Biology subjects

Pooresmaeili, A.

Publications and source records attributed to Pooresmaeili, A..

12 recordsLinked to original sources

bioRxiv2026

Pupil responses reveal temporally distinct signatures of value updating and decision strategy

Adaptive decision making depends on dopaminergic and noradrenergic systems supporting value learning and exploratory decision strategies, respectively, yet their contributions remain difficult to dissociate non-invasively. Here, we investigated whether pupil dynamics provide dissociable readouts of computational processes underlying value-based decision making across sensory modalities, potentially reflecting distinct neuromodulatory processes. Human participants performed a dynamic foraging task in which they chose between auditory, visual, or audio-visual options based on their estimated value, alongside a control task where choices were instructed. Behavior in the value-based task was well captured by a probabilistic choice model, revealing adaptive integration of reward history and a balance between exploration and exploitation. Pupil responses revealed temporally distinct computational signatures of decision strategy and value updating. Reaction time was associated with sustained pupil dilation throughout the decision process, whereas value differences between chosen and unchosen options selectively modulated pupil responses during stimulus evaluation and following feedback. These findings are consistent with computational processes linked to noradrenergic regulation of exploration-exploitation behavior and dopaminergic value updating, respectively. Both effects were significantly stronger during value-based than instructed decisions, indicating enhanced engagement of these computational processes when choices depended on learned reward values. Importantly, these effects were largely modality-independent, indicating a domain-general encoding of computational variables. Together, these findings identify pupil dynamics as a temporally sensitive and non-invasive marker of distinct computational stages underlying adaptive decision making and establish a framework for linking pupillometry to neuromodulatory theories of value learning and uncertainty processing.

neuroscience↗

bioRxiv2023

Interaction of spatial attention and the associated reward value of audiovisual stimuli

Reward value and selective attention both enhance the representation of sensory stimuli at the earliest stages of processing. It is still debated whether and how reward-driven and attentional mechanisms interact to influence perception. Here we ask whether the interaction between reward value and selective attention depends on the sensory modality through which the reward information is conveyed. Human participants first learned the reward value of uni-modal visual and auditory stimuli during a conditioning phase. Subsequently, they performed a target detection task on bimodal stimuli containing a previously rewarded stimulus in one, both, or neither of the modalities. Additionally, participants were required to focus their attention on one side and only report targets on the attended side. Our results showed a strong modulation of visual and auditory event-related potentials (ERPs) by spatial attention. We found no main effect of reward value but importantly an interaction effect was found as the strength of attentional modulation of the ERPs was significantly affected by the reward value. When reward effects were inspected separately with respect to each modality, auditory value-driven modulation of attention was found to dominate the ERP effects whereas visual reward value on its own led to no effect, likely due to its interference with the target processing. These results inspire a two-stage model where first the salience of a high reward stimulus is enhanced on a local priority map specific to each sensory modality, and at a second stage reward value and top-down attentional mechanisms are integrated across sensory modalities to affect perception.

neuroscience↗

bioRxiv2023

Modulation of perception by visual, auditory, and audiovisual reward predicting cues

Rewards influence information processing in the primary sensory areas specialized to process stimuli from a specific sensory modality. In real life situations, we receive sensory inputs not only from one single modality, but stimuli are often multisensory. It is however not known whether the reward-driven modulation of perception follows the same principles when reward is cued through a single or multiple sensory modalities. We previously showed that task-irrelevant reward cues modulate perception both intra- as well as cross-modally, likely through a putative enhancement in the integration of the stimulus parts into a coherent object. In this study, we explicitly test this possibility by assessing whether reward enhances the integration of unisensory components of a multisensory object in accordance with the supra-additive principle of multisensory integration. Towards this aim, we designed a simple detection task using reward predicting cues that were either unisensory (auditory or visual, both above the detection threshold) or multisensory (audiovisual). We conducted two experiments, behavioral (experiment 1) and simultaneous behavioral and neuroimaging testing (experiment 2). We expected that reward speeds up reaction times in response to all stimulus configurations, and that additionally the reward effects in multisensory cues fulfill the supra-additive principle of multisensory integration. We observed that reward decreased response times in both experiments with the strongest effect found for the multisensory stimuli in experiment 1. However, this behavioral effect did not fulfill the supra-additive principle. Neuroimaging results demonstrated sensory supra-additivity at the classical areas involved in multisensory integration such as the Superior Temporal areas (STS), while reward modulation was found in the midbrain and fronto-parietal areas, reflecting the typical areas that receive dopaminergic projections. However, reward did not enhance the supra-additivity in the STS compared to a no reward condition. Instead, we observed that some of the reward-related areas showed a sub-additive modulation by rewards and areas exhibiting a weaker supra-additive response to audiovisual stimuli, namely the fusiform gyrus, were modulated by rewards of audiovisual stimuli as measured by a conjunction analysis. Overall, our results indicate that reward does not enhance the multisensory integration through a supra-additive rule. These findings inspire a model where reward and sensory integration processes are regulated by two independent mechanisms, where sensory information is integrated at an early stage in a supra-additive manner, while reward modulates perception at a later stage sub-additively. Moreover, an associative area in the Fusiform gyrus exhibits a convergence of both reward and multisensory integration signals, indicating that it may be a hub to integrate different types of signals including rewards to disambiguate the information from different sensory modalities.

neuroscience↗

bioRxiv2023

Distinct mechanisms underlie value-driven modulation of visual cortex by previously rewarded visual and auditory stimuli

Past reward associations may be signaled by stimuli from different sensory modalities, however it remains unclear how different types of reward-associated stimuli modulate perception. In this human fMRI study, we employed a paradigm involving a visual discrimination task, where a visual target was simultaneously presented with either an intra-(visual) or a cross-modal (auditory) cue that was previously associated with rewards. We hypothesized that depending on the sensory modality of the cues distinct neural pathways underlie the value-driven modulation of visual areas. Two steps of analyses were conducted: first, using a multivariate approach, we confirmed that previously reward-associated cues enhanced the target representation in the early visual areas. Then, using effective connectivity analysis, we tested three possible patterns of communication across the brain regions that could underlie the modulation of visual cortex: a direct pathway from the frontal valuation areas to the visual areas, a mediated pathway through the attention-related areas, and a mediated pathway that additionally involved distinct sensory association areas for auditory and visual rewards. We found evidence for the third model and demonstrate that reward-related information is communicated across the valuation and attention-related brain regions such as the intraparietal sulcus across for both visual and auditory cues. Additionally, the long-range communication of reward information also involved the superior temporal areas in case of auditory reward-associated stimuli. These results suggest that in the presence of previously rewarded stimuli from different sensory modalities, a combination of domain-general and domain-specific mechanisms are recruited across the brain to adjust visual processing.

neuroscience↗

bioRxiv2022

Modality-specific and modality-general representations of reward value in frontal cortex

Standard neuroeconomics theories state that the value of different classes of stimuli, for instance the hedonic value of food versus music, is transformed to a common reference scale that is independent of their sensory properties. However, adaptive behaviour in a multimodal dynamic environment requires that our brain also encodes information about the sensory features of rewarding stimuli. How these two processes, i.e. deriving a common reference scale for valuation and maintaining sensitivity to the sensory contexts for goal-directed behaviour, are implemented in the brain remains inadequately understood. Here, we acquired fMRI data while human participants were engaged in a dynamic foraging task requiring them to integrate the reward history of auditory or visual choice options and update the subjective value assigned to each sensory modality. Univariate fMRI analysis revealed modality-specific and modality-general value representations in orbitofrontal cortex (OFC) and ventromedial prefrontal cortex (vmPFC), respectively. Crucially, modality-specific value representations were absent when the task involved instruction-based rather than value-based choices. The analysis of effective connectivity further demonstrated that the modality-specific value representations emerged as a result of selective bidirectional interactions across the auditory and visual sensory cortices, the corresponding OFC clusters and the vmPFC. These results show how a valuation process that is sensitive to the sensory context of rewarding stimuli is enabled in the brain.

neuroscience↗

bioRxiv2022

Egocentric Bias in Effort Comparison Tasks Is Driven by Sensory Asymmetries, Not Attribution Bias

When comparing themselves with others, people often perceive their own actions and behaviour favourably. This phenomenon is often categorised as a bias of attribution, with favourable self-evaluation resulting from differing explanations of ones own behaviour and that of others. However, studies on availability biases offer an alternative explanation, ascribing egocentric biases to the inherent sensory asymmetries between performing an action and merely observing it. In this study, we used a paradigm that allowed us to directly compare these two distinct sources of bias. Participants perceived the tasks they performed to be harder than the tasks they observed, but demonstrated no bias driven by favourable self-evaluation. Furthermore, the degree of overestimation of the difficulty of performed tasks was magnified as overall task difficulty increased. These findings suggest that egocentric biases are in part derived from sensory asymmetries inherent to the first-person perspective.

animal behavior and cognition↗

bioRxiv2021

Differential effects of intra-modal and cross-modal reward value on visual perception: ERP evidence

Stimuli associated with high reward modulate perception and such value-driven effects have been shown to originate from the modulation of the earliest stages of sensory processing in the brain. In natural environments objects comprise multiple features (imagine a rolling soccer ball, with its black and white patches and the swishing sound made during its motion), where each feature may signal different associations with previously encountered rewards. How perception of such an object is affected by the value associations of its constituent parts is unknown. The present study compares intra- and cross-modal value-driven effects on behavioral and electrophysiological correlates of visual perception. Human participants first learned the reward associations of visual and auditory cues. Subsequently, they performed a visual orientation discrimination task in the presence of previously rewarded visual or auditory cues (intra- and cross-modal cues, respectively) that were concurrently presented with the target stimulus. During the conditioning phase, when reward associations were learned and reward cues were the target of the task, reward value of both modalities enhanced the electrophysiological correlates of sensory processing in visual cortex. During the post-conditioning phase, when reward delivery was halted and previously rewarded stimuli were task-irrelevant, cross-modal value-enhanced behavioral measures of visual sensitivity whereas intra-modal value led to a trend for suppression. A similar pattern of modulations was found in the simultaneously recorded event-related potentials (ERPs) of posterior electrodes. We found an early (90-120 ms) suppression of ERPs evoked by high-value, intra-modal stimuli. Cross-modal cues led to a later value-driven modulation, with an enhancement of response positivity for high-compared to low-value stimuli starting at the N1 window (180-250 ms) and extending to the P3 (300-600 ms) responses of the posterior electrodes. These results indicate that visual cortex is modulated by the reward value of visual as well as auditory cues. Previously rewarded, task-irrelevant cues from the same or different sensory modality have a different effect on visual perception, as intra-modal high-value cues may interfere with the target processing, whereas cross-modal high-value cues boost the perception of the target.

neuroscience↗

bioRxiv2020

Previous motor actions outweigh sensory information in sensorimotor learning

Humans can use their previous experience in form of statistical priors to improve decisions. It is however unclear how such priors are learned and represented. Importantly, it has remained elusive whether prior learning is independent of the sensorimotor system involved in the learning process or not, as both modality-specific and modality-general learning have been reported in the past. Here, we used a saccadic eye movement task to probe the learning and representation of a spatial prior across a few trials. In this task, learning occurs in an unsupervised manner and through encountering trial-by-trial visual hints drawn from a distribution centered on the target location. Using a model-comparison approach, we found that participants prior knowledge is largely represented in the form of their previous motor actions, with minimal influence from the previously seen visual hints. By using two different motor contexts for response (looking either at the estimated target location, or exactly opposite to it), we could further compare whether prior experience obtained in one motor context can be transferred to the other. Although learning curves were highly similar, and participants seemed to use the same strategy for both response types, they could not transfer their knowledge between contexts, as performance and confidence ratings dropped to naive levels after a switch of the required response. Together, our results suggest that humans preferably use the internal representations of their previous motor actions, rather than past incoming sensory information, to form statistical sensorimotor priors on the timescale of a few trials.

neuroscience↗

bioRxiv2020

Dissociable effects of subliminal incentives on initiation and velocity control of goal-directed eye movements

Over the last decades, several studies have demonstrated that conscious and unconscious reward incentives both affect performance in physical and cognitive tasks, suggesting that goal-pursuit can arise from an unconscious will. Whether the planning of goal-directed saccadic eye movements during an effortful task can also be affected by subliminal reward cues has not been systematically investigated. We employed a novel task where participants had to make several eye movements back and forth between a fixation point and a number of peripheral targets. The total number of targets visited by the eyes in a fixed amount of time determined participants monetary gain. The magnitude of the reward at stake was briefly shown at the beginning of each trial and was masked by pattern images superimposed in time. We found that when reward cues were fully visible and thus consciously perceived, higher reward enhanced all saccade parameters. However, a dissociation was observed between the effects of subliminal rewards on saccade initiation and peak velocities. While truly subliminal reward cues did increase the number of saccades, they did not enhance saccades peak velocity. Additionally, participants who had reached a truly subliminal level of reward perception showed a decrement in accuracy as a function of reward across all visibility levels, as saccade endpoint error was larger when higher reward incentives were expected. This suboptimal speed-accuracy trade-off did not occur in the supraliminal group. These results suggest that although saccades initiation can be triggered by subconscious mechanisms, conscious awareness is required to optimally adjust the velocity and accuracy of eye movements based on the expected rewards.

neuroscience↗

bioRxiv2020

Deep Active Inference and Scene Construction

Adaptive agents must act in intrinsically uncertain environments with complex latent structure. Here, we elaborate a model of visual foraging - in a hierarchical context - wherein agents infer a higher-order visual pattern (a scene) by sequentially sampling ambiguous cues. Inspired by previous models of scene construction - that cast perception and action as consequences of approximate Bayesian inference - we use active inference to simulate decisions of agents categorizing a scene in a hierarchically-structured setting. Under active inference, agents develop probabilistic beliefs about their environment, while actively sampling it to maximise the evidence for their internal generative model. This approximate evidence maximization (i.e. self-evidencing) comprises drives to both maximise rewards and resolve uncertainty about hidden states. This is realised via minimization of a free energy functional of posterior beliefs about both the world as well as the actions used to sample or perturb it, corresponding to perception and action, respectively. We show that active inference, in the context of hierarchical scene construction, gives rise to many empirical evidence accumulation phenomena, such as noise-sensitive reaction times and epistemic saccades. We explain these behaviours in terms of the principled drives that constitute the expected free energy, the key quantity for evaluating policies under active inference. In addition, we report novel behaviours exhibited by these active inference agents that furnish new predictions for research on evidence accumulation and perceptual decision-making. We discuss the implications of this hierarchical active inference scheme for tasks that require planned sequences of information-gathering actions to infer compositional latent structure (such as visual scene construction and sentence comprehension). Finally, we propose experiments to contextualise active inference in relation to other formulations of evidence accumulation (e.g. drift-diffusion models) in tasks that require planning in uncertain environments with higher-order structure.

neuroscience↗

bioRxiv2019

Cross-modal integration of reward value during oculomotor planning

Reward value guides goal-directed behavior and modulates early sensory processing. Rewarding stimuli are often multisensory but it is not known how reward value is combined across sensory modalities. Here we show that the integration of reward value critically depends on whether the distinct sensory inputs are perceived to emanate from the same multisensory object. We systematically manipulated the congruency in monetary reward values and the relative spatial positions of co-occurring auditory and visual stimuli that served as bimodal distractors during an oculomotor task. The amount of interference induced by the distractors was used as an indicator of their perceptual salience. Our results across two experiments show that when reward value is linked to each modality separately, the value congruence between vision and audition determines the combined salience of the bimodal distractors. However, reward value of vision wins over the value of audition if visual and auditory stimuli have been experienced as belonging to the same audiovisual object prior to the learning of the reward values. The perceived spatial alignment of auditory and visual stimuli is a prerequisite for the integration of their reward values, as no effect of reward value was observed when the two modalities were perceived to be misaligned. These results show that in a task that highly relies on the processing of visual spatial information, the reward values from multiple sensory modalities are integrated with each other, each with their respective weights. This weighting depends on the congruency in reward values, exposure history, and spatial co-localization.

neuroscience↗

bioRxiv2018

I judge you by your profit: Judgments of effort exerted by selfand others are influenced by task contingent rewards

Effort constitutes a major part of cost-benefit calculations underlying decision making. Therefore, estimating the effort someone has spent on a task is a core dimension for evaluating own and others actions. It has been previously shown that self-judgments of effort are influenced by the magnitude of obtained rewards. It is unclear, however, whether the influence of reward on effort estimations is limited to self-judgments or whether reward incorporation represents a general computational principle when judging effort. Here we show that people also integrate reward magnitude when judging the effort exerted by others. Participants (N=48) performed an effortful sensorimotor task interleaved with a partner, while rating either their own or the other persons effort. After each trial but before the effort rating, both participants were informed about the obtained reward. We found that higher rewards led to higher estimations of exerted effort, in self-as well as other-judgments, and this effect was more pronounced for other-judgments. In both types of judgment, computational modelling revealed that reward information and the perceived level of exertion were combined in a Bayes optimal manner to form effort estimates. Remarkably, the extent to which rewards influenced effort judgments was positively correlated with conservative world-views, indicating that the basic computations underlying this behavioural phenomenon might be related to more general beliefs about the association between effort and reward in the society. The integration of reward information into retrospective effort judgments underscores the convergence of multiple information sources that supports adaptive learning and decision making in social contexts.

neuroscience↗