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[0] Schultz W, Tremblay L, Hollerman JR, Reward processing in primate orbitofrontal cortex and basal ganglia.Cereb Cortex 10:3, 272-84 (2000 Mar)

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ref: -0 tags: dopamine reward prediction striatum error striatum orbitofrontal reward date: 02-24-2012 21:26 gmt revision:1 [0] [head]

PMID-11105648 Involvement of basal ganglia and orbitofrontal cortex in goal-directed behavior.

  • Many regions have a complex set of activations, but dopamine neurons appear more homogenous: they report the error in reward prediction.
    • "The homogeneity of responsiveness across the population of dopamine neurons indicates that this error signal is widely broadcast to dopamine terminal regions where it could provide a teaching signal for synaptic modifications underlying the learning of goal-directed appetitive behaviors."
    • Signals are not contingent on the type of behavior needed to obtain the reward, and hence represent a relatively 'pure' reward prediction error.
  • Unlike dopamine neurons, many striatal neurons respond to predicted rewards, although at least some may reflect the relative degree of predictability in the magnitude of the responses to reward.
  • Neuronal activations in the orbitofrontal cortex appear to involve less integration of behavioral and reward-related information, but rather incorporate another aspect of reward, the relative motivational significance of different rewards.
  • Processing is hierarchical (or supposed to be so):
    • Dopamine neurons provide a relatively pure signal of an error in reward prediction,
    • Striatal neurons signal not only reward, but also behavioral contingencies,
    • Orbitofrontal neurons signal reward and incorporate relative reward preference.

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ref: Schultz-2000.03 tags: review orbitofrontal cortex basal ganglia dopamine reward reinforcement learning striatum date: 10-07-2008 03:53 gmt revision:1 [0] [head]

PMID-10731222[0] Reward processing in primate orbitofrontal cortex and basal ganglia

  • Orbitofrontal neurons showed three principal forms of reward-related activity during the performance of delayed response tasks,
    • responses to reward-predicting instructions,
    • activations during the expectation period immediately preceding reward and
    • responses following reward
    • above, reward-predicting stimulus in a dopamine neuron. Left: the animal received a small quantity of apple juice at irregular intervals without performing in any behavioral task. Right: the animal performed in an operant lever-pressing task in which it released a touch-sensitive resting key and touched a small lever in reaction to an auditory trigger signal. The dopamine neuron lost its response to the primary reward and responded to the reward-predicting sound.
  • for the other figures, read the excellent paper!

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