Behavioral Neuroscience

Our understanding of sex differences in reward learning has been limited due to the predominant study of males, yet recent studies have uncovered significant differences in the use of adaptive strategies, sensitivity to negative feedback, and impulsivity. Here, we evaluated sex differences in flexible learning in two domains: the learning of stimulus- and action-based associations and their reversals. During action-based learning, rats selected between two identical visual stimuli presented on a touchscreen, where the spatial location predicted a higher probability of reward. For stimulus-based learning, rats chose between two distinct visual stimuli presented in pseudorandom spatial locations, one of which was associated with a higher probability of reward. Reversal phases involved switching reward contingency between the two actions or stimuli. To gain a detailed understanding of diffferences across conditions, we modeled animals trial-by-trial choices using reinforcement learning (RL) models and examined their steady-state behavior to capture transitions between distinct behavioral states. We found that female rats were more likely to omit trials and take longer to initiate trials in both domains. The omissions were more frequent in late-stage action-based reversal learning, once learning had plateaued. Moreover, although the estimated parameters of the best-fitting RL model revealed some sex differences, the model that incorporated transitions between different behavioral states provided a better overall fit to the data. This model also revealed that across all reversal phases, females exhibited a higher transition-specific lapse rate than males, indicating greater task disengagement once there was no need for further learning. Together, our fine-grained analysis of behavior adds to a growing literature on sex differences in flexible reward learning.

Model-free and model-based computations are argued to distinctly update action values that guide decision-making processes. It is not known, however, if these model-free and model-based reinforcement learning mechanisms recruited in operationally based, instrumental tasks parallel those engaged by Pavlovian based behavioral procedures. Recently, computational work has suggested that individual differences in the attribution of incentive salience to reward predictive cues, i.e., sign- and goal-tracking behaviors, are also governed by variations in model-free and model-based value representations that guide behavior. Moreover, it is not appreciated if these systems that are characterized computationally using model-free and model-based algorithms are conserved across tasks for individual animals. In the current study, we used a within- subject design to assess sign-tracking and goal-tracking behaviors using a Pavlovian conditioned approach task, and, then characterized behavior using an instrumental multi-stage decision-making (MSDM) task in rats. We hypothesized that both Pavlovian and instrumental learning processes may be driven by common reinforcement-learning mechanisms. Our data confirm that sign-tracking behavior was associated with greater reward-mediated, model-free reinforcement learning and that it was also linked to model-free reinforcement learning in the MSDM task. Computational analyses revealed that Pavlovian model-free updating was correlated with model-free reinforcement learning in the MSDM task. These data provide key insights into the computational mechanisms mediating associative learning that could have important implications for normal and abnormal states. Significance StatementModel-free and model-based computations that guide instrumental, decision-making processes may also be recruited in Pavlovian based behavioral procedures. Here, we used a within-subject design to test the hypothesis that both Pavlovian and instrumental learning processes were driven by common reinforcement-learning mechanisms. Sign- tracking and goal-tracking behaviors were assessed in rats using a Pavlovian conditioned approach task, and, then instrumental behavior characterized using a multi- stage decision-making (MSDM) task. We report that sign-tracking behavior was associated with greater model-free, but not model-based, learning in the MSDM task. These data suggest that Pavlovian and instrumental behaviors are driven by conserved reinforcement-learning mechanisms.

Inferential reasoning is a vital cognitive ability that enables animals to navigate novel situations by leveraging existing relational knowledge of memory schema, with hypothesized roles of prefrontal cortical - hippocampal circuits. Transitive inference (TI) tasks test the ability of subjects to infer relationships within a value hierarchy (e.g., A>B>C>D>E) after being trained only on adjacent premise pairs (e.g., A-B, B-C, etc.). In rodents, current TI paradigms are primarily based on odor-cues and have several limitations that preclude investigation of physiological mechanisms underlying schemas and deliberation. To address these challenges, we developed a novel, automated spatial TI task for rats using a radial maze with maze arms as premise elements and a dedicated deliberation zone. Most rats successfully learned the premise pairs over training. Further, animals demonstrated rapid, successful inference (test pair B>D and control pair A>E) within a single test session, with higher initial accuracy than comparable premise pairs, indicating the use of schema-based inference. We also investigated vicarious trial and errors (VTE), a behavioral correlate of spatial deliberation. VTE behavior was elevated on choice trajectories early in learning, when novel premise pairs were introduced, and generally for incorrect trials, corresponding to the hypothesized association of VTEs with uncertainty. Further, rats also exhibited elevated VTE behavior with high variability during inference testing, with individual variability suggestive of varying strengths of schema usage. Our findings demonstrate the feasibility of a rodent spatial TI task that provides new insights into the behavioral correlates of schemas and deliberation for inferential reasoning.

The Progressive Ratio (PR) schedule is a popular test for measuring the motivational value of a reinforcer, in which subjects must exert an increasing amount of work to obtain each successive reward. Despite its popularity, the PR task hinges on a low-dimensional behavioral readout--breakpoint, or the maximum work requirement subjects are willing to complete before abandoning the task. Here, we show that with a simple modification, the PR task can be transformed into an optimization problem reminiscent of the patch-leaving foraging scenario, which has been analyzed extensively by behavioral ecologists, psychologists, and neuroscientists. In the Progressive Ratio with Reset (PRR) task, rats perform the PR task on one lever, but can press a second lever to reset the current ratio requirement back to its lowest value at the cost of enduring a reset delay, during which both levers are retracted. Rats used the reset lever adaptively on the PRR task, and their ratio reset decisions were sensitive to the cost of the reset delay. We derived an approach for computing the optimal bout length--the number of rewards to earn before pressing the reset lever that produces the greatest long-term rate of reward--and found that rats flexibly changed their behavior to approximate the optimal strategy. However, rats showed a systematic bias for bout lengths that exceeded the optimal length, an effect reminiscent of "overharvesting" in patch-leaving tasks. The PRR task thus represents a novel means of testing whether and how rats adapt their behavior to the cost-benefit structure of the environment in a way that connects deeply to the broader literature on associative learning and optimal foraging theory.

Cognitive flexibility can be defined as the ability to adaptively shift between choices or strategies based on environmental feedback and it is disrupted in numerous neuropsychiatric conditions. Individual differences in the computations supporting cognitive flexibility are poised to reveal mechanisms of neuropsychiatric risk and resilience. One critical variable well known to influence individual differences in neuropsychiatric risk is sex. While previous research has identified sex differences in value based decision making in mice, whether sex reflects a major source of variation in cognitive flexibility remains unknown. To directly assess sex-biased individual differences in cognitive flexibility, we developed a novel touchscreen Set Shift task that permits robust and continuous testing in mice. Using this task, we discovered that female mice completed significantly more rule shifts with fewer errors than males. We next employed a suite of computational models that revealed sex-biased individual differences in the computations underlying cognitive flexibility. Overall, our results suggest that following rule shifts, female mice learn the new rule faster and commit to exploiting rule choices sooner compared to males - sometimes because they commit to multiple rules simultaneously. This suggests that increased choice stability in female rodents enhances commitment to a strategy during periods of uncertainty and directly contributes to increased rule shifting. This supports the counterintuitive conclusion that a high degree of stable choice is a strong requirement for enhanced cognitive flexibility in the Set Shift task, one of the gold standard cognitive flexibility tasks.

The frontal cortex plays a critical role in decision-making. One specific frontal area, the anterior cingulate cortex, has been identified as crucial for setting a threshold for how much evidence is needed before a choice is made (Domenech & Dreher, 2010). Threshold is a key concept in drift diffusion models, a popular framework used to understand decision-making processes. Here, we investigated the role of the prelimbic cortex, part of the rodent cingulate cortex, in decision making. Male and female rats learned to choose between stimuli associated with high and low value rewards. Females learned faster, were more selective in their responses, and integrated information about the stimuli more quickly. By contrast, males learned more slowly and showed a decrease in their decision thresholds during choice learning. Inactivating the prelimbic cortex in female and male rats sped up decision making without affecting choice accuracy. Drift diffusion modeling found selective effects of prelimbic cortex inactivation on the decision threshold, which was reduced with increasing doses of the GABA-A agonist muscimol. Stimulating the prelimbic cortex through mu opioid receptors slowed the animals choice latencies and increased the decision threshold. These findings provide the first causal evidence that the prelimbic cortex directly influences decision processes. Additionally, they suggest possible sex-based differences in early choice learning.

Risky or maladaptive decision making is thought to be central to the etiology of both drug and gambling addiction. Salient audiovisual cues paired with rewarding outcomes, such as the jackpot sound on a win, can enhance disadvantageous, risky choice in both rats and humans, yet it is unclear which aspects of the cue-reward contingencies drive this effect. Here, we implemented six variants of the rat Gambling Task (rGT), in which animals can maximise their total sugar pellet profits by avoiding options paired with higher per-trial gains but disproportionately longer and more frequent time-out penalties. When audiovisual cues were delivered concurrently with wins, and scaled in salience with reward size, significantly more rats preferred the risky options as compared to the uncued rGT. Similar results were observed when the relationship between reward size and cue complexity was inverted, and when cues were delivered concurrently with all outcomes. Conversely, risky choice did not increase when cues occurred randomly on 50% of trials, and decision making actually improved when cues were coincident with losses alone. As such, cues do not increase risky choice by simply elevating arousal, or amplifying the difference between wins and losses. It is instead important that the cues are reliably associated with wins; presenting the cues on losing outcomes as well as wins does not diminish their ability to drive risky choice. Computational analyses indicate reductions in the impact of losses on decision making in all rGT variants in which win-paired cues increased risky choice. These results may help us understand how sensory stimulation can increase the addictive nature of gambling and gaming products.

Almost all individuals undergo reproductive and/or parenting experience at some point in their lives, and pregnancy and childbirth in particular are associated with alterations in the prevalence of several psychiatric disorders. Research in rodents shows that maternal experience affects spatial learning and other aspects of hippocampal function. In contrast, there has been little work in animal models concerning how reproductive experience affects cost-benefit decision making, despite the relevance of this aspect of cognition for psychiatric disorders. To begin to address this issue, reproductively experienced (RE) and reproductively naive (RN) female and male Long-Evans rats were tested across multiple tasks that assess different forms of cost-benefit decision making. In a risky decision-making task, in which rats chose between a small, safe food reward and a large food reward accompanied by variable probabilities of punishment, RE and RN males did not differ, whereas RE females chose the large risky reward significantly more frequently than RN females (greater risk taking). In an intertemporal choice task, in which rats chose between a small, immediate food reward and a large food reward delivered after a variable delay period, RE males chose the large reward more frequently than RN males, whereas RE females chose the large reward less frequently than RN females. Together, these results show distinct effects of reproductive experience on different forms of cost-benefit decision making in rats of both sexes, and highlight reproductive status as a variable that could influence aspects of cognition relevant for psychiatric disorders.

The cognitive mechanisms underlying behavior are often dynamic, shifting gradually or abruptly over time scales spanning years, to weeks, to minutes. Whether drug-induced changes in learning and decision-making follow similarly dynamic patterns remains unclear. To address this, we apply a reinforcement learning model to choice data from rats performing a two-step task for oral fentanyl and sucrose rewards. The model contains a set of agents with their own learning and decision-making rules that differentially influence choice, and, critically, each agents contribution to choice is allowed to vary across latent states that fluctuate over time. Using a dimensionality reduction method to align latent states across subjects, we identified three distinct states reflecting mixtures of goal-directed, habitual, and novelty-driven strategies. We found that acute fentanyl reward increased the frequency of transitions out of a goal-directed state into a habit-driven state, while chronic fentanyl exposure selectively diminished goal-directed control within a habit-dominant state, independent of sex. Together, these results demonstrate that fentanyl reshapes both the dynamics and cognitive architecture of decision-making, underscoring the utility of latent-state modeling combined with dimensionality reduction for uncovering drug-driven cognitive changes.

Orbitofrontal cortex (OFC) lesions cause deficits in flexible behavioural control, most notably response inhibition and has historically been linked to theories of response inhibition. This general inhibition hypothesis of OFC function has since been rejected by evidence that inhibitory behavioural control can be expressed following OFC damage, however the functional role of the OFC in the explicit learning of conditioned inhibition remains untested. Here we test whether muscimol disruption of OFC function during the learning stage of a Pavlovian conditioned inhibition procedure disrupted the learning of conditioned inhibitory associations. Muscimol abolished Inhibitory behavioural control during the learning phase, however learning about the conditioned inhibitor was intact when tested drug free in subsequent summation and retardation tests of conditioned inhibition. Muscimol also significantly impaired acquisition to control cues whose cue-outcome relationship did not change. In a second experiment, conditioned inhibition was found not to play a significant role in cue extinction (non-reinforcement), an effect that was disrupted by intra-OFC infusion of muscimol. These results confirm that the OFC is not functionally necessary for the learning of inhibitory associations but is critical to both the enhancement and suppression of responding when environmental contingencies change.

Sex differences have been documented in threat conditioning, but research into potential sex differences in avoidance paradigms, particularly active avoidance, remains limited. This research gap is particularly concerning given that women are disproportionately affected by stress- and anxiety-related disorders, characterized by maladaptive avoidance. Yet, preclinical research has historically focused on male subjects, limiting our understanding of the neurobiological mechanisms underlying sex differences in threat responses. To address this, we investigated sex-specific strategies in adult Long Evans rats (10 female, 9 male) using a modified platform-mediated avoidance (PMA) task that created a high-conflict choice between reward-seeking and safety. Behavior was tracked over 25 days, with analyses focusing on a stable performance phase (days 20-25) objectively defined using change point analysis. The study design included an initial cohort and a replication cohort to ensure the findings robustness. Females consistently prioritized safety, spending significantly more time foregoing reward to avoid foot shock, while males engaged in more persistent reward-seeking despite the risk of shock. This difference was not driven by differential reward motivation. Furthermore, female strategies were not significantly modulated by the estrous cycle. Thus, male and female rats employ fundamentally different strategies to resolve approach-avoidance conflict: females adopt a robust, safety-first strategy, while males demonstrate a risk-prone, reward-oriented approach. These findings highlight the importance of considering biological factors underlying threat responses, suggesting that characterizing these neural mechanisms may guide more targeted interventions for anxiety and trauma-related disorders.

Curiosity and exploration support learning and adaptive decision-making in uncertain environments. While these processes are sensitive to motivational context, it remains unclear how outcome valence shapes exploration across species. Human studies suggest that aversive contexts increase exploration, but these effects often rely on verbal framing and explicit instructions. To gain deeper insight into how exploration strategies emerge from experience alone, this study investigated the influence of hedonic valence on novelty seeking, exploration, and reinforcement learning in rhesus macaques. Using visual tokens as secondary reinforcers, we found that monkeys explored novel, uncertain options more frequently when exploitation would lead to losses rather than gains. However, our analyses clarified that this heightened novelty seeking was primarily a consequence of the monkeys employing an optimistic prior belief about the value of novelty, rather than a categorical, valence-dependent shift in their underlying curiosity or the information bonus associated with exploration. Approach and avoidance motivation did influence other aspects of reinforcement learning. Monkeys demonstrated faster learning from losses than from gains, indicating that they were averse to losing tokens. They also frequently chose an option and then quickly aborted their choice. These choice balks were strategic responses to approach-avoidance conflicts and uncertainty, and represented self-generated bouts of exploratory behavior that led to valence-dependent use of directed and random exploration. These findings suggest that different strategies are used to manage explore-exploit tradeoffs induced by novelty or internal motivational conflicts, revealing dissociable effects of curiosity and hedonic valence on reinforcement learning.

In monkeys, the muscarinic cholinergic receptor antagonist scopolamine is known to broadly disrupt learned behaviors, though the precise nature of the cognitive deficits has been questioned. Experimentally observable deficits in memory can be ascribed to poor attentional focusing, human interference as well as age, sex, and dosing regimen. Stress and social isolation can also play a role during behavioral testing, particularly in small nonhuman social primates like marmosets that have been used widely. In this study, we examine the effects of scopolamine in marmosets under conditions of reduced stress, attentional distraction, and human interference. Using a custom designed home-cage touchscreen-based testing system, we investigated the influence of scopolamine on the performance on a visual associative learning task. During self-paced, voluntary testing, monkeys learned to discriminate pairs of complex visual patterns through trial and error by touching the stimulus associated with reward. Using this approach, we demonstrated over 75% discrimination accuracy in the eight marmosets tested (male and female) within three days of home-cage testing. Although the averaged data revealed no impact of acute or chronic scopolamine injections on learning, modeling the choice data with trial-level analysis revealed both age- and sex-specific deficits. The results demonstrate the value of home-cage testing combined with trial-level analysis to reveal subtle behavioral changes, such as those brought about by scopolamine. Significance statementWe created a custom home cage testing system to test the effects of muscarinic cholinergic blockade on complex discrimination learning in marmoset monkeys. We found that systemic scopolamine administration disrupts visual association learning in a manner that was specific to older females. This deficit was hidden in session-averaged measures and only became evident in trial-level modeling of the choice data. Our findings demonstrate that cholinergic blockade impairs the dynamics of learning in marmosets and highlights the value of trial-level analysis for detecting nuanced pharmacological effects on primate cognition.

Cognitive flexibility, the capacity to adapt behaviour to changes in the environment, is impaired in a range of brain disorders, including substance use disorder and Parkinsons disease. Putative neural substrates of cognitive flexibility include mesencephalic pathways to the ventral striatum (VS) and dorsomedial striatum (DMS), hypothesised to encode learning signals needed to maximize rewarded outcomes during decision-making. However, it is unclear whether mesencephalic projections to the ventral and dorsal striatum are distinct in their contribution to flexible reward-related learning. Here, rats acquired a two-choice spatial probabilistic reversal learning (PRL) task, reinforced on an 80%:20% basis, that assessed the flexibility of behaviour to repeated reversals of response-outcome contingencies. We report that optogenetic stimulation of projections from the ventral tegmental area (VTA) to the nucleus accumbens shell (NAcbS) in the VS significantly impaired reversal learning when optical stimulation was temporally aligned with negative feedback (i.e., reward omission). Moreover, the exploitation-exploration parameter, {beta}, was increased (indicating greater exploitation of information) when this pathway was optogenetically stimulated after a spurious loss (i.e. an incorrect (20%) response at the 80% reinforrced location) compared to after a spurious win (i.e. a correct (20%) response at the 20% reinforced location). VTA [->] NAcbS stimulation during other phases of the behavioural task was without effect. Optogenetic stimulation of projection neurons from the substantia nigra (SN) to the DMS, aligned either with reward receipt or omission or prior to making a choice, had no effect on reversal learning. These findings are consistent with the notion that enhanced activity in VTA [->] NAcbS projections leads to maladaptive perseveration as a consequence of an inappropriate bias to exploitation via positive reinforcement.

Humans and other social animals can represent and navigate complex networks of social relationships in ways that are suggestive of representation and navigation in space. There is some evidence that cortical regions initially required for processing space have been adapted to include processing of social information. One candidate region for supporting both spatial and social information processing is the posterior parietal cortex (PPC). We examined the hypothesis that rats can transfer or generalize distance information across spatial and social domains and that this phenomenon requires the PPC. In a novel apparatus, rats learned to discriminate two conspecifics positioned at different spatial distances (near vs. far) in a goal-driven paradigm. Following spatial learning, subjects were tested on probe trials in which spatial distance was replaced with social distance (cagemate vs. less familiar conspecific). The PPC was chemogenetically inactivated during a subset of probe sessions. We predicted that, in control probe trials, subjects would select conspecifics whose social distance matched the previously learned spatial distance. That is, if trained on the near distance, the rat would choose the highly familiar cagemate, and if trained on the far distance, the rat would choose the less familiar conspecific. Subjects learned to discriminate conspecifics based on spatial distance in our goal-driven paradigm. Moreover, choice for the appropriate social distance in the first probe session was significantly higher than chance. This result suggests that rats transferred learned spatial information to social contexts. Contrary to our predictions, PPC inactivation did not impair spatial to social information transfer. Possible reasons are discussed. To our knowledge, this is the first study to provide evidence that spatial and social distance are processed by shared cognitive mechanisms in the rat model.

Impulsive choice is the suboptimal preference for a smaller-sooner (SS, "impulsive") option over a larger-later (LL, "self-controlled") option. Fixed-interval (FI) training delivers delayed-reinforcement trials to increase LL choices and improve FI timing precision. While there are plenty of studies exploring the neurobiological factors underlying impulsive choice, it is unknown what neurobiological changes account for the FI training effects. The prelimbic cortex (PL) region is implicated in both impulsive choice and timing. To investigate the role of the PL, we used designer receptors exclusively activated by designer drugs (GiDREADDs) to reversibly inhibit the PL during either the FI training phase or the follow-up impulsive choice task in male and female Sprague-Dawley rats. Compared to a control group, the GiDREADDs rats showed reduced LL choices when CNO was administered during the FI training or impulsive choice tasks. GiDREADDS did not alter response rates or latency to choose. Overall, these data demonstrate that inhibition of the PL increases impulsive choice and may block the effect of the FI training to improve self-control.

Aversive associative learning paradigms such as inhibitory avoidance (IA) are frequently used to examine episodic-like memories in rodents. In IA, rodents learn to associate a context with a footshock, followed by testing for memory strength in the original training context and for memory precision in a similar yet distinct neutral context. The present work assessed the effects of different contextual exposure procedures on memory strength and precision in IA at both recent and remote time points using male and female Long-Evans rats. An initial experiment found that rats kept in the lit (non-shock) compartment of the IA apparatus for 60 s during training, as opposed to 10 s, displayed enhanced memory strength, with discrimination between both chambers at the recent retention test and generalization at the remote retention test. Subsequent experiments investigated the effects of contextual pre-exposure the day before training. The results indicate that pre-exposure to the neutral context promoted generalization without altering memory strength compared to the first experiment. In contrast, pre-exposure to the aversive chamber promoted discrimination and enhanced memory strength. Notably, the different procedures yielded similar effects in both sexes. However, the results also indicate an overall pattern of greater contextual discrimination in females compared to males. These findings provide evidence for how different contextual exposures influence the degree of encoding at the time of training and a behavioral foundation for future studies examining the neurobiological mechanisms underlying memory strength and precision in IA, while highlighting the importance of using both sexes in initial behavioral work. Significance StatementStrength and precision are two fundamental properties of memory that can be simultaneously measured using inhibitory avoidance (IA), a type of context-footshock association task. However, little is known about how different context exposures alter rats encoding of these memories, thereby influencing subsequent memory strength and precision. Here, we found that pre-exposure to the neutral IA chamber decreased memory precision, whereas pre-exposure to the aversive IA chamber promoted memory strength and precision. Additionally, females demonstrated overall enhanced memory precision compared to males. These results indicate that different types of contextual exposures influence initial IA encoding and add to a limited body of research examining memory strength and precision in IA in both sexes.

The growing interest in ontogenetic studies of learning and memory, along with early-life perturbations, has led to the use of younger rodents as a key biological variable in many investigations. This development prompts an important question about whether procedures and apparatuses designed for studying learning and memory in adults should be simply adapted for use with younger and smaller rodents. The current study examined how arena size affects novel object recognition (NOR) performance in juvenile and adult rats. A commonly used larger arena reliably detected novel object preference in adults but not in juveniles. Adjusting the arena size based on average weight differences between age groups improved the consistency of NOR performance in juvenile rats. Sex differences were observed: adult males performed reliably across all arena sizes, whereas adult females required larger arenas to demonstrate effective NOR performance. These findings highlight the importance of tailoring arena dimensions to developmental stage and sex for accurate cognitive assessment. Specifically, they support the use of weight-based arena scaling as a methodological approach in developmental neurobehavioral research and emphasize the importance of careful design when studying female rodents. Future studies should explore similar environmental adjustments for other behavioral tests in juvenile and female populations.

Animals typically learn to solve decision tasks in the laboratory through trial and error, rather than through explicit instruction of decision rules. The decision rule used by the animal may be difficult to read out directly from choice or accuracy data, when multiple decision rules are possible given the task design. Here, we demonstrate that in rats performing a visual decision task, probe stimuli can be used to gain information about decision strategy, and in our task revealed variation in the decision strategies used across rats. Further, we find that in a more general version of this task, rats use varying decision strategies that differ from the optimal ideal observer strategy, but respond to manipulations of the stimulus distribution by adjusting their behavioral strategy. Therefore, we show that informative probe stimuli can be used in both training and testing to confirm and shape behavioral strategy in a perceptual decision task.

Studies of visual discrimination in rodents can confound the effects of cue salience with reward value, making it difficult to determine which factor guides choice behavior. We examined this issue by testing how changes in relative salience affect decision dynamics in rats performing a two-alternative forced-choice task in which rats chose between visual cues associated with high or low sucrose rewards. After initial training with high and low luminance cues, we introduced a novel cue of intermediate luminance as a "luminance shift" test. The intermediate luminance cue substituted for either the brighter or dimmer cue and had the same reward value as the cue that it replaced. We found that while rats maintained a preference for the higher-value option, the introduction of a perceptually more similar cue consistently reduced choice preference and eliminated latency differences compared to baseline. Using drift diffusion modeling, we determined that the luminance shifts primarily caused a reduction in the drift rate (the speed of evidence accumulation), reflecting increased difficulty in cue discrimination. This finding suggests that the relative salience of the options determines the efficiency of evidence accumulation in value-based decisions. Furthermore, this effect on drift rate shows a dissociation from our previous work (Palmer et al., 2024), where prefrontal cortex inactivation specifically affected only the decision threshold. Our results demonstrate that relative salience influences deliberation, with low-level perceptual features shaping the computational dynamics of value-based choice. Our findings clarify the distinct contributions of sensory input and prefrontal function in the decision process. Significance StatementThis study reveals that changes in the relative salience of visual stimuli shape the computational dynamics of value-based decisions. We trained rats to make visually guided choices and found that relative differences in the brightness of the stimuli affect how quickly the rats made decisions and how often they chose a higher-value option. Our findings, together with a recent study on the role of the prefrontal cortex in value-guided decisions (Palmer et al., 2024), suggest that separate factors influence choice dynamics in rodents: visual salience affects the speed of deliberation, while prefrontal activity regulates caution. This study helps clarify how sensory and higher cognitive variables relate to the distinct computational components of the decision process.