(10) Motor system Flashcards

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1
Q

What are the strengths to studying actions via behaviour?

A

Allows us to systematically investigate the output of the action system, how someone moves depending on target

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2
Q

What are the weaknesses of studying actions via behaviour?

A

Cannot tell us anything about the brain, only looks at output

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3
Q

How can you study actions behaviourally?

A
  • Use video or electronic recording equipment -allows one to record the position of body parts in space and time
  • Can measure speed, accuracy and kinematics (velocity, acceleration, etc.)
  • Improvements in equipment, performance enhancing
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4
Q

How can you study actions via Muscle Physiology (electromyography)?

A

can record activity of individual muscles or muscle fibres during action

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5
Q

What are the strengths of studying actions via Muscle Physiology (electromyography)?

A

Allows an understanding of how muscles operate

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6
Q

What are the weaknesses of studying actions via Muscle Physiology (electromyography)?

A

does not directly tell us anything about the brain

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7
Q

How do you study actions via Neurophysiology?

A

Implant electrodes in brain and record activity of individual neurons
-Can take a record of a number of neurons and measure their activity in real time

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8
Q

What are the strengths of studying actions via Neurophysiology??

A

Allows for excellent spatial and temporal resolution, exactly where in the brain

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9
Q

What are the weaknesses of studying actions via Neurophysiology??

A

cannot examine more than a miniscule percentage of the neurons at any one time, 10 million neurons in the brain

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10
Q

How do you study actions via Neuroimaging?

A

Put a subject in a brain scanner and measure blood flow while they perform a task

  • More blood flow = more brain activity
  • When neurons fire they use energy - need glucose
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11
Q

What are the strengths of studying actions via Neuroimaging??

A

Allows for a direct measure of activity in the human brain -has good spatial and fairly good temporal (at least for fMRI) resolution

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12
Q

What are the weaknesses of studying actions via Neuroimaging??

A

Many action processes take less than 2-4 seconds

-Hard to make many movements in a scanner environment

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13
Q

How do you study actions via Neuropsychology?

A

examine the consequences of brain damage in humans or animals
-If damage to one area is linked to a behavioural deficit, then can infer that area is necessary for that function

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14
Q

What are the strengths of studying actions via Neuropsychology??

A

Allows one to examine consequences of (in humans) naturally-occurring brain damage -can be used to show what areas are most important for a particular function, damage a certain area of the brain may effect behaviour: clear cause

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15
Q

What are the weaknesses of studying actions via Neuropsychology??

A

Cannot (in humans and often not in animals) place lesions where you want them and the size you want them
-Lesions often have effects on neurons far from the lesion site

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16
Q

How do you study actions via Transcranial Magnetic Stimulation (TMS)?

A

temporarily disrupt brain activity in healthy humans (or animals) using a high-powered magnetic coil
-As with neuropsychology, infer function from effects of TMS

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17
Q

What are the strengths of studying actions via Transcranial Magnetic Stimulation (TMS)?

A

A lot more ethical than giving people brain damage -can more or less precisely define the area of disruption and the time of disruption

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18
Q

What are the weaknesses of studying actions via Transcranial Magnetic Stimulation (TMS)?

A

not all areas can be tested, must be on the surface of the brain -must be very careful not to give the participant a seizure, can’t test deep inside the brain

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19
Q

How do you study actions via Computational Modelling?

A

devise mathematical models of how actions might be carried out by a set of neurons

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20
Q

What are the strengths of studying actions via Computational Modelling?

A

Approaches the question of brain function from a synthetic rather than analytical perspective

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21
Q

What are the weaknesses of studying actions via Computational Modelling?

A

Does not address how brain actually works

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22
Q

How do you study actions via Event-related potentials?

A

record electrical activity from the scalp

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23
Q

What are the strengths of studying actions via Event-related potentials?

A

Very good temporal resolution

24
Q

What are the weaknesses of studying actions via Event-related potentials?

A

Poor spatial resolution- what are you actually recording, large area

25
Q

Movements of a particular type tend to be conducted in a very similar fashion from one instance to the next, for example…

A

-E.g., reaching and grasping have very consistent velocity/acceleration/hand shape profiles

26
Q

-The unfolding of movement kinematics varies systematically with two factors:

A
  • 1) the characteristics of the target

- 2) the relation between the target and the hand

27
Q

What information does reaching rely on?

A

Reaching relies on extrinsic object properties e.g., distance, position, velocity

28
Q

What information does grasping rely on?

A

Grasping relies on intrinsic object properties e.g., size, shape, weight

29
Q

What did Milner & Goodale (1995) argue?

A

argued that perception and action rely on different parts of the brain

  • Perception and action said to use different visual information
  • Two visual systems - sight and movements
30
Q

What does perception involve?

A

‘Perception’ involves identifying objects on the basis of comparisons between what is seen and stored memories

31
Q

What does action involve?

A

‘Action’ involves moment-to-moment computations of a target’s relation to the body, where objects are in relation to you

32
Q

Input from the retina goes into two types of channels

A
  • A fast magnocellular (M) channel that relays information about motion and orientation
  • A slow parvocellular (P) channel that relays information about form and colour
33
Q

-The ventral stream largely contains

A

P type cells

34
Q

-The dorsal stream contains

A

both M and P cells

35
Q

Perception should be affected by such things as

A

colour and form that are coded in P cells

36
Q

Action should be more sensitive to such things as

A

motion and orientation that are coded in M cells

37
Q

Brain activity in the ventral and dorsal stream should be associated with

A

perception and action, respectively

38
Q

Contextual information (coded in the ventral stream) should affect

A
  • perceptions but not actions

- Thus, visual illusions should have small or null effects on actions

39
Q

What are the strengths of the perception action model?

A
  • It is simple and straightforward
  • It accommodates a fair amount of behavioural and neurological data
  • It makes several predictions
40
Q

What are the weaknesses of the perception action model

A
  • It is too simple and too straightforward

- It cannot explain the subtleties of much data

41
Q

Actions involve

A

‘planning’ and ‘on-line control’

42
Q

Planning uses a

A

motor program (a set of stored muscle commands called up from memory) to plan and initiate movement

43
Q

On-line control uses

A

visual and proprioceptive feedback to guide hand in flight

44
Q

Planning will be affected by cognitive factors such as

A

illusions and semantics, on-line control will not

45
Q

Activity related to planning and control will follow an inferior-superior gradient in the

A

parietal lobes

46
Q

Illusions do have larger effects early in a movement than

A

later

47
Q

-Recordings can be taken from the brain of the behaving macaque monkey, which involves

A

placing electrodes in the brain and recording the activity of single cell

48
Q

Prefrontal activity precedes an action by several hundred milliseconds, whereas Premotor activity precedes an action by

A

200-300 msec

49
Q

What regions of the parietal lobes can be associated with reaching

A

Reaching involves the caudal part of the superior parietal lobes (known as ‘parietal reach region’ or “PRR”)

50
Q

What regions of the parietal lobes can be associated with grasping

A

-Grasping involves the anterior intraparietal sulcus (AIP)

51
Q

What regions of the parietal lobes can be associated with eye movements

A

-Eye movements involve the lateral intraparietal region (LIP)

52
Q

What regions of the parietal lobes can be associated with planning movements

A

-Planning movements involves areas of the inferior parietal lobule (IPL)

53
Q

What regions of the parietal lobes can be associated with on-line control

A

-On-line control involves areas of the superior parietal lobe (SPL)

54
Q

Basal ganglia are active…

A

both before and during a movement

55
Q

Cerebellum seems linked with…

A

timing of actions and on-line adjustments

56
Q

Neurons in ventral premotor cortex appear to represent

A

actions

57
Q

How does PET and fMRI measure action?

A
  • PET works by intravenous injection of radioactive isotope that is taken up in the blood
  • fMRI works by measuring blood flow