Reward & Decision Making

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  1. Middle temporal area (V5/MT)
    extrastriate visual area, connections primarily from V1 and V2 motion; sensitive neurons with large receptive fields and preferred velocities (direction and speed) neurons encode for instantaneous strength of motion in preferred direction
  2. Lateral intraparietal area (LIP)
    (in terms of motor significance, important for planning) region of lateral bank of the intraparietal sulcus receives input from extrastriate cortices, including MT; major projections to FEF and SC; topographically organized code for direction and amplitude of saccades pre-saccadic and peri- saccadic neural activity associated with preferred saccades; proposed covert psychological processes in sensorimotor processing: attention, motor planning, and decision
  3. Frontal eye field (FEF)
    located posterior to the arcuate sulcus in prefrontal cortex motor function: microstimulation elicits saccades, pre- and peri-saccadic activity direct innervation of superior colliculus and other brainstem eye movement centers visual function: convergence of extrastriate input (MT, LIP, TEO) stereotyped activity with saccade to target in response field: initial burst of activity at target onset, then low rate into slow ramping activity to a pre-saccadic burst
  4. Newsome and Pare, Motion Discrimination
    key point: animal’s choice/behavior [aka which direction he would look] could be predicted from MT neuron activity; the experiment had a monkey stare at FP that had a certain amount of dots moving dots to the left or right; the coherence of the dots was the number of dots moving in the same direction; as the number of dots moving uniformly to one side increased (coherence increased), MT neuron spike rate increased; also behavioral performance/accuracy increased (duh, if the signal was clear you're going to make an eye movement in the right direction)
  5. Neuroeconomics: Platt and Glimcher
    key point: firing pattern in LIP tends to represent utility in choosing those two options (aka high firing correlates with high probability of reinforcement/magnitude of it)...LIP knows when it's going to get rewarded; task was that Macaque monkeys stares at center fixation --- two flanking circles appear (one’s green, other’s red) --- the fixation point changes color --- when the FP goes away they have to make an eye movement to one of the circles that matches in color; experimenters manipulated the probability and MAGNITUDE of the reward (either drops of juice or amount a color would correlate with recieving juice)
  6. reward functions to: (do 3 things)
    • 1) elicit approach behavior (either through innate mechanisms or learning)
    • 2) Increase the frequency and intensity of a behavior that leads to a reward (learning)
    • 3) Induce subjective feelings of pleasure (hedonia) and positive emotional states
  7. a Dopamine response at the time of a REWARD:
    response can be predicted using this formual: reward occurred (0, didn't or 1 did ) reward predicted (0 or 1). Predicted if there was a tone (aka CS) and rewarded if there was a reward after the delay
  8. two dopamine production areas in the brain:
    VTA (ventral tegmental area) goes through cortex, especially prefrontal, and the substantia nigra goes through the basal ganglia
  9. Schultz Reward Prediction Error
    argues that dopamine neurons activity is predicting the error in a reward; 3 trials: in the 1st, there is no CS (tone) but there is a reward, which is followed by DA response. In the 2nd there IS a CS, which is followed by a DA response and then a reward which is not followed by a DA response. In the 3rd, there is a CS followed by activity but then there is NO reward, and this lack of a reward is followed by a suppression in activity.
  10. Dopamine/the releasing systems have two roles:
    monitoring whether the brain-state maintains a belief, or whether it changes it
  11. primary reward vs secondary reward:
    Primary = innate in the environment (liquids, food) Secondary = learned through associations (money)
  12. MT projects to LIP which projects to FEF ----- SC
    GET IT!? that's the saccade decision network
Card Set:
Reward & Decision Making
2011-05-03 19:53:47

Quiz 3
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