Biology subjects

Iyer, E. S.

Publications and source records attributed to Iyer, E. S..

4 recordsLinked to original sources

bioRxiv2026

Shared Latent Decision Strategies Underlie Reward-Guided Behavior Across Species

Adaptive behavior requires that organisms learn which actions are rewarded and to update action selection when the environment changes. While human and non-human animals exhibit adaptive behavior, whether apparently similar behavior reflects common decision strategies remains unclear. Probabilistic reversal learning provides a cross-species assay of reward-guided choice, yet standard metrics such as accuracy or reward rate can obscure underlying strategies that generate choices. Here, we applied parallel probabilistic reversal learning tasks in mice and humans and used a generalized linear model-hidden Markov model to infer latent decision strategies from trial-by-trial behavior. Across species, choices were organized into stable behavioral states with differing reliance on choice history, reward history, and response bias. Among these latent states, we identify a conserved reward-learning strategy in mice and humans characterized by the greatest feedback sensitivity, reward efficiency, and adaptation after reversal. Simulating choice behavior using state-specific decision policies reproduced the empirical hierarchy of performance, confirming that the latent states capture meaningful behavioral strategies. Although mice and humans differ in the temporal dynamics of reward learning, both species ultimately converge on the same optimized strategy. These findings identify a conserved latent reward-learning strategy in mice and humans, defining a translational framework for studying how adaptive decision-making is shaped by task experience, stress, affective processes, and neural circuit function.

neuroscience↗

bioRxiv2026

Dopamine in the ventral and tail of striatum supports global and local evaluation in reward-threat conflict

Survival requires balancing reward seeking and threat avoidance, yet how distinct dopamine systems coordinate to support this remains unclear. Using a naturalistic foraging paradigm in which mice pursue water reward under threat from a monster object, we examined roles of dopamine projections to the ventral striatum (VS) and tail of the striatum (TS). Ablation of VS- projecting dopamine neurons impaired both distal reward pursuit and threat avoidance, with the impairment in threat avoidance paralleling effects of TS dopamine ablation. However, simultaneous recordings revealed different activity rules: VS dopamine tracked radial velocity towards the current goal as animals changed goals (reward or shelter), consistent with a temporal-difference error of spatial value, while TS dopamine encoded proximity and orientation to the threat, reflecting immediate sensory experience. Taken together, VS and TS dopamine evaluates distinct state information for avoidance. VS dopamine facilitates allocentric, goal- directed navigation, while TS dopamine facilitates egocentric, stimulus-driven threat responses.

neuroscience↗

bioRxiv2025

Sex-specific exploration accounts for differences in valence learning in male and female mice

Valence, the quality by which something is perceived as good or bad, appetitive or aversive, is a fundamental building block of emotional experience and a primary driver of adaptive behavior. Pavlovian fear and reward learning paradigms are widely used in preclinical research to probe mechanisms of valence learning but with limited consideration of sex as a biological variable despite known sex differences in neuropsychiatric disorders associated with impaired valence. Here, we compare appetitive-only, aversive-only and mixed-valence cue-outcome Pavlovian conditioning paradigms in male and female mice to dissociate effects of context, valence and salience in a sex-specific manner. Using a data-driven approach to identify behaviors indicative of valence learning in an unbiased manner, we compare task performance between paradigms in male and female mice. We show that while male and female mice acquire appetitive and aversive associations in both single- and mixed-valence paradigms, sex differences emerge in single-valence paradigms. Ultimately, we show that these apparent sex differences in valence learning are driven by non-specific baseline differences in exploratory behavior. Males explore more at baseline, altering their trajectory of cue-reward association acquisition whereas females explore less at baseline, increasing shock facilitated freezing in aversive-only contexts, masking cue discrimination. Overall, our findings illustrate how task design differentially impacts behavioral expression in male and female mice and demonstrate that mixed-valence paradigms afford a more accurate assessment of valence learning in both sexes.

neuroscience↗

bioRxiv2024

Uncertainty gates redundancy in reward integration in prefrontal-cortical and ventral-hippocampal nucleus accumbens inputs to tune engagement

The NAc, a highly integrative brain region controlling motivated behavior, is thought to receive distinct information from various glutamatergic inputs yet strong evidence of functional specialization of inputs is lacking. While circuit neuroscience commonly seeks specific functions for specific circuits, redundancy can be highly adaptive and is a critical motif in circuit organization. Using dual-site fiber photometry in an operant reward task, we simultaneously recorded from two NAc glutamatergic afferents to assess circuit specialization. We identify a common neural motif that integrates reward history in medial prefrontal cortex (mPFC) and ventral hippocampus (vHip) inputs to NAc. Then, by systematically degrading task complexity, dissociating reward from choice and action, we identify key circuit-specificity in the behavioral conditions that recruit encoding. While mPFC-NAc invariantly encodes reward, vHip-NAc encoding is uniquely anchored to loss. Ultimately, using optogenetic stimulation we demonstrate that both inputs co-operatively modulate task engagement. We illustrate how similar encoding, with differential gating by behavioral state, supports state-sensitive tuning of reward-motivated behavior.

neuroscience↗