bioRxiv Subject Collection: Neuroscience's Journal

Functional connectivity patterns as an early indicator of later very early preterm outcomes
Abnormal functional brain development associated with preterm birth has been widely reported; however, the neural brain architectures of later neurodevelopmental difficulties are not yet fully understood. Here, we applied connectome-based predictive modeling approaches to identify the brain networks associated with later neurocognitive scores at 2-3 years of age in very preterm infants (<31 weeks gestation, N=79) using resting-state functional magnetic resonance imaging (rs-fMRI). The whole-brain functional connectome soon after birth successfully predicted verbal ability at 3 years of corrected age (r=0.53, p=4.04x10^(-7)) and motor ability at age 2 (r=0.39, p=0.0004) in very preterm infants. In particular, we found that functional edges between the frontoparietal network and limbic, motor, and medial frontal networks at birth contributed significantly to the prediction of future verbal language ability, while the edges connecting the medial frontal network and motor and basal ganglia networks contributed the most to the prediction of future motor ability. In a separate validation analysis, we demonstrated that the mean connectivity strength among these top brain networks significantly differentiated (average accuracy 76%, p<0.001) poor from normal performers at 2 and 3 years corrected ages. These findings highlight regional functional connectivity soon after birth as a promising biomarker for identifying risks for later brain disorders, which could inform the targeted development of effective early treatments and interventions.

Digital Twin Brain Predicts rTMS Effects on Brain State Dynamics in Chronic Tinnitus
Predicting repetitive transcranial magnetic stimulation (rTMS) effects on whole-brain dynamics in clinical populations is crucial for developing personalized therapies and advancing precision medicine in brain disorders. This study provides the first proof-of-concept demonstrating that the Digital Twin Brain (DTB) can forecast rTMS effects on brain state dynamics in individuals with brain disorders (chronic tinnitus). First, we identified two aberrant brain states that predominantly overlapped with the somatomotor and default mode networks, respectively. Subsequently, we developed DTB for patients and derived regional responses for each brain region, revealing distinct roles of the parieto-occipital and frontal regions. Mechanistically, we examined the biological plausibility using tinnitus-specific risk genes and investigated the multi-scale neurobiological relevance. Clinically, we found that DTB can predict rTMS effects in an independent, longitudinal dataset (all r > 0.78). Particularly, the predictive capacity exhibits a state-specific nature. Overall, this work proposes a novel DTB-based framework for predicting rTMS effects in clinical populations and provides the first empirical evidence supporting its clinical utility. This approach may be generalizable to other brain disorders and neuromodulation techniques, promoting broader advancements in brain health.

Periventricular Diffusivity Reflects APOE4-modulated Amyloid Accumulation and Cognitive Impairment in Alzheimers Continuum
Background: Altered glymphatic-related fluid dynamics are increasingly recognized as a key feature of Alzheimers disease (AD). We generalized an established diffusion imaging technique to estimate periventricular diffusivity (PVeD), hypothesizing that fast diffusion signals in the periventricular region can reflect amyloid-beta deposition across the AD continuum. Methods: Participants from two multi-site cohorts (n = 440 and 414), comprising cognitively unimpaired individuals, those with mild cognitive impairment, and patients with AD, were included. We tested and validated the association of PVeD with amyloid-beta burden and core AD characteristics. Results: Lower PVeD was extensively associated with greater amyloid-beta burden, neurodegeneration, cognitive impairment, and clinical severity. Importantly, the relationship between PVeD and amyloid-beta burden was significantly modulated by APOE4 status, with APOE4 carriers showing a stronger negative association. Baseline PVeD also predicted longitudinal cognitive decline. Discussion: These findings suggest that periventricular fast diffusion signals can reflect APOE4-modulated amyloid-beta burden and cognitive decline in AD.

Platelet concentrate-derived extracellular vesicles promote adult hippocampal neurogenesis
Emerging evidence suggests that platelet concentrate (PC) derivatives harbor neuroregenerative potential. Here, we evaluated the neurogenic effects of PC-derived human platelet lysate (HPPL) and extracellular vesicles (pEVs) on neural precursor cells using both an ex vivo neurosphere assay and an in vivo intranasal delivery model in adult mice. pEVs selectively enhanced the proliferation of dentate gyrus (DG)-derived neurospheres, and this region-specific effect persisted even without exogenous growth factors. In line with these findings, short-term intranasal administration of pEVs significantly increased cell proliferation in the DG. Long-term (28-day) pEVs treatment further elevated the proportion of newborn mature neurons in the DG, whereas HPPL primarily increased both proliferation and the number of immature neurons. Proteomic profiling of DG tissue after pEV treatment revealed 111 differentially expressed proteins, enriched in pathways related to oxidative phosphorylation, myelination, Notch4 signaling, and MHC class I processing. These findings identify allogeneic PC-derived EVs as potent, cell-free agents capable of promoting adult hippocampal neurogenesis and brain repair through metabolic and immunoregulatory mechanisms.

Safety learning induces postsynaptic potentiation of direct pathway spiny projection neurons in the tail of the striatum
The association of a sensory cue with an outcome is a crucial step in learning to identify safe versus threatening situations. Here we assessed how learned sound-safety association alters neuronal activity in tail of the striatum (TS), where auditory cortical and thalamic inputs converge. Prior to training, foot shock elicited responses by TS direct and indirect pathway spiny projection neurons (SPNs), while sound tones produced no response. However, once the sound association was learned, sound tones strongly activated TS SPNs, even when the animal was under anesthesia. This conditioned auditory response occurred concurrently with alterations of direct pathway SPNs in the TS, including increased responses to cortical and auditory thalamic inputs, increased excitatory response with an enhanced ratio of NMDA to AMPA receptors, decreased responses to inhibitory input, and increased dendritic spines. This convergence of postsynaptic changes provides responses to relevant auditory cues during associative learning.

Spatial Dynamics and Functional Connectivity in EEG: Insights from Lexical Processing
Lexical processing is a core cognitive function involving the integration of semantic and symbolic information across distributed brain networks. In this study, we investigate the spatial dynamics and functional connectivity underlying lexical categorization using electroencephalography (EEG) data from a silent reading task. Participants were presented with words from two categories, social and numeric, while EEG signals were recorded and analyzed. Frequency band power and inter-electrode coherence were extracted as features to train Random Forest classifiers for word category prediction. The spatial dynamics model, based on band power from selected electrodes, achieved 100% classification accuracy and identified region- and frequency-specific contributions, notably in the theta and alpha bands across parietal and occipital regions. A complementary functional connectivity model achieved 85% accuracy, highlighting the role of inter-regional coherence in lexical differentiation. These findings demonstrate the potential of combining traditional EEG analysis with machine learning for decoding semantic categories, providing foundational insights for future brain-computer interface applications.

Calcium-permeable AMPAR in hippocampal parvalbumin-expressing interneurons protect against memory interference
Parvalbumin-expressing (PV+) interneurons exert exquisite control over spike output, and plasticity in these inhibitory circuits may be important for maintaining network stability in learning and memory. PV+ interneuron recruitment is primarily mediated by GluA2-lacking Ca2+-permeable AMPA receptors (CP-AMPAR), which support anti-Hebbian plasticity. However, the functional significance of CP-AMPAR-mediated plasticity remains unknown. Using a viral approach to artificially express the GluA2 subunit in hippocampal PV+ interneurons, we replaced CP-AMPAR with GluA2-containing receptors, and in doing so reduced synaptically-evoked Ca2+ transients and anti-Hebbian plasticity. Transfection of hippocampal PV+ interneurons with GluA2 resulted in delay-dependent spatial working memory deficits which increased across trials per session, and impaired reversal learning in the Morris water maze but not initial acquisition. Our data suggest that loss of CP-AMPAR-mediated plasticity in these cells leads to proactive interference, revealing a significant role for dynamic recruitment of PV+ interneurons in the segregation of memories and accurate memory retrieval.

Neuroanatomical and behavioral characterization of corticotropin releasing factor-expressing lateral Habenula neurons in mice
The lateral habenula (LHb), which plays a critical role in value-based decision-making and in stress responses, is linked to drug addiction and mood disorders. Prior research from our lab demonstrated the LHb's responsiveness to corticotropin-releasing factor (CRF), yet the origin of CRF inputs to this region remained elusive. Here, we mapped CRF projections to the LHb, revealing several contributing brain regions and a subpopulation of CRF-expressing LHb neurons (LHbCRF) along with their downstream targets. Chemogenetic activation of LHbCRF neurons did not affect conditioned place preference or anxiety-related behaviors in mice of either sex. However, it enhanced passive action-locking responses to a simulated aerial threat in both male and female mice as well as induced subtle sex-specific differences in escape latency which aligned with our observation of higher basal spontaneous activity in male LHbCRF neurons. These findings indicate that LHbCRF neurons can promote passive defensive responses to immediate danger, with baseline activity potentially influencing the timing of escape.

Proprioceptive and visual motion detection acuity contribute to children dynamic postural control
Acquiring efficient postural control strategies is key to children proper motor development. For that, the brain needs to continuously integrate sensory information and convert it into corrective motor commands. Although this entire process naturally hinges on the reliability of early senses, very few studies have investigated early sensory acuity and its role in postural stability during development. Clarifying this could lead to a better understanding of conditions, such as developmental coordination disorder (DCD), where the impairment of balance control is substantial. Here, we tested 25 typically developed school-aged children with a Visual Motion Detection test (VMDT), an ankle Joint Position Sense test (aJPST), force-plate assessed posturography, and the Movement Assessment Battery for Children - Second edition (MABC-2). We found a significant correlation between the balance score of the MABC-2 and both VMDT score (r = 0.60, p = 0.003) and aJPST score (r = -0.47, p = 0.02). However, no such relationship was found between the force-plate assessed sway amplitude during upright standing and the two sensory acuity scores. Importantly, the MABC-2 balance scores were associated with upright stability, but only to a limited extent. Given that the MABC-2 balance component factors in static and dynamic balance while posturography focuses only on static balance, our results point at a key role of early sensory acuity for dynamic balance. Together, these findings bring attention to possible clinical tools for motor impairment detection and subsequent rehabilitation strategies during development.

Neural dynamics encoding risky choices during deliberation reveal separate choice subspaces
Human decision-making involves the coordinated activity of multiple brain areas, acting in concert, to enable humans to make choices. Most decisions are carried out under conditions of uncertainty, where the desired outcome may not be achieved if the wrong decision is made. In these cases, humans deliberate before making a choice. The neural dynamics underlying deliberation are unknown and intracranial recordings in clinical settings present a unique opportunity to record high temporal resolution electrophysiological data from many (hundreds) brain locations during behavior. Combined with dynamic systems modeling, these allow identification of latent brain states that describe the neural dynamics during decision-making, providing insight into these neural dynamics and computations. Results show that the neural dynamics underlying risky decision, but not decisions without risk, converge to separate subspaces depending on the subject's preferred choice and that the degree of overlap between these subspaces declines as choice approaches, suggesting a network level representation of evidence accumulation. These results bridge the gap between regression analyses and data driven models of latent states and suggest that during risky decisions, deliberation and evidence accumulation toward a final decision are represented by the same neural dynamics, providing novel insights into the neural computations underlying human choice.

Single-dose DMT reverses anhedonia and cognitive deficits via restoration of neurogenesis in a stress-induced depression model.
Major depressive disorder (MDD) remains a leading cause of disability worldwide, with current treatments limited by delayed onset and low efficacy. The serotonergic psychedelic N,N-dimethyltryptamine (DMT) has shown rapid antidepressant effects in early clinical studies, yet its mechanisms and efficacy remain poorly characterized in established models of depression. Here, we evaluated the effects of a single dose of DMT in the Chronic Unpredictable Mild Stress (UCMS) paradigm, a robust mouse model recapitulating key features of MDD, including anhedonia and cognitive impairment. DMT administered after UCMS reversed depressive-like behavior and restored cognitive performance, outperforming chronic fluoxetine across most domains. When administered during the stress period, DMT prevented the development of anhedonia but did not rescue cognitive deficits, suggesting partial protection. Notably, DMT remained effective under isoflurane anesthesia, indicating that its therapeutic action can occur independently of the psychedelic experience. Histological analyses revealed that all DMT regimes significantly increased adult-born granule cell (abGC) integration and reduced the number of ectopically abnormally integrated abGCs. Together, our findings highlight the robust and multifaceted effects of DMT on behavior and neurogenesis, positioning it as a promising candidate for rapid-acting antidepressant strategies that target structural circuit repair.

Environmental enrichment selectively restores brain metabolic activity during cocaine abstinence
Background: Environmental enrichment (EE) is a promising strategy to promote recovery from addiction, but its neurobiological mechanisms remain poorly understood. This study investigates how exposure to EE during abstinence dynamically affects brain neuroadaptations induced by voluntary intake of cocaine. Methods: Using longitudinal 18FDG microPET imaging, we examined brain metabolic activity in rats following extended access cocaine self-administration. After establishing escalation of cocaine intake, rats were housed in either enriched or standard environments during a four-week abstinence period. Brain metabolic activity was assessed after one and four weeks of abstinence. Results: Cocaine self-administration produced widespread decreases in cortical metabolic activity, particularly in regions involved in executive function (orbitofrontal cortex, anterior cingulate) and interoception (insula), while increasing activity in emotional and motivational circuits (nucleus accumbens, amygdala, mesencephalon). EE selectively normalized these alterations through temporally distinct mechanisms: rapidly restoring nucleus accumbens and amygdala function while gradually affecting prefrontal cortical activity. After four weeks, rats housed in enriched environments showed significantly normalized metabolic activity in the orbitofrontal cortex and dorsolateral striatum compared to those in standard housing, with persistent changes in anterior cingulate cortex and ventral posterior hippocampus. Conclusions: Our findings reveal circuit-specific and temporally distinct effects of environmental enrichment on cocaine-induced brain alterations. These insights could inform the development of more targeted therapeutic approaches for addiction recovery.

Whey Protein Phospholipid Concentrate Supplementation Prevents High-Fat Diet Induced Cognitive Impairment in Wistar Rats by Promoting Brain Neuronal Connectivity and Sphingolipid Clearance
Whey protein phospholipid concentrate (WPPC), a byproduct of whey protein processing, is high in phospholipids and glycoconjugates which serve as substrates for fatty acids and sugar monomers (e.g. sialic acid) critical to neuronal myelin synthesis in the brain. This led us to hypothesize that WPPC will improve cognitive impairment induced by a high fat (HF) diet by promoting myelin turnover and improving myelin-dependent processes associated with encoding and storing memory. Male Wistar rats were randomized to one of four diets starting at weaning to ~6.5 months on age: a low-fat (LF) diet containing 10% fat by weight, a HF diet containing 45% fat by weight to induce cognitive impairment, and a HF diet containing either 1.6% or 10% WPPC by weight (n=12 per diet). Rats were subjected to cognitive testing after 2 and 4 months of dietary intervention and then implanted with chronic bipolar electrodes to measure axonal evoked responses within the entorhinal cortex-hippocampal circuitry. Phospholipid and sphingolipid components of myelin were quantified in the hippocampus. There were no significant differences in cognition measured by novel object recognition after 2 months of supplementation. At 4 months, rats on the HF diet performed significantly worse than rats on the LF, HF1.6 and HF10 diets. The beneficial effects of WPPC on cognition were due to a partial reversal in evoked response impairments in hippocampal memory storage. Additionally, hippocampus sphingolipids were higher in rats on the HF diet compared to the LF, HF1.6 and HF10 groups. These findings demonstrate that WPPC prevented cognitive impairment induced by a HF diet by regulating entorhinal cortex-hippocampal circuitries associated with memory storage, though modulating myelin turnover.

Cryptic intronic transcriptional initiation generates efficient endogenous mRNA templates for C9orf72-associated RAN translation
Intronic GGGGCC hexanucleotide repeat expansions in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Despite its intronic location, this repeat avidly supports synthesis of pathogenic dipeptide repeat (DPR) proteins via repeat-associated non AUG (RAN) translation. However, the template RNA species that undergoes RAN translation endogenously remains unclear. Using long-read based 5 prime RNA ligase mediated rapid amplification of cDNA ends (Repeat RLM RACE), we identified novel C9orf72 transcripts initiating within intron 1 in a C9BAC mouse model, patient derived iNeurons, and iNeuron derived polysomes. These cryptic m7G capped mRNAs are at least partially polyadenylated and are more abundant than transcripts derived from intron retention or circular intron lariats. In RAN translation reporter assays, novel intronic template transcripts, even those with short (32 nucleotide) leaders, exhibited robust expression compared to exon-intron and repeat-containing lariat reporters. To assess endogenous lariat repeat RNA contributions to RAN translation, we enhanced endogenous lariat stability by knocking down the lariat debranching enzyme Dbr1. However, this modulation did not impact DPR production in patient-derived iNeurons. These findings identify cryptic, linear, m7G capped intronic-initiating C9orf72 mRNAs as an endogenous template for RAN translation and DPR production, with implications for disease pathogenesis and therapeutic development.