Lecture 7

Question 1

Describe functions of:

Brain stem

Answer 1

• Controls most of autonomic functions (heart rate, respiration, blood pressure etc.)
• A relay station to spinal cord

Question 2

What are the 2 important areas on the posterior surface of brain stem?

Answer 2

1. Superior colliculus
2. Inferior colliculus

Question 3

Where are the superior/inferior colliculus located?

Answer 3

Posterior surface of brain stem

Question 4

Describe the function of:

Superior colliculus

Answer 4

Contains visual and motor neurons important for eye movement
* E.x. Visual grasp reflex, where eyes move automatically towards stimulus

Question 5

What kind of structure is the superior colliculus considered to be?

Answer 5

A visuomotor structure

Question 6

Describe the function of:

Inferior colliculus

Answer 6

Primary auditory capturer
* E.x. Turning towards unknown auditory stimulus

Question 7

What are the superior/inferior colliculus mediated by? What does this mean?

Answer 7

Mediated by brain stem
* Means they are subconscious and can be mediated very quickly (due to fewer neurons)

Acts as protective response

Question 8

What is an example of cerebromedullospinal disconnection?

Answer 8

“Locked-In Syndrome”

Question 9

Describe:

Locked-In Syndrome

Answer 9

Stroke involving brain stem that results in disconnection between things in the cerebral cortex and below the brain stem
* Individual is aware, but cannot communicate anything (appear brain dead)

Question 10

What is motor imagery? Why is it important?

Answer 10

Envisioning, thinking about yourself performing a motor action
* Improves task as motor imagery activates the same motor regions that are active in the actual motor action (except for primary motor region)

Question 11

How is motor imagery related to individuals with Locked-In Syndrome?

Answer 11

Like motor imagery, even though individuals could not communicate they had the same activated motor areas as subjects that could communicate

Question 12

Describe the location and function of:

Basal ganglia

Answer 12

• Important for movement initiation
• Subcortical structure

Question 13

Give an example of a condition where an individual has difficulty in movement initiation

Answer 13

Parkinson’s Disease
* Have difficult time turning, getting off a bike etc.
* Improves with visual/auditory cues, and dopamine; this will bypass the movement intiation sequence

Question 14

What is the basal ganglia linked to?

Answer 14

Direct Pathway
Indirect Pathway
Nigrostriatal Pathway

Question 15

Describe components of:

Direct pathway

Answer 15

• SNc (Substantia nigra compacta): Connects to striatum and modulate the striatum
• SNr (Substantia nigra reticulata) and GPi (Globus pallidus internal): Both release GABA (an inhibitory neurotransmitter), inhibits the thalamocortical pathway (critical for movement initiation)

Question 16

What pathway is critical for movement initiation?

Answer 16

Thalamocortical pathway

Question 17

What inhibits the thalamocortical pathway?

Answer 17

GABA, an inhibitory neurotransmitter

Question 18

Describe:

How decision to move is sent by cerebral cortex

Answer 18

1. Sends signal to striatum, using glutamate (an excitatory neurotransmitter)
2. Striatum inhibits SNr and GPi
3. Causes the disinhibition of thalamocortical pathway, leading to movement initiation

Question 19

What is glutamate considered as?

Answer 19

An excitatory neurotransmitter

Question 20

What is the nigrostriatal pathway?

Answer 20

A dopamine release pathway that facilitates activity in the direct pathway

Question 21

Describe the function of:

Indirect Pathway

Answer 21

• Designed to be antagonistic to direct pathway
• Hypothesized to inhibit movement

Question 22

What does damage to indirect pathway cause? Describe

Answer 22

Hemiballismus
* Large uncontrolled movement, causes incredible fatigue