basal ganglia (2)

Answer 17

-globus pallidus internal segment
-substantia nigra pars reticulata

Question 18

both outputs of basal ganglia (globus pallidus internal segment + substantia nigra pars reticulata) make excitatory/inhibitory connections on their targets

Answer 18

inhibitory
-GABAergic

Question 19

pallidum = ____ + ____

Answer 19

-globus pallidus
-substantia nigra pars reticulata

Question 20

excitatory/inhibitory connection between the striatum + the GPi + GPe

Answer 20

inhibitory

Question 21

excitatory/inhibitory connection between the striatum + the SNpr

Answer 21

inhibitory

Question 22

excitatory/inhibitory connection between the GPe + the subthalamic nucleus

Answer 22

inhibitory

Question 23

excitatory/inhibitory connections between the subthalamic nucleus onto globus pallidus + SNpr

Answer 23

excitatory
-this is the ONLY purely excitatory pathway among the intrinsic pathways of the basal ganglia

Question 24

the direct pathways of the basal ganglia have a net excitatory/inhibitory effect on thalamic neurons

Answer 24

excitatory
-which in turn, the thalamic neurons make excitatory connections onto cortical neurons

Question 25

direct pathways/thalamic neurons play a role in movement initiation by doing what

Answer 25

reducing inhibition

Question 26

how do basal ganglia influence movement

Answer 26

by regulaing the activity of upper motor neuronal circuits

Question 27

main output from the basal ganglia is excitatory/inhibitory

Answer 27

inhibitory (GABAergic)

Question 28

inhibit an inhibitory neuron =

Answer 28

excitatory

Question 29

____ circuit via a chain of neurons

Answer 29

disinhibitory

Question 30

see slide 10

Question 31

evidence from studies of eye movements- the basal ganglia influence movement by regulating the activity of upper motor neuronal circuits

Answer 31

-the basal ganglia disinhibits the generation of saccadic eye movements -cerebral cortex excitatory input to caudate medium spiny neurons -> inhibit inhibitory (GABAergic) SNpr neurons -> superior colliculus upper motor neurons excited -the basal ganglia initiates movement by inhibiting competing or non-synergistic motor programs that would interfere with sensory-driven or goal-directed behaviors

Question 32

reduction in tonic discharge from reticulata neurons ____ upper motor neurons of the superior colliculus, allowing them to generate the burst of APs that command the saccade

Answer 32

disinhibits

Question 33

what is the main recipient of afferents to the basal ganglia

Answer 33

striatum

Question 34

the destination of the incoming axons from the cortex are onto dendrites of a class of cells called ____

Answer 34

medium spiny neurons

Question 35

axons from medium spiny neurons converge on neurons in ____ + ____

Answer 35

-substantia nigra pars reticulata -globus pallidus

Question 36

what are the 2 major output structures of the basal ganglia

Answer 36

-globus pallidus internal segment (GPi) -substantia nigra pars reticulata (SNr) both of these structures make GABAergic, inhibitory connections on their targets

Question 37

the net effect of the ____ inputs that reach the striatum from the cortex is to ____ the ____ inhibitory cells of the globus pallidus + sustantia nigra pars reticulata

Answer 37

-phasic excitatory -disinhibit -tonically active

Question 38

2 sets of circuits of basal ganglia

Answer 38

-direct pathway -indirect pathway

Question 39

direct pathway serves to

Answer 39

release upper motoneurons from tonic inhibition -facilitates movement

Question 40

indirect pathway serves to

Answer 40

increase the tonic level of inhibition -inhibits movement

Question 41

direct pathway of basal ganglia system

Answer 41

caudate/putamen -> GP internal segment -> VA/VL thalamus -> frontal cortex

Question 42

indirect pathway of basal ganglia system

Answer 42

caudate/putamen -> GP external segment -> subthalamic nucleus -> GP internal segment -> VA/VL thalamus -> frontal cortex

Question 43

indirect + direct pathway ____

Answer 43

oppose each other -EXCEPT when dopamine is released onto the striatal medium spiny neurons, results in synergistic activity

Question 44

focused selection of circuits in the basal ganglia system

Answer 44

suppress competing motor programs that could interfere with the expression of sensory-driven or goal-directed behaviors

Question 45

circuits of basal ganglia system are organized in what fashion

Answer 45

center-surround -direct pathway tightly focused on GP internal segment + SNpr -indirect pathway highly diffuse covering a broad array of functional units

Question 46

what does dopamine facilitate

Answer 46

the expression of movement

Question 47

how does dopamine modulate basal ganglia circuits

Answer 47

by increasing/decreasing the excitability of medium spiny neurons

Question 48

striatal medium spiny neurons project to the ____

Answer 48

substantia nigra pars compacta (SNpc)

Question 49

what does dopamine's ability to increase or decrease excitability depend on

Answer 49

receptor type -D1 or D2

Question 50

excitatory inputs to the spiny cells that project to the INTERNAL GLOBUS PALLIDUS (direct pathwy) use what receptors

Answer 50

D1 dopamine receptors

Question 51

inhibitory inputs to the spiny cells that project to the EXTERNAL GLOBUS PALLIDUS (indirect pathway) using what receptors

Answer 51

D2 dopamine receptors

Question 52

D1 dopamine receptors = excitatory/inhibitory

Answer 52

excitatory

Question 53

D2 dopamine receptors = excitatory/inhibitory

Answer 53

inhibitory

Question 54

hypokinetic movement disorder

Answer 54

Parkinson's disease

Question 55

Parkinson's disease

Answer 55

-loss of dopamine-producing neurons and transient inhibition from caudate + putamen causes failure of disinhibition -spinal signals are not as strong causing failure of disinhibition

Question 56

pathways behind Parkinson's disease

Answer 56

-loss of dopamine-producing neurons in the SNpc and neighboring ventral tegmentum -> loss of nigrostriatal pathway -loss of the transient inhibition from the caudate and putamen to the GP internal segment (direct pathway) -> decreasing thalamic excitation of the motor cortex (hypokinetic)

Question 57

hypokinetic

Answer 57

reduction in movement

Question 58

in Parkinson's disease what degenerates

Answer 58

substantia nigra

Question 59

substantia nigra is Latin for what

Answer 59

black substance

Question 60

Parkinson's disease tips the balance in favor of activity in the direct/indirect pathway

Answer 60

indirect

Question 61

hyperkinetic movement disorder

Answer 61

Huntington's disease

Question 62

how is Huntingon's disease inherited

Answer 62

autosomally dominant inheritance

Question 63

Huntington's disease

Answer 63

atrophy of primarily the caudate + putamen + secondarily, frontal + temporal cortices

Question 64

Huntingon's disease pathway

Answer 64

loss of D2-expressing medium spiny neurons -> higher excitability of GP external segment -> decreases excitation of subthalamic nucleus to the GP internal segment -> overall decrease in inhibitory output from the basal ganglia

Question 65

selective loss of striatal neurons in the indirect pathway tips the balance in favor of the direct/indirect pathway

Answer 65

direct pathway

Question 66

reduced movement in Parkinson's disease/Huntington's disease

Answer 66

Parkinson's disease

Question 67

excessive movement in Parkinson's disease/Huntington's disease

Answer 67

Huntington's disease

Question 68

Huntington's disease causes excessive movements in ____

Answer 68

hemiballismus -damage to the subthalamic nucleus

Question 69

system forms a loop that originates from

Answer 69

most parts of the cortex

Question 70

enormous convergence in ____

Answer 70

basal ganglia

Question 71

project back up to ____ + ____

Answer 71

premotor + motor cortex

Question 72

how does basal ganglia regulate movement

Answer 72

by releasing movement via the direct pathway + focusing movements by the indirect pathway