Cortical Activity Research Articles

Abstract P189: Maternal Hyperandrogenemia Programs Hypoandrogenemia and Intrarenal Activation of Histone Deacetylase in Adult Male Offspring

Polycystic ovary syndrome ( PCOS ) is the most common endocrinopathy in young women. In-utero, children of ~80% of PCOS women in the US are exposed to maternal “hyperandrogenemia and obesity”. It remains unclear whether this exposure affects their cardiovascular ( CV ) health later in life. Using a well-characterized rat model of maternal PCOS, the hyperandrogenemic obese ( HAO ) dams, we previously showed that adult male, not female, offspring ( HAO F1 ) have enhanced blood pressure ( BP ) response to chronic angiotensin ( Ang ) II compared to sex-matched control offspring ( CON F1 ), suggesting their increased risk of later CV disease. Sex steroids have the potential to modulate epigenetics. Histone deacetylase ( HDAC ) and histone acetyltransferase ( HAT ) are markers of epigenetic modifications. HDACs have been shown to promote tumor necrosis factor ( TNF )-α expression and play a role in Ang II-induced hypertension. The present study was designed to test the hypothesis that male HAO F1 have intra-renal activation of HDAC and increased TNF-α that could play a role in their Ang II BP response. Methods: At 4 weeks ( wks ) of age, female SD rats were implanted (s.c.) with either 5α-dihydrotestosterone pellets (7.5 mg/90 d; HAO) or placebo pellets (CON) and mated at 9-12 wks. Offspring were obtained and weaned at 3 wks. Serum testosterone ( T; by LC/MS-MS), renal cortical TNF-α (Bioplex) and renal cortical nuclear HDAC and HAT activities (colorimetric assays) were measured in male offspring (1/litter, 16-24 wks, n=5-9). Results: Male HAO F1 had significantly lower serum T, higher renal cortical HDAC activity and TNF-α (430.2±124 vs 120.6±14 ng/dl, 0.97±0.1 vs 4.51±0.96 OD/min/mg protein and 423.7±47 vs 579.8±47 pg/g tissue, in male CON F1 vs male HAO F1 , respectively, p<0.05), and no change in their renal cortical HAT activity (vs male CON F1 ). Conclusion: Male offspring born to HAO dams develop hypoandrogenemia that is associated with intra-renal activation of HDAC that could be mediating their increased intra-renal inflammation (TNF-α expression) and mediating their exaggerated BP response to Ang II. Future studies will determine the causative relationship between hypoandrogenemia, HDAC activation and TNF-a and their role in the exaggerated pressor response to Ang II in those male offspring. Funding: AHA-24DIVSUP1273026 (JA), NIH-NIGMS P20GM121334 (JFR, NMS), R01HL135089 & R01AG075963 (JFR), AHA-22CDA938320 and 2024 Dean Franklin Award (NMS).

Activation of the mPFC-NAc Pathway Reduces Motor Impulsivity but Does Not Affect Risk-Related Decision-Making in Innately High-Impulsive Male Rats.

Attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUD) are characterized by exacerbated motor and risk-related impulsivities, which are associated with decreased cortical activity. In rodents, the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) have been separately implicated in impulsive behaviors, but studies on the specific role of the mPFC-NAc pathway in these behaviors are limited. Here, we investigated whether heightened impulsive behaviors are associated with reduced mPFC activity in rodents and determined the involvement of the mPFC-NAc pathway in motor and risk-related impulsivities. We used the Roman High- (RHA) and Low-Avoidance (RLA) rat lines, which display divergent phenotypes in impulsivity. To investigate alterations in cortical activity in relation to impulsivity, regional brain glucose metabolism was measured using positron emission tomography and [18F]-fluorodeoxyglucose ([18F]FDG). Using chemogenetics, the activity of the mPFC-NAc pathway was either selectively activated in high-impulsive RHA rats or inhibited in low-impulsive RLA rats, and the effects of these manipulations on motor and risk-related impulsivity were concurrently assessed using the rat gambling task. We showed that basal [18F]FDG uptake was lower in the mPFC and NAc of RHA compared to RLA rats. Activation of the mPFC-NAc pathway in RHA rats reduced motor impulsivity, without affecting risk-related decision-making. Conversely, inhibition of the mPFC-NAc pathway had no effect in RLA rats. Our results suggest that the mPFC-NAc pathway controls motor impulsivity, but has limited involvement in risk-related decision-making in our current model. Our findings suggest that reducing fronto-striatal activity may help attenuate motor impulsivity in patients with impulse control dysregulation.

Differential analgesic effects of high-frequency or accelerated intermittent theta burst stimulation of M1 on experimental tonic pain: Correlations with cortical activity changes assessed by TMS-EEG

Accelerated intermittent theta burst stimulation (AiTBS) has attracted much attention in the past few years as a new form of brain stimulation paradigm. However, it is unclear the relative efficacy of AiTBS on cortical excitability compared to conventional high-frequency rTMS. Using concurrent TMS and electroencephalogram (TMS-EEG), this study systematically compared the efficacy on cortical excitability and a typical clinical application (i.e. pain), between AiTBS with different intersession interval (ISIs) and 10-Hz rTMS. Participants received 10-Hz rTMS, AiTBS-15 (3 iTBS sessions with a 15-min ISI), AiTBS-50 (3 iTBS sessions with a 50-min ISI), or Sham stimulation over the primary motor cortex on four separate days. All four protocols included a total of 1800 pulses but with different session durations (10-Hz rTMS ​= ​18, AiTBS-15 ​= ​40, and AiTBS-50 ​= ​110 ​min). AiTBS-50 and 10-Hz rTMS were more effective in pain reduction compared to AiTBS-15. Using single-pulse TMS-induced oscillation, our data revealed low gamma oscillation as a shared cortical excitability change across all three active rTMS protocols but demonstrated completely opposite directions. Changes in low gamma oscillation were further associated with changes in pain perception across the three active conditions. In contrast, a distinct pattern of TMS-evoked potentials (TEPs) was revealed, with 10-Hz rTMS decreasing inhibitory N100 amplitude and AiTBS-15 reducing excitatory P60 amplitude. These changes in TEPs were also covarying with low gamma power changes. Sham stimulation indicated no significant effect on either cortical excitability or pain perception. These results are relevant only for provoked experimental pain, without being predictive for chronic pain, and revealed a change in low gamma oscillation, particularly around the very particular frequency of 40 ​Hz, shared between AiTBS and high-frequency rTMS. Conversely, cortical excitability (balance between excitation and inhibition) assessed by TEP recording was modulated differently by AiTBS and high-frequency rTMS paradigms.

Cycle-frequency content EEG analysis improves the assessment of respiratory-related cortical activity

Objective. Time-frequency (T-F) analysis of electroencephalographic (EEG) is a common technique to characterise spectral changes in neural activity. This study explores the limitations of utilizing conventional spectral techniques in examining cyclic event-related cortical activities due to challenges, including high inter-trial variability.Approach. Introducing the cycle-frequency (C-F) analysis, we aim to enhance the evaluation of cycle-locked respiratory events. For synthetic EEG that mimicked cycle-locked pre-motor activity, C-F had more accurate frequency and time localization compared to conventional T-F analysis, even for a significantly reduced number of trials and a variability of breathing rhythm.Main results. Preliminary validations using real EEG data during both unloaded breathing and loaded breathing (that evokes pre-motor activity) suggest potential benefits of using the C-F method, particularly in normalizing time units to cyclic activity phases and refining baseline placement and duration.Significance. The proposed approach could provide new insights for the study of rhythmic neural activities, complementing T-F analysis.

Cerebral Synchronization Between Mothers and Their Newborns During Breastfeeding.

Introduction: Breastfeeding is a fundamental biological function in mammals, allowing the progeny to develop in a physiological way. A physical and emotional dialog between mothers and offspring during breastfeeding has been described as part of the attachment relationship, and a synchronicity between maternal and neonatal brains can be hypothesized. This study aimed to assess if neonatal and maternal cortical areas activated during breastfeeding are functionally synchronized since the second day of life. Materials and Methods: Twenty mothers and their term newborns were enrolled. Cortical activation during breastfeeding was identified by multichannel near-infrared spectroscopy, which detects changes in haemoglobin concentration from multiple cortical regions. Functional activity was simultaneously detected (hyperscanning) in mothers and newborns' frontal and motor/primary somatosensory cortical areas during the first 5 minutes of breastfeeding. Cluster analysis and Student's t test were used to detect oxygenated haemoglobin increase, as cortical activation estimate. Wavelet transform coherence (WTC) analysis was used to identify a possible synchronization between maternal and neonatal activated cortical regions. Results: Mothers showed an activation of the central motor/primary somatosensory cortex, above the sagittal fissure. In newborns, the bilateral frontal cortex was activated. WTC analysis revealed two different cyclical synchronizations between mothers and infants' activated cortical regions. Conclusions: Such evidence may reflect a very early common sharing of experiences, possibly associated with reciprocal dynamic motor adjustments, hormonal coregulation, and somatic stimulations and sensations. The observed cyclical neural synchronization, between the mother and her newborn's cortex during breastfeeding, may play an important role in promoting their bonding.

Cognitive functioning in adults with chronic insomnia disorder- A cross-sectional study.

Chronic insomnia, affecting 15.9% of the population, is characterized by sustained hyperarousal and heightened somatic, cognitive, and cortical activity. Despite its prevalence, the precise impact of chronic insomnia on cognitive domains, particularly attention, working memory, and executive function, remains inadequately understood. This study aims to systematically investigate the cognitive functioning of adults with chronic insomnia. A meticulously matched cohort of 80 participants, comprising 40 with chronic insomnia and 40 controls, participated in this cross-sectional study. The diagnosis followed strict criteria outlined in the International Classification of Sleep Disorders-3. Neuropsychological assessments, including the Digit Span Test, Stroop Test, and Trail Making Test, were employed to scrutinize attention, working memory, and executive function. Robust metrics, such as the Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), Generalized Anxiety Disorder-7 (GAD-7), and Patient Health Questionnaire-9 (PHQ-9), supported the investigative approach. Analysis revealed notable deficits in backward digit span, digit symbol substitution test, and Stroop Test (cards B and C) among chronic insomnia subjects compared to non-insomniac counterparts. Trail Making Test B indicated prolonged completion times in the chronic insomnia cohort. Despite comparable levels of anxiety and depressive symptoms, the chronic insomnia group exhibited higher ISI and PSQI scores, indicating the severity of their sleep disturbances. This cross-sectional analysis reveals cognitive deficits associated with chronic insomnia, specifically impacting attention, working memory, and executive function. Even with meticulous demographic controls, chronic insomnia leaves a discernible impact on cognitive functions. The study underscores the need for precise cognitive evaluations to reveal the latent impact of chronic insomnia, offering insights for targeted interventions.

Association of Levels of CSF Osteopontin With Cortical Atrophy and Disability in Early Multiple Sclerosis.

To evaluate CSF inflammatory markers with accumulation of cortical damage as well as disease activity in patients with early relapsing-remitting MS (RRMS). CSF levels of osteopontin (OPN) and 66 inflammatory markers were assessed using an immune-assay multiplex technique in 107 patients with RRMS (82 F/25 M, mean age 35.7 ± 11.8 years). All patients underwent regular clinical assessment and yearly 3T MRI scans for 2 years while 39 patients had a 4-year follow-up. White matter lesion number and volume, cortical lesions (CLs) and volume, and global cortical thickness (CTh) were evaluated together with the 'no evidence of disease activity' (NEDA-3) status, defined by no relapses, no disability worsening, and no MRI activity, including CLs. The random forest algorithm selected OPN, CXCL13, TWEAK, TNF, IL19, sCD30, sTNFR1, IL35, IL16, and sCD163 as significantly associated with changes in global CTh. OPN and CXCL13 were most related to accumulation of atrophy after 2 and 4 years. In a multivariate linear regression model on CSF markers, OPN (p < 0.001), CXCL13 (p = 0.001), and sTNFR1 (p = 0.024) were increased in those patients with accumulating atrophy (adjusted R-squared 0.615). The 10 markers were added in a model that included all clinical, demographic, and MRI variables: OPN (p = 0.002) and IL19 (p = 0.022) levels were confirmed to be significantly increased in patients developing more CTh change over the follow-up (adjusted R-squared 0.619). CXCL13 and OPN also revealed the best association with NEDA-3 after 2 years, with OPN significantly linked to disability accumulation (OR 2.468 [1.46-5.034], p = 0.004) at the multivariate logistic regression model. These data confirm and expand our knowledge on the prognostic role of the CSF inflammatory profile in predicting changes in cortical pathology and disease activity in early MS. The data emphasize a crucial role of OPN.

Adaptive closed-loop modulation of cortical theta oscillations: Insights into the neural dynamics of navigational decision-making

Navigational decision-making tasks, such as spatial working memory (SWM), rely highly on information integration from several cortical and sub-cortical regions. Performance in SWM tasks is associated with theta rhythm, including low-frequency oscillations related to movement and memory. The interaction of the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC), reflected in theta synchrony, is essential in various steps of information processing during SWM. We used a closed-loop neurofeedback (CLNF) system to upregulate theta power in the mPFC and investigate its effects on circuit dynamics and behavior in animal models. Specifically, we hypothesized that enhancing the power of the theta rhythm in the mPFC might improve SWM performance. Animals were divided into three groups: closed-loop (CL), random-loop (RL), and OFF (without stimulation). We recorded local field potential (LFP) in the mPFC while electrical reward stimulation contingent on cortical theta activity was delivered to the lateral hypothalamus (LH), which is considered one of the central reward-associated regions. We also recorded LFP in the vHPC to evaluate the related subcortical neural changes. Results revealed a sustained increase in the theta power in both mPFC and vHPC for the CL group. Our analysis also revealed an increase in mPFC-vHPC synchronization in the theta range over the stimulation sessions in the CL group, as measured by coherence and cross-correlation in the theta frequency band. The reinforcement of this circuit improved spatial decision-making performance in the subsequent behavioral results. Our findings provide direct evidence of the relationship between specific theta upregulation and SWM performance and suggest that theta oscillations are integral to cognitive processes. Overall, this study highlights the potential of adaptive CLNF systems in investigating neural dynamics in various brain circuits.

Functional segregation and dynamic integration of the corticotectal descending signal in rat

The superior colliculus (SC) receives inputs from various brain regions in a layer- and radial subregion-specific manner, but whether the SC exhibits subregion-specific dynamics remains unclear. To address this issue, we recorded the spiking activity of single SC neurons while photoactivating cortical areas in awake head-fixed Thy1-ChR2 rats. We classified 309 neurons that responded significantly into 8 clusters according to the response dynamics. Among them, neurons with monophasic excitatory responses (7–12 ms latency) that returned to baseline within 20 ms were commonly observed in the optic and intermediate gray layers of centromedial and centrolateral SC. In contrast, neurons with complex polyphasic responses were commonly observed in the deep layers of the anterolateral SC. Cross-correlation analysis suggested that the complex pattern could be only partly explained by an internal circuit of the deep gray layer. Our results indicate that medial to centrolateral SC neurons simply relay cortical activity, whereas neurons in the deep layers of the anterolateral SC dynamically integrate inputs from the cortex, SNr, CN, and local circuits. These findings suggest a spatial gradient in SC integration, with a division of labor between simple relay circuits and those integrating complex dynamics.

Physical exercise on cortical brain activity in patients with mild cognitive impairment: A meta-analysis.

Physical exercise is recognized as a potential strategy to mitigate the cognitive decline associated with mild cognitive impairment (MCI). This systematic review aims to examine the specific effects of physical exercise on cortical brain activity in patients with MCI, an area that has not been thoroughly explored. We conducted a search across 9 electronic databases for randomized controlled trials assessing the impact of physical exercise on the cortical activity of patients with MCI. The search covered the period from database inception to September 2023. Literature screening, data extraction, and quality assessments were carried out by 2 independent researchers. Meta-analyses were conducted using RevMan 5.3, and publication bias was evaluated using STATA 17.0. This study primarily assessed P300 latency and amplitude, alongside cognitive evaluations using the mini-mental state examination and Montreal Cognitive Assessment. Six high-quality randomized controlled trials, involving a total of 360 participants, were included. Compared to the control group, significant enhancements were observed in the amplitude of central midline electrode (mean difference [MD] = 1.64 [95% confidence interval [CI], 0.92-2.36]; P < .00001), frontal midline electrode (MD = 2.70 [95% CI, 2.02-3.38]; P < .00001), and parietal midline electrode (MD = 2.42 [95% CI, 0.44-4.41]; P = .02). Latency periods of the central midline electrode (MD = -32.40 [95% CI, -40.27 to -24.54]; P < .00001), frontal midline electrode (MD = -12.57 [95% CI, -30.83 to 5.69]; P = .18), and parietal midline electrode (MD = -12.57 [95% CI, -30.83 to 5.69]; P = .81) were also notably influenced. Moreover, overarching cognitive functions as measured by mini-mental state examination (MD = 1.02 [95% CI, 0.61-1.43]; P < .00001) and Montreal Cognitive Assessment (MD = 1.39 [95% CI, 0.67-2.12]; P = .0002) exhibited marked improvement. This meta-analysis suggests that physical exercise can augment the P300 amplitude, reduce the P300 latency period, and, overall, enhance cognitive functionality in individuals with MCI.

Change of Cerebral Hemodynamic Signals during the Process of Swallowing Water, Acetic Acid Solution and Salt Solution in Healthy Adults: An fNIRS Study.

The aim of this preliminary study was to investigate the similarities and differences in cortical activation patterns during the swallowing of water, acetic acid solution and salt solution in healthy adults using functional near-infrared spectroscopy (fNIRS). Eighteen right-handed healthy adults were recruited and fNIRS was used to measure changes in concentrations of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HbR) in 35 channels during the swallowing of water, acetic acid solution and salt solution. The task-based experiment used a block-design in which participants alternated between resting blocks of 30 s and task blocks (swallowing water, acetic acid solution, or salt solution) of 30 s, repeated six times. Participants remained still during the resting blocks and performed a swallowing action every 6 s during the task blocks. Data preprocessing was conducted using NirSpark software and statistical analyses were performed using either one-sample or paired t-tests to compare differences in cortical activation in healthy participants between swallowing a water and acetic acid solution, as well as swallowing a water and salt solution. Compared to the resting state, nine brain regions, including primary somatosensory cortex (S1), primary motor cortex (M1), dorsolateral prefrontal cortex (DLPFC), Wernicke's area, premotor cortex (PMC), supplementary motor area (SMA), inferior frontal cortex (IFC), orbitofrontal cortex (OFC) and frontopolar area, were commonly activated during the process of swallowing water, acetic acid solution, and salt solution. The DLPFC, Broca's area, PMC and SMA showed higher activation levels during the swallowing of acetic acid solution when compared to swallowing water, with statistically significant differences (p < 0.05). The frontopolar area and OFC exhibited higher activation during the swallowing of salt solution when compared to water, also with statistically significant differences (p < 0.05). Multiple brain regions were activated during the swallowing of water, acetic acid solution and salt solution in healthy adults. Moreover, swallowing acetic acid solution leads to stronger activation of DLPFC, Broca's area, PMC and SMA, while swallowing salt solution leads to stronger activation of the frontopolar area and OFC.

Assessing Changes in Hand Tactile Sensitivity After Glabellar Botulinum Toxin Treatment.

We aimed to assess behavioral changes in tactile sensitivity in patients receiving cosmetic glabellar botulinum toxin-A injections. In this prospective cohort study, we conducted quantitative sensory testing on 20 patients receiving 15 to 35 units of glabellar botulinum toxin-A treatment between October 1, 2022 and March 8, 2023. We used modified Von Frey filaments to exert forces between 0.25 mN and 512 mN to the dorsal hand just prior to botulinum toxin-A injections. Filament tips were uniform, rounded, and 0.5 mm in diameter to prevent nociceptor activation. This process was repeated 4 to 6 weeks after injection to assess for any change in minimal mechanical detection thresholds. Minimal mechanical detection thresholds decreased (patients detected smaller amounts of force) overall, in patients with prior botulinum toxin-A treatment, and in patients without prior botulinum toxin-A treatment: 5.34 mN to 4.33 mN (p = 0.22), 6.43 mN to 5.97 mN (p = 0.31), and 4.44 mN to 3.00 mN (p = 0.53), respectively. Our results suggest that the plastic changes observed in previous studies do not necessarily result in clinically significant manifestations when utilizing small to moderate amounts of botulinum toxin-A for aesthetic correction of glabellar lines, thus highlighting the safety of botulinum toxin-A for this indication. Further research is required to gain a comprehensive understanding of whether hand-associated cortical activity is altered after aesthetic amounts of botulinum toxin are injected.

The viewing perspective effect in learning from instructional videos: A replication and neuroimaging extension

BackgroundThe viewing perspective effect refers to the finding that students learn better from instructional videos recorded from first-person perspective than third-person perspective, but little is known about the neural mechanism underlying this effect. AimsThis study investigates the underlying neural mechanism of the viewing perspective effect. SamplesParticipants were 60 university students in Experiment 1, and 65 university students in Experiment 2. MethodsExperiment 1 replicated previous studies by using paper folding tasks (i.e., butterfly and four-leaf clover). Participants were randomly assigned to the first-person view group (i.e., watching videos recorded from a first-person view) or the third-person view group (i.e., watching videos recorded from a third-person view). Experiment 2 extended viewing perspective research by using neuroimaging methodology. Participants were randomly assigned to the two groups as in Experiment 1, but with fNIRS probes placed on each student's head. Participants watched the butterfly video (watching phase) and then performed the task (imitation phase). ResultsThere was superior performance on the butterfly task with a first-person view over a third-person view in both experiments, replicating the viewing perspective effect. There was higher cortical activation in the first-person view group in the right dlPFC during the watching phase, and higher cortical activation in third-person view group in the left IPC during the imitation phase. ConclusionsThis study replicates viewing perspective effect and investigates the underlying neural mechanism of the viewing perspective effect.

Effects of transcranial magnetic stimulation on axonal regeneration in the corticospinal tract of female rats with spinal cord injury

BackgroundThis study investigates the potential of transcranial magnetic stimulation (TMS) to enhance spinal cord axon regeneration by modulating corticospinal pathways and improving motor nerve function recovery in rats with spinal cord injury (SCI). New methodTMS is a non-invasive neuromodulation technique that generates a magnetic field to activate neurons in the brain, leading to depolarization and modulation of cortical activity. Initially utilized for brain physiology research, TMS has evolved into a diagnostic and prognostic tool in clinical settings, with increasing interest in its therapeutic applications. However, its potential for treating motor dysfunction in SCI has been underexplored. ResultsThe TMS intervention group exhibited significant improvements compared to the control group across behavioral assessments, neurophysiological measurements, pathological analysis, and immunological markers. Comparison with existing methodsUnlike most studies that focus on localized spinal cord injury or muscle treatments, this study leverages the non-invasive, painless, and highly penetrating nature of TMS to focus on the corticospinal tracts, exploring its therapeutic potential for SCI. ConclusionsTMS enhances motor function recovery in rats with SCI by restoring corticospinal pathway integrity and promoting axonal regeneration. These findings highlight TMS as a promising therapeutic option for SCI patients with currently limited treatment alternatives.

Gesture encoding in human left precentral gyrus neuronal ensembles.

Understanding the cortical activity patterns driving dexterous upper limb motion has the potential to benefit a broad clinical population living with limited mobility through the development of novel brain-computer interface (BCI) technology. The present study examines the activity of ensembles of motor cortical neurons recorded using microelectrode arrays in the dominant hemisphere of two BrainGate clinical trial participants with cervical spinal cord injury as they attempted to perform a set of 48 different hand gestures. Although each participant displayed a unique organization of their respective neural latent spaces, it was possible to achieve classification accuracies of ~70% for all 48 gestures (and ~90% for sets of 10). Our results show that single unit ensemble activity recorded in a single hemisphere of human precentral gyrus has the potential to generate a wide range of gesture-related signals across both hands, providing an intuitive and diverse set of potential command signals for intracortical BCI use.

The direct and indirect pathways of the basal ganglia antagonistically influence cortical activity and perceptual decisions

The striatum, the main input nucleus of the basal ganglia, receives topographically organized input from the cortex and gives rise to the direct and indirect output pathways, which have antagonistic effects on basal ganglia output directed to the cortex. We optogenetically stimulated the direct and indirect pathways in a visual and a working memory task in mice that responded by licking. Unilateral direct pathway stimulation increased the probability of lick responses toward the contralateral, non-stimulated side and increased cortical activity globally. In contrast, indirect pathway stimulation increased the probability of responses toward the stimulated side and decreased activity in the stimulated hemisphere. Moreover, direct pathway stimulation enhanced the neural representation of a contralateral visual stimulus during the delay of the working memory task, whereas indirect pathway stimulation had the opposite effect. Our results demonstrate how these two pathways influence perceptual decisions and working memory and modify activity in the dorsal cortex.

Selective direct motor cortical influence during naturalistic climbing.

It remains poorly resolved when and how motor cortical output directly influences limb muscle activity through descending projections, which impedes mechanistic understanding of cortical movement control. Here we addressed this in mice performing an ethologically inspired all-limb climbing behavior. We quantified the direct influence of forelimb primary motor cortex (caudal forelimb area, CFA) on muscle activity comprehensively across the muscle activity states that occur during climbing. We found that CFA informs muscle activity pattern, mainly by selectively activating certain muscles while exerting much smaller, bidirectional effects on their antagonists. From Neuropixel recordings, we identified linear combinations (components) of motor cortical activity that covary with these effects, finding that these components differ from those that covary with muscle activity or kinematics. Collectively, our results reveal an instructive direct motor cortical influence on limb muscles that is selective within a motor behavior and reliant on a new type of neural activity subspace.

Characterizing Autism Spectrum Disorder through Fusion of Local Cortical Activation and Global Functional Connectivity using Game-Based Stimuli and a Mobile EEG System.

The deficit in social interaction skills among individuals with autism spectrum disorder (ASD) is strongly influenced by personal experiences and social environments. Neuroimaging studies have previously highlighted the link between social impairment and brain activity in ASD. This study aims to develop a method for assessing and identifying ASD using a social cognitive game-based paradigm combined with electroencephalography (EEG) signaling features. Typically developing (TD) participants and autistic preadolescents and teenagers were recruited to participate in a social game while 12-channel EEG signals were recorded. The EEG signals underwent preprocessing to analyze local brain activities, including event-related potentials (ERPs) and time-frequency features. Additionally, the global brain network's functional connectivity between brain regions was evaluated using phase-lag indices (PLIs). Subsequently, machine learning models were employed to assess the neurophysiological features. Results indicated pronounced ERP components, particularly the late positive potential (LPP), in parietal regions during social training. Autistic preadolescents and teenagers exhibited lower LPP amplitudes and larger P200 amplitudes compared to TD participants. Reduced theta synchronization was also observed in the ASD group. Aberrant functional connectivity within certain time intervals was noted in the ASD group. Machine learning analysis revealed that support-vector machines achieved a sensitivity of 100%, specificity of 91.7%, and accuracy of 95.8% as part of the performance evaluation when utilizing ERP and brain oscillation features for ASD characterization. These findings suggest that social interaction difficulties in autism are linked to specific brain activation patterns. Traditional behavioral assessments face challenges of subjectivity and accuracy, indicating the potential use of social training interfaces and EEG features for cognitive assessment in ASD.

Cortical dynamics of perception as trains of coherent gamma oscillations, with the pulvinar as central coordinator

Synchronization of spikes carried by the visual streams is strategic for the proper binding of cortical assemblies, hence for the perception of visual objects as coherent units. Perception of a complex visual scene involves multiple trains of gamma oscillations, coexisting at each stage in visual and associative cortex. Here, we analyze how this synchrony is managed, so that the perception of each visual object can emerge despite this complex interweaving of cortical activations. After a brief review of structural and temporal facts, we analyze the interactions which make the oscillations coherent for the visual elements related to the same object. We continue with the propagation of these gamma oscillations within the sensory chain. The dominant role of the pulvinar and associated reticular thalamic nucleus as cortical coordinator is the common thread running through this step-by-step description. Synchronization mechanisms are analyzed in the context of visual perception, although the present considerations are not limited to this sense. A simple experiment is described, with the aim of assessing the validity of the elements developed here. A first set of results is provided, together with a proposed method to go further in this investigation.

No Evidence of Musical Training Influencing the Cortical Contribution to the Speech-Frequency-Following Response and Its Modulation through Selective Attention.

Musicians can have better abilities to understand speech in adverse condition such as background noise than non-musicians. However, the neural mechanisms behind such enhanced behavioral performances remain largely unclear. Studies have found that the subcortical frequency-following response to the fundamental frequency of speech and its higher harmonics (speech-FFR) may be involved since it is larger in people with musical training than in those without. Recent research has shown that the speech-FFR consists of a cortical contribution in addition to the subcortical sources. Both the subcortical and the cortical contribution are modulated by selective attention to one of two competing speakers. However, it is unknown whether the strength of the cortical contribution to the speech-FFR, or its attention modulation, is influenced by musical training. Here we investigate these issues through magnetoencephalographic (MEG) recordings of 52 subjects (18 musicians, 25 non-musicians, and 9 neutral participants) listening to two competing male speakers while selectively attending one of them. The speech-in-noise comprehension abilities of the participants were not assessed. We find that musicians and non-musicians display comparable cortical speech-FFRs and additionally exhibit similar subject-to-subject variability in the response. Furthermore, we also do not observe a difference in the modulation of the neural response through selective attention between musicians and non-musicians. Moreover, when assessing whether the cortical speech-FFRs are influenced by particular aspects of musical training, no significant effects emerged. Taken together, we did not find any effect of musical training on the cortical speech-FFR.