eneuro

The Quebec 1000 Families (Q1K) platform has been designed to recruit, phenotype, and collect biospecimens from a large cohort of families with at least one member with autism spectrum disorder or a related neurodevelopmental condition. As part of the Q1K protocol, an experimental test battery was developed and validated using simultaneous high-density electroencephalography (EEG) and eye tracking (ET). We report on the general approach and design principles, multimodal EEG/ET integration, the tasks, and their validation, providing a blueprint for implement such a project. It also describes the cohort and its methods as a reference for future studies using this dataset. By releasing openly this experimental test battery, we aim to support task standardization and multi-project data pooling in autism and related neurodevelopmental disorders.

GapAutomated spike sorting algorithms have revolutionized the way neuronal activity is extracted from extracellular recordings, yet they remain imperfect. Specifically, inaccurate acceptance of noise-based units not only leaves researchers with clusters that require extensive manual curation, an essential but time-consuming process, that also leads to significant subjectivity in the selection of units. In an era of high-density probes like Neuropixels, where an hour of data can exceed 80 GB, manual curation is no longer scalable, automation of standard criteria can speed data curation and ensure quality of datasets. Here, we developed a semi-automated curation pipeline to label the quality of units after automated curation by Kilosort. ApproachOur algorithm standardizes criteria for labeling of Noise, Multi-Unit Activity (MUA), and Good Units using a combination of spike rate, spike timing metrics (from autocorrelogram), and waveform-based physiological features such as peak amplitude, slopes, half-width, and inter-channel correlation. Based on these features, clusters are assigned standardized labels (good, noise, multi-unit activity) that can be imported directly into Phy, where they serve as curation aids rather than absolute classifications, supporting but not replacing expert judgment. Heuristically, "noise" units are those unlikely to be neuronal in origin; "MUA" includes units with significant neural contribution (i.e., neuronal waveform) but with some degree of clear imperfection to be further cleaned, and "good" units are those without any clear deviation from ideal unit criteria. By ensuring accurate selection of acceptable units, we enable robust downstream analyses such as neural decoding and longitudinal tracking of neuron identity. Thresholds for all metrics were chosen to maximize the matching of algorithm output to that of 2 expert manual curators. Of note, users may alter thresholds either based on their own judgment or using an included tool to semi-automatically find thresholds that optimize SpikeCleaner with their own expert curation. Results: To benchmark, we compared the outputs of our algorithm to expert-labels curated in Phy by two expert users across three recordings. SpikeCleaner achieved an average of 97% accuracy vs. experts & 92% F1 score in classifying Single Units. It achieved an accuracy of 97% & 92% F1 score in full-category agreement (SU, MUA, Noise), and 97% accuracy & 95% F1 score in distinguishing Neuronal vs. Non-Neuronal units.

Neurophysiology datasets are becoming increasingly complex, combining behavioral measurements with high-dimensional neuronal activity recordings coming from optical and/or electrophysiological measurements. The Neurodata Without Borders (NWB) standard has emerged in the community as the format of record. While standardized and widely used preprocessing tools generating NWB files have been developed, extensible frameworks for scientific analysis downstream of the NWB ecosystem are still under-represented. We present CICADA, a Python framework dedicated to analysis of neurophysiological data in the standardized NWB format. The toolbox is built as three hierarchically-organized packages: cicada-nwb (NWB access layer), cicada-analysis (plugin-based analysis engine and tool library), and cicada-gui (PyQt5 desktop application at the head of the pipeline). Beyond this architectural separation, CICADA is built around a central design principle: supporting a continuum from turnkey use to full modularity. Researchers can use the complete GUI-driven cicada-gui workflow without writing code, programmatically use existing analysis plugins from cicada-analysis, contribute to new analysis plugins, reuse utilities from cicada-tools, or build entirely custom pipelines on top of the cicada-nwb access layer alone. The same analysis plugin runs identically in interactive GUI and parameter-configured headless modes, enabling reproducible multi-session, multi-animal group analyses. We illustrate the versatility of CICADA with example analyses of behavioral, calcium imaging (two-photon and widefield) and extracellular electrophysiology datasets from rodent laboratories. CICADA is open source, actively maintained, and designed so that any laboratory can contribute at any level of the stack without modifying the core framework.

Tonic glutamate signaling by ambient levels of extracellular glutamate has been implicated in development, brain injury, pathologies, and physiological activity. However, it has been difficult to assay extracellular glutamate changes with spatial and temporal resolution. Here, we utilize the rarely used ratiometric excitations properties of the fluorescence glutamate sensor iGluSnFr to enable the characterization of ambient glutamate levels in acute brain slices. This ratiometric imaging enables a spatial, temporal and calibratable assay of ambient glutamate and demonstrates regional differences in ambient glutamate and sensitivity to glutamate transporters and system Xc inhibition.

During natural vision, the human brain constantly has to account for self-produced interruptions of visual input, through blinks and saccades, to maintain a stable perception of the world. It remains unclear whether these event-related neural responses are treated similarly due to a common underlying mechanism. To systematically investigate this functional connection, we recorded synchronized mobile EEG and eye-tracking data from freely moving participants as they (visually) explored a city center. Our results replicate prior findings showing that a substantial portion of the neural response is aligned to event onsets in comparison to offset, underscoring the relevance of investigating the beginning and end of these events. Using advanced deconvolution techniques, we disentangled overlapping, time-locked neural contributions associated with the onsets and offsets of saccades and blinks. The results demonstrate that the deconvoluted neural kernels are highly correlated when comparing saccade onset to blink onset, as well as saccade offset to blink offset, for both evoked and induced activity across electrodes. Together, our findings demonstrate that despite their distinct physical profiles, saccades and blinks share a common neural signature that governs both their onset and offset dynamics during unconstrained real-world behavior. HighlightsO_LICo-registration of portable EEG and Eye-Tracking yielded meaningful real world data. C_LIO_LIWe studied blinks and saccades as natural interruptions of visual processes. C_LIO_LIAligning EEG data to onset and offset underscored the relevance of both timepoints. C_LIO_LIWe deconvoluted overlapping neural activity for onsets/offsets of saccades/blinks. C_LIO_LIERPs and TFRs are highly correlated for onset/offset of blinks and saccades. C_LI

Dopamine is involved in disorders that degrade cognition such as Parkinsons disease, ADHD, addiction, and schizophrenia; however, it is unclear how dopamine modulates brain circuits involved in cognitive processing. We investigated this problem by recording dopamine during interval timing, an elementary task that requires executive functions to estimate an interval of several seconds by making a motor response. We harnessed the fluorescent dopamine sensor dLight1.3b to record relative dopamine dynamics in the mouse dorsomedial striatum, which integrates information from cognitive cortical circuits and is required for interval timing. We found that: 1) dopamine activity ramped down during interval timing prior to increasing at reward delivery; 2) dopamine ramping dynamics predicted interval timing behavior; and 3) dopamine ramping dynamics were distinct between male and female mice and affected by amphetamine, a potent modulator of dopamine. These data provide insight into how dopamine modulates striatal circuits during interval timing and help better understand how dopamine dynamics contribute to cognitive dysfunction in dopamine-related brain diseases.

Traumatic brain injury (TBI) impacts millions of individuals annually causing death, disability, and a heightened risk for long-term neurological and neuropsychiatric disorders. In recent years the fruit fly, Drosophila melanogaster has become a valuable model organism to study the cellular and molecular responses following TBI. AP-1 mediated transcriptional responses to TBI have previously been identified in Drosophila using pan-glial approaches. Fruit flies possess multiple glial subtypes which vary greatly in both cellular morphology and function, including glia of the blood hemolymph barrier, cortex, astrocyte-like, and ensheathing glia. By generating and utilizing a nuclear localized AP-1 transcriptional reporter, we identified glial subtype-specific differences in the extent of AP-1 activation following injury. Our findings identify a strong AP-1 response in the blood hemolymph barrier and ensheathing glia, a moderate response in cortex glia and little to no AP-1 activation in astrocyte-like glia. In addition, we inhibited AP-1 signaling in each glial subtype and tested the effect on acute survival. We found that inhibition of the AP-1 response in neuropil ensheathing glia leads to increased mortality following mild and moderate TBI. These results show that AP-1 activation levels vary across glial subtypes after TBI, with activation in neuropil ensheathing glia having a particularly important role in promoting post-injury survival. ARTICLE SUMMARYUsing Drosophila as a model organism, we investigated the early molecular and cellular response to traumatic brain injury. Our findings substantiate the requirement of a functional glial associated AP-1 transcriptional activation response for survival. Using colocalization studies, we characterized the AP-1 glial response in six morphologically and functionally distinct glia subtypes. After TBI, we find high levels of AP-1 activation in glia of the hemolymph brain barrier, cortex glia, and ensheathing glia. We further show the importance of AP-1 transcription within the neuropil ensheathing glia subtype for optimal survival following TBI.

The development of a new integrated operant system was driven by two challenges in behavioral neuroscience: the high cost and technical complexity of commercial rigs, and their limited adaptability across experiments. We developed the NeuroHab, an integrated behavioral arena for high-fidelity operant conditioning and automated data collection in a single unified system. Food and water reward, conditioned-stimulus presentation, and event recording are tied together programmatically with easy-to-install open-source code to facilitate throughput and reproducibility. All behavioral events are processed by internal microcontrollers and logged with <1 ms latency (typical range 56-728 s). This precise timing is critical for integrating the system with two-photon imaging and electrophysiology, enabling real-time alignment of behavior with brain activity. The NeuroHab uses solenoid-actuated, capacitive-sensing Lickports that let an untethered mouse drink from an automated port, and delivers food via the Kravitz Lab FED3. Conditioned stimuli are presented by dedicated buzzer/LED modules. A central controller (the Core) coordinates all modules and logs event timestamps using TTL-low signaling between two microcontrollers, at a maximum recording rate of 16.67 Hz for single-pulse events. We have deployed the NeuroHab in over 50 behavior trials and over 20 sessions alongside a Mini two-photon microscope. At approximately $1,400, easily modified, and compatible with existing analysis tools, the NeuroHab lowers barriers to multimodal behavioral neuroscience. Significance StatementThe study of how neural activity gives rise to behavior depends on operant systems that are both temporally precise and affordable, yet commercial rigs are costly and difficult to adapt across experiments. We introduce the NeuroHab, an integrated, open-source operant platform that unifies reward delivery, conditioned-stimulus presentation, and event logging with sub-millisecond timing (typical latency 56-728 s). Built for approximately $1,400, the system forwards all behavioral timestamps to external acquisition hardware, enabling millisecond-scale alignment of behavior with two-photon imaging and electrophysiology. By lowering the cost and technical barriers to synchronized behavioral and neural recording, the NeuroHab makes multimodal, reproducible operant neuroscience accessible to a broad range of laboratories and adaptable to diverse experimental paradigms.

Abstract/SummaryEstrogens, commonly known for their role in sexual development and maturation, support a wide variety of brain functions, including cognition, neuroprotection, and sensory processing. For example, in a songbird auditory forebrain region, caudomedial nidopallium (NCM), neuroestrogens are elevated in response to conspecific vocal and social stimuli; in turn, elevated neuroestrogens in NCM are known to rapidly enhance auditory processing independent of sex. Despite the pivotal role of neuroestrogens for brain function, it remains largely unknown whether aromatase (neuroestrogen-synthesizing) neurons differ in their cellular and physiological properties from non-aromatase-expressing neurons, as might be expected from specializations seen in other steroidogenic cell types (e.g., adrenal cells). Therefore, we systematically profiled aromatase and nonaromatase expressing NCM neurons to determine how they might differ in synaptic and current input properties, using ex vivo whole-cell electrophysiology followed by immunohistochemistry to reveal aromatase expression. Current-clamp recordings revealed no differences between aromatase and nonaromatase neurons, aside from a modest divergence in the time to reach peak membrane afterhyperpolarization. Similarly, voltage-clamp recordings of post-synaptic currents revealed no significant differences between the two cell types, suggesting that they share similar synaptic input density. Therefore, aromatase and nonaromatase NCM neurons share similar intrinsic membrane properties (e.g. excitability) and synaptic input dynamics in the higher songbird pallium. Our findings leave open the possibility that diverging computational and/or modulatory roles for aromatase vs. non-aromatase neurons could be due to projection- or neurochemical-specificity in their afferents and efferents. Significance StatementNeuroestrogens, locally synthesized in the brain by aromatase-expressing neurons, modulate neural circuit function across diverse brain regions, yet it remains unclear whether these cells represent a specialized neuronal population. We used whole-cell electrophysiology and post hoc identification of recorded neurons in the zebra finch auditory forebrain to compare the intrinsic and synaptic properties of aromatase and nonaromatase neurons. Confirming and extending previous findings, we show that aromatase-expressing neurons are not defined by unique electrophysiological properties. Instead, they appear to be functionally integrated within auditory circuits, supporting an alternative idea that neuroestrogen signaling acts through flexible neuromodulatory mechanisms rather than specialized neuronal properties. These findings do not exclude the possibility that aromatase neurons receive selective modulatory input from other brain regions.

It has been demonstrated that people who stutter exhibit atypical motor control not only in speech tasks but also movements in the non-speech effector system, such as finger or arm motion. Notably, studies have reported that people who stutter show limited sensorimotor adaptation (i.e., updating subsequent movements in response to sensory errors) in both speech auditory-motor (i.e., updating speech movements in response to altered auditory feedback) and upper limb visuo-motor (i.e., updating arm movements in response to altered visual feedback) tasks. Given that speech auditory-motor adaptation is mostly if not entirely implicit (i.e., participants are unaware of the learning), it is thought that people who stutter have limited implicit adaptation in the speech effector system. It remains unclear however, whether such limited implicit learning also extends to upper limb visuomotor adaptation. Here, we examined implicit visuomotor learning in adults who stutter through the means of arm reaching adaptation to clamped visual feedback which provides a cursor that is fixed in direction (8{degrees} counterclockwise from targets) regardless of the participants actual hand location. All participants gradually adjusted their reach angle towards the clockwise direction, adapting in response to clamped feedback, but adults who stutter showed less adaptation compared to adults who do not stutter. In addition, computational modeling suggests that this implicit adaptation difficulties in stuttering individuals may reflect reduced error sensitivity. Together, our findings suggest that implicit sensorimotor learning difficulties in adults who stutter may generalize across multiple effector systems, providing important implications for understanding sensorimotor mechanisms underlying stuttering. Significance statementBy employing the clamped visual feedback paradigm during arm reaching movements, we demonstrated that adults who stutter showed less implicit visuomotor adaptation compared to adults who do not stutter. This study provides the first evidence that implicit sensorimotor adaptation limitations in developmental stuttering generalize across multiple effector systems. Our findings not only add to a growing body of evidence that stuttering is associated with domain-general sensorimotor difficulties but also point to specific underlying processes that may lead to stuttering.

Multisensory integration is a fundamental feature of cortical processing, yet the functional pathways that deliver visual signals to the auditory cortex remain poorly understood. While anatomical studies reveal multiple candidate projection routes, demonstrating their causal contribution requires targeted manipulation of neural activity. Here, we used cortical cooling to reversibly inactivate the posteromedial lateral suprasylvian cortex (PMLS) and the adjacent area 21 to determine the functional role of higher-order visual areas in generating visual responses within the auditory cortex of the ferret. Units responsive to sound, light, or combined audiovisual stimuli were found across all sampled auditory fields and cortical depths, with visual responses most prominent within the infragranular layers and the non-tonotopic secondary auditory cortex of the Anterior Ectosylvian Gyrus (AEG). Cortical cooling induced robust, bi-directional, and stimulus-specific modulations of firing rates in AC. Approximately 50% of visually responsive units exhibited a significant decrease or complete elimination of visual activity during cooling, confirming a functional role for visual input from PLMS/area 21 to AC. Surprisingly, cooling also revealed circuit-level complexities: a subset ([~]5%) of units showed enhanced or newly emergent visual responses during inactivation, suggesting that PMLS/area 21 normally exerts a gating influence over alternative visual pathways. Furthermore, contrary to feedforward anatomical predictions, neurons in the AEG--the region most heavily innervated by the cooled visual areas --were less frequently impacted by cooling than those in PEG. Together, these findings demonstrate that higher visual areas causally shape cross-modal processing in the auditory cortex through a complex mixture of direct excitation and network-level modulation.

A critical step in visual cortical maturation is refinement of receptive field (RF) size, producing higher acuity vision. This was previously studied using species with well-developed vision (e.g., carnivores, primates), in which visual experience was necessary for refinement but not maintenance of RFs in visual cortex. In contrast, in Syrian hamsters, a crepuscular species with low visual acuity, dark rearing had no effect on RF refinement in juveniles, but RFs re-enlarged in adulthood, resulting in reduced acuity. These inter-species differences raise the question of whether the need for visual experience is primarily related to the phylogenetic position of the species or to its ecological niche. Here we report that dark rearing had no effect on development or maintenance of RF properties of visual cortical neurons in nocturnal mice. Mice with lifelong visual deprivation refined and maintained their RF size over time. Furthermore, the development of stimulus direction tuning was unaffected by dark rearing. In contrast, surround suppression, orientation tuning and the sharpness of direction tuning were abnormal in dark reared mice. These and our previous results from hamsters show that species living in an ecological niche with minimal daylight exposure require little to no visual experience to develop and maintain refined RFs. This study is an important step in developing a better understanding of the role of visual experience in the development of visual processing circuitry and suggests that diurnal mammals may be a better model for human visual cortical development than mice.

Despite our best efforts to stay focused on a task, our arousal waxes and wanes over time. Lower levels of arousal are typically associated with drowsiness, whereas higher levels are often associated with stress. These changes in arousal move us away from ideal task performance and manifest as fluctuations in neural activity. We asked whether moment-by-moment neurofeedback could be used to counteract neural fluctuations and thereby regulate arousal levels. Here, we developed an intracortical brain-computer interface (BCI) in which animals used visual neurofeedback to maintain neural population activity in prefrontal cortex near a pre-specified activity target. We found animals used moment-to-moment neurofeedback to reduce neural fluctuations on timescales of seconds to hundreds of milliseconds, and that arousal-related regulation of neural activity was associated with BCI use. Our findings suggest that neurofeedback may enhance or restore regulation of neural activity, with potential clinical applications in conditions where such regulation is impaired.

Drosophila connectomic datasets provide increasingly comprehensive maps of neuronal morphology and synaptic connectivity, offering an unprecedented opportunity to explore the structural organization of its neural circuits. This calls for designing automated tools to interact with connectomic datasets at scale for efficiently exploring structural features embedded in the vast amount of data. Yet the central challenge remains the understanding of the functional logic of neural circuits. In order to understand how elements of the functional logic may emerge from this structural organization, it is critical to (i) characterize the objects in the natural environment in which brain circuits operate, and (ii) formulate how brain circuits represent and process the defined objects in the natural environment. To develop and demonstrate a methodology for these requirements, we focus on the Drosophila looming-evoked escape pathway. We modeled the trajectory of looming objects that are on a collision course (direct-hits) or pass-by the fly (near-misses): their projected images on the retina can be characterized by the solid angle (angular size) and elevation. We then analyzed the pathway's morphology across the OpticLobe, Hemibrain, and FlyWire connectome datasets. By abstracting their sub-neuronal structure and retinotopic organization, we constructed an executable circuit model that maps each structural element to a processing block. We demonstrate that this model separates direct hits from near misses well before the angular size could tell them apart. To accelerate the connectomic analysis step, we developed a Python toolset with an agentic, code-free workspace interface called NeuroGraphBench (NGB). NGB provides four composable morphology-analysis primitives and an AI agent that composes them to interactively respond to natural-language queries aided by visualization on an interactive 3D canvas. Thus, NGB automates tedious and repetitive tasks to enable faster and scalable connectomic exploration, keeping human reasoning, instead of writing code, at the center of an open-ended research inquiry.

Astrocytes play an important role in neuronal health. A critical function of astrocytes is to clear excess extracellular glutamate and prevent excitotoxicity. STAT3 is a transcription factor that promotes astrocyte development and astrocyte reactivity in neurodegenerative diseases and following central nervous system injury. To determine the innate molecular and behavioral functions of adult astrocyte-expressed STAT3 in a non-pathological state, we created conditional Stat3 astrocyte knockout mice (Stat3 aKO) using Stat3flox and the tamoxifen-activated Cre line, Aldh1l1-Cre/ERT2. We measured transcript levels of Gfap, a known STAT3 target gene, and glutamate transporter genes in the medial prefrontal cortex (PFC) of Stat3 aKO. Gfap, Slc1a2 and Slc17a8 transcripts were decreased in the PFC of Stat3 aKO of both sexes. GLT-1 protein, encoded by Slc1a2, was also reduced in the PFC of male Stat3 aKO. We recorded spontaneous excitatory post-synaptic currents (sEPSCs) in male Stat3 aKO and control prelimbic pyramidal neurons and found increased sEPSC amplitude, consistent with a hyper-glutamatergic state due to impaired glutamate clearance. To determine the behavioral consequences of STAT3 depletion in astrocytes, Stat3 aKO were tested for locomotor activity, anxiety-like behavior and binge ethanol consumption, behaviors linked to dysregulation of glutamate homeostasis. Stat3 aKO mice did not differ in locomotor activity or anxiety-like behavior; however, male Stat3 aKO mice consumed significantly less ethanol than controls. These results indicate that STAT3 in adult astrocytes is crucial for maintaining glutamate transporter levels in the adult brain and that astrocytic STAT3 promotes ethanol consumption in male mice. Main pointsO_LIGfap, Slc1a2 and Slc17a8 expression are lower in the cortex of Stat3 astrocyte knockout mice (Stat3 aKO) C_LIO_LIGLT-1 protein is decreased and glutamate neurotransmission is elevated in the cortex of male Stat3 aKO C_LIO_LIMale Stat3 aKO consume less ethanol C_LI

The early-onset, high-frequency hearing loss phenotype of CD-1 mice is rescued by the A88V mutation of the connexin 30 gap-junctional protein, despite a reduced endocochlear potential (EP), which drives cochlear hair cell receptor potentials. The mutation enables organ of Corti (OoC) extracellular receptor potentials to be similar in size to those of sensitive-hearing CBA/J mice, presumably through increased OoC resistance, despite smaller intracellular outer hair cell (OHC) receptor potentials. Low-frequency hearing in CD-1Cx30A88V/A88V mice is impaired, compared with those of CBA/J and wild-type CD-1 mice. To investigate the cellular basis of OoC resistance increase and EP decrease, we made in situ electrophysiological measurements from Deiters cells (DCs) in the OoC of homozygous CD-1Cx30A88V/A88V mice. DCs contribute to the OHC cytoskeletal scaffold and cochlear K+ recycling, and are interconnected by syncytial junctions comprising connexins 30 and 26. Measurements from CD-1Cx30A88V/A88V mice were compared with those from wild-type CD-1 mice, with sensitive hearing below 12 kHz, and from the CBA/J strain. Syncytial junctional-coupling between DCs of CD-1Cx30A88V/A88V mice was weaker, input resistance greater, potassium current expression was modified, and voltage-sensitive activation was shifted to more negative values compared to those of CD-1 and CBA/J mice. Inactivating potassium currents dominate in DCs of CBA/J and CD-1Cx30A88V/A88V mice with excellent high-frequency hearing, and sustained currents dominate in DCs of CD-1 mice with early-onset hearing loss. These findings are discussed in relation to maintenance of OoC electrochemistry, rescue of early-onset hearing loss, impaired low-frequency hearing in CD-1Cx30A88V/A88V mice, and the basis of high-frequency hearing.

Decisions are often modeled as a sequential process in which evidence accumulates until it reaches a threshold, triggering a response. Studies in freely moving animals raise questions about how ongoing behavior, not just stimulus properties, shapes this process. We trained rats of both sexes on a visual detection task with three luminance levels, each associated with the same reward outcome. Rats controlled cue duration through sustained head entries into a center port, yielding a measurable index of active sampling. Females consistently sampled longer than males. Sampling durations were shorter on error than correct trials, and reaction times were longer on error trials. We used drift diffusion models to relate these behaviors to the decision process. Luminance selectively affected the rate of evidence accumulation, with drift rate increasing monotonically across low, mid, and high luminance levels. Active sampling time was associated with the decision threshold, with longer sampling predicting higher thresholds in both sexes. The relationship between sampling time and drift rate differed by sex. Females showed a negative association between sampling duration and drift rate that was absent in males. These findings suggest that cue properties and active sampling make separable contributions to the decision process. These findings suggest that cue properties and active sampling make separable contributions to decision making, with a negative association between sampling duration and drift rate evident in females but not males.

The noradrenergic nucleus locus coeruleus (LC) is involved in numerous cognitive functions. Its activation often enhances sensory and motor performance and its activity correlates with arousal, which altogether suggest a general role in the mobilization of resources for cognition and action. We recently showed its strong and specific implication in physical effort and indirect evidence suggest that it might also be involved in cognitive effort. To address this question directly, we used a pharmacogenetic approach in rhesus macaques to selectively and reversibly inhibit LC neurons in a cognitively challenging task. Two monkeys were injected with viral vectors expressing inhibitory DREADDs (hM4Di) specifically in noradrenergic LC neurons, allowing reversible suppression of LC activity via systemic administration of deschloroclozapine (DCZ, 0.1 mg/kg). A third monkey served as a control and only received DCZ injections. Monkeys performed a simple hole-board task in which they searched for food rewards (raisins) hidden in a 5x5 grid of wells. In the transparent condition, rewards were visible, requiring minimal cognitive effort. In the opaque condition, rewards were hidden, such that monkey had to rely upon working memory to avoid revisiting empty wells. Thus, performance in opaque condition required more cognitive effort. Behavioral analysis showed that LC inhibition had no effect on performance in the transparent condition. However, in the opaque condition, it significantly impaired performance by increasing errors (revisits), without affecting the total number of rewards obtained, response times, or overall motivation. Monkeys compensated the decrease in success rate by performing more trials, indicating reduced efficiency rather than disengagement. These findings demonstrate that the LC plays a critical causal role in mobilizing cognitive resources for a demanding task. This is in line with the idea that the noradrenergic system contributes broadly to cognitive control and effort, extending previous findings on its involvement in physical effort. Overall, the study provides strong evidence linking LC activity to cognitive effort regulation, thereby complementing non-invasive studies in humans.

We previously reported, using in-vivo fiber photometry, that operant responding reinforced by access to a peer (social self-administration) is associated with phasic dopamine increases in nucleus accumbens (NAc) core following lever insertion (reward-availability cue) and gradual increases preceding lever-pressing. Here, we sought to replicate these findings and determine whether dopamine signals (1) generalize to responding for high-carbohydrate palatable food, (2) show opposite patterns during negative reinforcement (shock avoidance/escape), and (3) depend on whether reinforcers are experienced alone or together. We trained rats (n=11; 6 females) to lever-press for access to a same-sex peer (15 s/trial) and palatable food (45-mg pellet/trial), followed by shock avoidance/escape (0.18-0.26 mA). After training, we expressed the dopamine sensor GRAB-DA2m and implanted optic fibers into NAc core. We measured dopamine activity during sessions with either one- or three-reinforcers. During social self-administration, dopamine activity showed phasic increases following lever insertion and gradual increases preceding lever-pressing; responses were moderately greater during sessions with all three reinforcers. Palatable food self-administration showed a similar pattern, but responses were approximately twofold greater during single-reinforcer sessions. During shock avoidance/escape, dopamine activity showed phasic decreases at warning onset, lever insertion, and shock onset; responses were also greater during single-reinforcer sessions. Results suggest that NAc core dopamine signaling distinguishes positive from negative reinforcement and is modulated by reinforcer availability. Compared with single-reinforcer sessions, dopamine responses during food self-administration and shock avoidance/escape were reduced during sessions with all three reinforcers, whereas responses during social self-administration modestly increased. Significance statementNucleus accumbens (NAc) dopamine is critical for processing the valence of positive reinforcers, whereas its role in negative reinforcement is less well understood. Here, we extended our prior work on operant social self-administration to determine whether these findings generalize to food reinforcement, show the opposite pattern during operant negative reinforcement (shock avoidance/escape), and depend on whether reinforcers are experienced alone or together. Results suggest that NAc core dopamine activity differentiates positive and negative reinforcement and is modulated by the presence of other available reinforcers. Specifically, dopamine responses during food self-administration and shock avoidance/escape were reduced when all three reinforcers were available together compared with when each reinforcer was experienced alone, whereas responses during social self-administration showed the opposite pattern.

Cognitive functions encompass a large set of abstract constructs used for adapting our behavior to environmental constraints, each of them acting at specific timescales. For example, while working memory operates over several seconds or minutes, decision making occurs over much shorter periods. Solving a behavioral task thus relies on specific cognitive strategies that use several functions over time. Here, we investigated how two macaque monkeys coordinate working memory, selective attention, decision-making and executive control of eye movements during performance of a modified delay match-to-sample task. The economy of this task (including reward expected value and cost of errors) evolves on short timescales within trials. In addition, this task allowed us to manipulate engagement of cognitive resources at longer timescales. Using tools from signal detection theory, we closely analyze how monkeys performances evolve over time and infer their specific strategies in terms of control of cognitive functions. In addition, during covert attention, fixational eye movements and pupil size, provided reliable markers of slow variations in cognitive state across trials, although not of rapid within-trial changes in cognitive control. Together, these results show that each monkey adapted to the same task by implementing individual, dynamically evolving cognitive strategies across multiple timescales.