Ward Text

Question 1

Why can movement not solely be viewed as the endpoint of cognition?

Answer 1

1) It is possible to act on something that has not been consciously seen
2) we can not only produce actions, but also understand other’s actions
3) movement can occurr in absence of cognition (reflexes)

Question 2

What is the degrees of freedom problem?

Answer 2

There is a potentially infinite number of motor solutions for acting on objects

Question 3

What is a generalized motor program and what is it useful for?

Answer 3

A stored routine, simplifying computations

Question 4

What does somatosensation mean?

Answer 4

Cluster of perceptual processes relating to skin and body, indcluding touch, pain, thermal sensation and limb position

Question 5

What is proprioception?

Answer 5

Knowledge of position of limbs in space.

Question 6

What is sensorimotor transformation?

Answer 6

Linking of perceptual knowledge of objects in space and knowledge of position of body to enable objects to be acted on

Question 7

What is the Homunculus problem?

Answer 7

There is no I in the brain that makes decision, the I is just a product of firing neurons

Question 8

What are the tasks of the Primary Motor Cortex?

Answer 8

• essential for execution of voluntary movement

Question 9

What is meant by the somatotopically organization of the PMC?

Answer 9

• different regions of the PMC represent different regions of the body
• left hemisphere specialized for right side of body, vice versa
• some parts have larger representation because of need for fine levels of control

Question 10

What is hemiplegia?

Answer 10

Damage to one side of PMC results in failure to voluntarily move other side of body

Question 11

What is the role of the lateral and medial premotor cortex?

Answer 11

• lateral: linking action with visual objects in environment (external cues)
• observing actions of others (skill learning and imitation)
• medial, SMA: well-learned, spontaneous, self-generated actions that do not place strong demands on monitoring environment (internal cues)

Question 12

How is the direction of a resultant movement computed (Georgeopolus)?

Answer 12

Summing together vectors of a whole population of neurons

Question 13

Describe the Prefrontal Contributions to Action.

Answer 13

• involved in planning and higher aspects of the control of action
• holding things in mind, control of cognition/behavior
• selection of actions and their corresponding goald

Question 14

What happens if prefrontal regions become damaged?

Answer 14

No impaired movement, but actions become poorly organized. Movement execution does not necessarily reflect goals/intentions.

Question 15

Name two possible effects of a damaged prefrontal area.

Answer 15

• perseveration: repeating an action that has already been performed
• utilization behavior: impulsively acting on irrelevant objects
  = dysexecutive syndrome

Question 16

Explain the SAS Model.

Answer 16

• Supervisory Attentional System
• Explain control of cognition/goal-driven action
• automatical actions vs. actions that require attention (e.g. car)
• automatical actions may use schemas and do not require SAS
• intervention from SAS if novel action sequence has to be set up

Question 17

What is a schema?

Answer 17

Organized set of stored info (e.g. familiar routines)

Question 18

Describe contention scheduling.

Answer 18

mechanism that selects one schema to be enacted, activated by objects in the environment

Question 19

Try to explain repeating actions based on schemas.

Answer 19

Active schemas are not deactivated, therefore repeated

Question 20

What is frontal apraxia?

Answer 20

Failure in tasks of routine activity that involve setting up/maintaining sub-goals

Question 21

Describe the experiment by Libet et al.

Answer 21

• participants pressed key whenever they felt the urge
• reported time of urge
• EEG activity started several hundred ms before reporting
• brain had thus made unconscious decision to act before participants experienced conscious intention
• free will is an illusion

Question 22

What is a forward model?

Answer 22

• links together action intention with outcome
• representation of motor command (efference copy) used to predict the sensory consequences of an action
• tickling ourselves less ticklish because we predict sensation

Question 23

What is the Reafference principle?

Answer 23

I don’t know yet :(

Question 24

What are the two routes of visual processing?

Answer 24

What Route: Ventral

Where Route: Dorsal

Question 25

Explain the case of Patient DF.

Answer 25

- damaged ventral stream - impaired ability to recognize objects from vision - intact basic visual processes - letter box: orientation of slot could be rotated - difficulty matching orientation to presented alternatives - she was able to post a letter - suggests: dissociation between visual perception (impaired ventral stream) and visual control of action (using spared dorsal)

Question 26

Explain the consequences of a damaged dorsal stream.

Answer 26

- Deficits acting towards an object - Recognizing objects not a problem (in contrast to ventral damage) - failure to transform visual perceptual info into appropriate motor commands - not only because of vision or motoric functions, but a failure to integrate both

Question 27

What is optic ataxia?

Answer 27

Inability to use vision to accurately reach towards objects

Question 28

What is the advantage of having specialized neurons?

Answer 28

Stored Repertoire, brain does not have to compute aspects of action every time. May also enable certain types of action to become associated with familiar objects.

Question 29

What is ideomotor apraxia?

Answer 29

Inability to produce appropriate gestures given an object, word or command.

Question 30

What are Affordances?

Answer 30

Structual properties of objects imply certain usages

Question 31

What is the consequence of semantic dementia? How can patients still act on objects?

Answer 31

Lose semantic knowledge of objects, but are able to act on objects using affordances

Question 32

Explain the cause of Parkinson's disease.

Answer 32

- loss of dopaminergic neurons - poverty of spontaneous movements (hypokinetic) - increased output of indirect pathway (brakes) and decreasing direct pathway (accelerator) in cortex

Question 33

Is it possible for Parkinson patients to move normally?

Answer 33

- only failure in self-initiating action, can be overcome by external cues (fire) - there is a subcortical route that bypasses the basal ganglia and goes via the cerebellum - this route may be more involved in actions by enviromental cues

Question 34

Explain Huntington's disease, in comparison to Parkinsons.

Answer 34

- excess of spontaneous movements = hyperkinetic - depletion of inhibitory neurons - output of indirect pathway reduced, direct is NORMAL

Question 35

What is the cerebellar loop involved in?

Answer 35

Online coordination of movement by comparing intended motor acts with sensory outcomes.

Question 36

What is the task of the basal ganglia?

Answer 36

Regulating action via a balance of action-promoting and action-inhibiting pathways. Particularly involved in self-generated actions (prepared in SMA).