The structure and function of the descending tract Part 1

Question 1

What does voluntary movement entail

Answer 1

Voluntary movement involves planning, initiation and execution. Many different areas of the brain are required to produce complex and coordinated movements. Loss of each area lead to deficits in movement and movement control.

Question 2

Hierarchical organisation of the motor system 1-3

Answer 2

1-Cerebral cortex
2-Brainstem
3-Spinal Cord

Question 3

What are other areas of the brain that are involved with the Hierarchical organisation of the motor system called?

Answer 3

Parallel organisation

Question 4

What is the parallel system

Answer 4

other areas of the brain that are involved with the Hierarchical organisation of the motor system

Question 5

What are some of the areas in the parallel organisation

What do they do?

Answer 5

Basal nuclei
Cerebellum
Coordinate, regulate, refine movement

Question 6

What does the hiercherachy and parallel organisation look like?

Answer 6

Brainscape pictures/ capture 1

Folder and picture

Question 7

What are the steps taken before an electrical signal is sent down the brain to initiate voluntary movement

Answer 7

A linear sequence of steps with a series of transformations between coordinate systems:

1. Identify target/goal
2. Locate it in external space
3. Determine limb trajectory (internal representation of arm/hand relative to target)
4. Calculate the forces necessary to generate desired trajectory

Question 8

What do we use in our brain to Identify target/goal and Locate it in external space?

Answer 8

Visual system/ retinotopic space

Question 9

What do we use in our brain to Determine limb trajectory (internal representation of arm/hand relative to target)?

Answer 9

Body or hand centred system

Question 10

What do we use in our brain to Calculate the forces necessary to generate desired trajectory?

Answer 10

muscle- based reference frame

Question 11

What are motor areas

Answer 11

areas from which movement can be evoked by the lowest stimulus intensity

Question 12

What do cortical regions involved in movement do?

Answer 12

Plan, control and execute (initiate) movement

Question 13

What are the range of techniques that are used to identify the different motor areas

Answer 13

Stimulation studies
Lesion effects
Anatomical experiments
Imaging studies in humans Electrophysiological recordings

Question 14

What are some cortical regions involved in movement

Answer 14

Primary motor cortex
Premotor area
Supplementary motor cortex
Cingulate motor areas

Question 15

Where is the primary motor cortex located?

Answer 15

Precentral gyrus in the frontal lobe

Question 16

What is the role of the primary motor cortex

Answer 16

Prominent area in evoking movement
Encoding force, direction and the extent of movement
Upper neurons that reside here are key to voluntary movement

Question 17

Where is the Supplementary motor cortex located?

Answer 17

Frontal lobe

Question 18

Where is the Premotor area located?

Answer 18

frontal lobe

Question 19

What are the major association areas of the motor areas?

Answer 19

Supplementary motor cortex

Premotor area

Question 20

What are the Supplementary motor cortex

Premotor area known as?

Answer 20

major association areas

Question 21

What does the Supplementary motor cortex do?

Answer 21

enable us to make complex and purposeful movements

Question 22

What does the Premotor area do?

Answer 22

Aid in preparation for movement and integrating information from sensory and visual courtesies

Question 23

Where are Cingulate motor areas located?

Answer 23

Cingulate sulcus internal aspect of the brain

Question 24

What is the primary motor cortex also known as?

Answer 24

M1 or Broadmann’s area 4

Question 25

Where is the pre-central gyrus

Answer 25

Just in front of the central sulcus where it divides the frontal and parietal lobe

Question 26

What is the motor homunculus

Answer 26

Somatotopic map of the primary motor cortex

Question 27

What is feedback control of the voluntary movement

Answer 27

Proprioceptive information from voluntary movements are sent to the cerebrum and cerebellum

Question 28

What is an error signal in voluntary movement

Answer 28

Difference between desired and actual position

Question 29

What is the feedforward control of the voluntary movement and how is it important?

Answer 29

Sensory information gives advanced information

• anticipation of the required movement
• enables movement to be directed to the target

Question 30

How does sensory input bring about motor input for voluntary movement (Classical Hierarchy view Series of successive steps)

Answer 30

Target of movement identified by a ‘pooling of sensory information’ in the Posterior parietal cortex combined with information from the primary sensory cortex
Information transmitted to the supplementary motor and premotor areas (planning) and then to the primary motor cortex
Commands transmitted (via descending pathways) to spinal cord and brainstem motor nuclei

Question 31

How does sensory input bring about motor input for voluntary movement ( Parallel distribution model)

Answer 31

Numerous motor areas are all bi-
directionally connected

Each area contributes to several stages
of planning and executing a movement

Each cortical area makes a significant
contribution to descending pathways

Primary motor cortex contributes -50%
of fibres in the corticospinal tract