The Journal of Neuroscience

The locus coeruleus (LC) is the primary source of norepinephrine in the brain and has been implicated in the processes of attention, arousal, and perceptual decision making. Although prior work has linked transient LC activation to both sensory stimulus processing and motor processing, the precise contribution of LC to the distinct sensory and motor components of perceptual decisions remains unclear. Here, we recorded the spiking activity of single LC neurons in rhesus macaques while they performed a visual two-alternative forced-choice change detection task with a saccadic report, designed to cleanly dissociate sensory and motor contributions to LC activity. We found that the large majority of recorded neurons showed robust increases in response tightly locked to the choice saccade, while only a small fraction showed significant responses to the visual stimuli. Saccade-aligned LC responses did not vary with behavioral outcome, perceptual difficulty, reaction time, or session-wide fluctuations in perceptual sensitivity and criterion, indicating that LC motor-related signals were dissociated from perceptual performance. Together, these results demonstrated the existence of a subpopulation of LC neurons whose activity was tightly coupled to oculomotor output across both voluntary and involuntary eye movements during perceptual decision making, but were independent of perceptual decision accuracy. Our findings support a role for LC in facilitating motor preparation and execution in response to behaviorally significant sensory events.

Neuropeptides are found in nearly every brain neuron, and can modulate behaviors by regulating neuronal excitability, synaptic transmission, and plasticity. In contrast to the canonical view of neuropeptide release from nerve terminals, we previously reported the somatodendritic release of cholecystokinin (CCK) from ventral tegmental area (VTA) dopamine (DA) neurons. Release of CCK occurs during modest depolarization of VTA DA cells, and by activating CCK2Rs, potentiates synaptic transmission from GABAergic afferents. Here, recording from dopamine neurons in acute midbrain slices from male and female mice, we examined how somatodendritic release of CCK regulates synaptic plasticity and the extent of its influence. Depolarization of a dopamine neuron induced long-term potentiation (LTP) at GABAergic synapses, and in parallel somatodendritic CCK release produced long-term depression (LTD) at glutamatergic synapses. CCK-induced LTP persisted when postsynaptic G protein signaling in dopamine neurons was blocked, suggesting that CCK likely acts at GABAergic presynaptic terminals. Activation of kappa opioid receptors prevented CCK-dependent LTP of GABAergic synapses, indicating interaction between these two neuromodulatory signaling pathways in VTA. Surprisingly, depolarization of one dopamine neuron potentiated synapses onto both the depolarized neuron and neighboring dopamine neurons located up to [~]100 {micro}m away, indicating substantial spread of CCK signaling and synaptic modulation within the VTA region. Taken together, our findings demonstrate that somatodendritic CCK release bidirectionally coordinates synaptic strength across dopamine neurons, identifying a peptide-mediated feedback mechanism that shapes VTA circuit function. Significance StatementDopamine neurons in the ventral tegmental area (VTA) play central roles in reward, motivation, stress responses, and feeding behavior. While fast synaptic inputs regulate dopamine neuron firing on fast timescales, less is known about how slower neuromodulatory signals shape these circuits. We show that somatodendritic release of the neuropeptide cholecystokinin from dopamine neurons coordinately alters both inhibitory and excitatory synaptic strength and influences neighboring neurons within the VTA. This peptide-mediated feedback mechanism operates over a broader spatial scale than classical synaptic transmission and is regulated by kappa opioid signaling. These findings reveal how local peptide release can reshape dopamine circuit function and may contribute to changes in reward processing and feeding behavior.

In many mammals, the auditory system is immature at birth and undergoes activity-dependent refinement. The medial olivocochlear system (MOC) contributes to the maturation of central auditory connectivity by shaping spontaneous activity in the developing inner ear. Although altered MOC activity has been linked to electrical and synaptic dysfunctions in different central auditory nuclei, an in-depth analysis of the same synapse under conditions of absent versus enhanced MOC activity is lacking. In this work, we set out a physiological and structural analysis of the calyx of Held and the principal neurons of the medial nucleus of the trapezoid body (CH-MNTB) synapse at postnatal days 12-14 in three mouse models of either sex: wild-type (WT), 9 knock-in (9KI; with enhanced MOC activity), and 9 knock-out (9KO; which lacks MOC activity). Electrophysiological recordings in brain slices revealed a reduced synaptic strength efficacy in 9KI compared to WT, including smaller excitatory postsynaptic current (EPSC) amplitudes, stronger short-term depression during repetitive stimulation and a decrease readily releasable pool size. In contrast, 9KO mice showed minimal synaptic differences relative to WT. Serial block-face electron microscopy (SBEM) reconstructions demonstrated morphological alterations of the CH in both MOC-manipulated mouse models. However, 9KI mice exhibited the largest deviations, including fewer morphologically complex CHs and increased poly-innervation of MNTB cells. These results indicate that transient, well-regulated efferent control of cochlear activity is crucial for establishing accurate central auditory connectivity. Moreover, the enhancement of MOC activity drives more pronounced developmental changes in brainstem auditory circuitry than its absence. Significance StatementBefore hearing onset, inner hair cells in altricial mammals show spontaneous electrical activity crucial for proper auditory pathway development. This activity is finely regulated by descending efferent nerves from the central nervous system during a critical developmental period, ensuring precise auditory circuit formation. Our study shows that genetically manipulating efferent function --either by eliminating it or enhancing it-- leads to structural alterations and severe synaptic dysfunction within the auditory brainstem. These results indicate that transient, well-regulated efferent control of cochlear activity is crucial for establishing accurate central auditory connectivity. Importantly, enhancing efferent peripheral activity causes more pronounced central synaptic changes than its absence, highlighting the importance of balanced efferent modulation during early auditory system development for normal brainstem auditory function.

Interpersonal communication relies on integrating facial and vocal signals to extract multidimensional communicative information. How the absence of audition reshapes the communicative system remains unclear. We compared the performance of deaf (N=136) and hearing (N=135) adults across multiple domains, facial identity, emotional expression, speech, and global motion, through a series of unisensory and audiovisual psychophysical tasks. The results showed that, in hearing individuals, reliance on facial versus vocal signals differed across domains. In deaf individuals, auditory deprivation did not produce uniform enhancement or impairment of visual processing. Instead, they exhibited reduced sensitivity to dynamic emotional expressions and global motion, preserved sensitivity to facial identity (both static and dynamic) and static expressions, and enhanced categorization of facial speech. Notably, sensitivity to dynamic facial expressions and global motion was correlated, and both were explained by variations in fluid intelligence. Our results provide a systematic characterization of visual function across domains in deaf individuals, suggesting that the consequences of hearing loss are shaped both by the functional roles of audition within each domain and by broader cognitive adaptations. These findings advance understanding of cross-modal plasticity and inform the development of targeted ecologically valid accessibility and sensory-substitution strategies.

Everyday decisions unfold dynamically, with commitment shaped by a growing sense of urgency that can, when excessive, contribute to impulsive choices. Here we aimed at dissociating two modes of urgency regulation, control-driven (accuracy-oriented) and reward-driven (motivation-based), and asked whether their relative influence varies across individuals differing in impulsivity. We further investigated how these regulatory modes are implemented in the motor system, focusing on two modulatory effects: surround inhibition and broad modulation. Healthy participants, whose impulsivity was assessed with the UPPS urgency dimension, performed a modified Tokens task crossing control demands (low vs high control blocks) with motivational context (low vs high reward trials). In two separate sessions, single-pulse TMS was applied either over the hand motor representation to probe corticospinal excitability indexing surround inhibition, or over the leg representation to index broad modulations of motor activity. This design successfully dissociated the two regulatory modes: control-driven adjustments (across blocks) were most evident in less impulsive participants, whereas reward-driven adjustments (across trials) were most evident in more impulsive participants. Consistent with this dissociation, control-driven urgency regulation was associated with broad modulation of motor activity, whereas reward-driven urgency adjustments were associated with changes in surround inhibition. These motor signatures may serve as probes of the respective contributions of control- and reward-driven regulation even when they are not explicitly dissociated. Our findings suggest that impulsivity may not simply reflect "more urgency" but a different weighting of the influences that shape it during decision making, a hypothesis that can now be tested in clinical conditions.

Individuals with chronic tinnitus perceive a phantom sound that imposes either a bothersome and irrepressible distraction throughout waking hours or a relatively mild nuisance that often fades into subliminal awareness. The difference in tinnitus salience may reflect a general difference in inhibitory control over any distracting sound, whether externally or internally generated. To test this hypothesis, we investigated neural and behavioral signatures of external auditory distraction suppression in participants with chronic tinnitus that had mild or bothersome tinnitus but were otherwise matched for age and hearing loss. Participants in both groups underwent behavioral and EEG testing that asked them to report on a target stream of amplitude modulated tones that switched from a random arrangement to a repeating sequence. Using additional sounds that imposed varying levels of distraction, we documented neural and perceptual suppression of auditory distractors. Behaviorally, participants with mild versus bothersome tinnitus showed comparable reductions in accuracy in the presence of varying distractor loads. Neural synchronization to the target stimulus change rate provided a useful proxy for distraction effects but did not differ between tinnitus groups. Likewise, no group differences were observed in the neural synchronization to modulation rates of the target or distractor stimuli. Our results build on work showing that individuals with tinnitus perform as well as individuals with normal hearing on listening tasks in noisy environments and expand this observation into the neural representation of sounds. Suppression of the internally generated phantom percept does not appear to be linked to general deficits in suppressing distractors.

Speech production depends on the precise temporal integration of articulatory movements with phonation. While ventral primary motor cortex is known to encode articulatory features, how phonatory timing, and its coordination with articulation, is represented across cortical and cerebellar circuits remains poorly understood. Using 7T functional MRI, we examined neural representations during overt syllable production varying in place of articulation and voice onset time. Multivariate analyses revealed reliable, syllable-specific differences in activity patterns across both cortical and cerebellar speech regions. Ventral primary sensorimotor cortex distinguished syllables by place of articulation, whereas dorsal sensorimotor cortex was more sensitive to the timing of voice onset relative to articulation. Secondary sensorimotor speech areas, including the operculum and auditory cortex, showed a hybrid representational profile, integrating both articulatory and phonatory features. In the cerebellum, representational geometry was dominated by the place of articulation; however, overall syllable representations were most similar to those in the operculum, accounting for unique variance beyond that explained by ventral sensorimotor cortex. Together, these findings reveal feature-specific representational tuning across primary sensorimotor regions during speech production. The selective representational alignment between operculum and cerebellum may support the refinement of speech motor plans prior to execution.

We studied the effects of prioritization in a two-step retrocuing task in which participants hold two items in working memory, and the item not cued by the first cue cannot be dropped because it may be prioritized by the second cue. In Experiment 1, using a dense sampling procedure, we observed that recall performance oscillated at 15 Hz in the prioritization task, in comparison to 20 Hz in a matched task employing a neutral cue. Furthermore, the prioritized item was shielded from bias exerted by the uncued item, as well as from items from the previous trial. In Experiment 2, we recorded the EEG while participants performed variants of the two tasks. The prioritization cue uniquely triggered a phase reset at 15 Hz and an increase in oscillatory peaks at this frequency. Burst analysis ruled out bursting as a possible underlying factor. Time-resolved representational similarity analysis (RSA) revealed that the prioritization cue triggered representational transformations that were larger for the uncued item. The shielding effects of prioritization may arise from the transformation of the not-prioritized item into an "unprioritized" state that is implemented and maintained by a mechanism that cycles at 15 Hz.

Corticospinal projections from the primary somatosensory cortex (S1) form a distinct descending pathway that engages spinal dorsal horn circuits and modulates sensory processing. Despite advances in our understanding of the role of this pathway in the adult, the postnatal maturation of somatosensory corticospinal projections remains poorly defined. Here, we provide a quantitative anatomical analysis of the postnatal development of corticospinal projections from the hindlimb representation of S1 (S1hl) to the lumbar dorsal horn in mice. Using retrograde tracing, we show that lumbar-projecting S1hl corticospinal neurons are first detected at postnatal day (P) 9 and reach adult-like numbers in S1hl by P12. Using anterograde tracing we then show that S1hl CST axonal projections are initially confined to the dorsolateral funiculus when they reach the lumbar cord at P9, but then rapidly invade the lumbar dorsal horn, reaching peak grey matter terminal density at P14. During this early innervation period, projections transiently extend beyond their mature termination zones in laminae III-V before retracting and becoming confined to superficial laminae I-II by P17. Together, these findings define three developmental phases of somatosensory corticospinal dorsal horn connections: an initial arrival phase, followed by grey matter ingrowth, and finally laminar refinement of the terminal projections. These results provide an anatomical framework for understanding how descending corticospinal somatosensory control becomes integrated into spinal circuits during the early postnatal period.

Age-related hearing loss is the leading sensory deficit in older adults, yet audiometric thresholds at conventional frequencies often poorly predict speech understanding. Two competing hypotheses have emerged: extended high-frequency (eHF) hearing loss beyond 8 kHz may unmask variance in speech performance, while hidden hearing loss from cochlear synaptopathy---detectable via auditory brainstem response (ABR) wave I amplitude reduction---may degrade temporal coding independent of audiometry. Here, in 526 ears from 263 tinnitus-free adults in the Swedish Tinnitus Outreach Project (STOP) cohort, we show that eHF pure-tone average (10-16 kHz) is the single most age-sensitive auditory measure, explaining 64% of age-related variance (R{superscript 2} = 0.64) compared to only 16% for conventional audiometry (R{superscript 2} = 0.16). Moreover, eHF thresholds robustly predict both word and phoneme recognition in speech-weighted noise (+4 dB SNR), explaining 34-36% of speech variance (R{superscript 2} = 0.34-0.36)--substantially exceeding conventional pure-tone average (22-25%) and all ABR features (5-13%). In contrast, ABR Wave I amplitude--the putative marker of cochlear synaptopathy--contributes no additional explanatory power even in high-reliability recordings (ICC = 0.96). These findings challenge the translational relevance of cochlear synaptopathy to age-related speech deficits and suggest conduction delays, not synaptic loss, as the peripheral neural mechanism underlying speech comprehension decline in aging.

Language is inherently multisensory, with speech often accompanied by iconic gestures that convey semantic meaning related to actions, objects, or spatial relationships. Although the temporal coordination between speech and gesture is variable, the brain integrates these signals seamlessly. Yet, much of the cognitive mechanisms behind this integration remain unclear. This study investigates whether sensorimotor experience, specifically with ones own speech and gestures, enhances temporal sensitivity through internal forward models that guide audiovisual prediction. Participants first produced sentences with corresponding iconic gestures, which were audiovisually recorded. These recordings were later temporally manipulated and presented in a simultaneity judgment task, where participants evaluated both their own and others recordings. Results revealed narrower temporal binding windows (TBWs), indicating heightened sensitivity to audiovisual asynchrony, when participants judged their own speech-gesture recordings compared to those of others. To further explore the role of motor experience, we analysed individual variability in gesture-speech timing during production and found no reliable relationship between production variability and perceptual sensitivity, suggesting that perceptual precision is not simply a reflection of motor consistency. These findings demonstrate that sensorimotor experience with self-generated movements sharpens multisensory temporal integration, likely via predictive internal models, and underscore the functional role of predictive motor mechanisms in supporting temporal integration across perceptual and action systems.

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.

To compensate for self-generated movement-induced postural disturbances, the brain generates anticipatory postural adjustments (APA), ensuring smooth, coordinated actions. APA development continues into late adolescence, yet the specific pathways and mechanisms that remain immature in children are poorly understood. We studied APA mechanisms in 24 children (7-12 years old) using magnetoencephalography (MEG) while they performed the naturalistic bimanual load-lifting task (BLLT). In the BLLT, participants lift a load placed on one forearm with the contralateral hand while keeping the postural forearm horizontal, as if lifting a glass from a tray. To counteract forearm deflection caused by unloading, the brain generates APAs, which involve anticipatory inhibition of the postural Biceps brachii. We found that stronger anticipatory Biceps brachii inhibition was associated with reduced excitability, as indexed by high-gamma (90-130 Hz) suppression, and increased high-beta power (19-29 Hz) in the contralateral Supplementary Motor Area (SMA). Analysis of transient beta events revealed two functionally distinct burst types: (1) 19-24 Hz bursts: time-locked to immediate high-gamma suppression correlated with 26-28 Hz beta power; predicted stronger muscle inhibition and received directed input from middle frontal cortex and precentral gyrus; (2) 24-29 Hz bursts: linked to delayed ([~]100 ms) high-gamma suppression correlated with 8 Hz alpha power; predicted earlier and prolonged muscle inhibition and better forearm stabilization, but did not show directional influence from other regions. Results on anticipatory inhibition-related beta bursts replicated mechanisms reported in adults, suggesting that the efferent pathways and transient inhibitory processes underlying APA may already be mature in children. In contrast, higher-frequency beta bursts revealed a child-specific, complementary APA mechanism that may compensate for imprecise anticipatory inhibition. These results reveal two oscillatory mechanisms supporting APA in children and indicate that beta bursts may reflect both immediate cortical inhibition linked to muscle control and indirect alpha-mediated inhibition likely compensating for forearm instability.

Gentle tactile stimulation is associated with positive affect and social bonding, yet the central circuits engaged by such stimuli remain incompletely understood. The lateral parabrachial nucleus (lePB) is a key hub in ascending affective sensory pathways and is robustly activated by aversive stimuli, including pain. Here, we examined neuronal activation in the lePB and the likewise associated subparafascicular nucleus, parvocellular part (SPFp), following different tactile stimulation paradigms in mice. Behavioral analyses confirmed that the soft touch stimuli used in this study were not aversive: mice displayed low aversive facial grimace scores during brushing and von Frey stimulation compared with noxious heat, and showed a preference for a soft tactile environment in a place preference assay. Neuronal activation was assessed using Fos immunohistochemistry following exposure to brushing-based soft touch, a fur-roll paradigm, innocuous punctate touch (von Frey), or noxious heat. Soft touch protocols robustly increased Fos expression in the lePB compared with home cage controls, whereas innocuous punctate touch did not. Notably, the magnitude of activation produced by brushing-based stimuli was comparable to that induced by noxious heat. Using CalcaCre mice, we further found that soft touch recruited a subset of CGRP-expressing neurons in the lePB. In contrast, tactile stimulation produced only modest activation in the SPFp and did not strongly increase overall Fos expression in this region. Together, these findings demonstrate that affective tactile stimulation can engage neuronal populations within ascending parabrachial circuits, including CGRP neurons traditionally associated with nociceptive processing, suggesting that these pathways may encode the salience or affective significance of somatosensory stimuli rather than exclusively aversive input.

Perceiving hand gestures and inferring others actions and emotions from movements of hands and limbs play an important role in every-day interactions, especially in young children. The perception of categories such as limbs, bodies, or faces is supported by category-selective regions in the temporal lobe. Some category-selective regions, such as those reacting selectively to body parts or limbs, exist both on the ventral and on the lateral side of the temporal lobe, and are part of the ventral and lateral stream, respectively. While it was recently shown that limb-selective regions in the ventral stream shrink from childhood to adulthood, the developmental trajectory of limb-selective regions in the lateral stream remains unknown. To close this gap in knowledge, we acquired functional magnetic resonance imaging (fMRI) data in 21 children aged 10 - 12 years and 20 adults while they watched images of 10 visual categories including limbs and whole bodies. We first replicate the decrease of limb-selectivity from childhood to adulthood in the ventral temporal lobe. Across several analyses, our results further demonstrate that limb-selective regions in the lateral temporal lobe shrink as well, particularly in the left hemisphere. Underlining the specificity of our finding, we show that lateral body-selective regions show no significant development from childhood to adulthood. These findings advance our understanding of the developmental trajectories of limb- and body-selective regions and of the ventral and lateral visual streams more broadly.

AO_SCPLOWBSTRACTC_SCPLOWThe hippocampus receives convergent input from multiple sensory systems, yet in humans it has been studied almost exclusively through vision. Here we examine how the hippocampus contributes to sensory processing beyond the visual modality and to the multisensory integration of visual information with these other modalities. Participants were exposed to multiple repetitions of short naturalistic movie clips, each presented in four formats: auditory only, visual only, congruent audiovisual, and incongruent audiovisual (audio and video from different movies). Using high-resolution fMRI, we measured univariate activation and multivariate representations across the subfields and longitudinal axis of the human hippocampus. Whereas univariate analyses detected only visual responses across hippocampal subfields, with no activation for auditory stimuli and no benefit of congruent stimuli, multivariate analyses revealed robust representations of both auditory and visual scenes. The posterior hippocampus showed enhanced pattern similarity for congruent stimuli relative to unisensory stimuli, demonstrating multisensory facilitation. The anterior hippocampus showed crossmodal decoding between auditory and visual versions of the same clip, suggesting a more abstract representation. Finally, whole-brain searchlight analyses revealed parallel effects in cortical regions known to support multisensory integration. These findings advance understanding of auditory and multisensory coding in the human hippocampus, including the discovery of a functional dissociation along its longitudinal axis, from facilitation in posterior to generalization in anterior.

Episodic memory depends on neural representations encoded in the hippocampus. Experimental and computational evidence suggests that the hippocampus encodes pattern-separated representations that support later recall of episodic event elements. While extant data in humans predominantly focus on assaying the relationship between the similarity of spatial neural patterns at encoding and later memory performance, similarity of neural patterns in the temporal domain may also reveal encoding computations predictive of future memory. To examine how the similarity among temporal patterns of hippocampal activity during encoding relates to later episodic retrieval (associative cued recall and recognition memory), hippocampal activity was recorded from human participants (n=7) with implanted intracranial electrodes while they encoded arbitrary (A-B) paired-associates. Subsequent memory analyses first revealed that hippocampal high-frequency broadband power (HFB; 70-180Hz) was linked to a graded increase in memory strength; HFB power was greater during the encoding of pairs later correctly recalled relative to events later recognized and was lowest for events later forgotten. Second, and critically, subsequent memory analyses further revealed that more distinctive temporal patterns in the hippocampus during encoding -- indexed by the similarity of the HFB timeseries elicited by a given event to that elicited by other events -- were associated with superior subsequent memory performance. Finally, exploratory analyses revealed stimulus category effects on hippocampal HFB power during encoding and retrieval cuing. These results indicate that the temporal distinctiveness of hippocampal traces during encoding is important for subsequent retrieval of episodic event elements, consistent with theories that posit that pattern separation facilitates future remembering.

Reading, social interaction, and navigation rely on visuospatial computations by population receptive fields (pRFs) in category-selective regions of the ventral, lateral, and dorsal streams. However, how visuospatial computations vary across streams and category, or develop during adolescence is unknown. Using functional magnetic resonance imaging (fMRI) and pRF modeling in adolescents and adults, we investigate the development of pRFs and category-selectivity. Adolescents and adults show a consistent functional fingerprint whereby, pRF location, pRF size, and visual field coverage vary by category-selectivity, stream, and hemisphere. While pRF location is largely adult-like by adolescence, pRF size, visual field coverage, and category-selectivity exhibit region-specific increases and decreases from adolescence to adulthood. Together, these findings delineate a timeline of continued functional plasticity during adolescence and provide a multidimensional framework for understanding the organization of high-level visual cortex.

Executive functions comprise at least four major subdomains: Inhibitory Control, Updating, Shifting, and Working Memory. Cognitive abilities in these subdomains are partially separable and partially unified in a common cognitive control factor in humans, but how these functions are organized in the nonhuman primate (NHP) is largely unknown. Here, we used a multi-task assessment approach and found that NHPs show within single sessions reliable cognitive markers of Inhibitory Control in an antisaccade task, (ii) Updating abilities in a multidimensional continuous updating task, (iii) Working Memory in a delayed matching task, and (iv) Shifting abilities in a feature-based rule learning task. First, we found that subjects performance fell into three separable cognitive phenotypes with unique strengths and weaknesses across cognitive subdomains. Second, the most reliable cognitive metrics gave rise to four latent cognitive factors that quantify the relative independence of shifting/learning and working memory updating as well as independent variance explaining the abilities in inhibitory control of exogeneous versus endogenous interference. These findings support a 4-factor cognitive organization of executive functions in NHPs, with inter-subject differences of these factors forming cognitive phenotypes. Significance StatementCognitive abilities in Inhibitory Control, Shifting, Updating and Working Memory reflect four main executive functions (EFs). How independent these four subdomains are organized in nonhuman primates (NHPs) is unknown and has remained challenging to measure. We validated a multi-task assessment approach for NHPs that shows first, robust inter-individual differences of abilities in these subdomains that group subjects into cognitive phenotypes. Secondly, performance separated four latent cognitive factors underlying EFs supporting working memory updating, and shifting/learning, as well as two inhibitory control of interference from external or internal mental representations. These results suggest a 4-factor cognitive architecture of EFs in NHP.

Neural oscillations play a crucial role in cognition, and several studies emphasize the importance of considering them as traveling waves that propagate through brain regions. In scalp EEG, waves typically travel along the anterior-posterior axis: forward waves (occipital-to-frontal) predominate during sensory stimulation, while backward waves (frontal-to-occipital) emerge during rest and top-down modulation. Within the predictive coding framework, backward waves are proposed to convey predictive signals, whereas forward waves reflect sensory processes and feedforward propagation of prediction errors. In this study, we investigated traveling wave dynamics during a visual entrainment task in neurotypical (N=25) and autistic (Autism Spectrum Disorder - ASD) adults (N=24). Our results replicated previous findings in neurotypical participants, as we observed an increase in backward waves during rhythmic visual stimulation, consistent with enhanced top-down predictions. Notably, we observed the opposite pattern in the ASD group, characterized by a pronounced increase in forward waves at the entrained frequency during visual stimulation. These results align with predictive coding accounts of autistic perception, which hypothesize an imbalance between predictions and sensory evidence. Specifically, an increase in forward wave may reflect a bias toward bottom-up sensory signaling over predictive feedback, due to atypical hierarchical communication across brain regions in ASD. Together, our findings shed new light on the oscillatory dynamics involved in visual entrainment in neurotypical adults and provide novel evidence in favor of predictive coding accounts of autistic perception, as well as a consequent bias toward bottom-up sensory signaling over predictive feedback in a context of visual entrainment. Significance statementTraveling waves reflect the spatiotemporal propagation of neural oscillations, providing a window into hierarchical brain communication. By examining traveling wave dynamics during visual entrainment, we show that neurotypical adults exhibit increased backward (frontal-to-occipital) waves, consistent with enhanced top-down predictive signaling. In contrast, adults with Autism Spectrum Disorder (ASD) display a marked increase in forward (occipital-to-frontal) waves, indicating stronger bottom-up sensory drive. These findings provide electrophysiological evidence for atypical predictive processing in ASD, supporting predictive coding theories that propose an imbalance between sensory evidence and prior expectations. Our results highlight traveling waves as a sensitive neural marker of hierarchical signaling and predictive dynamics across typical and atypical perceptual systems.