task 8

Question 1

cisek

Answer 1

It is proposed that the competition between potential actions plays out in large part within this reciprocally interconnected fronto-parietal system. Within each cortical area, cells with different movement preferences mutually inhibit each other, creating a competition between distinct potential actions

This competition is biased by excitatory input from a variety of sources, including both cortical and subcortical region

The influence of all these biasing factors modulates the activity in frontal and parietal neurons, with information favouring a given action causing activity related to that action to increase, while information against an action causes it to decrease.

neurophysiological evidence for the modu- lation of fronto-parietal activity by ‘decision factors’ is very strong.

Question 2

stratum and decisonmaking

Answer 2

The striatum receives converging inputs from many sources, prominently from the cerebral cortex, but also from the thalamus, the amygdala, and elsewhere [21–24]. The striatum also receives dopamine signals that guide reinforcement learn- ing; the learned associations between a particular state and the set of actions with the highest expected values establish a decision policy that guides the subject’s behavior [25–29].

Question 3

DESCRIBE CISEK’S AFFORDANCE COMPETITION VIEW OF BRAIN FUNCTIONING. START WITH THE DISTINCTION THAT HE MAKES BETWEEN ACTION SELECTION AND ACTION SPECIFICATION.

Answer 3

Action specification: Is the accumulation of sensory info to create several potentially useful action plans (=how to perform an action?)
BUT: only action plans that are currently available, or more specifically related to the situation, are specified
 neural substrates: Visual cortex – Parietal lobe
Action selection: Selecting an action from specified action plans (= what action to perform?)
 Basal ganglia – PFC

Question 4

The affordance competition hypothesis:

Answer 4

Suggests that neural activity in fronto-parietal regions correlates with sensory + motor variables because it is involved in action specification by using sensory info
 modulated by decision variables because a competition between potential actions is influenced by various sources of biasing inputs
In a nutshell: Cells in the fronto-parietal system with different movement preferences will mutually inhibit each other, based on the biasing input that the individual receives
THUS: specific info will favor a given action which will cause increased activity related to that action, while info against an action will cause it to decrease (=comparable to ballot box model)
Activity for actions compete for further processing