Basal Ganglia And Motor Activity

Front 1

What are the parts of the basal ganglia (4) and what are their subdivision?

Back 1

1. Caudate + putamen (neostriatum)
2. Globus pallidus (lateral and medial)
3. Substantia nigra (pars compacta and reticularis)
4. Subthalamic nucleus

Front 2

What makes up afferent signals to the basal ganglia?

Efferent?

Back 2

Excitatory signals coming from the cerebral cortex, thalamus


Inhibitory projections to the thalamus

Front 3

What are the receptive areas of the basal ganglia?

Back 3

neostriatum (primary)
substantial nigra and subthalamic nuclei

Front 4

What are the thalamostriate pathways?

Back 4

Projections from the thalamus to the neostriatum

Front 5

What are the major sources of efferent projections to targets outside the basal ganglia?

Back 5

1. Medial globus pallidus
2. Pars reticularis of the substantia nigra

Front 6

What type of efferent projections leave the basal ganglia?

Where do they go?

Back 6

Inhibitory

VA/VL complex of the thalamus

Front 7

Inhibitory NT of the basal ganglia
a. Name
b. Where is it made

Back 7

a. GABA
b. neostriatum, globus pallidus, pars reticulata

Front 8

Excitatory NT of basal ganglia
a. Name
b. Where is it made

Back 8

a. Glutamate
b. Subthalamic nucleus

Front 9

NT of basal ganglia that can be excitatory or inhibitory
a. Name
b. Where is it made?

Back 9

a. Dopamine
b. Pars compacta

Front 10

What are 2 types of neurons that exist in the neostriatum?

Back 10

Medium 'spiny'
large 'aspiny'

Front 11

What do medium 'spiny' neurons of the neostriatum recieve? (3)

Back 11

1. Excitatory from cerebral cortex (corticostriate)
2. Excitatory from thalamus (thalamostriate)
3. Mixed excitatory/inhibitory from pars compacta (dopamine)

Front 12

Where do efferents from the medium 'spiny' neurons go?

Back 12

1. Both segments of the globus pallidus
2. Substantia nigra

Front 13

What is the nature of output from the basal ganglia?

Back 13

Inhibitory

Front 14

What are the 2 cortical regions that do NOT send projections to the neostriatum?

Back 14

1. primary visual cortex
2. auditory cortex

Front 15

What gives the globus pallidus its pallor?

Back 15

Myelinated fibers from the neostriatum traversing it

Front 16

What is the NT used in both segments of the globus pallidus?

Back 16

GABA - inhibitory

Front 17

Lateral globus pallidus
a. Inputs from where?
b. Outputs to where?

Back 17

a. neostriatal neurons expressing D2 receptor - inhibitory

b. Subthalamic nucleus (inhibitory)

Front 18

What are the 2 nuclei in the basal ganglia that send projections outside the basal ganglia?

Back 18

Medial globus pallidus
Pars reticularis

Front 19

Medial globus pallidus
a. Inputs from where?
b. Outputs?

Back 19

a. Neostriatal neurons (D1 receptor) -inhibitory, subtahalamic nucleus-excitatory

b. VA/VL complex of the thalamus - inhibitory

Front 20

What gives the pars compacta its dark appearance?

Back 20

neuromelanin, byproduct of dopamine synthesis

Front 21

Pars compacta of substantia nigra
a. inputs from...?
b. outputs to...?

Back 21

a. Striatum - inhibitory
b. Striatum - inhibitory or excitatory

Front 22

What NT is used by the pars compacta?

What determines if projections from the pars compacta are excitatory or inhibitory?

Back 22

Dopamine

Depends on receptor of target organ

Front 23

When is Dopamine excitatory?

When is dopamine inhibitory?

Back 23

Excitatory when target organ (neostriatal neuron) uses D1 receptors

Inhibitory when target uses D2 receptor

Front 24

What NT is used in the pars reticularis?

What are the afferent/efferent connections from the pars reticularis similar to?

Back 24

GABA - inhibitory

Connections of the medial globus pallidus

Front 25

Where does the subthalamic nucleus lie in coronal sections of the brain?

Back 25

Between the thalamus and the substantia nigra

Front 26

Subthalamic nucleus
a. Input from...?
b. Output to...?

Back 26

a. Lateral globus pallidus - inhibitory
b. Medial globus pallidus - excitatory

Front 27

What NT is used by projections from the subthalamic nucleus?

Back 27

Glutamate - excitatory

Front 28

What is disinhibition?

What are the parts in a classical disinhibitory circuit?

Back 28

Removal of an inhibitory influence

intermittently active inhibitory neuron --> tonically inhibitory neuron --> excitatory neuron

Activating the intermittently inhibitory neuron leads to increase in excitatory neuron activity

Front 29

What is the disinhibitory circuit involving the basal ganglia?

Back 29

Basal ganglia neurons affect the medial globus pallidus, which inhibits the thalamus, which sends excitatory projections to the cerebral cortex

Front 30

What is the direct motor pathway inhibitory loop?

Back 30

Cerebral cortex activates inhibitory neuron in neostriatum --> inhibits medial globus pallidus --> disinhibits thalamus, which can now excite the cerebral cortex

Front 31

How are the direct and indirect motor pathways related?

Back 31

Antagonistically

Direct --> excites motor cortex
Indirect --> inhibits motor cortex

Front 32

What is the indirect motor pathway?

Back 32

Inhibitory signals from neostriatum --> lateral globus pallidus (disinhibits) --> subthalamic nucleus is now free to excite medial globus pallidus --> more inhibition of motor cortex

Front 33

What is the prefrontal loop?

Back 33

Signals from pre-frontal cortex and orbital frontal cortex --> basal ganglia --> dorsal medial nucleus of thalamus --> cortex (influence cognition, memory, emotion, behavior)

Front 34

What are some cortical area functions associated with the basal ganglia besides voluntary movement? (4)

Back 34

1. cognition
2. memory
3. emotion
4. behavior

Front 35

What is the limbic loop?

Back 35

Signals from amygdala and hippocampus --> basal ganglia --> dorsal medial nuc. thalamus --> cortex (non-motor)

Front 36

What are 2 targets of non-motor projections from the basal ganglia?

What behaviors do they affect?

Back 36

1. Ventral tegmental area - dopamine-rich
2. Nucleus accumbens (ant. neostriatum)

Pleasure-seeking and addictive behavior

Front 37

What are hyperkinetic disturbances?

Hypokinetic disturbances?

Back 37

Abnormal, involuntary movements

Reduction of normal motor activity

Front 38

What is hemiballism?

Back 38

Random, involuntary flinging movements of limbs on one side of the body

Front 39

Where is the lesion that causes hemiballism?

Back 39

Contralateral subthalamic nucleus

Front 40

What is the pathway of lesion --> hemiballism

Back 40

Cut subthalamic nucleus --> no excitation of medial globus pallidus --> no inhibition of VA/VL thalamus --> increased excitation of motor cortex --> increased contralateral motor activity

Front 41

What type of disorder is Parkinson's Disease?

What is the loss?

Back 41

Hypokinetic = slowness of movement

Loss of dopamine-secreting neurons in the pars compacta of substantia nigra, Lewy body inclusions

Front 42

What is the pathway of Parkinsons?

Back 42

loss of dopamine in pars compacta --> decreased excititation of D1/decreased inhibition of D2 in neostriatum --> increased activity of inhibitory neurons in medial globus pallidus --> increased inhibition of motor thalamus --> decreased activity of motor cortex

Front 43

What type of disorder is Huntington's disease?

What is the loss?

Back 43

Hyperkinesia

abnormal expansion of CAG on chrom. 4 gene --> Loss of medium spiny neurons in the caudate/putamen projecting to the lateral globus pallidus

Front 44

What is the pathway of Huntington's?

Back 44

loss of projections from neostriatum to lat. globus pallidus --> increases inhibitory signal to subthalamic nucleus --> decreases excitatory signal to GPM --> decreases inhibition of thalamus --> increases thalamic input to motor cortex --> involuntary movements