Voluntary Action and the Neuroscience of Free Will

Question 1

What is the lateral route?

Answer 1

Parietal - premotor - M1 (Primary Motor Cortex)

Question 2

What is the medial route?

Answer 2

preSMA - SMA proper - M1

Question 3

Distinguish between SMA proper and pre-SMA

Answer 3

SMA proper: Motor area, many cells project posteriorly onto M1, some axons go directly to spinal cord

Pre-SMA: More cognitive area, few projections project posteriorly onto M1, no projections to spinal cord, strong connections with pre-frontal areas

Question 4

What are the four views of SMA/pre-SMA function?

Answer 4

1. Internal generation
2. Sequence and complexity
3. Inhibition
4. Initiation and consciousness

Question 5

SMA: reflex response or intentional decision? Explain.

Answer 5

The SMA seems to be related to internally generated actions, not entirely decoupled from externally stimuli, but no obvious external cause.

Question 6

What did Jenkins et al. (2000) find?

Answer 6

Increased activation for planned movement in the pre-SMA, increased activation for triggered movement in the SMA.

Question 7

What did Tanji (2001) demonstrate about the pre-SMA and SMA?

Answer 7

Pre-SMA neurons code for an entire action sequence as an entire chunk. SMA neurons fire between actions, seem to link or glue together individual parts during action while it’s being generated.

Question 8

Why is inhibition difficult to study?

Answer 8

By definition it does not produce behaviour.

Question 9

What is a major function of the Medial Prefrontal Cortex (MPFC) in relation to the external world?

Answer 9

Inhibits the actions that the external world tries to make us do. Suppressing the desire to respond to the world when it isn’t appropriate to do so.

Question 10

What is the lateral route’s relationship with the environment?

Answer 10

Drive towards it, how to interact with it.

Question 11

What is the medial route’s relationship with the environment?

Answer 11

Stopping, holding the exogenous influence.

Question 12

How do the internal generation and inhibition views overlap?

Answer 12

Internal generation suggests inhibiting the influence of the external world - deciding what to do rather than being dominated by external cues.

Question 13

What two abnormal behaviours give evidence for the inhibitory role of the SMA/pre-SMA?

Answer 13

Anarchic hand syndrome and utilization behaviour.

Question 14

What did Boccardi et al. (2002) show in patient UB and why?

Answer 14

Several episodes of utilization behaviour displaying non-requested by coherent activities when the environment cued them. Patient had a bilateral SMA lesion (apple story).

Question 15

What is the SMA’s relationship with free will?

Answer 15

RP from the SMA precedes conscious feeling of intention. Seem to tell me just before the action, giving the feeling of free will, but why? Kornhuber & Deecke (1966), Libet (1983).

Question 16

Lau et al., (2004) showed what about intentionality and the pre-SMA?

Answer 16

When participants are instructed to attend to their intention to act, rather than the action itself, there is greater activation in the pre-SMA. Activity in the pre-SMA reflects the representation of intention.

Question 17

What does Fried (2011) tell us about intentionality and action?

Answer 17

Neuronal activity can be used to predict action and the time of voluntary decision within a few hundred ms with 80% accuracy. Some neurons stop firing just before action - possibly inhibiting other actions?

Question 18

Fried et al. (1991)

Answer 18

Electrodes implanted in SMA, patients report urge to move right arm. Greater stimulation causes urge and movement.