An effect of serotonergic stimulation on learning rates for rewards apparent after long intertrial intervals

Iigaya, Kiyohito; Fonseca, Madalena S.; Murakami, Masayoshi; Mainen, Zachary F.; Dayan, Peter

doi:10.1038/s41467-018-04840-2

Cited by 94 publications

(100 citation statements)

References 68 publications

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“…6f-h). Moreover, only the lateral bias showed a dependence on the length of the previous intertrial interval (ITI) 37 : while both after-correct and after-error lateral biases became more positive for longer ITIs (i.e., favoring more repetitions), the transition bias remained unaffected ( Supplementary Fig. 2d).…”

Section: Discussionmentioning

confidence: 99%

Response outcomes gate the impact of expectations on perceptual decisions

et al. 2020

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Perceptual decisions are based on sensory information but can also be influenced by expectations built from recent experiences. Can the impact of expectations be flexibly modulated based on the outcome of previous decisions? Here, rats perform an auditory task where the probability to repeat the previous stimulus category is varied in trial-blocks. All rats capitalize on these sequence correlations by exploiting a transition bias: a tendency to repeat or alternate their previous response using an internal estimate of the sequence repeating probability. Surprisingly, this bias is null after error trials. The internal estimate however is not reset and it becomes effective again after the next correct response. This behavior is captured by a generative model, whereby a reward-driven modulatory signal gates the impact of the latent model of the environment on the current decision. These results demonstrate that, based on previous outcomes, rats flexibly modulate how expectations influence their decisions.

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Section: Discussionmentioning

confidence: 99%

Response outcomes gate the impact of expectations on perceptual decisions

et al. 2020

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“…Speed was also considered because of the tight relationship between pupil size and locomotion. Finally, the number of rewards was included as a predictor since 5-HT effects have been linked to reward valuation [33,43]. Predictors were z-scored before fitting the data.…”

Section: Multivariate Linear Regressionmentioning

confidence: 99%

Phasic activation of dorsal raphe serotonergic neurons increases pupil-linked arousal

Cazettes

Reato

Morais

et al. 2020

Preprint

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Variations in pupil size under constant luminance are closely coupled to changes in arousal state [1][2][3][4][5]. It is assumed that such fluctuations are primarily controlled by the noradrenergic system [6][7][8][9]. Phasic activity of noradrenergic axons precedes pupil dilations associated with rapid changes in arousal [7,9], and is believed to be driven by unexpected uncertainty [1,[10][11][12][13][14][15][16]. However, the role of other modulatory pathways in the control of pupil-linked arousal has not been as thoroughly investigated, but evidence suggests that noradrenaline may not be alone [7,17,18]. Administration of serotonergic drugs seems to affect pupil size [19][20][21][22][23], but these effects have not been investigated in detail. Here, we show that transient serotonin (5-HT) activation, like noradrenaline, causes pupil-size changes. We used phasic optogenetic activation of 5-HT neurons in the dorsal raphe nucleus (DRN) in head-fixed mice locomoting in a foraging task. 5-HT-driven modulations of pupil size were maintained throughout the photostimulation period and sustained for several seconds after the end of the stimulation. The activation of 5-HT neurons increased pupil size additively with locomotor speed, suggesting that 5-HT transients affect pupil-linked arousal independently from locomotor states. We found that the effect of 5-HT on pupil size depended on the level of environmental uncertainty, consistent with the idea that 5-HT may report a salience or surprise signal [24] . Together, these results challenge the classic view of the neuromodulatory control of pupil-linked arousal, revealing a tight relationship between the activation of 5-HT neurons and changes in pupil size.

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“…We used a hierarchical Bayesian, random effects analysis. [51][52][53] In this, the (suitably transformed) parameters h i of participant i are treated as a random sample from a Gaussian distribution with means and variance θ θ θ = {µ µ µ θ , Σ Σ Σ θ } characterising the whole population of subjects; and we find the maximum likelihood values of θ θ θ.…”

Section: Behavioral Model Fittingmentioning

confidence: 99%

“…We used each subject's maximum a posteriori (MAP) parameters, based on an hierarchical model fit, [51][52][53] to estimate subject-specific time courses of several variables, including the two separate value signals in our model: (i) discounted boosted-anticipatory value during wait periods (ii) discounted reward value during the same periods, and (iii) prediction errors at cue presentation. These signals were convolved with SPM's default canonical HRF ( Figure 1H; see Figure S4 for an example).…”

Section: Introductionmentioning

confidence: 99%

The value of what’s to come: neural mechanisms coupling prediction error and reward anticipation

Iigaya

Hauser

Kurth‐Nelson

et al. 2019

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Having something to look forward to is a keystone of well-being. Anticipation of a future reward, like an upcoming vacation, can be more gratifying than the experience of reward itself. Theories of anticipation have described how it causes behaviors ranging from beneficial information-seeking to harmful addiction. Here, we investigated how the brain generates and enhances anticipatory pleasure, by analyzing brain activity of human participants who received information predictive of future pleasant outcomes in a decision-making task. Using a computational model of anticipation, we show that three regions orchestrate anticipatory pleasure. We show ventromedial prefrontal cortex (vmPFC) tracks the value of anticipation; dopaminergic midbrain responds to information that enhances anticipation, while the sustained activity in hippocampus provides for functional coupling between these regions. This coordinating role for hippocampus is consistent with its known role in the vivid imagination of future outcomes. Our findings throw new light on the neural underpinnings of how anticipation influences decision-making, while also unifying a range of phenomena associated with risk and time-delay preference.

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An effect of serotonergic stimulation on learning rates for rewards apparent after long intertrial intervals

Cited by 94 publications

References 68 publications

Response outcomes gate the impact of expectations on perceptual decisions

Response outcomes gate the impact of expectations on perceptual decisions

Phasic activation of dorsal raphe serotonergic neurons increases pupil-linked arousal

The value of what’s to come: neural mechanisms coupling prediction error and reward anticipation

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