Task 1 - Basics

Question 1

Lateral pathways

Function and different types

Answer 1

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

Question 2

Ventromedial pathways

Function and different types

Answer 2

Involved in the control of posture and locomotion and are under brain stem control.
1. Vestibulospinal tracts
2. Tectospinal tract
3. Reticulospinal tracts seperated into
a) Pontine (medial) reticulospinal tract
b) Medullary (lateral) reticulospinal tract

Question 3

Corticospinal/pyramidal tract

Anatomy (7 steps)

Answer 3

1. Starts in neocortex (mainly motor cortex but also sensorymotor)
2. Through internal capsule
3. Base of the cerebral perduncle
4. Thorugh the pons
5. Form tract at the base of the medulla (medullary pyramid)
6. Pyramidal decussation
7. Terminate in dorsolateral region of ventral horns

Question 4

Rubrospinal tract

Anatomy (3 steps)

Answer 4

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

Question 5

Vestibulospinal tracts

Anatomy (2 steps)

Answer 5

1. Originate in the vestibular nuclei of the medulla, which relay sensory information from the vestibular labyrinth in the inner ear
   2a. One component projects bilaterally down the spinal cord and activates the cervical spinal circuits
   2b. Other component projects ipsilaterally to the lumbar spinal cord

Question 6

Tectospinal tract

Anatomy (Just origin)

Answer 6

Originates in the superior colliculus, which receives direct input from the retina, visual cortex, as well as somatosensory & auditory information

Question 7

Vestibulospinal tracts

Function

Answer 7

• One component helps control neck and back muscles, guiding head movement
• The other component helps maintain upright posture by facilitating extensor motor neurons of the leg

Question 8

Pontine (medial) reticulospinal tract

Function

Answer 8

• Enhances the antigravity reflexes of the spinal cord, by facilitating the extensors of the lower limbs.
• Most of the time, the activity of the ventral horn neurons maintains muscle length and tension

Question 9

Medullary (lateral) reticulospinal tract

Function

Answer 9

Has the opposite effect of the pontine tract; it liberates the antigravity muscles from reflex control.

Question 10

Origin of the corticospinal tract

Chouinard

Answer 10

• Corticospinal tract evolved as humans became more dexterous with their hands
• When we developed precision grip, corticospinal tract increased in size and had more terminations in ventral horn where lateral motor nuclei are

Question 11

Motor cortex

Anatomy

Answer 11

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

Question 12

Area 4

Anatomy

Answer 12

Area 4 is also known as primary motor cortex, motor strip or M1. It lies just anterior to the central sulcus.

Question 13

Area 6

Answer 13

Lies just anterior to area 4. It includes the premotor area (PMA) laterally and
the supplementary motor area (SMA) medially

Question 14

Area 4

Function

Answer 14

Electrical stimulation of area 4 invokes twitches of the muscles in a particular
region of the body on the contralateral side

Question 15

Area 6

Answer 15

• Electrical stimulation of area 6 can evoke more complex movements of either side of the body meaning it is a higher motor area in humans
• Plays an important role in the planning of movement, particularly complex movement sequences of the distal muscles.

Question 16

Hierachical classification

Bear

Answer 16

1. High - Strategy - Association areas of neocortex, basal ganglia
2. Middle - Tactics - Motor cortex, cerebellum
3. Low - Execution - Brain stem, spinal cord

Question 17

Hierachical classification

Gazzaniga

Answer 17

1. Top - Planning action based on goals, input and experience - Premotor and association areas of the cortex
2. Middle - Translating goal into movement - M1 and brain stem, basal ganglia and cerebellum
3. Lowest - Movement - Local circuits of motor neurons and interneurons in spinal cord

Question 18

Coding of movement in M1

Answer 18

• Pyramidal cells in M1 fire for a specific direction the most and for directions in the adjacent 45 in both directions (direction vectors)
• Use population coding to basically find the median of all of these directions (population vector) and thats where the movement goes

Question 19

Paresis

Answer 19

Weakness. Happens when there is partial damage to the upper parts of the motor system (alpha motor neurons and motor axons)

Question 20

Arflexia

Answer 20

An absence of their spinal reflexes, happens to affected area after severing of a motor nerve

Question 21

Hemiplegia

Answer 21

Paralysis that occurs only on one side of the body. Lesions of M1 usually result in hemiplegia of the contralateral side of the body and it mostly affects most distal effectors (e.g fingers or hand)

Question 22

Paraplegia

Answer 22

Paralysis that involves only the legs

Question 23

Quadriplegia

Answer 23

Paralysis that involves all 4 limbs

Question 24

Hypertonia

Answer 24

Dramatic and sometimes painful increase of muscle tone

Question 25

Babinski sign

Answer 25

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 26

Apraxia

Answer 26

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

Question 27

Ideomotor apraxia

Answer 27

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

Question 28

Ideational apraxia

Answer 28

Much more severe type - the patient’s knowledge about the intent of an action is disrupted.

Question 29

Brain-machine interface (BMI)

Answer 29

Recording neural activity and using decoding principles to decode the signals into commands that serve to control brainmachine interface systems.