Learning & Memory

Stored memories are useless unless they are available for retrieval. Thus, investigating different ways to modulate retrieval is crucial. Novelty has been extensively studied as a modulator of memory. In this study, we investigated whether exposure to a novel event, an innovative neuroscience lesson, can enhance memory retrieval and divergent thinking in high school students. Across three experiments, we assessed the timing and mechanisms underlying these effects. In experiment 1, we found that memory retrieval was enhanced when the novel lesson occurred immediately before a memory test, but not when it was presented one hour earlier. In experiment 2, we found that the same immediate novelty exposure improved divergent thinking performance. Finally, in experiment 3, we explored potential shared mechanisms using a competition protocol and revealed that novelty improved divergent thinking regardless of its timing relative to memory retrieval. However, memory retrieval benefited only when tested immediately before the divergent thinking task. These results suggest that novelty boosts both memory retrieval and divergent thinking, but through partially distinct mechanisms. Our findings demonstrate that a simple, real-world classroom intervention can effectively enhance key cognitive functions in students. Significance StatementStored memories are only valuable if they can be retrieved, and memory retrieval plays a key role in creative thinking. Here, we tested whether a simple, novel event, a neuroscience lesson, could enhance memory retrieval and creative thinking in a real-world classroom setting. We found that novelty improved both memory retrieval and divergent thinking, an aspect of creative thinking, when presented immediately before the task. Finally, we revealed a non-reciprocal competition effect between memory retrieval and divergent thinking. These findings highlight a practical, low-cost intervention to boost key cognitive functions in students, demonstrating that brief, well-timed novel experiences can support both learning and creative thinking in educational environments.

The midsession reversal (MSR) task is frequently used to study behavioral flexibility and decision strategies in animals. In a typical version of the task, subjects complete 80 trials in which they choose between two simultaneously presented stimuli, S1 and S2. During the first 40 trials, responses to S1 are reinforced, whereas responses to S2 are not. The contingencies then reverse without warning: From trial 41 to 80, only responses to S2 are reinforced. In birds, performance in this task is often characterized by anticipatory and perseverative errors around the reversal point, suggesting a reliance on elapsed time since the session began. In contrast, rats tested in operant conditioning chambers typically show near-optimal performance with few errors, a pattern often interpreted as evidence that rats rely primarily on local reinforcement cues rather than temporal information. The present study investigated whether rats exclusively rely on local cues in the MSR task or whether temporal information also contributes to the decision process. Two groups of rats were trained with different intertrial intervals (ITIs; 5 s or 10 s) while the reversal point remained fixed at Trial 41. During acquisition, both groups diplayed similar learning rates and near-optimal steady-state performance with minimal anticipatory or perseverative errors. However, when the ITI was manipulated in probe sessions, systematic shifts in switching behavior emerged. Rats adjusted their choices according to the temporal midpoint experienced during training rather than the nominal trial number of the reversal. These results suggest that rats rely on a mixed strategy that integrates local reinforcement cues with global timing information. Temporal control may therefore be present even when it is not expressed during standard training conditions.

Traumatic stress can cause long-lasting changes in cognition and affect, sometimes leading to diagnoses such as post-traumatic stress disorder (PTSD). The stress-enhanced fear learning (SEFL) model recapitulates understudied components of PTSD, such as stress-induced sensitization of fear learning. The SEFL procedure entails exposing mice to footshock stress followed later by fear conditioning in a different context. When tested later for recall of fear conditioning, previously stressed mice exhibit enhanced freezing compared to non-stressed controls. Studies have shown that dorsal and ventral dentate gyrus (DG) generates neural ensemble representations of contextual fear, such that fear recall involves reactivation of a sparse set of "engram cells" that were active during fear memory acquisition. How stress affects these hippocampal ensemble representations is unknown. We used SEFL and activity-dependent neuronal tagging with FosTRAP2 mice to investigate effects of stress on fear memory ensembles in rostral and caudal hippocampal DG. FosTRAP2/Ai6 mice received footshock stress or equivalent context exposure without shock in Context A on day 1. Five days later, mice received 1-shock conditioning in Context B and immediately received an injection of 4-OHT (55mg/kg) to tag fear acquisition neurons with the zsGreen reporter. One day later, mice were tested for fear recall in Context B and were perfused 90 minutes after testing. Confirming prior studies, prior stress potentiated 1-shock conditioning in Context B, with stressed mice displaying higher freezing in the Context B test session than non-stressed mice. At the level of neural activity, results showed stress had no effect on the number of zsGreen+ fear ensemble cells or the number of cfos+ recall-activated cells in rostral or caudal DG. However, stress increased reactivation (percentage of zsGreen+ cells expressing cfos) in the caudal but not rostral DG. The results suggest stress potentiates later fear learning by enhancing fear representations in caudal hippocampus, a region of the hippocampus specialized for integrating emotional and motivational valence into memory.

Accurate and efficient memory processing is essential for survival. Recent work in human subjects and animal models has suggested that memory processing may differ in meaningful ways between males and females. In mice, contextual fear memory (CFM) encoding, consolidation, and recall have been well studied, and the mouse hippocampus and amygdala have been implicated in these processes. The present study addresses how the specific contribution of these brain regions to each stage CFM processing in female vs. male mice. We find that male and female mice show no differences in CFM recall, nor in sleep behavior in the hours following single-trial contextual fear conditioning (CFC), which is essential for CFM consolidation. However, females - but not males - show significantly increased expression of cFos in dorsal hippocampal CA1 and CA2 neurons during CFM encoding. On the other hand, males - but not females - show increased cFos expression among DG granule cells during CFM consolidation. These findings highlight the fact that the neurobiological underpinnings of memory processing may differ between males and females, even when recall performance is identical. Scope statementHistorically, research on the neurobiological basis of memory processing has been carried out mainly in male subjects. Thus, our understanding of these mechanisms is biased towards male brain neurophysiology. Recent studies have variously reported performance differences for episodic memory tasks, in which male subjects perform better, worse, or the same as females. Here, we find that male and female mice perform similarly on a well-studied experimental memory task but nonetheless have differences in the relative activity of different brain structures during sequential stages of memory processing. This emphasizes the importance of including both males and females in memory studies, due to potential sex differences in the neurobiological substrates of memory.

Spatial memory is invaluable for most mobile organisms, yet nature of the underlying representations that we employ for spatial memory has been fiercely contested. On the one hand, the presence of place cells in the hippocampus and grid cells in the medial entorhinal cortex appear to support the argument spatial representations may follow Euclidean axioms, termed "the cognitive map hypothesis." On the other hand, decades of behavioral research in humans reveals that spatial memory often shows characteristic distortions, leading to the alternative, cognitive graph hypothesis, to account for this aspect of spatial memory. Importantly, the majority of laboratory studies tend to occur within novel environments in which participants often have only limited exposure and no personal relevance. We were interested in studying large-scale memory across multiple time scales: from a virtual environment (e.g., learned over several minutes) to a college campus (e.g., months to a few years) to a hometown environment (e.g., many years). Across several tasks, we found that participants exhibited systematic distortions in their memory for all of these environments. Likewise, we found significant correlations between performance on several spatial memory tasks (both between participants and within-participant analyses of patterns of errors), thus suggesting that these tasks tap into partially overlapping cognitive representations and supporting their construct validity. Altogether, our findings provide clear evidence for cognitive graph hypothesis and support the construct validity of several spatial memory tasks within large-scale, real-world environments that are learned over the course of several months to years. Public Significance StatementSpatial memory is key for our ability to live independent lives (e.g., patients with Alzheimers disease lose independence, partially due to disorientation in familiar environments). Typical laboratory-based measures of spatial memory use novel environments that may differ in complexity vs. real-world environments (e.g., size, layout, number of landmarks, duration of exploration, personal relevance). We leveraged breakthroughs in technology to study spatial memory across several tasks and temporal scales, from a novel environment navigated over the course of several minutes to a university campus (e.g., months to years) to hometowns (e.g., years to decades). We observed consistent evidence for systematic distortions in spatial memory, which supports the hypothesis that spatial memory is supported by a cognitive graph, thus posing an important challenge to the extremely influential Euclidean, "cognitive map" hypothesis that was awarded a Nobel Prize in 2014.

By relying on the observation of others experiences, humans learn about threat while avoiding harmful experiences. Yet, previous neuroscience research has focused on observational threats that are predictable. While the neurobiological distinction between temporally predictable (cued) and unpredictable (contextual) threats has been well-characterized in firsthand learning. In this study, we developed a novel observational paradigm in which participants learned from predictable (P) and unpredictable (U) observational threats, as well as a no-threat (N) condition and encountered the same conditions during an expression phase based on the NPU paradigm to investigate how the brain encodes predictable and unpredictable threat cues observed in others. Participants in Experiment 1 (n=20, male and female) and Experiment 2 (n=23, male and female) successfully learned threat contingencies, showing heightened threat expectations for predictable cues and unpredictable contexts. This converged with neural (fMRI, Experiment 2) responses in the anterior insula during the expression phase. Reflecting the dynamic process of learning, the amygdala responded to predictable threat cues with a linear decrease across trials. Interestingly, we found that responses to others pain was enhanced within the amygdala, insula and hippocampus, when participant could learn to predict threats, as compared to unpredictable conditions. Our findings suggest that humans learn to resolve temporal uncertainty, relying solely on observation, which thereby lays a foundation to the concept of fear and anxiety in social groups.

Cerebellar communication with the prefrontal cortex (PFC) may play a significant role in cognitive functions. Our previous studies found that rule-based (RB) category learning depends on the PFC in humans and rats. The PFC is also crucial for behavioral flexibility following rule-changes in various tasks. Very little is known regarding the role of the cerebellum in RB category learning. The current study was designed to determine whether the cerebellum plays a role in RB category learning, and in categorization following a rule switch. Female and male rats were given bilateral lesions of the lateral cerebellar nuclei (LCN) or a control surgery and trained on an RB category learning task followed by a category rule switch. A subset of rats was trained on a control discrimination task with the same trial procedures as the categorization task. Rats with LCN lesions took significantly longer to learn both the first and second category rules but were not impaired on the control task. Computational modeling revealed less task engagement and increased switching between engaged and non-engaged states in the LCN lesion group. Several measures of task performance indicated that the category learning deficit was not caused by a motor impairment, response bias, or an inability to discriminate the stimuli. The category learning deficits with LCN lesions were related to reduced accuracy of stimulus classification, an inability to maintain task engagement, and loss of flexibility. The results show, for the first time, that the cerebellum plays a crucial role in category learning and category rule-switching.

In associative fear learning, weak or temporally constrained training may fail to link a conditioned stimulus (CS) with an aversive unconditioned stimulus (US), particularly when the contextual representation is impaired (the immediate shock deficit). Here, we systematically tested behavioral conditions that enable linking of an initially neutral auditory memory trace to an aversive episode. Male C57BL/6 mice were studied in four experiments manipulating (i) preexposure to a CS tone, (ii) the duration of context exploration before immediate footshock, and (iii) whether CS memory was tested in a novel or a familiar-like context. A 5 s tone followed immediately by footshock did not induce reliable fear to either the CS or the training context. CS preexposure three days before conditioning did not facilitate CS aversive memory when animals were tested in a completely novel context. However, robust facilitation emerged when the CS memory was tested in a context similar to the preexposure/conditioning one, indicating strong contextual gating of CS retrieval. Extending context exploration before shock enabled CS fear learning, but reduced (and even reversed) the effect of CS preexposure, consistent with latent inhibition. Together, these results delineate behavioral constraints for linking an initially neutral cue memory to an aversive event and highlight contextual control over the coupling and expression of cue memory traces.

How does the structure of events influence the when and the where of experience in comparison to the what? We developed a novel virtual reality (VR) environment to understand how the quantity of information within nested structures influence participants memory for events. Participants moved through a series of virtual rooms (events) where images (items) appeared in randomised locations on a 3 by 3 grid located on a wall. Participants were asked to remember the what (old/new), when (timeline location), and where (grid location), of the images they experienced. Two types of nested events were tested (6 rooms, each containing 4 images; 3 rooms, each containing 8 images) without a difference in the number of seconds of presentation. We found a strong temporal compression effect at nested levels in which participants remembered early items and events happening later, and later items and events happening earlier, than the original experience. Crucially, presenting four-item events resulted in a greater compression rate than eight-item events. We also found greater temporal distances between pairs of items occurring within eight-item events than pairs of items which occurred on either side of a boundary. Memory for when depends on the compression of information within events.

Computational models and neurobehavioral data suggest that encoding variability affects forced-choice mnemonic discrimination. Here, we experimentally manipulated encoding variability on the forced-choice Mnemonic Similarity Task by varying stimulus repetitions during encoding. We first generated predictions from a global matching model. Behavioral data supported all predictions. Across most conditions, repetitions consistently enhanced mnemonic discrimination; however, when encoding variability was induced by 3-repetitions of the original version of the non-corresponding lure and 1-repetition of the target during learning, individuals exhibited increased interference. These findings provide further insight into theories of human memory, especially the effect of stimulus repetition on mnemonic discrimination.

Reports of honeybees demonstrating abstract concepts like sameness and difference marked a pivotal development in comparative psychology. Subsequent studies expanded the scope of concept learning in honeybee cognition, yet most evidence relies on a single method: the delayed-matching-to-sample task using a Y-maze. Whether this setup is uniquely effective or if alternative approaches could yield similar results remains unresolved. Additionally, the failure of bumblebees (Bombus spp.) to complete this task, despite honeybees demonstrating success, remains unexplained. This study compared the performance of honeybees (Apis mellifera) and bumblebees (Bombus terrestris) across matching-to-sample tasks with varying degrees of physical continuity between sample and target stimuli. The objectives were twofold: to evaluate an alternative method for assessing concept learning in both species and to investigate potential species differences in such tasks. Contrary to prior findings, neither species succeeded at the reported proficiency levels in simultaneous matching-to-sample tasks. Moreover, bumblebees outperformed honeybees in one task. These results are consistent with an explanation based on species-specific differences in visual attention mechanisms, and underscore the need for further research on concept learning in social bees.

Memory generalization allows individuals to extract and apply information from prior experiences to novel situations, supporting flexible learning and efficient decision-making. Theoretical models suggest that sleep should facilitate generalization, yet the literature examining its role in promoting generalization is mixed. We recruited 137 participants via Prolific to complete an image-location memory task over two sessions spaced 12 hours apart. Participants were randomly assigned to the Wake group (learning in the morning) or the Sleep group (learning in the evening). In Session 1, participants learned the location of stimuli on the screen and were tested on their memory five minutes later. Twelve hours later, in Session 2, they were tested on their memory again. Stimuli consisted of 160 images from eight semantic categories and were strategically positioned on-screen to test the effects of generalization on retrieval (i.e., category-based memory distortions and biases). After the delay, retrieval was less accurate and demonstrated more generalization. However, these effects were mostly independent of Group, with some evidence for enhanced generalization following a period of wakefulness over sleep. Generalization was also driven by time of day, with more generalization in the evening relative to the morning. Taken together, our results, based on a large online sample, do not support a role for sleep in promoting memory generalization. Significance StatementBehavior is often guided by memories of previous experiences. However, for behavior to be adaptive and flexible (e.g., when encountering never-before-seen stimuli), regularities about the world must be extracted from these memories. This process, termed memory generalization, has been hypothesized to rely on sleep. We used a large online sample to test sleeps role in generalization and found no support for this hypothesis. Our results suggest that sleep and wakefulness contribute to generalization equally, with the latter potentially having a larger contribution.

Visual working memory allows for the brief maintenance of information to serve behavioral goals. It has been shown that when the specific action required to serve a future goal is predictable, people can flexibly change a visual memory representation to incorporate an action-based one, demonstrating the goal-oriented nature of visual working memory. Can such flexibility also be observed within the visual domain, between color and space? In this eye-tracking study, participants remembered either a centrally presented color or a spatial position around fixation. Critically, when remembering a color the response wheel was either randomly rotated, or shown at a fixed rotation, on every trial. When fixed, every target color could be associated with a predictable position on the wheel during response. Do people incorporate this added spatial information in their behavior? Participants utilized color-space associations when remembering color: Response initiation happened faster when the color wheel was fixed compared to random, irrespective of whether an action could be planned or not. Next, we showed that gaze was biased towards the position of the spatial memory target during the delay, extending previous work on gaze biases. Importantly, also when remembering a color, gaze was biased towards the anticipated position of that color on the response wheel when it was fixed. Together, our results show a behavioral benefit of added spatial information for color memory, and systematic changes in gaze that reflect flexible utilization of space.

Habits in humans are commonly studied through outcome devaluation paradigms, but most existing tasks fail to capture the robustness of habitual behavior seen in animal models. I introduce two novel behavioral tasks designed to overcome these limitations. In the first task, ("shooting aliens task", n = 45), I simplified an existing instrumental learning task and implemented a novel intra-block reversal method in which stimulus positions changed unexpectedly within blocks while maintaining the same stimulus-action mappings. Participants also completed a classical devaluation phase with explicit reward changes. In the second task ("hands-attack task", n = 44), which relied on real-life avoidance behavior, devaluation was achieved by reversing reward contingencies and allowing participants to inhibit the dominant avoidance response in favor of a more effortful counterattack. Across both tasks, overtrained conditions led to more errors and longer response times after devaluation, confirming increased insensitivity to outcome change. Intra-block reversals in the shooting aliens task produced stronger habitual signatures than standard whole-block devaluation, revealing a greater cost of overriding automatic responses. In the hands-attack task, even without prior training, participants showed clear markers of habitual behavior, suggesting that real-world action patterns can replicate key features of laboratory habits. Interestingly, participants were more accurate in overriding overtrained responses when attacks were highly familiar, possibly due to enhanced perceptual processing, although this came at the cost of longer response times. These findings introduce two complementary tools that address key limitations in current paradigms: the intra-block reversal increases habit sensitivity without inflating working memory demands, while the hands-attack task captures naturalistic habit expression without artificial training, using a single, ecologically valid session. Both are suited for clinical applications, particularly where time constraints or cognitive load limit the feasibility of traditional approaches.

Nucleus accumbens (NAc) dopamine 2 receptor expressing medium spiny neurons (D2-MSNs) are involved in stress and aversive learning, where repeated stress increases excitatory spine density. Whether this plasticity reflects cue-specific learning or generalized stress response remains unknown. Using Pavlovian fear conditioning in Tac1-Cre/Tdtomato mice, we dissociated associative plasticity from the effects of foot shock stress. Acute fear conditioning produced distinct physiological outcomes between stress in the presence or absence of a cue. Conditioning for 7 days consolidated cue learning and increased excitatory transmission frequency via an increase in the total spine density. However, repeated exposure to foot shock did not lead to this synaptic remodeling. Our results suggest that morphological changes supporting synaptic plasticity on NAc D2-MSNs are due to cue-dependent learning, but not foot shock stress alone. We propose that NAc D2-MSNs encode learning and response to threat cues, which may heighten later stress responsivity.

Predictions can alter working memory (WM) representations. However, its effects may have been mischaracterized due to the use of precise predictions in previous experiments, where exact properties of upcoming memory items are cued in advance. Here we investigated a more ecologically valid scenario, in which we assessed the impact of diffuse predictions, where advance cues provided only partial knowledge about the targets. To investigate the resultant nature of the target representations in WM, we performed a series of multivariate analyses of EEG data. Forty participants judged whether a probe grating was rotated clockwise or counterclockwise relative to a memorized orientation, which was either predictable or unpredictable. Each memory item was preceded by a central color cue (red, green, or blue). In half of the trials, two of these (predictive) colors cued two non-overlapping 90{degrees} segments of orientations that the grating was sampled from. Thus, participants knew the range of possible orientations of these items, but not their exact orientation. In the other half of the trials, a third (non-predictive) color was presented, signaling that the item could have any possible orientation. Behavioral results revealed higher accuracy for predictable items, with systematic biases toward the center of the cued segment. EEG results revealed equally successful decoding of orientation for both predictable and unpredictable items during memory encoding. However, cross-condition decoding was significantly weaker than within-condition decoding, suggesting that the encoding format changed between conditions. Representational similarity analysis showed higher similarity between predictable items, with a representational bias towards the cued segment. Covariance matrices showed lower variance for predictable items while the representational space of predictable items was shrunk. These effects were absent during the maintenance phase. Together, our findings suggest that diffuse predictions alter the geometric layout of the neural representations and stabilize the neural code during WM encoding.

Visual false memory refers to our tendency to falsely recognize novel stimuli that are visually similar to seen stimuli. Visual false memory also occurs when stimuli are meaningful, suggesting that semantic information interferes with the encoding of visual details. However, the neural mechanisms of this semantic interference effect are largely unknown. In the present fMRI study, participants were scanned while encoding visually similar fonts presented with words (word-fonts) or pseudowords (pseudoword-fonts), and later, when recognizing old, new similar (lures), and new dissimilar (novel) fonts displayed in the same meaningless letter string. We performed (1) representational similarity analysis (RSA) at encoding to identify visual, visuosemantic, and semantic representations associated with subsequent visual true and false font recognition, (2) encoding-retrieval similarity (ERS) analysis to assess their reinstatement during retrieval, and (3) mediational analyses to examine hippocampal contributions. The study yielded three main findings. First, visuosemantic representations supported true font recognition when stored in right fusiform gyrus, but false recognition of word-fonts when stored in the left fusiform gyrus. Second, mirroring this pattern, reinstatement in right fusiform gyrus was associated with true font recognition, whereas reinstatement in left fusiform gyrus was linked to false recognition of word-fonts. Finally, posterior hippocampal activation reduced false font memory mainly for pseudoword-associated fonts via decreased reinstatement in perceptual regions, while anterior hippocampal activity increased false memory of word-fonts via enhanced reinstatement in semantic regions. Taken together, these findings reveal how distinct hippocampal-cortical pathways differentially bias memory towards perceptual specificity or semantic generalization. Significance StatementFalse memories are often triggered by visual similarity, but this study shows that meaning encoded during learning can distort memory for visual details, even when retrieval cues are meaningless. Participants learned fonts associated with words or pseudowords and judged whether similar lure fonts, shown on a meaningless letter string, were seen before. Although behavioral performance was similar across conditions, brain imaging revealed a key dissociation: the left fusiform gyrus and anterior hippocampus promote semantic generalization that increases false recognition, whereas the right fusiform gyrus and posterior hippocampus support perceptual specificity that protects against it. These findings reveal how distinct hippocampal-cortical pathways differentially bias memory toward truth or illusion.

Voltage-gated CaV2.2 channels are essential for neurotransmitter release throughout the nervous system including areas related to learning and memory like the hippocampus. Previous results have shown that CaV2.2 channels are involved in cognitive processes. However, a link between alternative splicing of the Cacna1b (gene that encodes for CaV2.2) pre-mRNA and cognitive processes has not been described. The Cacna1b pre-mRNA undergoes extensive cell-specific alternative splicing. In this body of work, we focus on the cassette exon 18a. Alternative splicing of exon 18a generates two splice variants, +18a-Cacna1b and {Delta}18a-Cacna1b. Exon 18a encodes a 21-amino acid sequence within the SYNaptic PRotein INTeraction (synprint) site. Splice variants containing exon 18a (+18a-CaV2.2) show reduced cumulative inactivation and increased Ca{superscript 2} current density compared to splice variants lacking exon 18a ({Delta}18a-CaV2.2), suggesting functional specialization. We previously showed that +18a-Cacna1b splice variants are enriched in cholecystokinin-expressing interneurons (CCK+INs). This neuronal type is strongly implicated in associative learning. Therefore, we tested whether alternative splicing of exon 18a contributes to associative learning. To test this hypothesis, we used genetically engineered mice that constitutively express either +18a-Cacna1b (+18a) or {Delta}18a-Cacna1b ({Delta}18a). We first validated that restricted splicing of exon 18a did not alter downstream alternative or constitutive spliced exons in the Cacna1b pre-mRNA, nor total CaV2.2 protein levels. We then performed a comprehensive behavioral analysis that included assessment of associate learning. We found that in the trace fear conditioning task, +18a mice exhibited less freezing during the trace interval in both the acquisition and memory phases compared to WT mice. Whereas {Delta}18a mice showed enhanced freezing during the same intervals relative to WT mice. These bidirectional phenotypes reveal that exon 18a shapes aversive associative learning. Furthermore, exon 18a splicing did not influence spatial working memory, spatial navigation under stress, nociceptive responses in basal and inflammatory conditions, overall locomotion or exploratory behavior. These results suggest that the behavioral impact of exon 18a splicing is highly selective. Together, our findings identify alternative splicing of exon 18a as a molecular contributor to associative learning.

Reward learning can bias attentional selection, but whether spatially biased reinforcement produces durable, context-general changes in spatial priority over days, and what neurophysiological signals track such learning, remains uncertain. We combined electroencephalography (EEG) and pupillometry with a multi-session spatial reward-learning paradigm (Chelazzi et al., 2014) in which targets could appear at eight locations and reward probability was systematically biased across locations during two days of training. A separate baseline/test visual detection task was administered before training and again four days after training to assess delayed transfer under cross-target competition. Training produced strong reward signals across measures. Feedback-locked ERPs (FRN and P300) differentiated outcome valence and reward magnitude and varied systematically with time-on-task, while pupil dilation was larger following high- than low-reward feedback and overall task-evoked responses decreased across blocks. Reward history also modulated stimulus-locked target processing: targets at high- versus low-reward locations differed reliably across N1/N2 and a late positivity, indicating multi-stage value-dependent influences on visual processing during active learning. In contrast, transfer was weak in both behavior and ERPs: behavioral indices did not show a reliable advantage for highly rewarded locations at delayed test, and neural evidence for persistence was limited to an N2 modulation in the most diagnostic high-versus-low comparison, which should be interpreted cautiously given low trial counts. Accordingly, we did not replicate the robust long-term spatial priority effect reported in the original study. Together, these findings reveal strong reward-learning signals but weak cross-task transfer, suggesting limits on how readily spatial reward learning consolidates into persistent, task-general spatial priority-map plasticity across contexts.

Brainstem arousal systems including the locus coeruleus noradrenaline system, re-spond transiently to behaviorally relevant events. Locus coeruleus activity also drives dilations of the pupil, which are often observed during cognitive tasks. The strength of pupil responses during encoding of stimulus material predicts the success of its later retrieval, which might reflect the impact of noradrenaline on synaptic plasticity and memory formation. The pupil also dilates in response to task-irrelevant sounds, which could therefore serve as a valuable tool for investigating causal effects of phasic, pupil-linked arousal on cognition. Here, we evaluated whether task-irrelevant white noise sounds affect memory formation and memory-based decisions. These sounds were played before, during or after the presentation of memoranda (images or spoken words). Memory success was measured in recognition and free recall tasks the day after. Trial-to-trial variations in the amplitude of pupil dilations during word encoding without task-irrelevant sounds predicted memory success. Task-irrelevant white-noise sounds also robustly dilated the pupil but did not improve memory formation for the words or the images. We conclude that pupil-linked arousal processes triggered by task-irrelevant sounds differ from those recruited endogenously during memory for-mation, for example in states of increased emotionality or attention.