bioRxiv Subject Collection: Neuroscience's Journal

Behavioral Signature of Trihexyphenidyl in The Tor1a (DYT1) Knockin Mouse Model of Dystonia
Dystonia is a neurological disorder characterized by involuntary repetitive movements and abnormal postures. Animal models have played a pivotal role in studying the pathophysiology of dystonia. However, many genetic models, e.g. the Tor1a+/{Delta}E (DYT1) mouse, lack an overt motor phenotype, despite significant underlying neuronal abnormalities within the striatum and other motor control regions. Because the striatum is implicated in action sequencing, it is possible that the behavioral defect arises as a disruption in the frequency and temporal ordering of behaviors, rather than execution, which cannot be captured using traditional behavioral assays, thus limiting drug discovery efforts. To address this challenge, we used MoSeq, an unsupervised behavioral segmentation framework, to compare the continuous free behavior of control Tor1a+/+ mice and knockin Tor1a+/{Delta}E mutant mice in response to the anti-dystonia drug trihexyphenidyl. Although minimal baseline differences in behavioral organization were detected, both genotypes exhibited robust and consistent shifts in behavioral space structure after treatment with trihexyphenidyl. Further, we demonstrate differences in the behavioral space structure of male vs female mice after trihexyphenidyl challenge. The distinct behavioral signatures evoked by trihexyphenidyl and biological sex, a known risk factor for dystonia, suggest that the analysis of the temporal structure of continuous free behavior provides a sensitive and novel approach to the discovery of therapeutics for the treatment of dystonia.

Level Up the Brain! Novel PCA Method Reveals Key Neuroplastic Refinements in Action Video Gamers
Action video games (AVGs) offer a natural and ecologically rich experimental paradigm for studying how sustained cognitive demands drive behaviorally induced neuroplastic changes in the brain. We demonstrate that long-term AVG players, referred to in this study as gamers, may perhaps be reducing visuomotor information surprise during decision-making by more effectively resolving internal conflict in competing motor plans and thus reducing overall visuomotor uncertainty. To explain how this effect occurs over a prolonged period, we utilized the Cognitive Resource Reallocation (CRR) framework, defined as the dynamic redistribution of metabolic and functional resources to support behaviorally relevant neuroplastic adaptation under repeated, demanding task conditions. Using a novel region-cumulative principal component analysis (rcPCA) approach, we identified key brain regions that explain inter-subject variability, improving statistical power by isolating the most informative regions and reducing the burden of multiple comparisons. Our findings show that prolonged AVG experience plausibly promotes more efficient visuomotor decision-making through top-down cognitive clarity, reflected in the unobstructed transformation of learned value into goal-directed action and bottom-up motor readiness, both of which track with improved visuomotor performance in gamers. The convergence of these factors would effectively reduce internal conflict, mitigate visuomotor uncertainty, and enable rapid yet skillful action selection. Through prolonged action video game exposure, their brains reflect neuroplastic refinements that point towards more effective reduction in internal conflict over competing plans for transforming visuomotor information into skillful action selection, a key factor in high-pressure environments and consistent with CRR. More broadly, these insights show how repeated cognitive challenges could reasonably perturb behaviorally relevant neurodynamics and promote enhanced cognitive abilities.

Beyond Reorganization: Intrinsic cortical hierarchies constrain experience-dependent plasticity in sensory-deprived humans
Innate cortical organisation and postnatal sensory experience interact dynamically to shape the functional architecture of the human brain. Using naturalistic stimulation, functional gradient analyses, and comparative approaches in congenitally blind, congenitally deaf, and typically developed individuals, we investigated how intrinsic hierarchical structures and sensory experiences influence cortical organisation. Our findings demonstrate that the principal functional gradients spanning from unimodal sensory to transmodal association cortices are consistently preserved across all groups, suggesting a robust genetically determined cortical scaffold. Nonetheless, congenital sensory deprivation selectively reshapes the geometry of modality-specific gradients, characterised by reduced functional differentiation within sensory-deprived cortical regions. These geometric contractions promote experience-driven plastic reorganization, enabling deprived sensory areas to establish enhanced functional connectivity with transmodal and non-deprived sensory cortices. Critically, this reorganisation aligns systematically with pre-existing cortical gradients, highlighting intrinsic hierarchical constraints that guide experience-dependent plasticity. Moreover, sensory-deprived regions exhibiting heightened connectivity actively engage in processing structured perceptual information from intact modalities, reflecting specific feature-driven cross-modal adaptations. Collectively, these results underscore a fundamental duality in cortical organisation: innate hierarchical principles impose constraints on cortical architecture, while sensory experience drives adaptive refinement, demonstrating the brain's intrinsic capacity for flexible functional reconfiguration in response to sensory deprivation.

Parallel emergence of perisomatic inhibition and ripples in the developing hippocampal circuit
During hippocampal Sharp Wave Ripples, sequences of awake coding activities are replayed with a rhythmic timing and high level of synchrony favorable for synaptic plasticity and transfer of information to downstream structures. Previous work reported the emergence of ripples at P10 in the CA1 region, together with the development of inhibition. On the other hand, neither the relationships between perisomatic inhibition and ripples or their developmental emergence have been investigated in CA3, in which ripples have a different frequency profile (90-110Hz instead of 140-200Hz in CA1), functional perisomatic inhibitory circuits have different properties, and some developmental aspects such as neurogenesis or interneuron maturation are early compared to CA1. We have here investigated the hypothesis of a conjoint and earlier appearance and maturation of ripples and perisomatic inhibition in the CA3 hippocampal region compared to CA1. We report a parallel sequence of events in CA3 and CA1, starting with the early expression of perisomatic GABAergic synaptic activity combined with the emergence of ripple activity. Interestingly, perisomatic inhibition and ripple activity follow parallel maturation trajectories, beginning in CA3 at P7 with immature (i.e. unfunctional) inhibition and immature ripples (proto-ripples) with labile oscillatory frequency. Mature functional perisomatic inhibition and clear high-frequency ripple activity progressively emerge between P10 and P12, reaching adult-like properties by P13. A similarly progressive maturation of ripples occurs in CA1, from P11 to P15. The progressive emergence of functional inhibition and specific patterns of neuronal activity likely support the progressive emergence of cognitive function to which they are necessary prerequisite.

Mesoscale differences in brain organization in schizophrenia revealed by topological data analysis
We uncover a novel, mesoscale perspective of the differences in the white-matter connectome between healthy controls (HC) and subjects with schizophrenia (SCH) us- ing a method developed from computational algebraic topology: persistent homology (PH) via clique topology. We extract and compare topological motifs found in the structural connectomes of the subjects in the two groups and find significant differ- ences. We compare our results with those obtained from easy-to-interpret null models to build an understanding of the connectivity patterns found in the data, and we explore the overlap of mesoscale structures found in two different datasets, COBRE (Center of Biomedical Research Excellence) and HCP (Human Connectome Project). Differences in acquisition usually render experiments recorded on different scanners incomparable, but here we see that there are shared structures. Our method offers a way to estab- lish connectomic fingerprinting that could lead to a neuroimaging-based diagnosis of schizophrenia and other psychiatric and neurological conditions as well as the develop- ment of new treatments.

A Single-Cell Atlas of DNA Methylation in Autism Spectrum Disorder Reveals Distinct Regulatory and Aging Signatures
Autism spectrum disorder (ASD) is a common, genetically and clinically heterogeneous neurodevelopmental condition. Despite this diversity, studies of postmortem brain tissue have revealed convergent molecular changes across the cortex, including reduced synaptic function in subsets of excitatory and inhibitory neurons and increased glial reactivity. Whether these features are reflected in cell type specific epigenetic signatures remains unknown. Here, we present the first single-cell analysis of DNA methylation (DNAm) coupled with transcriptomics in ASD. Using snmCTseq, we profiled DNAm and gene expression from over 60,000 nuclei across 49 donors. We identified thousands of differentially methylated regions (DMRs) in ASD, enriched in promoters and regulatory elements active during both prenatal development and in adult cortex. ASD related methylation changes were spatially localized but uncorrelated with gene expression, and were small in magnitude compared to robust age associated effects. Age DMRs were concentrated in excitatory neurons, enriched in known cognitive aging pathways, and revealed distinct roles for CG and non CG methylation in the aging brain. Finally, we explored age by diagnosis interactions, identifying a reduction in inhibitory neuron abundance with age in ASD relative to controls, highlighting this area as a promising direction for future research.

Horizontally Tiled Network of Cortico-Basal Ganglia Modules Performs Reinforcement Learning
The neocortex and basal ganglia nuclei are connected along regions that share the same topography and are arranged side-by-side. Inspired by the anatomical characteristics of the cerebrum, we developed a network in which the modules of the neocortex-basal ganglia unit were arranged in a horizontally tiled manner. By applying this network to reinforcement learning tasks, we demonstrated that reinforcement learning can be achieved through horizontal signals passing between modules. Each module not only performs its calculation but also provides signals to adjacent modules. This lateral transmission takes advantage of the differences in the projection ranges of the three basal ganglia pathways, the direct, indirect, and hyperdirect pathways, which have been examined in physiologic studies. We found that these differences enabled temporal-difference-error computations. This study proposes a novel strategy for information processing based on neocortical-basal ganglia circuits, highlighting the computational significance of their anatomically and physiologically clarified features.

Tracking visual rhythms: a concert of sensory and motor simulation
Neural oscillations have been proposed to model external temporal structure by phase-coupling to environmental rhythms, thereby supporting adaptive perception. However, there is little evidence supporting these theories, particularly in the visual domain, and the underlying mechanisms remain unclear. Using MEG and a new empirical approach we addressed this issue. Participants attended 1.3 and 2 Hz visual displays of rotating Gabors and judged either the timing or content of these events. We show behaviourally-relevant rate-specific phase-coupling in motor structures to - and beyond - the visual rhythm specifically when judging temporal features of the display. We subsequently devised a rate-specific decoding measure to show that visual structures track anticipated, temporally-precise content regardless of task. This sensory simulation predicted the temporal tracking in motor structures. We consequently propose a mechanism by which automatic, temporally-specific sensory simulation yields an information envelope read out by motor areas when estimating temporal characteristics in our environment.

Cortical sculpting of a rhythmic motor program
Motor cortex is the principal driver of discrete, voluntary movements like reaching. Correspondingly, current theories describe muscle activity as a function of cortical dynamics. Tasks like speech and locomotion, however, require the integration of voluntary commands with ongoing movements orchestrated by largely independent subcortical centers. In such cases, motor cortex must receive inputs representing the state of the environment and the state of subcortical networks, then transform these inputs into commands that modulate the rhythmic motor pattern. Here, we study this transformation in mice performing an obstacle traversal task, which combines a spinal locomotor pattern with voluntary cortical adjustments. Cortical dynamics contain a prominent representation of motor preparation that is linked to obstacle proximity and robust to removal of somatosensory or visual input, and also maintain a representation of the state of the spinal pattern generator. Readout signals resembling commands for obstacle traversal are consistent across trials, but small in amplitude. Using computational modeling, we identify a simple algorithm that generates the appropriate commands through phase-dependent gating. Together, these results reveal a regime in which motor cortex does not fully specify muscle activity, but must sculpt an ongoing, spinally-generated program to flexibly control behavior in a complex and changing environment.

Volume Control for a Cortical Network
Excitability is a fundamental property of cortical networks, shaping their responses to input. Here, we use ionic direct current (iDC) to modulate excitability with sub-10-ms temporal resolution and submillimeter spatial precision across the cortical surface, greatly surpassing the capabilities of pharmacological tools. In anesthetized rats, we recorded laminar neural responses in the S1HL cortex to spontaneous delta oscillations and to foot stimulation with and without iDC delivered to the cortical surface. Cathodic iDC suppressed, and anodic iDC enhanced, evoked responses across recording sites. iDC shifted the spatiotemporal excitability pattern in a graded manner, paralleling the effects of weaker or stronger foot stimuli. A computational model reproduced these effects and implicated dendritic summation at the axon initial segment (AIS) as a key mechanism for bidirectional modulation. This approach enables precise, causal manipulation of cortical responsiveness in vivo and offers a platform for dissecting functional circuits and developing targeted neurotherapeutic interventions.

Ultrastructural analysis of synapses after induction of spike-timing-dependent plasticity
Repeated sequential activation of connected neurons causes lasting changes in synaptic strength, a process known as spike-timing-dependent plasticity (STDP). Recently, sequential spike patterns have been induced without electrodes, using two spectrally separated channelrhodopsins. However, due to the difficulty of labeling and localizing the few connecting synapses between the stimulated pre and postsynaptic neurons (~1-5 per neuron pair), ultrastructural analysis after STDP has not been reported. Here, we optogenetically induce STDP at CA3-CA1 hippocampal synapses and identify stimulated boutons and spines in CA1 using transmission electron microscopy (TEM). Presynaptic CA3 neurons express vesicle-targeted horseradish peroxidase, cre recombinase and cre-dependent ChrimsonR, a red light activatable channelrhodopsin. Postsynaptic neurons express violet light activatable CheRiff and dAPEX2, an enhanced ascorbate peroxidase. In transmission electron microscopy, presynaptic boutons and postsynaptic spines are readily identifiable with well-preserved ultrastructural features. Our labeling strategy allows ultrastructural analysis of optogenetically manipulated neurons and their synapses.

Combining Machine Learning and Multiplexed, In Situ Profiling to Engineer Cell Type and Behavioral Specificity
A promising strategy for the precise control of neural circuits is to use cis-regulatory enhancers to drive transgene expression in specific cells. However, enhancer discovery faces key challenges: low in vivo success rates, species-specific differences in activity, challenges with multiplexing adeno-associated viruses (AAVs), and the lack of spatial detail from single-cell sequencing. In order to accelerate enhancer discovery for the dorsal spinal cord--a region critical for pain and itch processing--we developed an end-to-end platform, ESCargoT (Engineered Specificity of Cargo Transcription), combining machine learning (ML)-guided enhancer prioritization, modular AAV assembly, and multiplexed, in situ screening. Using cross-species chromatin accessibility data, we trained ML models to predict enhancer activity in oligodendrocytes and in 15 dorsal horn neuronal subtypes. We first demonstrated that an initial enhancer, Excit-1, targeted excitatory dorsal horn neurons and drove reversal of mechanical allodynia in an inflammatory pain model. To enable parallel profiling of a 27-enhancer-AAV library delivered intraspinally in mice, we developed a Spatial Parallel Reporter Assay (SPRA) by integrating a novel Golden-Gate assembly pipeline with multiplexed, in situ screening. Regression adjustment for spatial confounding enabled specificity comparisons between enhancers, demonstrating the ability to screen enhancers targeting diverse cell types (oligodendrocytes, motoneurons, dorsal neuron subtypes) in one experiment. We then validated two candidates, targeting Exc-LMO3 and Exc-SKOR2 neurons, respectively. In a companion paper by Noh et al, our colleagues show that the functional specificity of the Exc-SKOR2-targeting enhancer, unlike Excit-1, is capable of blocking the sensation of chemical itch in mice. These enhancers were derived from the macaque genome but displayed functional sensitivity in mice. This platform enables spatially resolved, multiplexed in vivo enhancer profiling to accelerate discovery of cell-targeting tools and gene therapy development.

Neural activity flows through cortical subnetworks during speech production
Speech production entails several processing steps that encode linguistic and articulatory structure, but whether these computations correspond to spatiotemporally discrete patterns of neural activity is unclear. To address this issue, we used electrocorticography to directly measure the brains of neurosurgical participants performing an interactive speech paradigm. We observed a broad range of cortical modulation profiles, and subsequent clustering analyses established that responses comprised distinct classes associated with sensory perception, planning, motor execution, and task-related suppression. These activity classes were also localized to separate neural substrates, indicating their status as specialized networks. We then parsed dynamics in the planning and motor networks using unsupervised dimensionality reduction, which revealed subnetworks that were sequentially active throughout preparation and articulation. These results therefore support and extend a localizationist model of speech production where cortical activity flows within and across discrete pathways during language use.

Neuromorphic hierarchical modular reservoirs
Modularity is a fundamental principle of brain organization, reflected in the presence of segregated sub-networks that enable specialized information processing. These small, densely connected modules are often nested within larger, higher-order modules, giving rise to a hierarchical modular architecture. This structure is posited to balance information segregation in specialized neuronal communities and global integration via intermodular communication. Yet, how hierarchical modularity shapes network function remains unclear. Here we introduce a simple blockmodeling framework for generating and comparing multi-level hierarchical modular networks and implement them as recurrent neural net-work reservoirs to evaluate their computational capacity. We show that hierarchical modular networks enhance memory capacity, support multitasking, and give rise to a broader range of temporal dynamics compared to strictly modular and random networks. These functional advantages can be traced to topological features enriched in hierarchical modular networks, which include reciprocal and cyclic network motifs. To test whether the computational advantages of hierarchical modularity subsist in empirical human brain structural connectivity patterns, we develop a novel hierarchical modularity-preserving network null model, allowing us to isolate the positive effect of empirical hierarchical modularity patterns on memory capacity. To evaluate the biomimetic validity of connectome-informed reservoir dynamics, we compare reservoir timescales to empirical brain timescales derived from MEG data and find that hierarchical modularity contributes to shaping brain-like neural timescales. Altogether, across multiple benchmarks, these results show that hierarchical modularity endows networks with computationally advantageous properties, providing insight into the relationship between neural network structure and function with potential applications for the design of neuromorphic computing architectures.

The role of dopamine-sensitive motor cortical circuits in the development and execution of skilled forelimb movements
Dopamine signalling in the motor cortex is crucial for motor skill learning. Here we resolve the spatiotemporal dopamine dynamics and the activity of local dopaminoceptive circuits during the formation and execution of motor skills. We trained head-fixed mice to perform skilled forelimb movements with a joystick to collect water rewards, while simultaneously monitoring dopamine release and calcium dynamics in the forelimb area of motor cortex. We found that dopamine release events and calcium transients were temporally linked to joystick movements and reward consumption. Dopamine dynamics and population level activity of dopamine-receptive neurons scaled with the vigor of forelimb movements and tracked the relationship between actions and their consequences. Optogenetic photoinhibition of cortical dopaminoceptive circuits reduced the number of rewarded joystick movements. Our findings show how phasic dopamine signals in the motor cortex facilitate reinforcement motor learning of skilled behavior.

The Topological Architecture of Brain Identity
Accurately identifying individuals from brain activity--functional fingerprinting--is a powerful tool for understanding individual variability and detecting brain disorders. Most current approaches rely on functional connectivity (FC), which measures pairwise correlations between brain regions. However, FC is limited in capturing the higher-order, multiscale structure of brain organization. Here, we propose a novel fingerprinting method based on homological scaffolds, a topological representation derived from persistent homology of resting-state fMRI data. Using data from the Human Connectome Project (n = 100), we show that scaffold-based fingerprints achieve near-perfect identification accuracy ([~] 100%), outperforming FC-based methods (90%), and remain robust across preprocessing pipelines, atlas choices, and even with drastically shortened scan durations. Unlike FC, in which fingerprinting features localize within networks, scaffolds derive their discriminative power from inter-network connections, revealing the existence of individual mesoscale organizational signatures. Finally, we show that scaffolds act as bridges between redundancy and synergy, by balancing redundancy along high-FC border edges with high synergy across the topological voids that the cycles define. These findings establish topological scaffolds as a powerful tool for capturing individual variability, revealing that unique signatures of brain organization are encoded in the interplay between mesoscale network integration and information dynamics.

MRI-Based Structural Development of the Human Newborn Hypothalamus
Background: Preclinical evidence suggests that intrauterine exposures can impact hypothalamic structure at birth and future disease risk, yet early human data are limited. Methods: Hypothalamic volumes were measured from 699 T1-weighted MRI scans from 631 newborns (54% female; 27-45 weeks postmenstrual age/PMA) in the Developing Human Connectome Project. Linear mixed-effects models tested associations with prenatal exposures: gestational age (GA) at birth, PMA at scan, sex, maternal body mass index (BMI), and smoking. Findings were partially replicated in the Adolescent Brain and Child Development (ABCD) Study (release 5.1) data (16,934 observations from 11,207 participants). Results: Absolute hypothalamus volume increased with PMA (+5.5%/week, t=39.9, p<10^-10), but not after adjusting for brain volume (t=1.2, p=0.24). Males showed larger absolute (+3.3%, t=3.2, p=0.002) but smaller relative hypothalamus volume (t=-2.8, p=0.005). Lower GA was linked to larger relative hypothalamus volume (t=-6.5, p<10^- 9), with evidence for sex moderation (t=-2.4, p=0.019). Smoking during pregnancy was associated with smaller hypothalamus volume in newborns (t=-2.05, p=0.04; dose dependence: t=-2.9, p<0.01). Smoking remained associated with reduced hypothalamus volume in adolescents (t=-2.8, p=0.005). Conclusions: The findings suggest that the hypothalamus is a crucial and underexplored target of perinatal influences for understanding the origins of long-term health and disease.

Preserved cerebellar functions despite structural degeneration in older adults
Aging is frequently perceived negatively due to its association with the decline of various brain and bodily functions. While it is evident that motor abilities deteriorate with age, it is incorrect to assume that all aspects of movement execution are equally affected. The cerebellum, a brain region that is closely involved in motor control among other functions, undergoes clear structural changes with aging. While several studies suggest that cerebellar degeneration causes age related motor control deficits, other studies suggest that the cerebellum might act as a motor reserve and compensate for its structural degeneration, leaving cerebellar motor function intact despite cerebellar degeneration. The present study aims at thoroughly investigating the impact of age on cerebellar function across an array of tasks and domains. We investigated cerebellar motor and cognitive functions across the lifespan by examining 50 young adults (20 to 35 years), 80 older adults (55 to 70 years), and 30 older old adults (over 80 years). Participants completed a test battery comprising seven motor control tasks and one cognitive task, each designed to probe cerebellar function through different paradigms. This multi task approach allowed for a comprehensive evaluation of performance patterns, providing a balanced perspective on cerebellar function across the different age groups. In addition, we analyzed outcomes from the same tasks that, while related to movement, were not specifically linked to cerebellar function. Structural magnetic resonance imaging was also conducted to assess whether cerebellar atrophy was present in the older and older old groups compared to the young. Our results revealed that, despite age-related cerebellar degeneration, cerebellar functions in older adults remained intact compared to young adults, even in adults above 80 years old. In contrast, the sensorimotor measures that were not directly linked to cerebellar function exhibited a clear pattern of decline in older adults, and were further deteriorated in the older-old adults compared to the older adults. These findings indicate that cerebellar motor control functions remain largely preserved with age, providing compelling evidence that the cerebellum possesses a remarkable degree of functional resilience and redundancy. This suggests that cerebellar circuits may be uniquely equipped to preserve function despite structural degeneration.

Biomechanical simplification of the motor control of whisking
Animal nervous systems must coordinate the sequence and timing of numerous muscles - a challenging control problem. The challenge is particularly acute for highly mobile sensing structures with many degrees of freedom, such as eyes, pinnae, hands, forepaws, and whiskers, because these low-mass, distal sensors require complex muscle coordination. This work examines how the geometry of the rat whisker array simplifies coordination required for "whisking" behavior [1-3]. During whisking, 33 intrinsic ("sling") muscles are the primary drivers [4-12] of the rapid, rhythmic protractions of the large mystacial vibrissae (whiskers), which vary more than sixfold in length and threefold in base diameter [13-16]. Although whisking is a rhythmic, centrally-patterned behavior [17-24], rodents can change the position, shape, and size of the whisker array, indicating considerable voluntary control [25-34]. To begin quantifying how the array's biomechanics contribute to whisking movements, we used three-dimensional anatomical reconstructions of follicle and sling muscle geometry to simulate the movement resulting from a "uniform motor command," defined as equal firing rates across all sling muscle motor neurons. This simulation provides a baseline profile of protraction under anatomically realistic but uniformly driven conditions. It does not isolate neural from biomechanical contributions but helps identify deviations that suggest active control. Simulations reveal that all follicles rotate through approximately equal angles, regardless of size. The angular fanning of the whiskers at their bases increases monotonically throughout protraction, while maximum distance between whisker tips occurs at approximately 90% of resting muscle length, after which whisker tips converge and sensing resolution increases monotonically.

Cholinergic modulation of dopamine release drives effortful behavior
Effort is costly: given a choice, we tend to avoid it1. But in many cases, effort adds value to the ensuing rewards2. From ants3 to humans4, individuals prefer rewards that had been harder to achieve. This counterintuitive process may promote reward-seeking even in resource-poor environments, thus enhancing evolutionary fitness5. Despite its ubiquity, the neural mechanisms supporting this behavioral effect are poorly understood. Here we show that effort amplifies the dopamine response to an otherwise identical reward, and this amplification depends on local modulation of dopamine axons by acetylcholine. High-effort rewards evoke rapid acetylcholine release from local interneurons in the nucleus accumbens. Acetylcholine then binds to nicotinic receptors on dopamine axon terminals to augment dopamine release when reward is delivered. Blocking the cholinergic modulation blunts dopamine release selectively in high-effort contexts, impairing effortful behavior while leaving low-effort reward consumption intact. These results reconcile in vitro studies, which have long demonstrated that acetylcholine can trigger dopamine release directly through dopamine axons6-11; with in vivo studies that failed to observe such modulation12-14, but did not examine high-effort contexts. Our findings uncover a mechanism that drives effortful behavior through context-dependent local interactions between acetylcholine and dopamine axons.

Twinfilin-1 phosphorylation in reelin signaling regulates actin dynamics and spine development
Reelin is an extracellular glycoprotein essential for neuronal migration, spine development, and synaptic plasticity. Impaired reelin signaling is linked to neurological disorders, including schizophrenia and autism. While reelin mutant (reeler) mice exhibit behavioral deficits associated with impaired spine formation, the underlying molecular mechanisms remain unclear. We identified Twinfilin-1 (Twf1) as a downstream effector of reelin signaling via phosphoproteomic analysis, based on its reduced tyrosine phosphorylation in reeler mice. We found that Src regulated Twf1 phosphorylation at tyrosine 309, and reelin stimulation increased Twf1 phosphorylation in neurons, an effect blocked by the Src inhibitor PP2. A phospho-resistant Twf1 mutant (Twf1 Y309F) showed reduced capping protein binding and a lower F/G-actin ratio. Twf1Y309F mice exhibited cognitive deficits, reduced spine density, smaller spine head size, and a decreased F/G-actin ratio in synaptosomes. These findings highlight Twf1 phosphorylation as a key component of reelin signaling involved in actin remodeling and spine development.

Schizophrenia-associated 22q11.2 deletion elevates striatal acetylcholine and disrupts thalamostriatal projections to produce amotivation in mice
Schizophrenia is a complex neurodevelopmental disorder characterized by cognitive dysfunction, hallucinations, and negative symptoms such as amotivation. Negative symptoms are largely resistant to current antipsychotic treatments, and the neural circuits underlying amotivational states remain poorly defined. Here, using a mouse model of schizophrenia-associated 22q11.2 deletion syndrome (22q11DS), we report amotivation and weakened glutamatergic synaptic transmission between the thalamic parafascicular nucleus (Pf) and the dorsomedial striatum (DMS). Thalamostriatal disruption is attributed to hyperactivity of striatal cholinergic interneurons (CHIs), which is associated with enhanced Trpc3 and Pex51 (Trip8b) gene expression. Elevated acetylcholine levels in the DMS act on presynaptic M2 muscarinic receptors to weaken Pf-DMS glutamatergic transmission. Importantly, disruption of Pf-DMS synaptic transmission or hyperactivation of CHIs are each sufficient to cause amotivation in wild-type mice. These results identify a striatal hypercholinergic state and subsequent thalamostriatal disruption as core pathogenic events causing amotivation in 22q11DS, providing potential therapeutic targets.

Combined Auditory, Tactile, and Visual fMRI Reveals Sensory-Biased and Supramodal Working Memory Regions in Human Frontal Cortex
Selectivity for sensory modality characterizes distinct subregions of the human brain, well beyond the primary sensory cortices. We previously identified frontal and posterior cortical regions that are preferentially recruited for visual vs. auditory attention and working memory (WM). Here, we extend our approach to include tactile cognition and to characterize cortical regions recruited by WM in each of three sensory modalities. The joint organization of visual-selective, auditory-selective, tactile-selective, and supramodal WM recruitment within individual subjects has not been fully investigated previously. Male and female human subjects participated in a blocked fMRI task requiring them to perform N-back WM judgements in auditory, visual, or tactile (haptic) modalities. We confirmed our prior reports of multiple visual-biased and auditory-biased frontal lobe regions. We also observed several bilateral tactile-selective regions abutting previously described visual- and auditory-selective regions, including dorsal and ventral precentral sulcus, the postcentral sulcus, and the anterior intraparietal sulcus. Several cortical regions were recruited by WM in all three sensory modalities in individual subjects, including precentral sulcus, inferior frontal sulcus, intraparietal sulcus, anterior insula and pre-supplementary motor area. Supramodal regions exhibited substantial overlap with visual-biased regions in frontal and parietal cortex and comparatively little overlap with tactile- or auditory-biased regions. Lastly, resting-state analyses revealed that auditory-, visual- and tactile-selective WM regions segregate into modality-specific networks that span frontal and posterior cortex. Together, these results shed light on the functional organization of sensory-selective and supramodal regions supporting higher-order cognition.

SIGNIFICANCE STATEMENTUsing within-subject fMRI analyses of three different sensory modalities, we identify the fine-scale architecture of sensory-biased and supramodal working memory structures within human frontal cortex. Sixteen bilateral frontal lobe regions are identified: five auditory-biased, four visual-biased, two tactile-biased, and five multiple-demand / supramodal regions. These parcels are largely distinct with the notable exception that the visual-biased regions each partially overlap with supramodal regions, suggesting a tight link between visual and supramodal working memory representations. Sensory-biased frontal lobe regions form modality-specific networks with traditionally-identified posterior sensory cortical regions. The findings demonstrate a pervasive role for sensory modality in the functional organization of frontal cortex and offer a fine-scale parcellation of the human frontal lobe regions supporting working memory.

Functional Specialization of Angular Gyrus and Precuneus Subregions for Perspective-Guided Autobiographical Memory Retrieval
Autobiographical memory (AM) retrieval involves goal-directed and reconstructive processes that unfold over time. A key feature of this process is the visual perspective adopted during remembering, which shapes subjective memory experience. Using fMRI, we cued participants to retrieve AMs from an own-eyes, observer, or natural perspective followed by an event probe. Our design dissociates preparatory (cue phase) and reconstructive (probe phase) mechanisms to isolate the neural signatures of retrieval orientation, the strategic use of cues to optimize retrieval. Whole-brain and ROI analyses revealed that the angular gyrus (AG) and precuneus support perspective-guided retrieval in distinct ways. During the cue phase, PGp showed greater activity for instructed perspectives than natural retrieval, consistent with preparatory perspective selection. During the probe phase, observer-perspective retrieval elicited greater activity in PGp and precuneus (7P), supporting sustained perspective maintenance. Brain-behavior models linked PGp and 7P activity to greater vividness and perspective stability, while precuneus (7M) activity was negatively associated with emotional intensity, especially in the observer condition. These findings reveal phase- and subregion-specific contributions of posterior parietal cortex to the subjective qualities of memory. AG subregions support goal-directed perspective selection and implementation, while precuneus subregions flexibly modulate phenomenological features during memory reconstruction.

Visual Working Memory Guides Attention Rhythmically
How does internal representation held in visual working memory (VWM), known as the attentional template, guide attention? A longstanding debate concerns whether only one (Single-Item-Template theory) or multiple (Multiple-Item-Template theory) items serve as attentional templates simultaneously. Here we propose a Rhythmic-Item-Template hypothesis, successfully reconciling these seemingly contradictory theories. Using the classical VWM-guided attention task, we found that two VWM items alternately dominate behavioral guidance in theta-rhythmic (4-8 Hz), with anti-correlated activation states in time, and more importantly, this rhythmic oscillation was not driven by the retro-cue processing. Neural recordings revealed that occipital alpha-oscillation (8-14 Hz) governed item-specific prioritization and its amplitude closely tracked subjects behavioral guidance, while frontal theta-oscillations phase-led and coupled with occipital alpha-oscillations during the item transition. Our Rhythmic-Item-Template results not only resolve previous Single-Item-Template versus Multiple-Item-Template debate but also advance our understanding of how distributed brain rhythms coordinate flexible resource allocation in multi-item memory systems.