Exploring the interplay between mechanisms of neuroplasticity and cardiovascular health in aging adults: A multiple linear regression analysis study

BACKGROUND

Neuroplasticity and cardiovascular health behavior are critically important factors for optimal brain health.

OBJECTIVE

To assess the association between the efficacy of the mechanisms of neuroplasticity and metrics of cardiovascular heath in sedentary aging adults.

METHODS

We included thirty sedentary individuals (age = 60.6 ± 3.8 y; 63 % female). All underwent assessments of neuroplasticity, measured by the change in amplitude of motor evoked potentials elicited by single-pulse Transcranial Magnetic Stimulation (TMS) at baseline and following intermittent Theta-Burst (iTBS) at regular intervals. Cardiovascular health measures were derived from the Incremental Shuttle Walking Test and included Heart Rate Recovery (HRR) at 1-min/2-min after test cessation. We also collected plasma levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and c-reactive protein.

RESULTS

We revealed moderate but significant relationships between TMS-iTBS neuroplasticity, and the predictors of cardiovascular health (|r| = 0.38 to 0.53, p < .05). HRR1 was the best predictor of neuroplasticity (β = 0.019, p = .002). The best fit model (Likelihood ratio = 5.83, p = .016) of the association between neuroplasticity and HRR1 (β = 0.043, p = .002) was selected when controlling for demographics and health status. VEGF and BDNF plasma levels augmented the association between neuroplasticity and HRR1.

CONCLUSIONS

Our findings build on existing data demonstrating that TMS may provide insight into neuroplasticity and the role cardiovascular health have on its mechanisms. These implications serve as theoretical framework for future longitudinal and interventional studies aiming to improve cardiovascular and brain health. HRR1 is a potential prognostic measure of cardiovascular health and a surrogate marker of brain health in aging adults.

Power and connectivity changes on electroencephalogram in postoperative cerebellar mutism

INTRODUCTION

Cerebellar mutism syndrome is a debilitating postoperative neurological complication following posterior fossa surgery in children. It is characterized by a significant lack or loss of speech. Injury to the dentato-thalamo-cortical pathway is thought to be the main anatomical substrate of cerebellar mutism syndrome; however, few studies have investigated the physiological changes using computed electroencephalogram.

CASE REPORT

Herein, we report a case of a nine-year-old girl who developed cerebellar mutism syndrome after excision of an ependymoma of the fourth ventricle and was followed up with evaluation of aphasia, gross motor function, and scalp electroencephalograms. Her language, dysmetria and gait ataxia gradually improved until day 605 after onset. Computed electroencephalogram analyses were performed for the relative power spectrum and connectivity at each frequency band. On the three electroencephalograms at days 109, 299, and 605 after onset, the relative power spectrum at the delta band transiently decreased and then increased, and the relative power spectrums at theta, beta, and gamma bands transiently increased and then decreased. Only the relative power spectrum in the alpha band continuously increased in the occipital area. Additionally, brain connectivity in the delta, beta, and gamma bands increased continuously.

CONCLUSION

We report a case of cerebellar mutism syndrome with recovery of language, dysmetria and gait ataxia in 20 months. Electroencephalogram analyses indicated transient changes in the powers of brain activity and continuous improvements in connectivity during the long follow-up, reflecting the plasticity and remodeling of brain function after cerebellar mutism syndrome. Power and connectivity analyses for EEG might be a tool to investigate underlying pathophysiology of cerebellar mutism syndrome.

Associations between grip strength, brain structure, and mental health in > 40,000 participants from the UK Biobank

BACKGROUND

Grip strength is a widely used and well-validated measure of overall health that is increasingly understood to index risk for psychiatric illness and neurodegeneration in older adults. However, existing work has not examined how grip strength relates to a comprehensive set of mental health outcomes, which can detect early signs of cognitive decline. Furthermore, whether brain structure mediates associations between grip strength and cognition remains unknown.

METHODS

Based on cross-sectional and longitudinal data from over 40,000 participants in the UK Biobank, this study investigated the behavioral and neural correlates of handgrip strength using a linear mixed effect model and mediation analysis.

RESULTS

In cross-sectional analysis, we found that greater grip strength was associated with better cognitive functioning, higher life satisfaction, greater subjective well-being, and reduced depression and anxiety symptoms while controlling for numerous demographic, anthropometric, and socioeconomic confounders. Further, grip strength of females showed stronger associations with most behavioral outcomes than males. In longitudinal analysis, baseline grip strength was related to cognitive performance at ~9 years follow-up, while the reverse effect was much weaker. Further, baseline neuroticism, health, and financial satisfaction were longitudinally associated with subsequent grip strength. The results revealed widespread associations between stronger grip strength and increased grey matter volume, especially in subcortical regions and temporal cortices. Moreover, grey matter volume of these regions also correlated with better mental health and considerably mediated their relationship with grip strength.

CONCLUSIONS

Overall, using the largest population-scale neuroimaging dataset currently available, our findings provide the most well-powered characterization of interplay between grip strength, mental health, and brain structure, which may facilitate the discovery of possible interventions to mitigate cognitive decline during aging.

Is there hemispheric specialization in the chronic pain brain?

Organismal bilateral symmetry is associated with near-identical halves of the central nervous system, with certain functions displaying specialization through one brain hemisphere. The processing of pain in the brain as well as brain plasticity in the context of painful injuries have garnered much attention in recent decades. Noninvasive brain imaging studies in pain-free human subjects have identified multiple brain regions that are linked to the sensory and affective components of pain. Longlasting adaptations in brains of chronic pain sufferers have likewise been described, suggesting a mechanism for pain chronification. Invasive molecular and biochemical studies in animal models have expanded on these findings, with added emphasis on the role of specific genes and molecules involved. To date, the extent of hemispheric asymmetry in the context of pain is not well-understood. This topical review evaluates the evidence of hemispheric specialization observed in humans and rodent models of pain and compares it to findings where such asymmetry is absent. Our review shows conflicting information regarding the existence of pain-related asymmetry, and if so, the side to which it can be localized. This could be due to the heterogeneity of pain processing pathways, heterogeneity in study parameters, as well as differences in data reporting. With the advent of progressively sophisticated non-invasive tools that can be used in human subjects, in addition to more precise methods to visualize and control specific brain regions or neuronal ensembles in animal models, we predict that the next few decades will witness a better understanding of the supraspinal control and processing of chronic pain, including the role of each of its hemispheres.

Chronic treatment with enhancer drugs modifies the gene expression of selected parameters related to brain plasticity in rats under stress conditions

Selegiline, also known as L-deprenyl, and (2R)-1-(1-benzofuran-2-yl)-N-propylpentane-2-amine (BPAP) were found to induce enhancement of monoamine neurotransmission in low and very low doses. In addition, these enhancers may modify glutamatergic neurotransmission. The aim of the present study was to test the hypothesis that under stress conditions, chronic treatment with enhancer drugs has a positive impact on the glutamatergic system and other parameters related to brain plasticity, stress-related systems, and anxiety behavior. We exposed male Wistar rats to a chronic mild stress procedure combined with chronic treatment with two synthetic enhancer drugs. The gene expression of GluR1, an AMPA receptor subunit was reduced by repeated treatment with deprenyl in the hippocampus and with both BPAP and deprenyl in the prefrontal cortex. A significant reduction of NMDA receptor subunit GluN2B expression was observed in the hippocampus but not in the prefrontal cortex. Deprenyl treatment led to an enhancement of hippocampal BDNFmRNA concentrations in stress-exposed rats. Treatment with enhancer drugs failed to induce significant changes in stress hormone concentrations or anxiety behavior. In conclusion, the present study in chronically stressed rats showed that concomitant treatment with enhancer drugs did not provoke substantial neuroendocrine changes, but modified gene expression of selected parameters associated with brain plasticity. Observed changes may indicate a positive influence of enhancer drugs on brain plasticity, which is important for preventing negative consequences of chronic stress and enhancement of stress resilience. It may be suggested that the changes in glutamate receptor subunits induced by enhancer drugs are brain region-specific and not dose-related.

The Multicomponent Day-Care Program Prevents Volume Reduction in a Memory-Related Brain Area in Patients with Mild Cognitive Impairment

INTRODUCTION

Mild cognitive impairment (MCI) is considered an important period for interventions to prevent progression to dementia. Nonpharmacological interventions for MCI include exercise training, cognitive intervention, and music therapy. These play an important role in improving cognitive function, but their effects on brain plasticity in individuals with MCI are largely unknown. We investigated the effects of a multicomponent day-care program provided by the University of Tsukuba Hospital on the longitudinal brain volume changes in MCI patients.

METHODS

MCI patients who participated in the multicomponent day-care program and underwent whole-brain magnetic resonance imaging (MRI) twice during their participation (n = 14), were included. We divided them into two groups according to their attendance rate and conducted a between-group analysis of longitudinal volume changes in the whole cerebral cortex. Regional brain volumes derived from the patients' MRI were calculated with Freesurfer 6.0.0.

RESULTS

The neuroimaging analysis demonstrated that the left rostral anterior cingulate cortex volume was significantly preserved in the high-attendance group compared to that of the low-attendance group.

CONCLUSION

Our results suggest that continuous participation in a multicomponent day-care program could help prevent a volume reduction in memory-related brain areas in patients with MCI.

Amateur singing benefits speech perception in aging under certain conditions of practice: behavioural and neurobiological mechanisms

Limited evidence has shown that practising musical activities in aging, such as choral singing, could lessen age-related speech perception in noise (SPiN) difficulties. However, the robustness and underlying mechanism of action of this phenomenon remain unclear. In this study, we used surface-based morphometry combined with a moderated mediation analytic approach to examine whether singing-related plasticity in auditory and dorsal speech stream regions is associated with better SPiN capabilities. 36 choral singers and 36 non-singers aged 20-87 years underwent cognitive, auditory, and SPiN assessments. Our results provide important new insights into experience-dependent plasticity by revealing that, under certain conditions of practice, amateur choral singing is associated with age-dependent structural plasticity within auditory and dorsal speech regions, which is associated with better SPiN performance in aging. Specifically, the conditions of practice that were associated with benefits on SPiN included frequent weekly practice at home, several hours of weekly group singing practice, singing in multiple languages, and having received formal singing training. These results suggest that amateur choral singing is associated with improved SPiN through a dual mechanism involving auditory processing and auditory-motor integration and may be dose dependent, with more intense singing associated with greater benefit. Our results, thus, reveal that the relationship between singing practice and SPiN is complex, and underscore the importance of considering singing practice behaviours in understanding the effects of musical activities on the brain-behaviour relationship.

Altered cortical activity in patients with lower limb amputation based on EEG microstate

Previous studies have revealed significant changes in electroencephalogram (EEG) microstates in neuropsychiatric diseases, including schizophrenia, depression, and dementia. To explore the resting-state EEG microstate with amputation, we collected the EEG datasets from 15 patients with lower limb amputation and 20 healthy controls. Then, we analyzed the parameters of four classical EEG microstates (A-D) between the two groups. Specifically, the parameters were statistically analyzed, including duration, occurrence rate, time coverage, and transition rate. According to the results, the duration of microstate C (t = 2.95, p = 0.005) in the lower limb amputation group was significantly smaller compared with the control group, while the occurrence rate of microstate B (t = -2.22, p = 0.03) and D (t = -3.35, p = 0.002) were significantly larger in the lower limb amputation group. In addition, the transition rate of microstate differed significantly in AC, CA, DB between the two groups. Our results implied: (1) amputation has changed the resting-state EEG microstate; (2) EEG microstate analysis can be an approach to explore the alteration of cortical function.

The effects of monophasic anodal transcranial pulsed current stimulation on corticospinal excitability and motor performance in healthy young adults: A randomized double-blind sham-controlled study

INTRODUCTION

Transcranial pulsed current stimulation (tPCS) could be used to deliver electrical pulses at different frequencies to entrain the cortical neurons of the brain. Frequency dependence of these pulses in the induction of changes in corticospinal excitability (CSE) has not been reported.

OBJECTIVE

We aimed to assess the effect of anodal tPCS (a-tPCS) at theta (4 Hz), and gamma (75 Hz) frequencies on CSE as assessed by the peak-to-peak amplitude of transcranial magnetic stimulation (TMS) induced motor evoked potentials (MEPs) and motor performance.

METHOD

In a randomized double-blinded sham-controlled cross over design study, seventeen healthy participants attended three experimental sessions and received either a-tPCS at 4 Hz, 75 Hz, or sham a-tPCS with 1.5 mA for 15 min. The amplitude of TMS induced resting MEPs and time for completion of the grooved pegboard test were recorded at baseline, immediately after, and 30-min after a-tPCS.

RESULTS

Both a-tPCS at 75 Hz and 4 Hz showed significantly increased CSE compared to sham. The a-tPCS at 75 Hz induced significantly higher CSE changes compared to 4 Hz. There was a significant increase in intracortical facilitation and a significant reduction in short-interval intra-cortical inhibition with both 4 and 75 Hz stimulation. However, the inhibition and facilitation did not correlate with CSE. Motor performance was unaffected by the interventions.

CONCLUSION

The high CSE changes in M1 in a-tPCS at 75 Hz provides an initial understanding of the frequency-specific effect of a-tPCS. More research is needed to establish this concept and to assess its behavioural relevance.

Clinical phenotype modulates brain's myelin and iron content in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is associated with brain pathology extending beyond temporal lobe structures. We sought to look for informative patterns of brain tissue properties in TLE that go beyond the established morphometry differences. We hypothesised that volume differences, particularly in hippocampus, will be paralleled by changes in brain microstructure. The cross-sectional study included TLE patients (n = 25) from a primary care center and sex-/age-matched healthy controls (n = 55). We acquired quantitative relaxometry-based magnetic resonance imaging (MRI) data yielding whole-brain maps of grey matter volume, magnetization transfer (MT) saturation, and effective transverse relaxation rate R2* indicative for brain tissue myelin and iron content. For statistical analysis, we used the computational anatomy framework of voxel-based morphometry and voxel-based quantification. There was a positive correlation between seizure activity and MT saturation measures in the ipsilateral hippocampus, paralleled by volume differences bilaterally. Disease duration correlated positively with iron content in the mesial temporal lobe, while seizure freedom was associated with a decrease of iron in the very same region. Our findings demonstrate the link between TLE clinical phenotype and brain anatomy beyond morphometry differences to show the impact of disease burden on specific tissue properties. We provide direct evidence for the differential effect of clinical phenotype characteristics on processes involving tissue myelin and iron in mesial temporal lobe structures. This study offers a proof-of-concept for the investigation of novel imaging biomarkers in focal epilepsy.

Tracking tDCS induced grey matter changes in episodic migraine: a randomized controlled trial

BACKGROUND

Occipital transcranial direct current stimulation (tDCS) is an effective and safe treatment for migraine attack prevention. Structural brain alterations have been found in migraineurs in regions related to pain modulation and perception, including occipital areas. However, whether these structural alterations can be dynamically modulated through tDCS treatment is understudied.

OBJECTIVE

To track longitudinally grey matter volume changes in occipital areas in episodic migraineurs during and up to five months after occipital tDCS treatment in a single-blind, and sham-controlled study.

METHODS

24 episodic migraineurs were randomized to either receive verum or sham occipital tDCS treatment for 28 days. To investigate dynamic grey matter volume changes patients underwent structural MRI at baseline (prior to treatment), 1.5 months and 5.5 months (after completion of treatment). 31 healthy controls were scanned with the same MRI protocol. Morphometry measures assessed rate of changes over time and between groups by means of tensor-based morphometry.

RESULTS

Before treatment, migraineurs reported 5.6 monthly migraine days on average. A cross-sectional analysis revealed grey matter volume increases in the left lingual gyrus in migraineurs compared to controls. Four weeks of tDCS application led to a reduction of 1.9 migraine days/month and was paralleled by grey matter volume decreases in the left lingual gyrus in the treatment group; its extent overlapping with that seen at baseline.

CONCLUSION

This study shows that migraineurs have increased grey matter volume in the lingual gyrus, which can be modified by tDCS. Tracking structural plasticity in migraineurs provides a potential neuroimaging biomarker for treatment monitoring.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03237754 . Registered 03 August 2017 - retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03237754 .

Synaptic plasticity mechanisms behind TMS efficacy: insights from its application to animal models

Neural plasticity is defined as a reshape of communication paths among neurons, expressed through changes in the number and weights of synaptic contacts. During this process, which occurs massively during early brain development but continues also in adulthood, specific brain functions are modified by activity-dependent processes, triggered by external as well as internal stimuli. Since transcranial magnetic stimulation (TMS) produces a non-invasive form of brain cells activation, many different TMS protocols have been developed to treat neurological and psychiatric conditions and proved to be beneficial. Although neural plasticity induction by TMS has been widely assessed on human subjects, we still lack compelling evidence about the actual biological and molecular mechanisms. To support a better comprehension of the involved phenomena, the main focus of this review is to summarize what has been found through the application of TMS to animal models. The hope is that such integrated view will shed light on why and how TMS so effectively works on human subjects, thus supporting a more efficient development of new protocols in the future.

Engagement of a parieto-cerebellar network in prism adaptation. A double-blind high-definition transcranial direct current stimulation study on healthy individuals

Prism Adaptation (PA) is a non-invasive method to investigate visuomotor control. Recent neurostimulation studies have proposed an interpretation of the mechanisms underlying PA based on functioning of brain networks, instead of focusing on single brain areas. To test the functioning of the network during a classical PA procedure, here we used for the first time High-Definition transcranial Direct Current Stimulation (HD-tDCS) to simultaneously inhibit or facilitate brain activity in two main nodes of the network, namely the parietal cortex and the cerebellum, in healthy individuals. The main results showed that simultaneous anodal HD-tDCS over the two regions reduced terminal errors during exposure to prism glasses as compared to cathodal and sham stimulation. Conversely, cathodal HD-tDCS reduced after-effect as compared to anodal and sham stimulation following prism removal. Overall, these results provide new insights on the network related to the deployment of PA mechanisms and demonstrate the feasibility of using non-invasive HD-tDCS to modulate the adaptive mechanisms of PA.

Brain plasticity and hearing disorders

Permanently changed sensory stimulation can modify functional connectivity patterns in the healthy brain and in pathology. In the pathology case, these adaptive modifications of the brain are referred to as compensation, and the subsequent configurations of functional connectivity are called compensatory plasticity. The variability and extent of auditory deficits due to the impairments in the hearing system determine the related brain reorganization and rehabilitation. In this review, we consider cross-modal and intra-modal brain plasticity related to bilateral and unilateral hearing loss and their restoration using cochlear implantation. Cross-modal brain plasticity may have both beneficial and detrimental effects on hearing disorders. It has a beneficial effect when it serves to improve a patient's adaptation to the visuo-auditory environment. However, the occupation of the auditory cortex by visual functions may be a negative factor for the restoration of hearing with cochlear implants. In what concerns intra-modal plasticity, the loss of interhemispheric asymmetry in asymmetric hearing loss is deleterious for the auditory spatial localization. Research on brain plasticity in hearing disorders can advance our understanding of brain plasticity and improve the rehabilitation of the patients using prognostic, evidence-based approaches from cognitive neuroscience combined with post-rehabilitation objective biomarkers of this plasticity utilizing neuroimaging.

The future orientation of constructive memory: An evolutionary perspective on therapeutic hypnosis and brief psychotherapy

We explore a new distinction between the future, prospective memory system being investigated in current neuroscience and the past, retrospective memory system, which was the original theoretical foundation of therapeutic hypnosis, classical psychoanalysis, and psychotherapy. We then generalize a current evolutionary theory of sleep and dreaming, which focuses on the future, prospective memory system, to conceptualize a new evolutionary perspective on therapeutic hypnosis and brief psychotherapy. The implication of current neuroscience research is that activity-dependent gene expression and brain plasticity are the psychobiological basis of adaptive behavior, consciousness, and creativity in everyday life as well as psychotherapy. We summarize a case illustrating how this evolutionary perspective can be used to quickly resolve problems with past obstructive procrastination in school to facilitate current and future academic success.

Effective connectivity decreases in specific brain networks with postparalysis facial synkinesis: a dynamic causal modeling study

Currently, the treatments for postparalysis facial synkinesis are still inadequate. However, neuroimaging mechanistic studies are very limited and blurred. Instead of mapping activation regions, we were devoted to characterizing the organizational features of brain regions to develop new targets for therapeutic intervention. Eighteen patients with unilateral facial synkinesis and 19 healthy controls were enrolled. They were instructed to perform task functional magnetic resonance imaging (eye blinking and lip pursing) examinations and resting-state scans. Then, we characterized group differences in task-state fMRI to identify three foci, including the contralateral precentral gyrus (PreCG), supramarginal gyrus (SMG), and superior parietal gyrus (SPG). Next, we employed a novel approach (using dynamic causal modeling) to identify directed connectivity differences between groups in different modes. Significant patterns in multiple regions in terms of regionally specific actions following synkinetic movements were demonstrated, although the resting state was not significant. The couplings from the SMG to the PreCG (p = 0.03) was significant in the task of left blinking, whereas the coupling from the SMG to the SPG (p = 0.04) was significant in the task of left smiling. We speculated that facial synkinesis affects disruption among the brain networks, and specific couplings that are modulated simultaneously can compensate for motor deficits. Therefore, behavioral or brain stimulation technique treatment could be applied to alter reorganization within specific couplings in the rehabilitation of facial function.

Large-scale functional network dynamics in human callosal agenesis: Increased subcortical involvement and preserved laterality

In the human brain, the corpus callosum is the major white-matter commissural tract enabling the transmission of sensory-motor, and higher level cognitive information between homotopic regions of the two cerebral hemispheres. Despite developmental absence (i.e., agenesis) of the corpus callosum (AgCC), functional connectivity is preserved, including interhemispheric connectivity. Subcortical structures have been hypothesised to provide alternative pathways to enable this preservation. To test this hypothesis, we used functional Magnetic Resonance Imaging (fMRI) recordings in children with AgCC and typically developing children, and a time-resolved approach to retrieve temporal characteristics of whole-brain functional networks. We observed an increased engagement of the cerebellum and amygdala/hippocampus networks in children with AgCC compared to typically developing children. There was little evidence that laterality of activation networks was affected in AgCC. Our findings support the hypothesis that subcortical structures play an essential role in the functional reconfiguration of the brain in the absence of a corpus callosum.

Peak Activation Shifts in the Sensorimotor Cortex of Chronic Stroke Patients Following Robot-assisted Rehabilitation Therapy

Background:

Ischemic stroke is the most common cause of complex chronic disability and the third leading cause of death worldwide. In recovering stroke patients, peak activation within the ipsilesional primary motor cortex (M1) during the performance of a simple motor task has been shown to exhibit an anterior shift in many studies and a posterior shift in other studies.

Objective:

We investigated this discrepancy in chronic stroke patients who completed a robot-assisted rehabilitation therapy program.

Methods:

Eight chronic stroke patients with an intact M1 and 13 Healthy Control (HC) volunteers underwent 300 functional magnetic resonance imaging (fMRI) scans while performing a grip task at different force levels with a robotic device. The patients were trained with the same robotic device over a 10-week intervention period and their progress was evaluated serially with the Fugl-Meyer and Modified Ashworth scales. Repeated measure analyses were used to assess group differences in locations of peak activity in the sensorimotor cortex (SM) and the relationship of such changes with scores on the Fugl-Meyer Upper Extremity (FM UE) scale.

Results:

Patients moving their stroke-affected hand had proportionally more peak activations in the primary motor area and fewer peak activations in the somatosensory cortex than the healthy controls (P=0.009). They also showed an anterior shift of peak activity on average of 5.3-mm (P<0.001). The shift correlated negatively with FM UE scores (P=0.002).

Conclusion:

A stroke rehabilitation grip task with a robotic device was confirmed to be feasible during fMRI scanning and thus amenable to be used to assess plastic changes in neurological motor activity. Location of peak activity in the SM is a promising clinical neuroimaging index for the evaluation and monitoring of chronic stroke patients.

Seasonal changes in the hippocampal formation of hoarding and non-hoarding tits

The hippocampal formation (HF) processes spatial memories for cache locations in food-hoarding birds. Hoarding is a seasonal behavior, and seasonal changes in the HF have been described in some studies, but not in others. One potential reason is that birds may have been sampled during the seasonal hoarding peak in some studies, but not in others. In this study, we investigate the seasonal changes in hoarding and HF in willow tits (Poecile montanus). We compare this to seasonal changes in HF in a closely related non-hoarding bird, the great tit (Parus major). Willow tits near Oulu, Finland, show a seasonal hoarding peak in September and both HF volume and neuron number show a similar peak. HF neuronal density also increases in September, but then remains the same throughout winter. Unexpectedly, the great tit HF also changes seasonally, although in a different pattern: the great tit telencephalon increases in volume from July to August and decreases again in November. Great tit HF volume follows suit, but with a delay. Great tit HF neuron number and density also increase from August to September and stay high throughout winter. We hypothesize that seasonal changes in hoarding birds’ HF are driven by food-hoarding experience (e.g., the formation of thousands of memories). The seasonal changes in great tit brains may also be due to experience-dependent plasticity, responding to changes in the social and spatial environment. Large-scale experience-dependent neural plasticity is therefore probably not an adaptation of food-hoarding birds, but a general property of the avian HF and telencephalon.

Early deafness leads to re-shaping of functional connectivity beyond the auditory cortex

Early sensory deprivation, such as deafness, shapes brain development in multiple ways. Deprived auditory areas become engaged in the processing of stimuli from the remaining modalities and in high-level cognitive tasks. Yet, structural and functional changes were also observed in non-deprived brain areas, which may suggest the whole-brain network changes in deaf individuals. To explore this possibility, we compared the resting-state functional network organization of the brain in early deaf adults and hearing controls and examined global network segregation and integration. Relative to hearing controls, deaf adults exhibited decreased network segregation and an altered modular structure. In the deaf, regions of the salience network were coupled with the fronto-parietal network, while in the hearing controls, they were coupled with other large-scale networks. Deaf adults showed weaker connections between auditory and somatomotor regions, stronger coupling between the fronto-parietal network and several other large-scale networks (visual, memory, cingulo-opercular and somatomotor), and an enlargement of the default mode network. Our findings suggest that brain plasticity in deaf adults is not limited to changes in the auditory cortex but additionally alters the coupling between other large-scale networks and the development of functional brain modules. These widespread functional connectivity changes may provide a mechanism for the superior behavioral performance of the deaf in visual and attentional tasks.

Resting-state functional brain connectivity is related to subsequent procedural learning skills in school-aged children

This magnetoencephalography (MEG) study investigates how procedural sequence learning performance is related to prior brain resting-state functional connectivity (rsFC), and to what extent sequence learning induces rapid changes in brain rsFC in school-aged children. Procedural learning was assessed in 30 typically developing children (mean age ± SD: 9.99 years ± 1.35) using a serial reaction time task (SRTT). During SRTT, participants touched as quickly and accurately as possible a stimulus sequentially or randomly appearing in one of the quadrants of a touchscreen. Band-limited power envelope correlation (brain rsFC) was applied to MEG data acquired at rest pre- and post-learning. Correlation analyses were performed between brain rsFC and sequence-specific learning or response time indices. Stronger pre-learning interhemispheric rsFC between inferior parietal and primary somatosensory/motor areas correlated with better subsequent sequence learning performance and faster visuomotor response time. Faster response time was associated with post-learning decreased rsFC within the dorsal extra-striate visual stream and increased rsFC between temporo-cerebellar regions. In school-aged children, variations in functional brain architecture at rest within the sensorimotor network account for interindividual differences in sequence learning and visuomotor performance. After learning, rapid adjustments in functional brain architecture are associated with visuomotor performance but not sequence learning skills.

Intra- and inter-hemispheric structural connectome in agenesis of the corpus callosum

Agenesis of the corpus callosum (AgCC) is a congenital brain malformation characterized by the complete or partial failure to develop the corpus callosum. Despite missing the largest white matter bundle connecting the left and right hemispheres of the brain, studies have shown preserved inter-hemispheric communication in individuals with AgCC. It is likely that plasticity provides mechanisms for the brain to adjust in the context of AgCC, as the malformation disrupts programmed developmental brain processes very early on. A proposed candidate for neuroplastic response in individuals with AgCC is strengthening of intra-hemispheric structural connections. In the present study, we explore this hypothesis using a graph-based approach of the structural connectome, which enables intra- and inter-hemispheric analyses at multiple resolutions and quantification of structural characteristics through graph metrics. Structural graph metrics of 19 children with AgCC (13 with complete, 6 with partial AgCC) were compared to those of 29 typically developing controls (TDC). Associations between structural graph metrics and a wide range of neurobehavioral outcomes were examined using a multivariate data-driven approach (Partial Least Squares Correlation, PLSC). Our results provide new evidence suggesting structural strengthening of intra-hemispheric pathways as a neuroplastic response in the acallosal brain, and highlight regional variability in structural connectivity in children with AgCC compared to TDC. There was little evidence that structural graph properties in children with AgCC were associated with neurobehavioral outcomes. To our knowledge, this is the first report leveraging graph theory tools to explicitly characterize whole-brain intra- and inter-hemispheric structural connectivity in AgCC, opening avenues for future research on neuroplastic responses in AgCC.

Emerging neurodevelopmental perspectives on mathematical learning

Strong foundational skills in mathematical problem solving, acquired in early childhood, are critical not only for success in the science, technology, engineering, and mathematical (STEM) fields but also for quantitative reasoning in everyday life. The acquisition of mathematical skills relies on protracted interactive specialization of functional brain networks across development. Using a systems neuroscience approach, this review synthesizes emerging perspectives on neurodevelopmental pathways of mathematical learning, highlighting the functional brain architecture that supports these processes and sources of heterogeneity in mathematical skill acquisition. We identify the core neural building blocks of numerical cognition, anchored in the posterior parietal and ventral temporal-occipital cortices, and describe how memory and cognitive control systems, anchored in the medial temporal lobe and prefrontal cortex, help scaffold mathematical skill development. We highlight how interactive specialization of functional circuits influences mathematical learning across different stages of development. Functional and structural brain integrity and plasticity associated with math learning can be examined using an individual differences approach to better understand sources of heterogeneity in learning, including cognitive, affective, motivational, and sociocultural factors. Our review emphasizes the dynamic role of neurodevelopmental processes in mathematical learning and cognitive development more generally.

Dissociable plasticity of visual-motor system in functional specialization and flexibility in expert table tennis players

Specialization and flexibility are two basic attributes of functional brain organization, enabling efficient cognition and behavior. However, it is largely unknown what plastic changes in specialization and flexibility in visual-motor areas occur in support of extraordinary motor skills in expert athletes and how the selective adaptability of the visual-motor system affects general perceptual or cognitive domains. Here, we used a dynamic network framework to investigate intrinsic functional specialization and flexibility of visual-motor system in expert table tennis players (TTP). Our results showed that sensorimotor areas increased intrinsic functional flexibility, whereas visual areas increased intrinsic functional specialization in expert TTP compared to nonathletes. Moreover, the flexibility of the left putamen was positively correlated with skill level, and that of the left lingual gyrus was positively correlated with behavioral accuracy of a sport-unrelated attention task. This study has uncovered dissociable plasticity of the visual-motor system and their predictions of individual differences in skill level and general attention processing. Furthermore, our time-resolved analytic approach is applicable across other professional athletes for understanding their brain plasticity and superior behavior.

fNIRS & e-drum: An ecological approach to monitor hemodynamic and behavioural effects of rhythmic auditory cueing training

Converging evidence suggests a beneficial effect of rhythmic music-therapy in easing motor dysfunctions. Nevertheless, the neural systems underpinning both the direct effect and the influence of rhythm on movement control and execution during training in ecological settings are still largely unknown. In this study, we propose an ecological approach to monitor brain activity and behavioural performance during rhythmic auditory cueing short-term training. Our approach envisages the combination of functional near-infrared spectroscopy (fNIRS), which is a non-invasive neuroimaging technique that allows unconstrained movements of participants, with electronic drum (e-drum), which is an instrument able to collect behavioural tapping data in real time. The behavioural and brain effects of this short-term training were investigated on a group of healthy participants, who well tolerated the experimental settings, since none of them withdrew from the study. The rhythmic auditory cueing short-term training improved beat regularity and decreased group variability. At the group level, the training resulted in a reduction of brain activity primarily in premotor areas. Furthermore, participants with the highest behavioural improvement during training showed the smallest reduction in brain activity. Overall, we conclude that our study could pave the way towards translating the proposed approach to clinical settings.