Task 8

Question 1

8.1: Cisek’s Affordance Competition view of brain functioning –> action selection

Answer 1

• natural environment presents animals with many opportunities and demands for action all the time e.g. food –> satiate hunger; predator–> caution/evasion
• cannot perform all behaviours simultaneously ==> action selection

Question 2

8.1: Cisek’s Affordance Competition view of brain functioning –> action specification

Answer 2

animal must tailor the actions it performs to the environment in which it is situated e.g., grasping a fruit –> accurate guidance of the hand to the location of the fruit ==> action specification

Question 3

8.1: Cisek’s Affordance Competition view of brain functioning –> how do action selection & specification interact?

Answer 3

processes occur continuously & simultaneously, in an ongoing competition for the currently most relevant action

Question 4

8.1: Cisek’s Affordance Competition view of brain functioning –> What are ‘affordances’?

Answer 4

constant competition between internal representations of the potential actions

Question 5

8.1: Why does Cisek think that the parietal cortex plays an essential role in this ongoing competition?

Answer 5

parietal cortical areas are strongly & reciprocally interconnected with frontal regions involved in movement control –> LIP is interconnected with FEF (–> saccades), MIP with PMd & primary motor cortex (M1) (–> limbs), AIP with ventral premotor cortex (PMv)

Question 6

8.1: Where does Cisek think the competition between potential actions play out?

Answer 6

mostly within reciprocally interconnected fronto-parietal system

Question 7

8.1: How does the PFC via attentional modulation bias the ongoing competition?

Answer 7

-along the dorsal stream –> increasing influence of attentional modulation, with information from particular regions of interest enhanced while information from other regions is suppressed
—> parietal representation of external space becomes increasingly sparse as one moves away from striate cortex
–> only the most promising targets for movements make it so far to be represented in the parietal cortex
==> competition is biased by input from BG & PFC regions which collect information for action selection

Question 8

8.1: What does Cisek mean by saying “Selective attention is seen as an early mechanism for action selection”?

Answer 8

• Because only the most promising targets for movements make it so far to be represented in the parietal cortex
• reduces the volume of information that is transformed into action-related representations

Question 9

8.2: What is Cisek’s (2007) view of the functional organization of the parietal “affordance” path towards action (i.e., from the parietal cortex to the frontal cortex)?

Answer 9

• begins in visual cortex & proceed rightward across the parietal lobe, transforming visual information into representations of potential actions
• three neural populations along thisroute:
• -> leftmost: encoding of potential visual targets, modulated by attentional selection
• middle: potential actions encoded in parietal cortex
• rightmost: activity in premotor regions
• each population is depicted as a map of neural activity, with activity peaks corresponding to the lightest regions
• as action specification occurs across the fronto-parietal cortex, distinct potential actions compete for further processing
• competition is biased by input from BG & PFC regions which collect information for action selection
• PFC: sends votes
• BG: value-based DM

Question 10

8.2: Compare Cisek’s view with Binkofsky & Bixbaum from task 1- substreams

Answer 10

• B&B: only 2 substreams

- Cisek: more than 2 substreams

Question 11

8.2: Compare Cisek’s view with Binkofsky &Bixbaum from task 1- attention

Answer 11

• B&B: not much influence of early attention

- Cisek: attention influences which actions are represented –> early attention

Question 12

8.2: Compare Cisek’s view with Binkofsky & Bixbaum from task 1- dependency on movement/effector?

Answer 12

• B&B: substreams involve different brain regions but these are NOT dependent on effector
• Cisek: different substreams comprise different brain regions depending on movement/effector

Question 13

8.2: Compare Cisek’s view with Binkofsky & Bixbaum from task 1- competition & bias signals

Answer 13

• B&B: competition between streams is possible but this is NOT influenced by bias signals
• Cisek: competition between multiple potential actions that is resolved by bias signals (from BG & PFC)

Question 14

8.2: Compare Cisek’s view with Binkofsky & Bixbaum from task 1- feedback

Answer 14

• B&B: no role of feedback
• Cisek: overt feedback (from environment) & internal feedback (from cerebellum) will influence future potential action decisions

Question 15

8.2: Compare Cisek’s view with Binkofsky & Bixbaum from task 1- serial or parallel?

Answer 15

• B&B: relatively serial view of processing

- Cisek: more parallel processing

Question 16

8.3: Where in the brain do decisions take place according to Cisek’s view?

Answer 16

• made within the very same neural circuits that control the execution of those actions
• Fronto-parietal circuit (PMd & MIP) –> DM based on visually guided reaching
• -> Uses info from PFC
• if a decision begins to emerge in one region, then it will propagate outward to other regions
• DM through distributed consensus
• -> accumulation of evidence in favour of given choice

Question 17

8.3: Where in the brain do decisions take place according to Cisek’s view? –> example (ideomotor vs ideational apraxia)

Answer 17

• Ideomotor apraxia: impairments of the implementation of these concepts
• Ideational apraxia: impairments of the conceptual representation of actions
• Ideomotor apraxia –> dorsal networks for action specification
• Ideational apraxia –> ventral networks for action selection

Question 18

8.3: Where in the brain do decisions take place according to Cisek’s view? –> example with ideational apraxia

Answer 18

• predict deficits in object use due to problems in ‘‘affordances’’ triggering appropriate actions
• may thus arise due to wrong actions being generated according to errors in affordances
• E.g., object may be recognized for its use, yet present the actor with graspable features (affordances) that may be similar to other objects (e.g., grasping a toothbrush may be similar to grasping a knife) and lead to activation of subsequent action representations that are inappropriate for the object at hand
• unable to select from these competing actions (or inhibit them)

Question 19

8.3: Where in the brain do decisions take place according to Cisek’s view? –> relate to flow chart (task 0)

Answer 19

• in all loops/ pathways
• -> competition, but in end all need to be in consensus in order to make decision (threshold idea) (finding a compromise) –> in the end one action is decided for
• depends on context; bias signals from BG& PFC
• depends on motivation, cognition, motor…
• flow chart: all steps in the middle

Question 20

8.4: Describe the filter-view on the dorsal attention system & their attention mechanisms

Answer 20

• traditional filter view (dorsal attention system): attention as regulator of sensory representations –> limited subset of sensory signals reach processing stages
  -attention mechanisms lead to a selection of only a small number of possible objects being represented
  neutrally

Question 21

8.4: Introduce the notion of priority maps (see the flow chart in task 1) (Krauzlis et al., 2014).

Answer 21

-KRAUZLIS: dorsal attention system sets priorities for processing particular stimuli over others –> these priorities stem from the current task that a person is engaged in (i.e. the dominant state)

Question 22

8.4: Explain how this view is only half of the story; that taking a wider perspective leads to the insight that these priority maps serve the larger good of goal-directed behavior –> simple example (for instance the grocery problem in task 0)

Answer 22

• change due to external circumstances
• priority maps serve the larger good of goal-directed behaviour
• e.g. you usually prefer bananas BUT if bananas are green or if you’ve eaten them a week in a row –> you’d decide for pineapple
• -> SO priority maps change due to external circumstances (motivation, cognition, etc)

Question 23

8.4: Explain the paper title “Attention as an effect not a cause” (Krauzlis et al., 2014).

Answer 23

• Attention: effect of interpreting sensory data
  -consequence of circuits centered on BG involved in value-based motor & non-motor DM
  -competition between possible interpretations of current state by BG rather than competition to determine how sensory data is represented in neocortex
  -states differ in weights they assign to various inputs
  -filter like properties associated with attention result from particular weights applied to inputs that define current state
  ==> FILTER LEADS TO ATTENTION! (Cisek& Krauzlis)
  –> Cisek: fronto-parietal pathway/network filtering leads to attention (more abstract form of DM)
  -BG also plays a role; integrates both movement parameters & decision variables such as reward
  -PFC: decision making (advanced action selection)
  –> Krauzlis: basal ganglia state estimation leads to attention (different states; if attention shifts, state shifts) –> Krauzlis: competition in BG
  ==> ATTENTION IS NOT A CAUSAL CAUSE

Question 24

8.5: Explain the concept of a state (Krauzlis et al., 2014).

Answer 24

=current condition of a subject in its environment

Question 25

8.5: How is the concept of a state used in the paper to give attention to its correct position in the larger process of goal-directed decision making? (Krauzlis et al., 2014)

Answer 25

• each state = template for particular situation & dedicates what the relevant stimuli, actions & rules are
• specific stimuli attended = specific state
• involves interpreting different info (e.g features of external world, internal status of subject)

Question 26

8.5: Why do the authors think that the BG are essential in the competition between states? (Krauzlis et al., 2014)

Answer 26

• competition between possible interpretations of current states
• learn associations between states & set of actions with the highest expected reward (reward –> dopamine)
• receive info from many different areas (input) & weights inputs according to the current state
• if state changes, attention shifts!!!

Question 27

8.6: Similarities between the views of Cisek & of Krauzlis et al. –> Competition

Answer 27

• -> Cisek: internal representations of potential actions are in constant competition
• competition in frontal-parietal loop
• competition is resolved by PFC& BG –> underestimates importance of BG
• -> Krauzlis: competition between possible interpretations of current state within BG –> stresses importance of BG

Question 28

8.6: Similarities between the views of Cisek & of Krauzlis et al. –> Subordinate role of attention

Answer 28

Cisek:

• many possible actions are eliminated from processing by selective attention mechanism which limit sensory info that can be transformed into action
• attention results from a filter, letting through less and less info as info processing progresses from lower-levels to the higher-levels
• > attention results from filter/biasing input to change representations of sensory info (“votes”)

Krauzlis:

• attention arises as a result of competition of possible states in BG
• different sensory info & knowledge is unequally important between the different competing states -> their impact on perception & action is limited by which of those states is currently dominating
• -> attention not necessary to change representation of sensory info (representation of sensory info/state is relevant for chaning attention)

Question 29

8.6: Similarities between the views of Cisek and of Krauzlis et al. –> Primacy of goals

Answer 29

Cisek:

• PFC & BG function as a gate for action execution
• key to this gate are certain decision variables - which decide which action is in line with goals

Krauzlis:
-BG estimates the most appropriate state for the current situation to decide which action is in line with current goals

Question 30

Cisek –> subpathways of dorsal pathway (LIP & MIP): responsible for movements of what?

Answer 30

LIP –> saccades

MIP –> limbs

Question 31

Krauzlis BG role of attention

Answer 31

• attention arises as a functional consequence of circuits in BG
• -> sensory input
• -> internal state
• -> state estimation
• -> decision policy

Question 32

8.6: Similarities between the views of Cisek & of Krauzlis et al. –> Priority maps

Answer 32

• Cisek: under the influence of attentional modulations & biases, only the most promising targets for movements make it so far to be represented in the parietal cortex
• Krauzlis: dorsal attention system sets priorities for processing particular stimuli over others ->these priorities stem from the current task that a person is engaged in (i.e., the dominant state)