Biology subjects

Shestakova, A.

Publications and source records attributed to Shestakova, A..

5 recordsLinked to original sources

bioRxiv2025

Reward impulsivity is linked to addictive-like behaviors towards sweet food and sugary drinks but not fatty food

Overconsumption of hyperpalatable food is a worldwide problem. Although many previous studies have shown the link between monetary delay discounting and propensity to overconsume food, the studies did not focus on the link between delay discounting and various subcategories of palatable food. In the present study, we investigate the link between the individual propensity to choose smaller immediate rather than larger delayed reward and the degree of problematic eating behavior for five types of palatable food (sweets, sugary drinks, fatty food, salty snacks, and starchy food). The delay discounting task was used to measure propensity to choose immediate rather than delayed rewards, while the degree of addictive-like behavior was measured using the modified Yale food addiction scale (mYFAS) for each food category. Both model-free and model-based analysis showed that there is a significant correlation between the addiction score for sweet food and the tendency to choose smaller immediate rather than larger delayed rewards. A model-based analysis showed the same significant correlation for sugary drinks. However, no such correlation was observed for other food categories (fatty, salty, or starchy food), suggesting that reward impulsivity may play different roles in addictive-like behavior towards various food categories.

neuroscience↗

bioRxiv2022

Ambiguous tDCS: transcranial direct current stimulation effects on performance of monetary incentive delay task reinforcement learning

Transcranial electrical stimulation (tES) serves as a powerful technique for assessing the causal role of specific brain regions in behavior, including decision-making. While tES studies investigating sensorimotor function yield unequivocal results, cognitive research reveals considerable ambiguity and diversity in stimulation-related effects. The consequences of transcranial direct current stimulation (tDCS) on cognitive functioning are not consistently predictable based on the current direction (cathodal or anodal), which limits its applicability in cognitive research. In the present study, we further explored tES effect ambiguity in cognitive tasks by modulating medial frontal cortex (MFC) activity in an auditory monetary incentive delay (MID) task, where participants responded to acoustic cues encoding expected monetary losses using cathodal tDCS. We analyzed feedback-related negativity (FRN), reflecting prediction error processing when participants encountered losses compared to no losses during two subsequent MID task sessions, and exogenous P2 response to stimulus onset unrelated to anticipated monetary incentives. We anticipated an inhibitory cathodal tDCS effect on both P2 response and FRN. Contrary to our expectations, we observed a facilitatory effect of cathodal tDCS on FRN, replicating our earlier results (Gorin et al., 2022). No effect of stimulation was observed on P2; however, tDCS influenced the learning effect of P2. The difference in P2 amplitude between the first and second sessions, observed in the sham group, was absent in the group that received cathodal tDCS. We offered the interpretation of the complex picture of tES effects during auditory MID performance in light of brain plasticity theory for P2 and reward-learning mechanisms for FRN. Importantly, our findings regarding the multidirectionality of tDCS effects on cognitive function challenge the utility of tES as a readily employable method for testing brain causality in highly complex neurocognitive events, such as decision-making.

neuroscience↗

bioRxiv2020

Adaptive learning under strategic and structural uncertainty: the case of auction games

In games of incomplete information individual players make decisions facing a combination of structural uncertainty about the underlying parameters of the environment, and strategic uncertainty about the actions undertaken by their partners. How well are human actors able to cope with these uncertainties, and what models best describe their learning in such environments? We use a double auction task with different competitive and informational environments to characterize learning abilities of the single human participants (buyers) in a range of adaptive learning models covering reinforcement learning, directional learning and belief learning. Results show that real behaviour is best described using simple models of directional learning type with minimal knowledge assumptions about information efficiency of prices. This behavior is consistent with bounded rationality and risk aversion: human subjects try to maximize their chance for transaction, and do so using the simplest learning rule.

animal behavior and cognition↗

bioRxiv2018

Action in auctions: neural and computational mechanisms of bidding behavior

Competition for resources is a fundamental characteristic of evolution. Auctions have been widely used to model competition of individuals for resources, and bidding behavior plays a major role in social competition. Yet how humans learn to bid efficiently remains an open question. We used model-based neuroimaging to investigate the neural mechanisms of bidding behavior under different types of competition. Twenty-seven subjects (nine male) played a prototypical bidding game: a double action, with three \"market\" types, which differed in the number of competitors. We compared different computational learning models of bidding: directional learning models (DL), where the model bid is \"nudged\" depending on whether it was accepted or rejected, along with standard reinforcement learning models (RL). We found that DL fit the behavior best and resulted in higher payoffs. We found the binary learning signal associated with DL to be represented by neural activity in the striatum distinctly posterior to a weaker reward prediction error signal. We posited that DL is an efficient heuristic for valuation when the action (bid) space is continuous. Indeed, we found that the posterior parietal cortex represents the continuous action-space of the task, and the frontopolar prefrontal cortex distinguishes among conditions of social competition. Based on our findings we proposed a conceptual model that accounts for a sequence of processes that are required to perform successful and flexible bidding under different types of competition.

neuroscience↗

bioRxiv2016

RL mechanisms of short-term plasticity of auditory cortex

The decision-making process is exposed to modulatory factors, and, according to the expected value (EV) concept the two most influential factors are magnitude of prospective behavioural outcome and probability of receiving this outcome. The discrepancy between received and predicted outcomes is reflected by the reward prediction error (RPE), which is believed to play a crucial role in learning in dynamic environment. Feedback related negativity (FRN), a frontocentral negative component registered in EEG during feedback presentation, has been suggested as a neural signature of RPE. In modern neurobiological models of decision-making the primary sensory input is assumed to be constant over the time and independent of the evaluation of the option associated to it. In this study we investigated whether the electrophysiological changes in auditory cues perception is modulated by the strengths of reinforcement signal, represented in the EEG as FRN.\n\nWe quantified the changes in sensory processing through a classical passive oddball paradigm before and after performance a neuroeconomic monetary incentive delay (MID) task. Outcome magnitude and probability were encoded in the physical characteristics of auditory incentive cues. We evaluated the association between individual biomarkers of reinforcement signal (FRN) and the degree of perceptual learning, reflected by changes in auditory ERP components (mismatch negativity and P3a). We observed a significant correlation of MMN and valence - dFRN, reflecting differential processing of gains and omission of gains. Changes in P3a were correlated to probability - dFRN, including information on salience of the outcome, in addition to its valence.\n\nMID task performance evokes plastic changes associated with more fine-grained discrimination of auditory anticipatory cues and enhanced involuntary attention switch towards these cues. Observed signatures of neuro-plasticity of the auditory cortex may play an important role in learning and decision-making processes through facilitation of perceptual discrimination of valuable external stimuli. Thus, the sensory processing of options and the evaluation of options are not independent as implicitly assumed by the modern neuroeconomics models of decision-making.

neuroscience↗