Activity-dependent neural plasticity from bench to bedside

Transition and dynamic reconfiguration in late-life depression based on hidden Markov model

Late-life depression is characterized by persistent emotional distress and cognitive dysfunction, yet understanding the specific brain dynamics and molecular mechanisms involved remains limited. Here, we employed a hidden Markov model to analyze resting-state functional magnetic resonance imaging data from 154 patients with late-life depression and 147 healthy controls. This analysis revealed 12 recurring brain states with distinct spatiotemporal patterns and identified atypical dynamic features across several networks. Notably, patients exhibited significantly higher transition probabilities for entering, exiting, and maintaining in the positive activation state of the default mode network, with genes linked to this state mainly enriched in regulation of neuronal synaptic plasticity and cognitive processes. Hierarchical clustering further found a critical entry and exit point between two high-level meta-states with opposing activation patterns, highlighting large-scale network dysfunction and potential molecular mechanisms associated with late-life depression through the decoding of brain states.

Closed-loop vagus nerve stimulation aids recovery from spinal cord injury

Decades of research have demonstrated that recovery from serious neurological injury will require synergistic therapeutic approaches. Rewiring spared neural circuits after injury is a long-standing goal of neurorehabilitation1,2. We hypothesized that combining intensive, progressive, task-focused training with real-time closed-loop vagus nerve stimulation (CLV) to enhance synaptic plasticity3 could increase strength, expand range of motion and improve hand function in people with chronic, incomplete cervical spinal cord injury. Here we report the results from a prospective, double-blinded, sham-controlled, randomized study combining gamified physical therapy using force and motion sensors to deliver sham or active CLV (ClinicalTrials.gov identifier NCT04288245). After 12 weeks of therapy composed of a miniaturized implant selectively activating the vagus nerve on successful movements, 19 people exhibited a significant beneficial effect on arm and hand strength and the ability to perform activities of daily living. CLV represents a promising therapeutic avenue for people with chronic, incomplete cervical spinal cord injury.

Endogenously generated patterns of neural activity sculpt axon connectivity

Neural activity is crucial in establishing functional circuit connectivity in the central nervous system. Prior to the onset of sensory experience, sensory organs spontaneously generate patterned neural activity, which is essential for sculpting and refining immature circuit connectivity coordinating functional and physiological responses to the external world in advance. How these endogenous patterns of neural activity drive circuit refinement is a major long-standing question; however, it has been impeded, at least partly, by technical difficulties in visualizing circuit refinement and patterned spontaneous activity in living animals. In this review, I discuss recent progress in visualizing circuit refinement processes and patterned spontaneous activity at the single-axon level in the mammalian visual system and consider how endogenous patterns of spontaneous activity drive fine-scale axon refinement during development.

Enhancing Neuroplasticity for Post-Stroke Motor Recovery: Mechanisms, Models, and Neurotechnology

Stroke remains a significant global health challenge, imposing substantial socioeconomic burdens. Post-stroke neurorehabilitation aims to maximize functional recovery and mitigate persistent disability through effective neuromodulation, while many patients experience prolonged recovery periods with suboptimal outcomes. This review explores innovative neurotechnologies and therapeutic strategies enhancing neuroplasticity for post-stroke motor recovery, with a particular focus on the subacute and chronic phases. We examine key neuroplasticity mechanisms and rehabilitation models informing neurotechnology use, including the vicariation model, the interhemispheric competition model, and the bimodal balance-recovery model. Building on these theoretical foundations, current neurotechnologies are categorized into endogenous drivers of neuroplasticity (e.g., task-oriented training, brain-computer interfaces) and exogenous drivers (e.g., brain stimulation, muscular electrical stimulation, robot-assisted passive movement). However, most approaches lack tailored adjustments combining volitional behavior with brain neuromodulation. Given the heterogeneous effects of current neurotechnologies, we propose that future directions should focus on personalized rehabilitation strategies and closed-loop neuromodulation. These advanced approaches may provide deeper insights into neuroplasticity and potentially expand recovery possibilities for stroke patients.

Rhythms of relief: perspectives on neurocognitive mechanisms of music interventions in ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder characterized by multiple neurocognitive deficits. Research suggests that music interventions, both active and passive, may be an effective complementary method of addressing ADHD challenges. This narrative review discusses seven potential neurocognitive mechanisms through which music interventions may help mitigate or alleviate ADHD symptoms, including executive function enhancement, timing improvement, arousal regulation, default mode network modulation, neural entrainment, affective management, and social bonding facilitation. Our study synthesized evidence from ADHD-specific studies and examined parallels to other populations to identify possible pathways through which music therapy could exert its effect. The paper also discusses the implications of individualized music interventions tailored to specific neurocognitive profiles in ADHD, advocating additional research to refine and optimize these approaches. Overall, music therapy has substantial potential as a complementary treatment for ADHD, offering new avenues for addressing the psychosocial and cognitive aspects of this condition.

Adenosine and Cortical Plasticity

Brain plasticity is the ability of the nervous system to change its structure and functioning in response to experiences. These changes occur mainly at synaptic connections, and this plasticity is named synaptic plasticity. During postnatal development, environmental influences trigger changes in synaptic plasticity that will play a crucial role in the formation and refinement of brain circuits and their functions in adulthood. One of the greatest challenges of present neuroscience is to try to explain how synaptic connections change and cortical maps are formed and modified to generate the most suitable adaptive behavior after different external stimuli. Adenosine is emerging as a key player in these plastic changes at different brain areas. Here, we review the current knowledge of the mechanisms responsible for the induction and duration of synaptic plasticity at different postnatal brain development stages in which adenosine, probably released by astrocytes, directly participates in the induction of long-term synaptic plasticity and in the control of the duration of plasticity windows at different cortical synapses. In addition, we comment on the role of the different adenosine receptors in brain diseases and on the potential therapeutic effects of acting via adenosine receptors.

Insights into the dependence of post-stroke motor recovery on the initial corticospinal tract connectivity from a computational model

There is a consensus that motor recovery post-stroke primarily depends on the degree of the initial connectivity of the ipsilesional corticospinal tract (CST). Indeed, if the residual CST connectivity is sufficient to convey motor commands, the neuromotor system continues to use the CST predominantly, and motor function recovers up to 80%. In contrast, if the residual CST connectivity is insufficient, hand/arm dexterity barely recovers, even as the phases of stroke progress. Instead, the functional upregulation of the reticulospinal tract (RST) often occurs. In this study, we construct a computational model that reproduces the dependence of post-stroke motor recovery on the initial CST connectivity. The model emulates biologically plausible evolutions of primary motor descending tracts, based on activity-dependent or use-dependent plasticity and the preferential use of more strongly connected neural circuits. The model replicates several elements of the empirical evidence presented by the Fugl-Meyer Assessment (FMA) subscores, which evaluate the capabilities for out-of-synergy and in-synergy movements. These capabilities presumably change differently depending on the degree of the initial CST connectivity post-stroke, providing insights into the interactive dynamics of the primary descending motor tracts. We discuss findings derived from the proposed model in relation to the well-known proportional recovery rule. This modeling study aims to present a way to differentiate individuals who can achieve 70 to 80% recovery in the chronic phase from those who cannot by examining the interactive evolution of out-of-synergy and in-synergy movement capabilities during the subacute phase, as assessed by the FMA.

Involvement of ubiquitination in Alzheimer's disease

The hallmark pathological features of Alzheimer's disease (AD) consist of senile plaques, which are formed by extracellular β-amyloid (Aβ) deposition, and neurofibrillary tangles, which are formed by the hyperphosphorylation of intra-neuronal tau proteins. With the increase in clinical studies, the in vivo imbalance of iron homeostasis and the dysfunction of synaptic plasticity have been confirmed to be involved in AD pathogenesis. All of these mechanisms are constituted by the abnormal accumulation of misfolded or conformationally altered protein aggregates, which in turn drive AD progression. Proteostatic imbalance has emerged as a key mechanism in the pathogenesis of AD. Ubiquitination modification is a major pathway for maintaining protein homeostasis, and protein degradation is primarily carried out by the ubiquitin-proteasome system (UPS). In this review, we provide an overview of the ubiquitination modification processes and related protein ubiquitination degradation pathways in AD, focusing on the microtubule-associated protein Tau, amyloid precursor protein (APP), divalent metal transporter protein 1 (DMT1), and α-amino-3-hyroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. We also discuss recent advances in ubiquitination-based targeted therapy for AD, with the aim of contributing new ideas to the development of novel therapeutic interventions for AD.

Spatiotemporal dynamics of cortical somatosensory network in typically developing children

Sense of touch is essential for our interactions with external objects and fine control of hand actions. Despite extensive research on human somatosensory processing, it is still elusive how involved brain regions interact as a dynamic network in processing tactile information. Few studies probed temporal dynamics of somatosensory information flow and reported inconsistent results. Here, we examined cortical somatosensory processing through magnetic source imaging and cortico-cortical coupling dynamics. We recorded magnetoencephalography signals from typically developing children during unilateral pneumatic stimulation. Neural activities underlying somatosensory evoked fields were mapped with dynamic statistical parametric mapping, assessed with spatiotemporal activation analysis, and modeled by Granger causality. Unilateral pneumatic stimulation evoked prominent and consistent activations in the contralateral primary and secondary somatosensory areas but weaker and less consistent activations in the ipsilateral primary and secondary somatosensory areas. Activations in the contralateral primary motor cortex and supramarginal gyrus were also consistently observed. Spatiotemporal activation and Granger causality analysis revealed initial serial information flow from contralateral primary to supramarginal gyrus, contralateral primary motor cortex, and contralateral secondary and later dynamic and parallel information flows between the consistently activated contralateral cortical areas. Our study reveals the spatiotemporal dynamics of cortical somatosensory processing in the normal developing brain.

Adaptive myelination causes slow oscillations in recurrent neural loops

The brain is known to be plastic, i.e., capable of changing and reorganizing as it develops and accumulates experience. Recently, a novel form of brain plasticity was described which is activity-dependent myelination of nerve fibers. Since the speed of propagation of action potentials along axons depends significantly on their degree of myelination, this process leads to adaptive change of axonal delays depending on the neural activity. To understand the possible influence of the adaptive delays on the behavior of neural networks, we consider a simple setup, a neuronal oscillator with delayed feedback. We show that introducing the delay plasticity into this circuit can lead to the occurrence of slow oscillations which are impossible with a constant delay.

Remote neurocognitive interventions for attention-deficit/hyperactivity disorder - Opportunities and challenges

Improving neurocognitive functions through remote interventions has been a promising approach to developing new treatments for attention-deficit/hyperactivity disorder (AD/HD). Remote neurocognitive interventions may address the shortcomings of the current prevailing pharmacological therapies for AD/HD, e.g., side effects and access barriers. Here we review the current options for remote neurocognitive interventions to reduce AD/HD symptoms, including cognitive training, EEG neurofeedback training, transcranial electrical stimulation, and external cranial nerve stimulation. We begin with an overview of the neurocognitive deficits in AD/HD to identify the targets for developing interventions. The role of neuroplasticity in each intervention is then highlighted due to its essential role in facilitating neuropsychological adaptations. Following this, each intervention type is discussed in terms of the critical details of the intervention protocols, the role of neuroplasticity, and the available evidence. Finally, we offer suggestions for future directions in terms of optimizing the existing intervention protocols and developing novel protocols.

Neuronal and synaptic adaptations underlying the benefits of deep brain stimulation for Parkinson's disease

Deep brain stimulation (DBS) is a well-established and effective treatment for patients with advanced Parkinson's disease (PD), yet its underlying mechanisms remain enigmatic. Optogenetics, primarily conducted in animal models, provides a unique approach that allows cell type- and projection-specific modulation that mirrors the frequency-dependent stimulus effects of DBS. Opto-DBS research in animal models plays a pivotal role in unraveling the neuronal and synaptic adaptations that contribute to the efficacy of DBS in PD treatment. DBS-induced neuronal responses rely on a complex interplay between the distributions of presynaptic inputs, frequency-dependent synaptic depression, and the intrinsic excitability of postsynaptic neurons. This orchestration leads to conversion of firing patterns, enabling both antidromic and orthodromic modulation of neural circuits. Understanding these mechanisms is vital for decoding position- and programming-dependent effects of DBS. Furthermore, patterned stimulation is emerging as a promising strategy yielding long-lasting therapeutic benefits. Research on the neuronal and synaptic adaptations to DBS may pave the way for the development of more enduring and precise modulation patterns. Advanced technologies, such as adaptive DBS or directional electrodes, can also be integrated for circuit-specific neuromodulation. These insights hold the potential to greatly improve the effectiveness of DBS and advance PD treatment to new levels.

Disturbed laterality of non-rapid eye movement sleep oscillations in post-stroke human sleep: a pilot study

Sleep is known to promote recovery post-stroke. However, there is a paucity of data profiling sleep oscillations in the post-stroke human brain. Recent rodent work showed that resurgence of physiologic spindles coupled to sleep slow oscillations (SOs) and concomitant decrease in pathological delta (δ) waves is associated with sustained motor performance gains during stroke recovery. The goal of this study was to evaluate bilaterality of non-rapid eye movement (NREM) sleep-oscillations (namely SOs, δ-waves, spindles, and their nesting) in post-stroke patients vs. healthy control subjects. We analyzed NREM-marked electroencephalography (EEG) data in hospitalized stroke-patients (n = 5) and healthy subjects (n = 3). We used a laterality index to evaluate symmetry of NREM oscillations across hemispheres. We found that stroke subjects had pronounced asymmetry in the oscillations, with a predominance of SOs, δ-waves, spindles, and nested spindles in affected hemisphere, when compared to the healthy subjects. Recent preclinical work classified SO-nested spindles as restorative post-stroke and δ-wave-nested spindles as pathological. We found that the ratio of SO-nested spindles laterality index to δ-wave-nested spindles laterality index was lower in stroke subjects. Using linear mixed models (which included random effects of concurrent pharmacologic drugs), we found large and medium effect size for δ-wave nested spindle and SO-nested spindle, respectively. Our results in this pilot study indicate that considering laterality index of NREM oscillations might be a useful metric for assessing recovery post-stroke and that factoring in pharmacologic drugs may be important when targeting sleep modulation for neurorehabilitation post-stroke.

Disturbed laterality of non-rapid eye movement sleep oscillations in post-stroke human sleep: a pilot study

Sleep is known to promote recovery post-stroke. However, there is a paucity of data profiling sleep oscillations post-stroke in the human brain. Recent rodent work showed that resurgence of physiologic spindles coupled to sleep slow oscillations(SOs) and concomitant decrease in pathological delta(δ) waves is associated with sustained motor performance gains during stroke recovery. The goal of this study was to evaluate bilaterality of non-rapid eye movement (NREM) sleep-oscillations (namely SOs, δ-waves, spindles and their nesting) in post-stroke patients versus healthy control subjects. We analyzed NREM-marked electroencephalography (EEG) data in hospitalized stroke-patients (n=5) and healthy subjects (n=3) from an open-sourced dataset. We used a laterality index to evaluate symmetry of NREM oscillations across hemispheres. We found that stroke subjects had pronounced asymmetry in the oscillations, with a predominance of SOs, δ-waves, spindles and nested spindles in one hemisphere, when compared to the healthy subjects. Recent preclinical work classified SO-nested spindles as restorative post-stroke and δ-wave-nested spindles as pathological. We found that the ratio of SO-nested spindles laterality index to δ-wave-nested spindles laterality index was lower in stroke subjects. Using linear mixed models (which included random effects of concurrent pharmacologic drugs), we found large and medium effect size for δ-wave nested spindle and SO-nested spindle, respectively. Our results indicate considering laterality index of NREM oscillations might be a useful metric for assessing recovery post-stroke and that factoring in pharmacologic drugs may be important when targeting sleep modulation for neurorehabilitation post-stroke.

Early adversity changes the economic conditions of mouse structural brain network organization

Early adversity can change educational, cognitive, and mental health outcomes. However, the neural processes through which early adversity exerts these effects remain largely unknown. We used generative network modeling of the mouse connectome to test whether unpredictable postnatal stress shifts the constraints that govern the organization of the structural connectome. A model that trades off the wiring cost of long-distance connections with topological homophily (i.e., links between regions with shared neighbors) generated simulations that successfully replicate the rodent connectome. The imposition of early life adversity shifted the best-performing parameter combinations toward zero, heightening the stochastic nature of the generative process. Put simply, unpredictable postnatal stress changes the economic constraints that reproduce rodent connectome organization, introducing greater randomness into the development of the simulations. While this change may constrain the development of cognitive abilities, it could also reflect an adaptive mechanism that facilitates effective responses to future challenges.

Improved connectivity and cognition due to cognitive stimulation in Alzheimer's disease

Background

Due to the increasing prevalence of Alzheimer's disease (AD) and the limited efficacy of pharmacological treatment, the interest in non-pharmacological interventions, e.g., cognitive stimulation therapy (CST), to improve cognitive dysfunction and the quality of life of AD patients are on a steady rise.

Objectives

Here, we examined the efficacy of a CST program specifically conceptualized for AD dementia patients and the neural mechanisms underlying cognitive or behavioral benefits of CST.

Methods

Using neuropsychological tests and MRI-based measurements of functional connectivity, we examined the (neuro-) psychological status and network changes at two time points: pre vs. post-stimulation (8 to 12 weeks) in the intervention group (n = 15) who received the CST versus a no-intervention control group (n = 15).

Results

After CST, we observed significant improvement in the Mini-Mental State Examination (MMSE), the Alzheimer's Disease Assessment Scale, cognitive subsection (ADAS-cog), and the behavioral and psychological symptoms of dementia (BPSD) scores. These cognitive improvements were associated with an up-regulated functional connectivity between the left posterior hippocampus and the trunk of the left postcentral gyrus.

Conclusion

Our data indicate that CST seems to induce short-term global cognition and behavior improvements in mild to moderate AD dementia and enhances resting-state functional connectivity in learning- and memory-associated brain regions. These convergent results prove that even in mild to moderate dementia AD, neuroplasticity can be harnessed to alleviate cognitive impairment with CST.

The gut-brain connection: Exploring the influence of the gut microbiota on neuroplasticity and neurodevelopmental disorders

Neuroplasticity refers to the ability of brain circuits to reorganize and change the properties of the network, resulting in alterations in brain function and behavior. It is traditionally believed that neuroplasticity is influenced by external stimuli, learning, and experience. Intriguingly, there is new evidence suggesting that endogenous signals from the body's periphery may play a role. The gut microbiota, a diverse community of microorganisms living in harmony with their host, may be able to influence plasticity through its modulation of the gut-brain axis. Interestingly, the maturation of the gut microbiota coincides with critical periods of neurodevelopment, during which neural circuits are highly plastic and potentially vulnerable. As such, dysbiosis (an imbalance in the gut microbiota composition) during early life may contribute to the disruption of normal developmental trajectories, leading to neurodevelopmental disorders. This review aims to examine the ways in which the gut microbiota can affect neuroplasticity. It will also discuss recent research linking gastrointestinal issues and bacterial dysbiosis to various neurodevelopmental disorders and their potential impact on neurological outcomes.

Tunicamycin induces depression-like behaviors in male rats, accompanied by initiated chaperon-mediated autophagy and decreased synaptic protein expression in the hippocampus

BACKGROUND AND AIM

Endoplasmic reticulum (ER) stress participates in the occurrence and development of depression, but the underlying mechanism is not fully understood. This study aimed to investigate the behavioral performance and intracerebral molecular changes in an ER stress model of male rats.

METHODS

Intrahippocampal injection of tunicamycin (TM) was performed on male rats as a model of ER stress. The body weight was determined, and behavioral tests, including sucrose preference test (SPT), open field test (OFT), and forced swimming test (FST), were performed to evaluate depressive and anxiety-like phenotypes within 8 days after injection. The levels of chaperone-mediated autophagy (CMA), synaptic proteins, and neuroinflammation related factors in this model were measured via real-time quantitative PCR and Western blot analysis.

RESULTS

Intrahippocampal injection of TM (2 or 1 μg) induced depression-like behaviors in rats, as indicated by the reduced body weight, sucrose preference in SPT, central time in OFT, and increased immobility time in FST. The mRNA and protein levels of GRP78, ATF4, CHOP, LAMP2A, IL-1β, IL-6, and TNF-α were significantly increased, while the expressions of MEF2D, PSD95, SYN, p-CREB (Ser133), and BDNF were significantly decreased in the hippocampus in the model group compared with the sham group.

CONCLUSIONS

These results confirmed that intrahippocampal injection of TM was a valid method to induce an ER stress rat model with depression-like behaviors accompanied by decreased synaptic protein expression and neuroinflammation. The alteration in CMA-related proteins in this ER stress depression model indicated the involvement of CMA in the development of depression.

Status epilepticus in pediatric patients severity score (STEPPS) as an outcome predictor in children

Background Status epilepticus (SE) is a neurological emergency, with short-term mortality ranging from 0.9 to 3.6% in children. The disease burden of SE includes morbidity, treatment costs, and mortality. Various scoring tools for predicting outcomes in adult SE cases have been widely studied, but there are few tools for predicting outcomes in children with SE. Objective To evaluate the usefulness of status epilepticus in pediatric patients severity score (STEPSS), a clinical score for predicting functional outcome and mortality in pediatric patients with status epilepticus, as well as to identify characteristics of SE patients. Methods This retrospective cohort study included 88 pediatric patients with status epilepticus aged >1 month to ?18 years by consecutive sampling, who were treated at Dr. Sardjito Hospital, Yogyakarta. All subjects underwent assessment by STEPPS score, which were compared to functional outcome assessed by Pediatric Overall Performance Capacity (POPC) score and mortality. Results STEPPS > 3 was significantly correlated with poor functional outcome (OR 2.85; 95%CI 1.04 to 7.87; P=0.043), but was not significantly correlated with mortality outcome in children with SE (P=0.411). Conclusion STEPPS score with cut-off >3 can be used as a predictor of poor functional outcome in pediatric patients with SE aged >1 month to ?18 years, but cannot be used as a predictor of mortality.

Circuit engineering: Rewiring adult outer retina connections

Rewiring and repairing neural circuitry has long been an important goal in neuroscience research. A new study employing clever genetic tools successfully restored synaptic connections in the adult mammalian outer retina and accompanying visually evoked behavior.

Alterations of presynaptic proteins in autism spectrum disorder

The expanded use of hypothesis-free gene analysis methods in autism research has significantly increased the number of genetic risk factors associated with the pathogenesis of autism. A further examination of the implicated genes directly revealed the involvement in processes pertinent to neuronal differentiation, development, and function, with a predominant contribution from the regulators of synaptic function. Despite the importance of presynaptic function in synaptic transmission, the regulation of neuronal network activity, and the final behavioral output, there is a relative lack of understanding of the presynaptic contribution to the pathology of autism. Here, we will review the close association among autism-related mutations, autism spectrum disorders (ASD) phenotypes, and the altered presynaptic protein functions through a systematic examination of the presynaptic risk genes relating to the critical stages of synaptogenesis and neurotransmission.

Dementia-Associated Compulsive Singing (DACS): Presentation of Unpublished Clinical Cases Miniseries

Dementia-associated compulsive singing (DACS) is a neurotransmettitorial-based behavioral disturbance, characterized by an unabating melodic expression, occurring in patients that suffer from evolved dementia. Previously described only as a "punding" aspect of the dopamine dysregulation syndrome (DDS) in the Parkinson's disease (PD), compulsive singing has now been described, for the first time, in four non-PD patients effectively treated with Haloperidol or Quetiapine. Unlike the DDS-associated conditions, in our cases DACS is not pharmacologically induced, being that all patients were L-dopa-free. We detected a diffuse hyperintensity of the white matter and brain atrophy, with insular shrinkage as well as ventricular system and/or sub-arachnoid space enlargement in our DACS patients. Furthermore, similarly to the other behavioral symptoms of dementia, DACS also seems to be correlated to the degree of cognitive and functional impairment, rather than its subtype. In conclusion, DACS is a non-cognitive, unpublished clinical aspect of evolved dementia, which is interesting due to the involvement of the extra-nigral dopaminergic system, resulting in an unabating altered behavior, but also to the enrichment of our knowledge in the involutional diseases of the central nervous system and their physiopathological manifestations.

Calanus Oil Supplementation Does Not Further Improve Short-Term Memory or Brain-Derived Neurotrophic Factor in Older Women Who Underwent Exercise Training

Purpose

In our study, we examined changes in short-term episodic memory and brain-derived neurotrophic factor (BDNF) in women after an exercise program alone or in combination with omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation.

Patients and Methods

Fifty-five healthy elderly women (65-80 years) were randomly split into two groups: in the first group were women attending an exercise program while taking wax esters-rich oil (Calanus) supplementation (n = 28) and in the other group were women undergoing the same exercise program while taking placebo (n = 27). The 16-week exercise program consisted of functional circuit training (twice a week) and Nordic walking lessons (once a week). Short-term episodic memory was evaluated by the Czech screening Test "Pojmenování OBrázků A jejich Vybavení" (POBAV) baseline and after the program lasting 16 weeks.

Results

Our results show that short-term memory significantly improved following the exercise program, but there was no added value in using n-3 PUFA supplements. BDNF values did not differ between baseline and follow-up in either group. However, there was a statistically significant positive relationship between relative change (%) in the POBAV test and VO2peak in the placebo group (r = 0.49).

Conclusion

Despite the added value of n-3 PUFA supplementation not being proven, our results may strengthen the importance of physical activity in averting age-related memory decline and dementia.

Modulation of neural co-firing to enhance network transmission and improve motor function after stroke

Stroke is a leading cause of disability. While neurotechnology has shown promise for improving upper limb recovery after stroke, efficacy in clinical trials has been variable. Our central thesis is that to improve clinical translation, we need to develop a common neurophysiological framework for understanding how neurotechnology alters network activity. Our perspective discusses principles for how motor networks, both healthy and those recovering from stroke, subserve reach-to-grasp movements. We focus on neural processing at the resolution of single movements, the timescale at which neurotechnologies are applied, and discuss how this activity might drive long-term plasticity. We propose that future studies should focus on cross-area communication and bridging our understanding of timescales ranging from single trials within a session to across multiple sessions. We hope that this perspective establishes a combined path forward for preclinical and clinical research with the goal of more robust clinical translation of neurotechnology.

Multimodal neuroimaging fusion biomarkers mediate the association between gut microbiota and cognition

Background The field of microbiota-gut-brain research in animals has progressed, while the exact nature of gut microbiota-brain-cognition relationship in humans is not completely elucidated, likely due to small sample sizes and single neuroimaging modality utilized to delineate limited aspects of the brain. We aimed to comprehensively investigate such association in a large sample using multimodal MRI. Methods Fecal samples were collected from 157 healthy young adults and 16S sequencing was used to assess gut microbial diversity and enterotypes. Five brain imaging measures, including regional homogeneity (ReHo) and functional connectivity density (FCD) from resting-state functional MRI, cerebral blood flow (CBF) from arterial spin labeling, gray matter volume (GMV) from structural MRI, and fractional anisotropy (FA) from diffusion tensor imaging, were jointly analyzed with a data-driven multivariate fusion method. Cognition was evaluated by 3-back and digit span tasks. Results We found significant associations of gut microbial diversity with ReHo, FCD, CBF, and GMV within the frontoparietal, default mode and visual networks, as well as with FA in a distributed set of juxtacortical white matter regions. In addition, there were FCD, CBF, GMV, and FA differences between Prevotella- versus Bacteroides-enterotypes in females and between Prevotella- versus Ruminococcaceae-enterotypes in males. Moreover, the identified neuroimaging fusion biomarkers could mediate the associations between microbial diversity and cognition. Conclusions Our findings not only expand existing knowledge of the microbiota-gut-brain axis, but also have potential clinical and translational implications by exposing the gut microbiota as a promising treatment and prevention target for cognitive impairment and related brain disorders.

The decay and consolidation of effector-independent motor memories

Learning a motor adaptation task produces intrinsically unstable or transient motor memories. Despite the presence of effector-independent motor memories following the learning of novel environmental dynamics, it remains largely unknown how those memory traces decay in different contexts and whether an "offline" consolidation period protects memories against decay. Here, we exploit inter-effector transfer to address these questions. We found that newly acquired motor memories formed with one effector could be partially retrieved by the untrained effector to enhance its performance when the decay occurred with the passage of time or "washout" trials on which error feedback was provided. The decay of motor memories was slower following "error-free" trials, on which errors were artificially clamped to zero or removed, compared with "washout" trials. However, effector-independent memory components were abolished following movements made in the absence of task errors, resulting in no transfer gains. The brain can stabilize motor memories during daytime wakefulness. We found that 6 h of wakeful resting increased the resistance of effector-independent memories to decay. Collectively, our results suggest that the decay of effector-independent motor memories is context-dependent, and offline processing preserves those memories against decay, leading to improvements of the subsequent inter-effector transfer.

Emergence of synaptic organization and computation in dendrites

Single neurons in the brain exhibit astounding computational capabilities, which gradually emerge throughout development and enable them to become integrated into complex neural circuits. These capabilities derive in part from the precise arrangement of synaptic inputs on the neurons' dendrites. While the full computational benefits of this arrangement are still unknown, a picture emerges in which synapses organize according to their functional properties across multiple spatial scales. In particular, on the local scale (tens of microns), excitatory synaptic inputs tend to form clusters according to their functional similarity, whereas on the scale of individual dendrites or the entire tree, synaptic inputs exhibit dendritic maps where excitatory synapse function varies smoothly with location on the tree. The development of this organization is supported by inhibitory synapses, which are carefully interleaved with excitatory synapses and can flexibly modulate activity and plasticity of excitatory synapses. Here, we summarize recent experimental and theoretical research on the developmental emergence of this synaptic organization and its impact on neural computations.

Understanding Language Reorganization With Neuroimaging: How Language Adapts to Different Focal Lesions and Insights Into Clinical Applications

When the language-dominant hemisphere is damaged by a focal lesion, the brain may reorganize the language network through functional and structural changes known as adaptive plasticity. Adaptive plasticity is documented for triggers including ischemic, tumoral, and epileptic focal lesions, with effects in clinical practice. Many questions remain regarding language plasticity. Different lesions may induce different patterns of reorganization depending on pathologic features, location in the brain, and timing of onset. Neuroimaging provides insights into language plasticity due to its non-invasiveness, ability to image the whole brain, and large-scale implementation. This review provides an overview of language plasticity on MRI with insights for patient care. First, we describe the structural and functional language network as depicted by neuroimaging. Second, we explore language reorganization triggered by stroke, brain tumors, and epileptic lesions and analyze applications in clinical diagnosis and treatment planning. By comparing different focal lesions, we investigate determinants of language plasticity including lesion location and timing of onset, longitudinal evolution of reorganization, and the relationship between structural and functional changes.

The Bidirectional Social-Cognitive Mechanisms of the Social-Attention Symptoms of Autism

Differences in social attention development begin to be apparent in the 6th to 12th month of development in children with Autism Spectrum Disorder (ASD) and theoretically reflect important elements of its neurodevelopmental endophenotype. This paper examines alternative conceptual views of these early social attention symptoms and hypotheses about the mechanisms involved in their development. One model emphasizes mechanism involved in the spontaneous allocation of attention to faces, or social orienting. Alternatively, another model emphasizes mechanisms involved in the coordination of attention with other people, or joint attention, and the socially bi-directional nature of its development. This model raises the possibility that atypical responses of children to the attention or the gaze of a social partner directed toward themselves may be as important in the development of social attention symptoms as differences in the development of social orienting. Another model holds that symptoms of social attention may be important to early development, but may not impact older individuals with ASD. The alterative model is that the social attention symptoms in infancy (social orienting and joint attention), and social cognitive symptoms in childhood and adulthood share common neurodevelopmental substrates. Therefore, differences in early social attention and later social cognition constitute a developmentally continuous axis of symptom presentation in ASD. However, symptoms in older individuals may be best measured with in vivo measures of efficiency of social attention and social cognition in social interactions rather than the accuracy of response on analog tests used in measures with younger children. Finally, a third model suggests that the social attention symptoms may not truly be a symptom of ASD. Rather, they may be best conceptualized as stemming from differences domain general attention and motivation mechanisms. The alternative argued for here that infant social attention symptoms meet all the criteria of a unique dimension of the phenotype of ASD and the bi-directional phenomena involved in social attention cannot be fully explained in terms of domain general aspects of attention development.

Involvement of Paired Immunoglobulin-like Receptor B in Diabetes-Associated Cognitive Dysfunction Through Modulation of Axon Outgrowth and Dendritic Remodeling

Type 2 diabetic patients have high risk of developing cognitive dysfunction, in which neural structural plasticity has played a pivotal role. Paired immunoglobulin-like receptor B (PirB), a receptor mainly expressed in neurons, acts as a critical inhibitor of neurite outgrowth and neural plasticity. However, the role of PirB in type 2 diabetes-associated cognitive dysfunction remains unknown. In this study, learning and memory impairment was observed in 24-week-old db/db mice by performing Morris water maze task, and the number of synapses along with the length of postsynaptic density by transmission electron microscopy were reduced in the hippocampus of db/db mice. Furthermore, PirB expression in the hippocampus of db/db mice was significantly upregulated using western blotting and immunofluorescence analysis. In cultured hippocampal neurons, high glucose treatment reduced the length of the longest neurite as well as axon initial segment (AIS), whereas silencing PirB expression rescued high glucose-induced neurite outgrowth inhibition, but not AIS. Additionally, cognitive deficits, dendrite morphology defects, and synapse-related proteins loss in db/db mice were alleviated when PirB knockdown was performed by adeno-associated virus injection. In conclusion, PirB is involved in diabetes-associated cognitive dysfunction through modulation of axon outgrowth and dendritic remodeling, providing a potential therapeutic target for diabetes-associated cognitive dysfunction.

Targeting Sensory and Motor Integration for Recovery of Movement After CNS Injury

The central nervous system (CNS) integrates sensory and motor information to acquire skilled movements, known as sensory-motor integration (SMI). The reciprocal interaction of the sensory and motor systems is a prerequisite for learning and performing skilled movement. Injury to various nodes of the sensorimotor network causes impairment in movement execution and learning. Stimulation methods have been developed to directly recruit the sensorimotor system and modulate neural networks to restore movement after CNS injury. Part 1 reviews the main processes and anatomical interactions responsible for SMI in health. Part 2 details the effects of injury on sites critical for SMI, including the spinal cord, cerebellum, and cerebral cortex. Finally, Part 3 reviews the application of activity-dependent plasticity in ways that specifically target integration of sensory and motor systems. Understanding of each of these components is needed to advance strategies targeting SMI to improve rehabilitation in humans after injury.

Brain Structural Changes in Carpal Tunnel Syndrome Patients: From the Perspectives of Structural Connectivity and Structural Covariance Network

BACKGROUND

Carpal tunnel syndrome (CTS) is a common peripheral entrapment neuropathy. However, CTS-related changes of brain structural covariance and structural covariance networks (SCNs) patterns have not been clearly studied.

OBJECTIVE

To explore CTS-related brain changes from perspectives of structural connectivity and SCNs.

METHODS

Brain structural magnetic resonance images were acquired from 27 CTS patients and 19 healthy controls (HCs). Structural covariance and SCNs were constructed based on gray matter volume. The global network properties including clustering coefficient (Cp), characteristic path length (Lp), small-worldness index, global efficiency (Eglob), and local efficiency (Eloc) and regional network properties including degree, betweenness centrality (BC), and Eloc of a given node were calculated with graph theoretical analysis.

RESULTS

Compared with HCs, the strength of structural connectivity between the dorsal anterior insula and medial prefrontal thalamus decreased (P < .001) in CTS patients. There was no intergroup difference of area under the curve for Cp, Lp¸ Eglob, and Eloc (all P > .05). The real-world SCN of CTS patients showed a small-world topology ranging from 2% to 32%. CTS patients showed lower nodal degrees of the dorsal anterior insula and medial prefrontal thalamus, and higher Eloc of a given node and BC in the lateral occipital cortex (P < .001) and the dorsolateral middle temporal gyrus (P < .001) than HCs, respectively.

CONCLUSION

CTS had a profound impact on brain structures from perspectives of structural connectivity and SCNs.

Linking immune-mediated damage to neurodegeneration in multiple sclerosis: could network-based MRI help?

Inflammatory demyelination characterizes the initial stages of multiple sclerosis, while progressive axonal and neuronal loss are coexisting and significantly contribute to the long-term physical and cognitive impairment. There is an unmet need for a conceptual shift from a dualistic view of multiple sclerosis pathology, involving either inflammatory demyelination or neurodegeneration, to integrative dynamic models of brain reorganization, where, glia-neuron interactions, synaptic alterations and grey matter pathology are longitudinally envisaged at the whole-brain level. Functional and structural MRI can delineate network hallmarks for relapses, remissions or disease progression, which can be linked to the pathophysiology behind inflammatory attacks, repair and neurodegeneration. Here, we aim to unify recent findings of grey matter circuits dynamics in multiple sclerosis within the framework of molecular and pathophysiological hallmarks combined with disease-related network reorganization, while highlighting advances from animal models (in vivo and ex vivo) and human clinical data (imaging and histological). We propose that MRI-based brain networks characterization is essential for better delineating ongoing pathology and elaboration of particular mechanisms that may serve for accurate modelling and prediction of disease courses throughout disease stages.

Changes in Default Mode Network Connectivity in Resting-State fMRI in People with Mild Dementia Receiving Cognitive Stimulation Therapy

Group cognitive stimulation therapy (CST) is a 7-week activity-based non-pharmacological intervention for people with mild to moderate dementia. Despite consistent evidence of clinical efficacy, the cognitive and brain mechanisms of CST remain unclear. Theoretically, group CST as a person-centred approach may work through promoting social interaction and personhood, executive function, and language use, especially in people with higher brain/cognitive reserve. To explore these putative mechanisms, structural MRI and resting-state functional MRI data were collected from 16 people with mild dementia before and after receiving CST, and in 13 dementia controls who received treatment as usual (TAU). Voxel-based morphometry (VBM) and resting-state functional connectivity (rs-FC) analyses were performed. Compared with TAU, the CST group maintained the total brain volume/total intracranial volume (TBV/TICV) ratio. Increased rs-FC in the default mode network (DMN) in the posterior cingulate cortex and bilateral parietal cortices nodes was observed in the CST over TAU groups between pre- and post-intervention timepoints. We provided preliminary evidence that CST maintains/enhances brain reserve both structurally and functionally. Considering the role of DMN in episodic memory retrieval and mental self-representation, preservation of personhood may be an important mechanism of CST for further investigation.

The Journal of Neuroscience's 40th Anniversary: Looking Back, Looking Forward

Some of us fortunate enough to have published a paper in The Journal of Neuroscience in its inaugural year (1981) have been asked to write a Progressions article addressing our views on the significance of the original work and how ideas about the topic of that work have evolved over the last 40 years. These questions cannot be effectively considered without placing them in the context of the incredible growth of the overall field of neuroscience over these last four decades. For openers, in 1981, the Nobel Prize was awarded to three neuroscience superstars: Roger Sperry, David Hubel, and Torsten Wiesel. Not a bad year to launch the Journal With this as a backdrop, I divide this Progressions article into two parts. First, I discuss our original (1981) paper describing classical conditioning in Aplysia californica, and place our results in the context of the state of the field at the time. Second, I fast forward to the present and consider some of remarkable progress in the broad field of learning and memory that has occurred in the last 40 years. Along the way, I also reflect briefly on some of the amazing advances, both technical and conceptual, that we in neuroscience have witnessed.

Bilateral transcranial direct current stimulation attenuated symptoms of alcohol use disorder: A systematic review and meta-analysis

BACKGROUND

Alcohol use disorder is one of the common substance use disorders leading to mental and health problems. Despite the potential positive effects of transcranial direct current stimulation (tDCS) on symptoms of various substance use disorder, how specific tDCS protocols effectively influence on individuals with alcohol use disorder is still controversial. This systematic review and meta-analysis investigated beneficial effects of tDCS on symptoms of alcohol use disorder.

METHOD

Eighteen total studies met our inclusion criteria, and we used 25 total comparisons from the qualified studies for the data synthesis. We estimated effect sizes by quantifying changes in alcohol craving and consumption between active tDCS protocol and sham groups. In addition, three moderator variable analyses determined whether tDCS effects on symptoms of alcohol use disorder were different based on (a) bilateral versus unilateral tDCS protocols, (b) specific targeted regions, and (c) multiple sessions versus single session of tDCS protocols.

RESULTS

Random-effects model meta-analysis revealed small positive tDCS effects on alcohol craving and consumption. Specifically, bilateral tDCS protocols significantly reduced alcohol craving, and further anodal tDCS on right dorsolateral prefrontal cortex (DLPFC) and cathodal tDCS on left DLPFC revealed significant positive effects. The multiple sessions of tDCS protocols showed better effects on reducing alcohol craving.

CONCLUSIONS

The current findings suggested that bilateral tDCS protocols including anodal tDCS on right DLPFC and cathodal tDCS on left DLPFC with multiple sessions may effectively improve tDCS effects on symptoms of alcohol use disorder.

Epidural cerebellar stimulation drives widespread neural synchrony in the intact and stroke perilesional cortex

BACKGROUND

Cerebellar electrical stimulation has shown promise in improving motor recovery post-stroke in both rodent and human studies. Past studies have used motor evoked potentials (MEPs) to evaluate how cerebellar stimulation modulates ongoing activity in the cortex, but the underlying mechanisms are incompletely understood. Here we used invasive electrophysiological recordings from the intact and stroke-injured rodent primary motor cortex (M1) to assess how epidural cerebellar stimulation modulates neural dynamics at the level of single neurons as well as at the level of mesoscale dynamics.

METHODS

We recorded single unit spiking and local field potentials (LFPs) in both the intact and acutely stroke-injured M1 contralateral to the stimulated cerebellum in adult Long-Evans rats under anesthesia. We analyzed changes in the firing rates of single units, the extent of synchronous spiking and power spectral density (PSD) changes in LFPs during and post-stimulation.

RESULTS

Our results show that post-stimulation, the firing rates of a majority of M1 neurons changed significantly with respect to their baseline rates. These firing rate changes were diverse in character, as the firing rate of some neurons increased while others decreased. Additionally, these changes started to set in during stimulation. Furthermore, cross-correlation analysis showed a significant increase in coincident firing amongst neuronal pairs. Interestingly, this increase in synchrony was unrelated to the direction of firing rate change. We also found that neuronal ensembles derived through principal component analysis were more active post-stimulation. Lastly, these changes occurred without a significant change in the overall spectral power of LFPs post-stimulation.

CONCLUSIONS

Our results show that cerebellar stimulation caused significant, long-lasting changes in the activity patterns of M1 neurons by altering firing rates, boosting neural synchrony and increasing neuronal assemblies' activation strength. Our study provides evidence that cerebellar stimulation can directly modulate cortical dynamics. Since these results are present in the perilesional cortex, our data might also help explain the facilitatory effects of cerebellar stimulation post-stroke.

Building a circuit through correlated spontaneous neuronal activity in the developing vertebrate and invertebrate visual systems

During the development of the vertebrate nervous systems, genetic programs assemble an immature circuit that is subsequently refined by neuronal activity evoked by external stimuli. However, prior to sensory experience, the intrinsic property of the developing nervous system also triggers correlated network-level neuronal activity, with retinal waves in the developing vertebrate retina being the best documented example. Spontaneous activity has also been found in the visual system of Drosophila Here, we compare the spontaneous activity of the developing visual system between mammalian and Drosophila and suggest that Drosophila is an emerging model for mechanistic and functional studies of correlated spontaneous activity.

Role of Sox2 in Learning, Memory, and Postoperative Cognitive Dysfunction in Mice

Postoperative cognitive dysfunction (POCD) is a significant clinical issue. Its neuropathogenesis has not been clearly identified and effective interventions for clinical use to reduce POCD have not been established. This study was designed to determine whether environmental enrichment (EE) or cognitive enrichment (CE) reduces POCD and whether sex-determining region Y-box-2 regulated by sirtuin 1, plays a role in the effect. Eighteen-month-old male mice were subjected to right-common-carotid-artery exposure under sevoflurane anesthesia. Some of them stayed in cages with EE or CE after the surgery. Learning and memory of mice were tested by a Barnes maze and fear conditioning, starting 2 weeks after the surgery. Sex-determining region Y-box-2 (Sox2) in the brain was silenced by small hairpin RNA (shRNA). Immunofluorescent staining was used to quantify Sox2-positive cells. Surgery reduced Sox2-positive cells in the hippocampus (64 ± 9 cells vs. 91 ± 9 cells in control group, n = 6, p < 0.001) and impaired learning and memory (time to identify target box one day after training sessions in the Barnes maze test: 132 ± 53 s vs. 79 ± 53 s in control group, n = 10, p = 0.040). EE or CE applied after surgery attenuated this reduction of Sox2 cells and POCD. Surgery reduced sirtuin 1 activity and CE attenuated this reduction. Resveratrol, a sirtuin 1 activator, attenuated POCD and surgery-induced decrease of Sox2-positive cells. Silencing shRNA reduced the Sox2-positive cells in the hippocampus and impaired learning and memory in mice without surgery. These results suggest a role of Sox2 in learning, memory, and POCD. EE and CE attenuated POCD via maintaining Sox2-positive cells in the hippocampus.

The Ties That Bind: Aberrant Plasticity and Networks Dysfunction in Movement Disorders-Implications for Rehabilitation

Background: Movement disorders encompass various conditions affecting the nervous system. The pathological processes underlying movement disorders lead to aberrant synaptic plastic changes, which in turn alter the functioning of large-scale brain networks. Therefore, clinical phenomenology does not only entail motor symptoms but also cognitive and motivational disturbances. The result is the disruption of motor learning and motor behavior. Due to this complexity, the responsiveness to standard therapies could be disappointing. Specific forms of rehabilitation entailing goal-based practice, aerobic training, and the use of noninvasive brain stimulation techniques could "restore" neuroplasticity at motor-cognitive circuitries, leading to clinical gains. This is probably associated with modulations occurring at both molecular (synaptic) and circuitry levels (networks). Several gaps remain in our understanding of the relationships among plasticity and neural networks and how neurorehabilitation could promote clinical gains is still unclear. Purposes: In this review, we outline first the networks involved in motor learning and behavior and analyze which mechanisms link the pathological synaptic plastic changes with these networks' disruption in movement disorders. Therefore, we provide theoretical and practical bases to be applied for treatment in rehabilitation.

Microbial memories: Sex-dependent impact of the gut microbiome on hippocampal plasticity

Germ‐free rodents, raised in the absence of a measurable gut microbiome, have been a key model to study the microbiome‐gut‐brain axis. Germ‐free mice exhibit marked behavioural and neurochemical differences to their conventionally raised counterparts. It is as yet unclear how these neurochemical differences lead to the behavioural differences. Here, we test the electrophysiological properties of hippocampal plasticity in adult germ‐free mice and compare them to conventionally raised counterparts. Whilst basal synaptic efficacy and pre‐synaptic short‐term plasticity appear normal, we find a striking alteration of hippocampal long‐term potentiation specifically in male germ‐free slices. However, the spike output of these neurons remains normal along with altered input‐output coupling, potentially indicating homeostatic compensatory mechanisms, or an altered excitation/inhibition balance. To our knowledge this is the first time the electrophysiological properties of the hippocampus have been assessed in a microbiome deficient animal. Our data indicate that the absence of a microbiome alters integration of dendritic signalling in the CA1 region in mice.

Five Features to Look for in Early-Phase Clinical Intervention Studies

Neurorehabilitation relies on core principles of neuroplasticity to activate and engage latent neural connections, promote detour circuits, and reverse impairments. Clinical interventions incorporating these principles have been shown to promote recovery and demote compensation. However, many clinicians struggle to find interventions centered on these principles in our nascent, rapidly growing body of literature. Not to mention the immense pressure from regulatory bodies and organizational balance sheets that further discourage time-intensive recovery-promoting interventions, incentivizing clinicians to prioritize practical constraints over sound clinical decision making. Modern neurorehabilitation practices that result from these pressures favor strategies that encourage compensation over those that promote recovery. To narrow the gap between the busy clinician and the cutting-edge motor recovery literature, we distilled 5 features found in early-phase clinical intervention studies-ones that value the more enduring biological recovery processes over the more immediate compensatory remedies. Filtering emerging literature through this lens and routinely integrating promising research into daily practice can break down practical barriers for effective clinical translation and ultimately promote durable long-term outcomes. This perspective is meant to serve a new generation of mechanistically minded and caring clinicians, students, activists, and research trainees, who are poised to not only advance rehabilitation science, but also erect evidence-based policy changes to accelerate recovery-based stroke care.

Impaired Potentiation of Theta Oscillations During a Visual Cortical Plasticity Paradigm in Individuals With Schizophrenia

Long-term potentiation (LTP) is a form of experience-dependent synaptic plasticity mediated by glutamatergic transmission at N-methyl-D-aspartate receptors (NMDARs). Impaired neuroplasticity has been implicated in the pathophysiology of schizophrenia, possibly due to underlying NMDAR hypofunction. Analogous to the high frequency electrical stimulation used to induce LTP in vitro and in vivo in animal models, repeated high frequency presentation of a visual stimulus in humans in vivo has been shown to induce enduring LTP-like neuroplastic changes in electroencephalography (EEG)-based visual evoked potentials (VEPs) elicited by the stimulus. Using this LTP-like visual plasticity paradigm, we previously showed that visual high-frequency stimulation (VHFS) induced sustained changes in VEP amplitudes in healthy controls, but not in patients with schizophrenia. Here, we extend this prior work by re-analyzing the EEG data underlying the VEPs, focusing on neuroplastic changes in stimulus-evoked EEG oscillatory activity following VHFS. EEG data were recorded from 19 patients with schizophrenia and 21 healthy controls during the visual plasticity paradigm. Event-related EEG oscillations (total power, intertrial phase coherence; ITC) elicited by a standard black and white checkerboard stimulus (~0.83 Hz, several 2-min blocks) were assessed before and after exposure to VHFS with the same stimulus (~8.9 Hz, 2 min). A cluster-based permutation testing approach was applied to time-frequency data to examine LTP-like plasticity effects following VHFS. VHFS enhanced theta band total power and ITC in healthy controls but not in patients with schizophrenia. The magnitude and phase synchrony of theta oscillations in response to a visual stimulus were enhanced for at least 22 min following VHFS, a frequency domain manifestation of LTP-like visual cortical plasticity. These theta oscillation changes are deficient in patients with schizophrenia, consistent with hypothesized NMDA receptor dysfunction.

Transcriptomic characterization of microglia activation in a rat model of ischemic stroke

Microglia are key regulators of inflammatory response after stroke and brain injury. To better understand activation of microglia as well as their phenotypic diversity after ischemic stroke, we profiled the transcriptome of microglia after 75 min transient focal cerebral ischemia in 3-month- and 12-month-old male spontaneously hypertensive rats. Microglia were isolated from the brains by FACS sorting on days 3 and 14 after cerebral ischemia. GeneChip Rat 1.0ST microarray was used to profile the whole transcriptome of sorted microglia. We identified an evolving and complex pattern of activation from 3 to 14 days after stroke onset. M2-like patterns were extensively and persistently upregulated over time. M1-like patterns were only mildly upregulated, mostly at day 14. Younger 3-month-old brains showed a larger microglial response in both pro- and anti-inflammatory pathways, compared to older 12-month-old brains. Importantly, our data revealed that after stroke, most microglia are activated towards a wide spectrum of novel polarization states beyond the standard M1/M2 dichotomy, especially in pathways related to TLR2 and dietary fatty acid signaling. Finally, classes of transcription factors that might potentially regulate microglial activation were identified. These findings should provide a comprehensive database for dissecting microglial mechanisms and pursuing neuroinflammation targets for acute ischemic stroke.

Network-based brain computer interfaces: principles and applications

Brain-computer interfaces (BCIs) make possible to interact with the external environment by decoding the mental intention of individuals. BCIs can therefore be used to address basic neuroscience questions but also to unlock a variety of applications from exoskeleton control to neurofeedback (NFB) rehabilitation. In general, BCI usability critically depends on the ability to comprehensively characterize brain functioning and correctly identify the user's mental state. To this end, much of the efforts have focused on improving the classification algorithms taking into account localized brain activities as input features. Despite considerable improvement BCI performance is still unstable and, as a matter of fact, current features represent oversimplified descriptors of brain functioning. In the last decade, growing evidence has shown that the brain works as a networked system composed of multiple specialized and spatially distributed areas that dynamically integrate information. While more complex, looking at how remote brain regions functionally interact represents a grounded alternative to better describe brain functioning. Thanks to recent advances in network science, i.e. a modern field that draws on graph theory, statistical mechanics, data mining and inferential modelling, scientists have now powerful means to characterize complex brain networks derived from neuroimaging data. Notably, summary features can be extracted from these networks to quantitatively measure specific organizational properties across a variety of topological scales. In this topical review, we aim to provide the state-of-the-art supporting the development of a network theoretic approach as a promising tool for understanding BCIs and improve usability.