Pathways and centres involved in movement

Question 1

What is the basal ganglia involved in and how does it do this? (3)

Answer 1

1. initiation
2. control
3. cessation

of movement

• by providing a feedback mechanism to the cerebral cortex

Question 2

Where do most outputs from the basal ganglia go through?

Answer 2

thalamus

Question 3

What do most outputs from the basal ganglia do? (2)

Answer 3

1. dampen
2. excite

cerebral cortex

Question 4

What do lesions of the basal ganglia lead to?

Answer 4

dyskinesia

Question 5

What is dyskinesia?

Answer 5

abnormal and involuntary movements

Question 6

Where does the basal ganglia develop from?

Answer 6

telencephalic grey matter

Question 7

What makes up the telencephalic grey matter? (4)

Answer 7

1. caudate nucleus
2. lentiform nuclues
3. amygdala
4. claustrum

Question 8

What is the lentiform nucleus made up of? (2)

Answer 8

1. putamen

2. globus pallidus

Question 9

What makes up the functional basal ganglia? (5)

Answer 9

1. caudate nucleus
2. putamen
3. globus pallidus
4. subthalamus
5. substantia nigra

Question 10

What is the globus pallidus split into and what parts of the substansia nigra is this related to?

Answer 10

1. interna - pars reticulata

2. externa

Question 11

What do the pars compact cells in the substantial nigra contain?

Answer 11

melanin

Question 12

What else is the basal ganglia involved in other than initiation, cessation and control of movement? (2)

Answer 12

1. cognitive processes

• perception
• learning
• memory
• abstract thought

2. emotion

Question 13

How does the basal ganglia modulate cortical output?

Answer 13

by using multiple, parallel looping circuits from cerebral cortex back to cerebral cortex

Question 14

NOTE

Answer 14

learn the basal ganglia excitatory and inhibitory cycle

Question 15

How does the basal ganglia influence movement?

Answer 15

1. influence motor areas of cortex

• thalamus projects to motor cortex
• mainly premotor and supplementary motor areas

2. motor cortex influences LMNs

• directly via the corticospinal pathway
• indirectly via connections to brainstem centres from which UMNs arise (reticulospinal pathway)

Question 16

What does the direct pathway of the basal ganglia do?

Answer 16

facilitate behaviour and movements that are required and appropriate

Question 17

What does the indirect pathway of the basal ganglia do?

Answer 17

inhibit unwanted behaviour and movements

Question 18

Which pathway leads to excitation of the cortex from the thalamus and hence facilitates ongoing movement?

Answer 18

direct pathway

Question 19

Which pathway leads to inhibition of the cortex from the thalamus hence inhibiting unwanted movement?

Answer 19

indirect pathway

Question 20

What two things need to happen when flexing your fingers and what pathways do these involve?

Answer 20

1. CONTRACT flexors - direct pathway

2. RELAX extensors - indirect pathway

Question 21

What is the role of the pars compacta in the substantial nigra (x3) and what does it release?

Answer 21

ROLE

• initiate moevement
• modulatory role in movement
• opposing effects on the direct and direct pathways

RELEASES

• dopamine

Question 22

What happens if the substantia nigra is diminished?

Answer 22

you are not able to initiate movement

Question 23

What happens if the basal ganglia is damaged?

Answer 23

1. disordered movements on the CONTRALATERAL side
2. Hypokinesia (slow movement)
   - poor initiation
3. Rigidity
4. Tremor

Question 24

What is the name of the disease of the basal ganglia where the nigrostriatal input is disrupted?

Answer 24

Parkinsons

Question 25

What are the other degenerative changes that affect the basal ganglia circuitry and what disorders do these lead to? (give an example)

Answer 25

1. degeneration of the subthalamic nucleus
   - excitatory to globus pallidus
2. degeneration of inhibitory fibres form striatum to globes pallidus

LEADS TO

• hyperkinetic disorders - unwanted movements occur
  e. g. Chorea - Huntingtons disease