Electrophysiology publications

Humans and other animals can solve new problems, even on the first attempt. This capacity to generate novel problem-solving behavior has been hypothesized to depend on brain mechanisms for recombining units of knowledge using systems of procedural rules, or grammars . Yet, whether and how the brain represents and implements grammars remains unclear, in large part due to the lack of neural recordings (typically performed in animal models) during grammar-based problem solving (typically studied in humans). Here, we address that gap, and in turn identify an underlying neural basis of grammatical behavior. We designed a visual–motor construction task in which macaque monkeys trace complex, often novel, geometric figures by generating a sequence of strokes, each a distinct shape, like a circle, dash, or chevron (action symbols 1 ). Critically, sequencing was guided by a learned hierarchical action grammar A n B m C k , meaning “repeat shape A, then repeat shape B, then repeat shape C”, where the number of repetitions (n, m, and k) varied across problems. Behavior was internally generated (no cues guiding stroke order), problem-directed (to construct a specific image), and exhibited zero-shot generalization (successful on the first trial for novel problems, including harder ones)--key hallmarks of grammar use. To identify underlying neural substrates, we recorded from multiple frontal cortical areas previously implicated in rule use or action sequencing. Activity during drawing encoded key structural properties of the action grammar: (i) shape index (A, B, C), (ii) abstract role (e.g., the role A independent of the specific shape), and (iii) ordinal position within a shape repeat. Moreover, all three properties were strongest in a single region, the pre-supplementary motor area (preSMA). We suggest the possibility that this conjunction of representations is a signature of an implementation of an iterative algorithm resembling a “for-loop” program: internally tracking how many repetitions remain for each shape index and switching to the next when complete. Our study establishes a paradigm for studying the neural basis of grammar-guided novel behavior and identifies in preSMA a dynamic representation of grammatical structure supporting such behavior.

Music listening is one of the most compelling and rewarding activities humans engage in spontaneously. But what exactly catches people”s attention when listening to music remains unclear. Musicologists have argued that tension - release dynamics in music constitute crucial features of the listening experience. They arise from the intertwining of different low-level and high-level features and sit at the core of music enjoyment by engaging listeners dynamically. This study aims to characterize the relationship between tension dynamics and engagement during naturalistic music listening. Using canonical correlation analysis, we decoded the music envelope from EEG and ECoG responses and found that musical tension patterns, as reported by listeners, were predictive of fluctuations in the coupling between the music and the neural response. Importantly, tension dynamics were significantly correlated with neural measures of envelope tracking even after controlling for loudness and musical expectations, confirming the specific and crucial role of musical tension in engaging listeners. These results shed new light on how musical structure gives rise to internal response modulations that, in turn, dynamically reflect musical engagement. This interplay may underlie the pervasive and emotionally rewarding nature of music. Significance Statement This work addresses a fundamental question in cognition: how engagement dynamically modulates complex auditory input processing. We investigate this issue within the well-controlled yet ecologically valid context of music perception. At the core of the musical experience lies the perception of tension – the shifting sense of expectancy, instability, and resolution that guides listening across time. We show that fluctuations in musical tension, shaped by musical structure, reliably predict modulations of auditory engagement, thereby illuminating an understudied phenomenon: what makes music engaging.

Background With age, even mild acoustic injuries can accumulate - ultimately leading to a characteristic clinical picture of age-related hearing loss with the risk of cognitive decline. Age-related hearing loss is currently attributed to the loss of a most vulnerable auditory fiber type contributing to hearing in background noise. Here, we investigated the potential of a new drug, a more stable chemical variant of Dendrogenin B (DX243) that is predicted to display a protective function on neurite outgrowth, rather than on cell survival. Methodology In the rat animal model, DX243 was tested on hearing thresholds, cortical local field potentials (LFP), auditory steady-state responses (ASSR), auditory brainstem responses (ABR), growth function of notched-noise stimuli, inner hair cell (IHC) ribbon numbers, and multi-click pulse responses (MCP) before and after auditory trauma (AT). Results No auditory evoked LFP response changes were seen in the prefrontal cortex, visual cortex, or hippocampus. In contrast, a permanent decline of auditory evoked LFP amplitudes in the auditory cortex (AC) was measured 2 weeks after AT. Daily injection of DX243 for 2 weeks prevented the AT-induced decline in LFP activity, a protective effect that continued for 6 weeks following the final injection. Through a protective effect of DX243 on a trauma-induced decline of LFP in response to amplitude-modulated tones >80 Hz, a subcortical origin of the drug-effect was suggested. DX243 showed no effect on hearing sensitivity and did not affect subcortical processing of sound features that depend on phase-locking at the stimulus onset (e.g., near-threshold ASSR responses, close-to-threshold ABR growth functions, or spontaneous cortical LFP responses). However, with the same dose-response dependency as shown for cortical LFP effects, DX243 significantly protected from AT-induced decreases in ABR growth functions for loud sound stimuli and in background noise, protected from AT-induced loss of IHC ribbons and AT-induced decline of fast ABRs with decreasing time intervals. Conclusion These findings suggest DX243 as a novel neuroprotective drug, that specifically protects auditory fibers contributing to the coding of the temporal envelope and detection of tones in masking noise, tasks of our auditory senses, both of which, if they fail, lead to age-related speech-in-noise comprehension deficits.

Introduction The abrupt cessation of chronic benzodiazepine administration is associated with the development of withdrawal symptoms like increased susceptibility to seizures or seizure development in both animals and humans. Although withdrawal phenomena have been studied in detail in adult animals, information about their development and nature in the immature brain is lacking. Substantial experimental evidence suggests that exposure to BZDs early in life permanently alters brain circuitry and functions. However, the possible long-term modification of seizure propensity has not yet been studied. Methods Clonazepam (CZP) was injected into rat pups daily at a dose of 1 mg/kg for five consecutive days, starting on postnatal day 7 (P7) and continuing until P11. Seizure susceptibility was assessed using a pentylenetetrazol (PTZ)-induced seizure model. PTZ induces three types of seizures in rodents that differ by developmental profile and manifestations: convulsive myoclonic seizures (mS) and generalized tonic-clonic seizures (GTCS), and absence-like rhythmic spike-and-wave EEG activity (RMA). Seizures were induced with a single threshold dose of 50–60 mg/kg on days 2, 4, 7, 10, or 14, or with three additive doses of 20 mg/kg on days 7 and 14, or 3 months after the end of treatment. Convulsions accompanying mS and GTCS were detected behaviorally, and RMA was detected in EEG recordings. Results The effects of early-life CZP exposure on susceptibility to PTZ-induced seizures were highly dependent on the interval after treatment cessation and the seizure type. Cessation of CZP after a single PTZ threshold dose resulted in an increase in seizure severity compared to controls that was driven by an increased incidence of GTCS lasting 1 week (up to P18). Early-life CZP exposure led to decreased latency to the first RMA and increased RMA frequency after the first PTZ dose of 20 mg/kg in adult (P90) animals, but it did not change RMA parameters in juvenile rats. Conclusion Abruptly ceasing clonazepam administration in infant rats results in the development of withdrawal phenomena, represented by a striking increase in seizure propensity. Interestingly, transient augmentation of GABAergic inhibition during critical periods of synaptogenesis and neural network formation and maturation permanently modifies susceptibility to PTZ-induced epileptiform activity.

This work presents three open datasets featuring various levels of processing, containing neural recordings from the auditory cortex of rats. These recordings were obtained during experiments using the auditory oddball paradigm before, during and after the local microiontophoretic application of acetylcholine. The primary objective of these datasets is to investigate how the brain processes predictable versus unexpected auditory stimuli, and the role of cholinergic inputs during such processing. The data include multi-unit recordings of neuronal activity during the presentation of standard and deviant tones, classified by stimulus type and cortical sub-region. These resources enable quantitative investigations of deviance detection, stimulus-specific adaptation, cholinergic modulation and predictive-coding mechanisms at multiple temporal scales.

Facial gestures are one fundamental set of communicative behaviors in primates, generated through the dynamic arrangement of many fine muscles. Anatomy shows that facial muscles are under direct control from multiple cortical regions, and studies of patients with focal lesions suggest that lateral frontal cortices control voluntary movements and medial emotional expressions. By directly measuring single-neuron activity from both sets of areas, we found that lateral and medial cortical face motor regions encode both types of gestures. They do so through area-specific temporal activity patterns, distinguishable well prior to movement onset. Our results show that cortical regions projecting in parallel downstream form a continuum of gesture coding, from dynamic to temporally stable, to produce socially appropriate motor outputs during communication.

Excessive daytime sleepiness, i.e., the inability to sustain wakefulness during the day, is a common Parkinson's disease (PD) non-motor symptom. Elevated cortico-basal ganglia beta oscillatory power (8-35 Hz) is a pathophysiological signature of PD motor signs. The relationship between beta oscillatory power and daytime sleepiness, however, remains unclear. Here, we examined the relationship between beta power and daytime vigilance in parkinsonian nonhuman primates. We administered dopaminergic medication to alter cortico-basal ganglia beta power and measured its effect on daytime vigilance. The beta power from motor cortex (MC) and subthalamic nucleus (STN), and wake quantity were derived in the following conditions: OFF-medication, ON-medication, and decay of medication effect. STN low-beta (8-20 Hz) power negatively correlated with wake quantity, suggesting that elevated STN low-beta power could disrupt sustenance of wakefulness. The cortical low-beta power did not correlate with wakefulness. Interestingly, STN and MC high-beta (21-35 Hz) power positively correlated with wake quantity. Our data provide evidence for an association between beta power and daytime vigilance in parkinsonism in addition to its known relationship with PD motor signs. These findings could inform targeted treatments to promote wakefulness in PD by selectively suppressing (e.g., low-beta) and/or amplifying (e.g., high-beta) cortico-basal ganglia beta oscillatory power.

The Rubber Voice Illusion is an auditory analogue of the classic Rubber Hand Illusion, a “mind-trick” for the voice. When speakers hear a stranger’s utterances that are perfectly time‑locked and syllable‑matched to their own voice, many momentarily adopt that alien voice as self‑generated. We used this illusion to probe the integrity of predictive auditory mechanisms across the psychosis continuum. Sixty healthy adults completed three Talk‑Listen conditions while high‑density EEG was recorded: veridical (live playback of own voice), stranger‑match (congruent stranger voice) and stranger‑mismatch (incongruent). Behaviorally, only the congruent condition evoked a sense of Ownership and Agency over the stranger’s voice, paired with an upward shift in fundamental frequency toward the higher-pitched stranger voice - an implicit indication of voice adaptation. Neurophysiologically, the canonical speaking-induced suppression was replicated, and suppression was significantly smaller in participants who scored high on Peters et al. Delusions Inventory. In controls, greater pitch shift was associated with stronger neural suppression, suggesting a functioning self-suppression mechanism; conversely, in high-schizotypy individuals, the relationship reversed, despite pitch shifting toward the stranger’s pitch, they exhibited reduced suppression, indicating decoupling between motor output and sensory prediction. The study provides further evidence to the intricate relationship of neural mechanisms underlying self-generated actions with sensory processing in the psychosis continuum.

Visual selective attention is not wired into the brain fully formed and immutable but is acquired and refined as animals learn by interacting with their environment. Here we investigated this process by studying neuronal activity in the superior colliculus (SC) of male and female mice that learned different meanings of the same visual stimuli. We recorded spiking activity of neurons across the superficial and deep SC layers in three cohorts of mice, each trained using a tailored set of task rules that attributed different levels of behavioral relevance to the visual stimuli. Experimental conditions across the three tasks were carefully matched for visual stimulation and task engagement. We found that several markers of attention-related activity depended on the level of learned behavioral relevance, with the strongest effects in deep SC. First, for activity evoked by cue onset, visual responses in superficial SC were larger in animals that exhibited higher learned relevance. In deep SC, the presence of visual onset responses depended entirely on the learned behavioral relevance. Second, traditional attention-related modulation, defined as enhanced steady-state activity for the visual stimulus at the cued location, was also stronger with higher learned relevance, and this effect was limited to deep SC. Finally, the response to the visual change at the cued location was virtually absent when learned behavioral relevance was low but was prominent after visual training. Together, these results reveal that several fundamental features of attention-related modulation depend on the behavioral relevance learned through task-specific training, including aspects of stimulus-driven attention.

Psychedelics lead to profound changes in subjective experience and behaviour, which are typically conceptualised in psychological terms rather than corresponding to an altered brain state or a distinct state of vigilance. Here, we performed chronic electrophysiological recordings from the neocortex concomitant with pupillometry in freely moving adult male mice following an injection of a short-acting psychedelic 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT). We report an acute induction of a dissociated state, characterised by prominent slow oscillations in the cortex and marked pupil dilation in behaviourally awake, moving animals. REM sleep was initially markedly suppressed, but was overcompensated in the subsequent 48 hours, while administration of 5-MeO-DMT immediately after sleep deprivation attenuated the subsequent rebound of sleep slow-wave activity. We argue that the occurrence of a dissociated state combining features of waking and sleep may fundamentally underpin the known and hypothesised effects of psychedelics — from dream-like hallucinations to reopening of the critical period for plasticity.

Foraging in the wild requires coordinated switching of critical functions, including goal-oriented navigation and context-appropriate action selection. Nevertheless, few studies have examined how different functions are represented in the brain during naturalistic foraging. To address this question, we recorded multiple single-unit activities from the medial prefrontal cortex (mPFC) of rats seeking a sucrose reward in the presence of an unpredictable attack posed by a robotic predator (Lobsterbot). Simultaneously recorded ensemble activities from neurons were analyzed in reference to various behavioral indices as the animal moved freely across the foraging area (F) between the nest (N) and the goal (E) area. An artificial neural network, trained with simultaneously recorded neural activity, estimated the rat’s current distance from the Lobsterbot. The accuracy of distance estimation was the highest in the middle F-zone in which the dominant behavior was active navigation. The spatial encoding persisted in the N-zone when non-navigational behaviors such as grooming, rearing, and sniffing were excluded. In contrast, the accuracy decreased as the animal approached the E-zone, when the activity of the same neuronal ensembles was more correlated with events related to dynamic decision-making between food procurement and Lobsterbot evasion. A population-wide analysis confirmed highly heterogeneous encoding by the region. To further assess the decision-related activity in the E-zone, a naive Bayesian classifier was trained to predict the success and failure of avoidance behavior. The classifier predicted the avoidance outcome as much as 6 s before the head withdrawal. In addition, two sub-populations of recorded units with distinct temporal dynamics contributed differently to the prediction. These findings suggest that an overlapping population of mPFC neurons may switch between two heterogeneous modes, encoding relevant locations for goal-directed navigation or an imminent situational challenge.

Parvalbumin-expressing inhibitory neurons (PVNs) stabilize cortical network activity, generate gamma rhythms, and regulate experience-dependent plasticity. We found that PVNs act like a volume knob in the mouse auditory cortex (ACtx), bi-directionally adjusting neural and perceptual sensitivity to sound level over a 20 dB range. PVN-based gain adjustments were "sticky," such that a single bout of PVN activation at 40 Hz-but not at 1 or 70 Hz-sustainably dampened ACtx sound responsiveness, enhanced feedforward inhibition, and behaviorally desensitized mice to loudness. We then developed a mouse model of adult-onset hyperacusis by demonstrating ACtx hyperactivity, PVN hypofunction, and loudness hypersensitivity following a restricted noise-induced cochlear lesion. We found that several minutes of 40-Hz PVN stimulation in noise-exposed mice sustainably dampened ACtx hyperactivity and restored normal loudness sensitivity for 1 week. These findings demonstrate that sensory disorders caused by permanent peripheral injuries can be reversed by patterned stimulation of cortical circuits that directly regulate perception.

There is growing evidence that perceptual difficulties associated with age-related hearing loss are not solely due to cochlear damage and are exacerbated by central nervous system changes. We examined electrophysiological (EEG) responses to clicks and diffusion kurtosis imaging in 49 older (29 female) and 26 younger (20 female) adults to determine the extent to which auditory nerve (AN) deficits in older adults contributed to functional and structural changes throughout the auditory system. Older adults exhibited smaller AN responses, similar brainstem responses, and larger auditory cortex (AC) responses, demonstrating progressive "central gain." Audiometric thresholds were not predictive of EEG measures. Reduced AN function predicted deficits in cortical microstructure (lower AC fractional anisotropy) in older adults, consistent with microstructure degeneration. These lower fractional anisotropy values in the AC of older adults also predicted larger AC responses and more central gain. Older adults exhibited significantly lower AC fractional anisotropy and kurtosis fractional anisotropy coupled with higher mean and radial diffusivity compared to younger adults. AC fractional anisotropy, radial diffusivity, axial diffusivity, and mean diffusivity were all significant predictors of speech-in-noise (SIN) recognition in older adults. The results suggest that reduced afferent input in older adults not only results in functional changes throughout the auditory system consistent with progressive gain but also contributes to deficits in AC structure beyond those explained by age alone, contributing to SIN recognition deficits. Understanding the complex effects of age, reduced AN input, central gain, and AC microstructure on SIN recognition may provide potential therapeutic targets for intervention.

In birds, detection of sound source azimuth begins in the nucleus laminaris (NL), which computes interaural time differences (ITDs). Inhibition has been proposed to protect NL neurons from losing ITD sensitivity with increasing sound level, although the nature of this inhibition is incompletely understood. Anatomical studies show GABAergic synapses throughout NL and first order nuclei, while in vitro studies in chicken NL showed that GABAergic inhibitory postsynaptic potentials (IPSPs) shorten membrane time constants, perhaps to allow the membrane potential to follow rapid synaptic currents accurately over a range of sound levels. Given the importance of inhibition in regulating auditory brainstem activity, we examined the nature of inhibitory input to NL in vivo. The Superior Olivary Nucleus (SON) is the major source of descending GABAergic inhibition to the ipsilateral nucleus magnocellularis (NM), nucleus angularis (NA) and NL, and receives excitatory input from NA and NL. We used viral tracers to reveal projections from SON to NL, and characterized response types within SON. In NL, we isolated inhibitory synaptic contributions from extracellular field potentials through the iontophoretic application of blockers of GABA (gabazine) or glycine (strychnine). These blockers increase onset and offset responses evoked by tonal stimuli, but did not shift best ITD. The co-application of gabazine and strychnine revealed supra-linear summation of GABA and glycine. Profiles of synaptic activation revealed more prominent inhibition following stimulus offset, suggesting inputs to NL originate from both sustained and offset response types of the SON. These heterogeneous responses may represent separate SON neuronal populations. Together, our results support the role of SON inhibition in increasing the dynamic range of ITD tuning of NL neurons.

Objective: The purpose of this paper is to present a chronic, preclinical, pilot study of a multi-electrode auditory nerve implant. To date, the most successful auditory neuroprosthesis is the cochlear implant, but these devices have known limitations. Intraneural stimulation of the auditory nerve is a promising alternative, but preclinical investigations of multi-electrode devices have been limited to acute or semi-chronic studies. Methods: Six cats were chronically implanted in the right auditory nerve with a 15-channel Utah Slant ArrayTM. The array's position in the internal auditory canal was confirmed using computed tomography. Electrode impedance and evoked responses were recorded regularly during the indwelling period to evaluate performance. Results: Two of the six implants met endpoint criteria at 6 months, with stable electrode impedances and robust evoked responses on at least 50% of their channels. Another two implants exhibited stable electrode impedances, but activation thresholds increased over three months. Two implants failed within the first two weeks due to device migration caused by connector-related issues. Conclusion: This study reports the first successful chronic deployment of an multi-electrode auditory nerve implant in a preclinical model. Two implanted cats exhibited stable chronic performance, marked by a consistent set of electrodes capable of eliciting evoked responses. The failure modes of the remaining four cats are discussed and recommendations are made to stabilize implant placement. The study lays a solid foundation for future chronic safety and efficacy investigations as part of an effort to translate this new neuroprosthetic technology into the clinic.

Basal forebrain cholinergic neurons (BFCNs) densely innervate auditory cortex (ACtx), conveying signals linked to internal brain states and external sensory cues. Acetylcholine (ACh) is known to rapidly modulate cortical circuits through nicotinic ACh receptor (nAChR)-mediated activation of layer 1 inhibitory neurons (L1-INs). However, BFCN terminals are also abundant in deeper layers, where their functional impact has received less attention. Using multi-plex in situ labeling across cortical layers and cell types, we found that layer 6 pyramidal neurons (L6-PNs) are highly enriched in diverse transcripts for nAChR subunits and muscarinic ACh receptors (mAChRs). In vivo optogenetic activation of BFCN axons revealed persistent modulation of regular spiking units in L2-6 but a rapid phasic activation only in L6. In acute slices, optogenetic activation of BFCN axons elicited fast nAChR-mediated excitatory post-synaptic potentials in L6-PNs, comparable to responses in L1-INs, and slower mAChR-mediated inhibitory responses. These findings identify L1-INs and excitatory L6-PNs as two major hubs for BFCN modulation of cortical circuits. By recruiting distinct receptor mechanisms and circuit motifs in L1 and L6, BFCNs may engage parallel pathways of cholinergic control that couple fast, transient modulation with slower, sustained regulation to shape cortical perception and plasticity.

Auditory evoked responses undergo notable changes during childhood, likely reflecting modifications in synaptic signaling in the auditory cortex. Particularly robust response, observed around 200 to 300 ms post stimulus (N/M250), has been consistently reported in children but is absent in adults. This long-latency response, evoked even in passive listening conditions, may indicate heightened sensory pathway responsiveness, facilitating experience-driven cortical plasticity. However, it remains unclear whether this delayed activation pattern is an intrinsic, species-general feature of brain development. We recorded cortical auditory evoked responses to monaural sine-wave tones/click sounds in 3 age groups (preadolescents, adolescents, and young adults) of human subjects and rats. Following short-lived early responses, both species exhibited a long-latency (150 to 450 ms) response in the auditory cortex. In both species, the relative amplitude of the long-latency response, compared to early responses, was increased in younger individuals. In human children, single-trial analysis demonstrated more consistent trial-by-trial timing of the response in this later time window than in the adult-typical 100-ms response in the earlier time window. Given its emergence in purely passive conditions, and across species, the robust current activity in late time window could represent a distinct synaptic event and may serve as a marker of the maturational stage, particularly in GABAergic cortical circuits.

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 use electrocorticography to directly measure the brains of neurosurgical participants performing an interactive speech paradigm. We observe a broad range of cortical modulation profiles, and subsequent clustering analyses establish that responses comprised distinct classes associated with sensory perception, planning, motor execution, and task-related suppression. These activity classes are also localized to separate neural substrates, indicating their status as specialized networks. We then parse dynamics in the planning and motor networks using unsupervised dimensionality reduction, which reveals subnetworks that are 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.

Introduction: Learning-induced cortical reorganization is facilitated by neuromodulator release. However, the precise temporal relationship between neuromodulator release and neural activity required to induce plasticity is not well understood. In single synapses, eligibility traces regulate plasticity such that neuromodulator arrival must occur within seconds of activity. Cortical plasticity can also be induced by pairing neuromodulator release with neural activity, but it is unknown whether plasticity in populations of neurons is regulated by the same temporal constraints. Methods: To determine whether the synaptic eligibility trace regulates cortical plasticity, we used vagus nerve stimulation (VNS) to drive neuromodulator release 3 s before, 1 s before, concurrent with, or 3 s after tone-evoked activity in auditory cortex. After 20 days of pairing, we used in vivo electrophysiology to quantify the proportion of auditory cortex responding to the paired tone frequency. Results: We found that VNS 1 s before or concurrent with tone onset significantly expanded the representation of the paired tone frequency (-1s, p = 0.04; 0s, p = 0.02), whereas 3 s before or after did not (-3s, p = 0.87; +3s, p = 0.53). Confirming the role of neuromodulators in this eligibility trace, we found that depletion of norepinephrine prevented VNS-tone pairing-induced plasticity (0s + DSP4, p = 0.23). Discussion: Our study demonstrates that cortical plasticity is regulated by time constraints similar to the synaptic eligibility trace and highlights the importance of considering the timing of neuromodulator release when employing methods to enhance plasticity.

Peripheral nerve injuries lead to diminished function and pain via nociplastic phenomena. We propose a new strategy called directed functional reinnervation, in which nerves are reassigned to new peripheral targets with the intention of altering circuit function. Here, we redirect the saphenous sensory nerve into a skeletal muscle graft to curb nociplasticity and provide benign sensations or useful inputs for prosthetic applications. Electrophysiological functional characterization demonstrated robust afferent responses to mechanical stimulation of the muscle. Immunofluorescence staining indicated widespread innervation of various synapses within the muscle graft. With immediate graft placement, the injured nerve's dorsal root ganglia revealed comparable levels of nociceptive markers to uninjured nerves, suggesting a molecular basis for the prevention of pain sensitization. These findings contribute to the mechanism by which skeletal muscle grafts alleviate neuropathic pain and can be used as a sensory transmitter in conjunction with neural interfaces.