The structure and function of the descending tract Part 1 Flashcards

1
Q

What does voluntary movement entail

A

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.

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2
Q

Hierarchical organisation of the motor system 1-3

A

1-Cerebral cortex
2-Brainstem
3-Spinal Cord

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3
Q

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

A

Parallel organisation

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4
Q

What is the parallel system

A

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

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5
Q

What are some of the areas in the parallel organisation

What do they do?

A

Basal nuclei
Cerebellum
Coordinate, regulate, refine movement

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6
Q

What does the hiercherachy and parallel organisation look like?

A

Brainscape pictures/ capture 1

Folder and picture

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7
Q

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

A

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
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8
Q

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

A

Visual system/ retinotopic space

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9
Q

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

A

Body or hand centred system

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10
Q

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

A

muscle- based reference frame

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11
Q

What are motor areas

A

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

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12
Q

What do cortical regions involved in movement do?

A

Plan, control and execute (initiate) movement

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13
Q

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

A

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

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14
Q

What are some cortical regions involved in movement

A

Primary motor cortex
Premotor area
Supplementary motor cortex
Cingulate motor areas

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15
Q

Where is the primary motor cortex located?

A

Precentral gyrus in the frontal lobe

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16
Q

What is the role of the primary motor cortex

A

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

17
Q

Where is the Supplementary motor cortex located?

A

Frontal lobe

18
Q

Where is the Premotor area located?

A

frontal lobe

19
Q

What are the major association areas of the motor areas?

A

Supplementary motor cortex

Premotor area

20
Q

What are the Supplementary motor cortex

Premotor area known as?

A

major association areas

21
Q

What does the Supplementary motor cortex do?

A

enable us to make complex and purposeful movements

22
Q

What does the Premotor area do?

A

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

23
Q

Where are Cingulate motor areas located?

A

Cingulate sulcus internal aspect of the brain

24
Q

What is the primary motor cortex also known as?

A

M1 or Broadmann’s area 4

25
Q

Where is the pre-central gyrus

A

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

26
Q

What is the motor homunculus

A

Somatotopic map of the primary motor cortex

27
Q

What is feedback control of the voluntary movement

A

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

28
Q

What is an error signal in voluntary movement

A

Difference between desired and actual position

29
Q

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

A

Sensory information gives advanced information

  • anticipation of the required movement
  • enables movement to be directed to the target
30
Q

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

A

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

31
Q

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

A

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