Neuroscience Week 4: Basal Ganglia Motor Loop

Question 1

The associative motor cortex is located in

Answer 1

Supplementary motor area

or

premotor area

Question 2

Basal Ganglia Pathway Overview

Answer 2

Question 3

Associative Cortex and Basal Ganglia pathway

Answer 3

Associative cortex to Basal Ganglia

(basal ganglia have no direct connections to LMN)

Basal ganglia through the globus paladus connects with the thalamus (basal ganglia supervise output of primary cortex and alter the excitability of the primary motor cortex through the thalamus)

The final output of the basal ganglia on the thalamus is inhibitory

so how well it works depends on if the thalamus can be regulated properly and pathology is too much (Parkinson’s) or too little inhibition (Huntington’s Disease)

Question 4

Parkinson’s Gait

Answer 4

small steps

hunched over

turn slowly little steps

Question 5

Choreiform Gait

Answer 5

unable to filter out unwanted movements

such as in Huntingtins Disease

Question 6

Identify

Answer 6

Question 7

Structures and methods Involved in regulating motor function of basal ganglia

Answer 7

• Subthalamic nucleus

and

• Substantia nigra

through dopamine

Question 8

Identify

Answer 8

Question 9

Brief description of motor loop of basal ganglia

Answer 9

• premotor area glutamatergic input to putamen (excitatory input)
• information flows through basal ganglia
• medial segment of globus paladus sends GABA input to thalamus and has an inhibitory role on the thalamus (inhibitory)
• Thalamus sends Glutamate signal to cerebral cortex (excitatory)
• Thalamalcortical input determines the ability to properly carry out those movements

Question 10

too much thalamocortical input

Answer 10

too many unwanted movements

Question 11

too little thalamicortical activation

Answer 11

cannot initiate a movement

Question 12

Basal Ganglia Motor Loop

Answer 12

Question 13

Basal Ganglia parallel processing loops

4 listed

Answer 13

Question 14

Basal Ganglia Motor loop

Answer 14

regulates motor activity

Question 15

Basal Ganglia Oculomotor Loop

Answer 15

regulation of eye movements

Question 16

Basal Ganglia Prefrontal loop

Answer 16

problems with cognition

Question 17

Basal Ganglia Limbic Loop

Answer 17

important in emotion and …….

Question 18

Basal Ganglia Parallel Processing loops are regulated by?

Answer 18

Dopamine

Question 19

Basal Ganglia vs Cerebellum control of movement

Answer 19

Question 20

Question 1

Answer 20

C Modulating thalamic inputs to motor cortex

Question 21

Motor loop pathways of the Basal Ganglia

2 listed

Answer 21

• Direct Pathway - Facilitates movement
• Indirect Pathway - Inhibits Movement

Question 22

Motor loop pathways of the Basal Ganglia: Direct Pathway

Answer 22

Motor Cortex Glutamate +→x Putamen GABA -→| Globus Paladus internal segment (GPI) This is inhibited so it doesn’t happen as much (GABA -→|) Thalamus Glutamate +→x Motor cortex

So when the cortex excites putamen it is hyperactive and inhibits GPI so the thalamus is disinhibited and directs/facilitates movement

Question 23

Motor loop pathways of the Basal Ganglia: Indirect Pathway

Answer 23

Motor Cortex Glutamate +→x Putamen GABA -→| Globus Paladus external segment GABA -→| Subthalamic Nucleus Glutamate +→x Globus Paladus internal segment (GPI) GABA -→| Thalamus

So excites the GPI and inhibits the Thalamus and inhibits movement

Question 24

Putamen and Globus Palladus neuron neurotransmitter types

Answer 24

>90% are GABAergic projection neurons

Question 25

Motor loop pathways of the Basal Ganglia: Direct & Indirect Pathway Firing Patterns

Answer 25

Question 26

Question 2

Answer 26

B. Activation of the indirect pathway involves the subthalamic nucleus

Question 27

dopaminergic regulation of Basal Ganglia direct pathway

Answer 27

* D1 Receptor makes neurons more excitable * stimulates Direct pathway * In parkinsons have a lack of Dopamine and as a result, have a difficulty facilitating movement * Dopamine makes these neurons more likely to fire

Question 28

dopaminergic regulation of Basal Ganglia Indirect pathway

Answer 28

D2 Receptor are inhibitory neuromodulators make neurons less likely to fire and make them require more glutamate to fire makes these neurons less likely to fire

Question 29

Basal Ganglia Direct pathway Dopamine Receptor

Answer 29

D1 Stimulatory Neuromodulator ↑cAMP

Question 30

Basal Ganglia indirect pathway Dopamine receptor

Answer 30

D2 Receptor inhibitory neuromodulator ↓cAMP ↑K⁺ currents ↓ volatage gates Ca²⁺ currents

Question 31

D1 and D2 receptors

Answer 31

Question 32

Basal Ganglia Direct Pathway D1 receptors

Answer 32

Question 33

Basal Ganglia Indirect Pathway D2 receptors

Answer 33

Question 34

Question 3

Question 35

Parkinson's Disease degeneration of?

Answer 35

degeneration of Nigrostriatal DA Neurons

Question 36

Loss of dopamine in Basal Ganglia Circuitry

Answer 36

Decreased activation of Direct pathway Loss of dopaminergic inhibition of Indirect pathway

Question 37

Cardinal signs of Parkinson's Disease 6 listed

Answer 37

Resting **T**remor (goes away with activity) **R**idgity with cogwheeling Bradykinesia (**A**kinesia) difficulty rising (slowness of movement) **P**osture instability **S**huffling gait Micrographia Parkinson's TRAPS your body

Question 38

Basal Ganglia side and control

Answer 38

* Right BG circuitry to left side of body * Left BG circuitry to right side of body

Question 39

Deep brain stimulation for Parkinsons disease

Answer 39

place low-frequency electrodes to stimulation Inhibition of STN (Subthalamic nucleus) or GPi great therapeutic value and alleviates some motor symptoms

Question 40

Question 4

Answer 40

E. all of the above

Question 41

Huntington's disease brain

Answer 41

almost no head of caudate/putamen

Question 42

Huntington's disease Etiology

Answer 42

Autosomal Dominant Disorder

Question 43

Huntington's disease Pathophysiology

Answer 43

no inhibitory output to the thalamus and the thalamus goes crazy and there is too much excitatory input to motor cortex

Question 44

Pyramidal signs or ranking of common movement disorders

Answer 44

Basal ganglia signs (extrapyramidal signs)

Question 45

Stroke in subthalamic nucleus on one side

Answer 45

hemiballismus - wild flinging of one limb or arm on the contralateral side and is most frequently unilateral

Question 46

Common mixed movement disorders

Answer 46

Question 47

question 5

Question 48

basal ganglia have no direct connections to

Answer 48

LMNs