Task 1 - The Basics

Question 1

Lateral pathways

Answer 1

Involved in voluntary movement of the distal musculature and are under direct cortical control
1. Corticospinal tract
2. Rubrospinal tract

Question 2

Ventromedial pathways

Answer 2

Involved in the control of posture and locomotion and are under brain stem control
1. Vestibular tracts
2. Tectospinal tracts
3. Reticulospinal tracts (2)

Question 3

Corticospinal tract

5 steps

Answer 3

1. Starts in motor cortex
2. Through the cerebral peduncle
3. Forms the medullary pyramid
4. Decussates when going over into spinal cord
5. Collect in lateral column of spinal cord

Question 4

Rubrospinal tract

3 steps

Answer 4

1. Starts in the red nucleus
2. Axons decussate in the pons
3. Join the corticospinal tract in the lateral column of the spinal cord

Question 5

Vestibulospinal tracts

3

Answer 5

1. Originates in the vetsibular nuclei of the medulla
2. Then either to the spinal cord where it activates cervical spinal circuits
3. Or to the lumbar spinal cord which then facilitates motor neuron in legs

Question 6

Tectospinal tracts

Answer 6

1. Originates in the superior colliculus
2. Through the medulla
3. Ends in the spinal cord

Question 7

Pontine (medial) reticulospinal tract

Answer 7

1. Starts in pontine reticular formation
2. Through medulla
3. End in cervical spinal cord

Question 8

Medullary reticulopinal tract

Answer 8

1. Starts in medullary reticular formation
2. Ends in cervical spinal cord

Question 9

Origin of the corticospinal tract

Answer 9

• Corticospinal tract evolved as primates became more dexterous with their hands.
• As primates developed precision grip, the corticospinal tract increased in its overall size.
• This was accompanied by the emergence of corticospinal terminations in the ventral horn where the lateral motor nuclei are located

Question 10

Motor cortex

Answer 10

A region of the frontal lobe, including areas 4 and 6.

Question 11

Area 4

Answer 11

• Also known as primary motor cortex, motor strip or M1.
• It lies just anterior to the central sulcus.
• Electrical stimulation of area 4 invokes twitches of the muscles in a particular region of the body on the contralateral side

Question 12

Area 6

Answer 12

• Lies just anterior to area 4. It includes the premotor area (PMA) laterally and the supplementary motor area (SMA) medially
• Electrical stimulation of area 6 can evoke more complex movements of either side of the body; it is a higher motor area in humans

Question 13

Coding of movement in Area 4

Answer 13

• Pyramidal cells in area 4 show individual direction tuning (direction vector)
• The actual direction seems to be determined by population coding, specifically by a population vector

Question 14

Hemiplegia

Answer 14

Paralysis that occurs only on one side of the body, usually affects the most distal effectors (e.g. fingers or hand).

Question 15

Paraplegia

Answer 15

Paralysis that involves only the legs

Question 16

Quadriplegia

Answer 16

Paralysis that involves all 4 limbs

Question 17

Spasticity

Answer 17

A condition, which is often permanent, characterized by a dramatic & sometimes painful increase of muscle tone (hypertonia) and spinal reflexes (hyperreflexia)

Question 18

Babinski sign

Answer 18

• An indication of motor tract damage
• Sharply scratching the sole of the foot from the heel toward the toes causes reflexive upward flexion of the big toe and an outward fanning of the other toes.

Question 19

Apraxia

Answer 19

A selective inability to perform complex (but not simple) motor acts.
Two types:
1. Ideomotor apraxia
2. Ideational apraxia

Question 20

Ideomotor apraxia

Answer 20

The patient has a rough sense of the desired action but has problems executing it properly

Question 21

Ideational apraxia

Answer 21

The patient’s knowledge about the intent of an action is disrupted, the more severe type

Question 22

Function of the dorsal premotor area

Answer 22

• Important for making associations involving motor stimuli
• PM neurons fir after presentation of cue that instructs a motor response

Meaning it can direct movement based on sensory information

Question 23

Function of Ventral premotor area

Answer 23

• Hand movement required for manipulation of an object
• PMv neuron fire when monkeys view or grab objects
• In some monkeys it also contains mirror neurons which are important for understanding actions made by others

Question 24

How do premotor areas influence primary motor area?

Answer 24

• All nonprimary motor areas have some direct connection to the spinal cord, challenging hierarchy assumption
• M1 i connected to nonprimary motor areas but not really with the rest of the cortex, so nonprimary areas are important for connection to sensory information

Question 25

What does the SMA do?

Answer 25

While premotor cortex is more about sensory guided action, the SMA is more about action guided by personal preferences and goals

Question 26

Function of the Corticospinal tract

Answer 26

Responsible for voluntary movement and skilled motor control

Question 27

Function of Rubrospinal tract

Answer 27

Facilitates fine motor control, especially of the distal muscles, and regulates muscle tone.

Question 28

Function of Vestibulospinal tract

Answer 28

Maintains balance, posture, and head stabilization by integrating information from the vestibular system.

Question 29

Function of Tectospinal tract

Answer 29

Mediates reflexive head and eye movements in response to visual and auditory stimuli.

Question 30

Function of Reticulospinal tract

Answer 30

Regulates muscle tone, posture, and autonomic functions (one enhances antigravity effect and one liberates antigravity effect)