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Anxious individuals have difficulty learning the causal statistics of aversive environments.

Browning M, Behrens TE, Jocham G, O'Reilly JX, Bishop SJ - Nat. Neurosci. (2015)

Bottom Line: Statistical regularities in the causal structure of the environment enable us to predict the probable outcomes of our actions.We tested this using an aversive learning task manipulating environmental volatility.This was linked to reduced sensitivity of the pupil dilatory response to volatility, potentially indicative of altered norepinephrinergic responsivity to changes in this aspect of environmental information.

View Article: PubMed Central - PubMed

Affiliation: Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK.

ABSTRACT
Statistical regularities in the causal structure of the environment enable us to predict the probable outcomes of our actions. Environments differ in the extent to which action-outcome contingencies are stable or volatile. Difficulty in being able to use this information to optimally update outcome predictions might contribute to the decision-making difficulties seen in anxiety. We tested this using an aversive learning task manipulating environmental volatility. Human participants low in trait anxiety matched updating of their outcome predictions to the volatility of the current environment, as predicted by a Bayesian model. Individuals with high trait anxiety showed less ability to adjust updating of outcome expectancies between stable and volatile environments. This was linked to reduced sensitivity of the pupil dilatory response to volatility, potentially indicative of altered norepinephrinergic responsivity to changes in this aspect of environmental information.

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Task Structurea) Example trial. Participants had to choose one of two shaped Gabor patches. Each shape contained a two digit number which indicated the magnitude of electrical shock that might be received should that shape be chosen. Following option presentation, onset of a response cue indicated that participants could make their choice. After response, a variable interval was followed by outcome delivery. The shape associated with the electrical shock for that trial was displayed in the centre of the screen for 2s. If the participant had chosen this shape, an electrical shock of the indicated magnitude was delivered at the onset of the outcome period. b) Outcome probabilities across the course of the task. The task comprised two blocks. In the stable block (shaded), one shape (for example, the circle) had a 75% probability of resulting in an electrical shock being delivered, if it was chosen; the other shape (e.g. a square) has a 25% probability of resulting in shock delivery. In the volatile block (unshaded) the probability that choice of a given shape would result in shock delivery switched every 20 trials between 80% and 20%. Participants were randomly assigned to complete the task with the stable block first (as shown), or with the volatile block first.
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Figure 1: Task Structurea) Example trial. Participants had to choose one of two shaped Gabor patches. Each shape contained a two digit number which indicated the magnitude of electrical shock that might be received should that shape be chosen. Following option presentation, onset of a response cue indicated that participants could make their choice. After response, a variable interval was followed by outcome delivery. The shape associated with the electrical shock for that trial was displayed in the centre of the screen for 2s. If the participant had chosen this shape, an electrical shock of the indicated magnitude was delivered at the onset of the outcome period. b) Outcome probabilities across the course of the task. The task comprised two blocks. In the stable block (shaded), one shape (for example, the circle) had a 75% probability of resulting in an electrical shock being delivered, if it was chosen; the other shape (e.g. a square) has a 25% probability of resulting in shock delivery. In the volatile block (unshaded) the probability that choice of a given shape would result in shock delivery switched every 20 trials between 80% and 20%. Participants were randomly assigned to complete the task with the stable block first (as shown), or with the volatile block first.

Mentions: On each trial, participants had to choose one of two shaped, isoluminant, gabor patches - either of which might result in the delivery of an electrical shock (Fig 1a). In the stable task block, one of the two shapes consistently predicted shock delivery with a probability of 75%, the other shape resulting in shock delivery on the remaining trials. In the volatile task block, the shape most predictive of shock delivery reversed on five occasions within the block (Fig 1b). On each trial, each shape was associated with a specific magnitude of electrical shock that would be delivered if the shape was chosen and if it resulted in shock administration on that trial. This magnitude was displayed in the centre of each shape. Magnitude values were scaled between 1 and 99, where 1 equated to a subjective pain level of 1, and 99 to a subjective pain level of 7. The trial-wise magnitudes of the shocks for each shape were chosen from independent random distributions (see online Methods). To perform the task optimally participants had to integrate the information about shock magnitude and shock probability, the latter needing to be inferred from the outcome of previous trials. The shape chosen and time taken to select it was recorded. Pupil dilatory responses were also measured. Due to equipment failure, behavioral and pupil data were lost from one participant (excluded) and pupil data from two further participants.


Anxious individuals have difficulty learning the causal statistics of aversive environments.

Browning M, Behrens TE, Jocham G, O'Reilly JX, Bishop SJ - Nat. Neurosci. (2015)

Task Structurea) Example trial. Participants had to choose one of two shaped Gabor patches. Each shape contained a two digit number which indicated the magnitude of electrical shock that might be received should that shape be chosen. Following option presentation, onset of a response cue indicated that participants could make their choice. After response, a variable interval was followed by outcome delivery. The shape associated with the electrical shock for that trial was displayed in the centre of the screen for 2s. If the participant had chosen this shape, an electrical shock of the indicated magnitude was delivered at the onset of the outcome period. b) Outcome probabilities across the course of the task. The task comprised two blocks. In the stable block (shaded), one shape (for example, the circle) had a 75% probability of resulting in an electrical shock being delivered, if it was chosen; the other shape (e.g. a square) has a 25% probability of resulting in shock delivery. In the volatile block (unshaded) the probability that choice of a given shape would result in shock delivery switched every 20 trials between 80% and 20%. Participants were randomly assigned to complete the task with the stable block first (as shown), or with the volatile block first.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644067&req=5

Figure 1: Task Structurea) Example trial. Participants had to choose one of two shaped Gabor patches. Each shape contained a two digit number which indicated the magnitude of electrical shock that might be received should that shape be chosen. Following option presentation, onset of a response cue indicated that participants could make their choice. After response, a variable interval was followed by outcome delivery. The shape associated with the electrical shock for that trial was displayed in the centre of the screen for 2s. If the participant had chosen this shape, an electrical shock of the indicated magnitude was delivered at the onset of the outcome period. b) Outcome probabilities across the course of the task. The task comprised two blocks. In the stable block (shaded), one shape (for example, the circle) had a 75% probability of resulting in an electrical shock being delivered, if it was chosen; the other shape (e.g. a square) has a 25% probability of resulting in shock delivery. In the volatile block (unshaded) the probability that choice of a given shape would result in shock delivery switched every 20 trials between 80% and 20%. Participants were randomly assigned to complete the task with the stable block first (as shown), or with the volatile block first.
Mentions: On each trial, participants had to choose one of two shaped, isoluminant, gabor patches - either of which might result in the delivery of an electrical shock (Fig 1a). In the stable task block, one of the two shapes consistently predicted shock delivery with a probability of 75%, the other shape resulting in shock delivery on the remaining trials. In the volatile task block, the shape most predictive of shock delivery reversed on five occasions within the block (Fig 1b). On each trial, each shape was associated with a specific magnitude of electrical shock that would be delivered if the shape was chosen and if it resulted in shock administration on that trial. This magnitude was displayed in the centre of each shape. Magnitude values were scaled between 1 and 99, where 1 equated to a subjective pain level of 1, and 99 to a subjective pain level of 7. The trial-wise magnitudes of the shocks for each shape were chosen from independent random distributions (see online Methods). To perform the task optimally participants had to integrate the information about shock magnitude and shock probability, the latter needing to be inferred from the outcome of previous trials. The shape chosen and time taken to select it was recorded. Pupil dilatory responses were also measured. Due to equipment failure, behavioral and pupil data were lost from one participant (excluded) and pupil data from two further participants.

Bottom Line: Statistical regularities in the causal structure of the environment enable us to predict the probable outcomes of our actions.We tested this using an aversive learning task manipulating environmental volatility.This was linked to reduced sensitivity of the pupil dilatory response to volatility, potentially indicative of altered norepinephrinergic responsivity to changes in this aspect of environmental information.

View Article: PubMed Central - PubMed

Affiliation: Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK.

ABSTRACT
Statistical regularities in the causal structure of the environment enable us to predict the probable outcomes of our actions. Environments differ in the extent to which action-outcome contingencies are stable or volatile. Difficulty in being able to use this information to optimally update outcome predictions might contribute to the decision-making difficulties seen in anxiety. We tested this using an aversive learning task manipulating environmental volatility. Human participants low in trait anxiety matched updating of their outcome predictions to the volatility of the current environment, as predicted by a Bayesian model. Individuals with high trait anxiety showed less ability to adjust updating of outcome expectancies between stable and volatile environments. This was linked to reduced sensitivity of the pupil dilatory response to volatility, potentially indicative of altered norepinephrinergic responsivity to changes in this aspect of environmental information.

Show MeSH
Related in: MedlinePlus