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Contrasting Roles for Orbitofrontal Cortex and Amygdala in Credit Assignment and Learning in Macaques.

Chau BK, Sallet J, Papageorgiou GK, Noonan MP, Bell AH, Walton ME, Rushworth MF - Neuron (2015)

Bottom Line: Recent studies have challenged the view that orbitofrontal cortex (OFC) and amygdala mediate flexible reward-guided behavior.A second experiment confirmed the existence of signals for adaptive stay/shift behavior in lOFC and reflecting irrelevant reward in the amygdala in a probabilistic learning task.Our data demonstrate that OFC and amygdala each make unique contributions to flexible behavior and credit assignment.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University of Oxford, OX1 3UD, Oxford, UK; Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong. Electronic address: boltonchau@gmail.com.

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Object Discrimination Reversal Task(A) Each trial started with an inter-trial interval (ITI) showing a blank screen. Two options were then presented on the screen, monkeys chose one of the options by reaching the touch sensor placed in front of it (decision phase). Juice reward was delivered if a correct option was chosen (outcome phase).(B) The task was designed with a two-option deterministic reversal schedule. Each session began with one correct option that led to a reward and one incorrect option that did not lead to a reward. The stimulus-reward contingencies reversed after monkeys performed 50 and 100 rewarded trials.(C) On average, the accuracies of all monkeys were low on the early trials in a block and gradually increased.(D) Performance averaged across testing sessions within subject. Each line represents data from one subject. The raster plots in (C) and (D) indicate trials in a block with accuracies significantly higher than 0.5 (p < 0.05).(E and F) Example sessions from two different subjects. Accuracies were calculated by using a moving average window of 5 trials. The dotted lines indicate reversals. The raster plots indicate the reward (green) and no reward (red) outcome events.
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fig1: Object Discrimination Reversal Task(A) Each trial started with an inter-trial interval (ITI) showing a blank screen. Two options were then presented on the screen, monkeys chose one of the options by reaching the touch sensor placed in front of it (decision phase). Juice reward was delivered if a correct option was chosen (outcome phase).(B) The task was designed with a two-option deterministic reversal schedule. Each session began with one correct option that led to a reward and one incorrect option that did not lead to a reward. The stimulus-reward contingencies reversed after monkeys performed 50 and 100 rewarded trials.(C) On average, the accuracies of all monkeys were low on the early trials in a block and gradually increased.(D) Performance averaged across testing sessions within subject. Each line represents data from one subject. The raster plots in (C) and (D) indicate trials in a block with accuracies significantly higher than 0.5 (p < 0.05).(E and F) Example sessions from two different subjects. Accuracies were calculated by using a moving average window of 5 trials. The dotted lines indicate reversals. The raster plots indicate the reward (green) and no reward (red) outcome events.

Mentions: Four monkeys performed the deterministic ODR task (experiment 1; Figure 1A); they had to discriminate which of two options led to a reward at the beginning of a session. The reward assignment reversed after the monkeys performed the 50th rewarded trial and then it reversed again after the 100th rewarded trial. The daily session stopped after the monkey performed 150 rewarded trials in total (Figure 1B). The animals encountered new stimuli at the beginning of each day of testing. On average, the monkeys performed 183.4 trials (81.8% correct) in each session and each monkey contributed four to six sessions in this dataset. To investigate the animals’ behavior, we split each session into three blocks (block 1: the initial learning period before any reversals; blocks 2 and 3: after the first and second reversal, respectively) and calculated the average accuracy of each trial as a function of its position in the block (trial 1, trial 2, trial 3, and so on; Figure 1C). The monkeys typically showed poor accuracy on early trials but they were consistently above 50% correct after the ninth trial of a block (t3 > 3.920, p < 0.030; Figure 1C). When block 1 and blocks 2 + 3 were analyzed separately, the first trials of block 1 had a higher accuracy (38%), due to random decisions, than comparable trials in blocks 2 + 3 (0%) due to post-reversal decisions (Figure S1). The average performance of each monkey is shown in Figure 1D. To illustrate performance on individual testing sessions, the data were smoothed by calculating a running average over five trials that stopped at the last four trials of a block to avoid inclusion of trials in different blocks within a given average. Figures 1E and 1F show monkeys’ performances in two example sessions.


Contrasting Roles for Orbitofrontal Cortex and Amygdala in Credit Assignment and Learning in Macaques.

Chau BK, Sallet J, Papageorgiou GK, Noonan MP, Bell AH, Walton ME, Rushworth MF - Neuron (2015)

Object Discrimination Reversal Task(A) Each trial started with an inter-trial interval (ITI) showing a blank screen. Two options were then presented on the screen, monkeys chose one of the options by reaching the touch sensor placed in front of it (decision phase). Juice reward was delivered if a correct option was chosen (outcome phase).(B) The task was designed with a two-option deterministic reversal schedule. Each session began with one correct option that led to a reward and one incorrect option that did not lead to a reward. The stimulus-reward contingencies reversed after monkeys performed 50 and 100 rewarded trials.(C) On average, the accuracies of all monkeys were low on the early trials in a block and gradually increased.(D) Performance averaged across testing sessions within subject. Each line represents data from one subject. The raster plots in (C) and (D) indicate trials in a block with accuracies significantly higher than 0.5 (p < 0.05).(E and F) Example sessions from two different subjects. Accuracies were calculated by using a moving average window of 5 trials. The dotted lines indicate reversals. The raster plots indicate the reward (green) and no reward (red) outcome events.
© Copyright Policy - CC BY
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4562909&req=5

fig1: Object Discrimination Reversal Task(A) Each trial started with an inter-trial interval (ITI) showing a blank screen. Two options were then presented on the screen, monkeys chose one of the options by reaching the touch sensor placed in front of it (decision phase). Juice reward was delivered if a correct option was chosen (outcome phase).(B) The task was designed with a two-option deterministic reversal schedule. Each session began with one correct option that led to a reward and one incorrect option that did not lead to a reward. The stimulus-reward contingencies reversed after monkeys performed 50 and 100 rewarded trials.(C) On average, the accuracies of all monkeys were low on the early trials in a block and gradually increased.(D) Performance averaged across testing sessions within subject. Each line represents data from one subject. The raster plots in (C) and (D) indicate trials in a block with accuracies significantly higher than 0.5 (p < 0.05).(E and F) Example sessions from two different subjects. Accuracies were calculated by using a moving average window of 5 trials. The dotted lines indicate reversals. The raster plots indicate the reward (green) and no reward (red) outcome events.
Mentions: Four monkeys performed the deterministic ODR task (experiment 1; Figure 1A); they had to discriminate which of two options led to a reward at the beginning of a session. The reward assignment reversed after the monkeys performed the 50th rewarded trial and then it reversed again after the 100th rewarded trial. The daily session stopped after the monkey performed 150 rewarded trials in total (Figure 1B). The animals encountered new stimuli at the beginning of each day of testing. On average, the monkeys performed 183.4 trials (81.8% correct) in each session and each monkey contributed four to six sessions in this dataset. To investigate the animals’ behavior, we split each session into three blocks (block 1: the initial learning period before any reversals; blocks 2 and 3: after the first and second reversal, respectively) and calculated the average accuracy of each trial as a function of its position in the block (trial 1, trial 2, trial 3, and so on; Figure 1C). The monkeys typically showed poor accuracy on early trials but they were consistently above 50% correct after the ninth trial of a block (t3 > 3.920, p < 0.030; Figure 1C). When block 1 and blocks 2 + 3 were analyzed separately, the first trials of block 1 had a higher accuracy (38%), due to random decisions, than comparable trials in blocks 2 + 3 (0%) due to post-reversal decisions (Figure S1). The average performance of each monkey is shown in Figure 1D. To illustrate performance on individual testing sessions, the data were smoothed by calculating a running average over five trials that stopped at the last four trials of a block to avoid inclusion of trials in different blocks within a given average. Figures 1E and 1F show monkeys’ performances in two example sessions.

Bottom Line: Recent studies have challenged the view that orbitofrontal cortex (OFC) and amygdala mediate flexible reward-guided behavior.A second experiment confirmed the existence of signals for adaptive stay/shift behavior in lOFC and reflecting irrelevant reward in the amygdala in a probabilistic learning task.Our data demonstrate that OFC and amygdala each make unique contributions to flexible behavior and credit assignment.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University of Oxford, OX1 3UD, Oxford, UK; Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong. Electronic address: boltonchau@gmail.com.

Show MeSH
Related in: MedlinePlus