Cognitive functions and underlying parameters of human brain physiology are associated with chronotype

Meta-analyses of executive function deficits in chemotherapy-treated rodent models

People diagnosed with cancer who undergo chemotherapy commonly encounter cognitive changes, particularly in executive functions (EFs). EFs support goal-directed behaviours, with EF deficits implicated in various neurocognitive impairments. We conducted five meta-analyses of the rodent models to investigate the impact of chemotherapy across five EF domains. A systematic search across PubMed, Web of Science, Scopus, and PsycINFO yielded 56 eligible papers. Our findings supported the clinical literature suggesting the selective impact of chemotherapy on different EF domains. Specifically, chemotherapy-treated animals performed significantly more poorly than controls in tasks assessing working memory, behavioural flexibility, and problem-solving, with no significant group differences in inhibition or attention. Subgroup analyses revealed that alkylating agents, antitumor antibiotics, and combination therapies were strongly associated with working memory deficits, whereas mitotic inhibitors were not. Rodent species, strain, age, sex, number of treatments, and time of behavioural assessment since the end of treatment did not moderate the drug effect on any assessed EF domains. To increase the generalisability and translational validity of the results, the overall reporting quality of animal studies needs to be improved with more details on randomisation, blinding, sample sizes, and criteria for animal exclusions.

Theta-Burst Stimulation of the Right Temporoparietal Junction and Implicit Theory of Mind in Autism

OBJECTIVES

Theory of mind (ToM), or mentalizing, is the ability to attribute mental states to oneself and others and is altered in individuals with autism spectrum disorder (ASD). Recent evidence suggests that implicit rather than explicit ToM is impaired in individuals with ASD. The right temporoparietal junction (rTPJ), which plays a crucial role in ToM, has altered activity in ASD and is a potential terget by noninvasive brain stimulation.

MATERIALS AND METHODS

In a randomized single-blind placebo-controlled study, we investigated, for what we believe is the first time, the effects of theta-burst stimulation of the rTPJ on implicit ToM and egocentric bias in 17 adolescents with ASD. Participants (mean age = 13.84 ± 3.32 years) were randomly assigned to three sessions of continuous theta-burst stimulation (cTBS), intermittent theta-burst stimulation (iTBS), and sham stimulation in a counterbalanced order. Stimulation intensity was set to 80% of the active motor threshold during cTBS and iTBS, with the coil centered on the rTPJ (CP6). Immediately after each stimulation, cognitive correlates of ToM, including implicit mentalizing and egocentric bias, were evaluated using the computerized Buzz-lightyear task.

RESULTS

Both cTBS and iTBS significantly improved implicit ToM compared with sham stimulation, with cTBS yielding a numerically larger effect (379.2 milliseconds) than did iTBS (191.3 milliseconds), although this difference was not statistically significant. No effect was found on the egocentric bias index.

CONCLUSIONS

These findings show a causal link between the rTPJ activation and implicit mentalizing in ASD, suggesting that theta-burst stimulation of this region can be used to enhance ToM in ASD. Targeting the rTPJ may improve implicit mentalizing in ASD and other disorders with impaired ToM.

Chronotype impact on mating, desire for sex and sexual activity in humans

Research on assortative mating by chronotype in previous years has yielded contradictory results. The aim of the study was to examine whether non-cohabiting partners in short-term relationships shared the same chronotype. A sample of 100 heterosexual couples completed the Composite Scale of Morningness (CSM) questionnaire and responded to additional questions. No evidence of assortative mating for chronotype was found, but there was a significant positive correlation between male and female time of waking up, time of greatest desire for sex and actual time of sexual activity. Additionally, female chronotype was significantly associated with the timing of peak sexual desire. Morning-type women declared the greatest desire for sex at 15:00-18:00 more frequently than evening-types. In case of actual sexual activity, men and women declared 21:00-00:00 most often, regardless of chronotype. It is likely that adapting to social schedules aligns activity timing across different chronotypes. They are performing their activities during which they get to know each other at similar times. While chronotype may not be critical in initiating relationships, it could influence the maintenance of long-term relationship satisfaction.

Embracing Internal States: A Review of Optimization of Repetitive Transcranial Magnetic Stimulation for Treating Depression

Repetitive transcranial magnetic stimulation (rTMS) is a rapid and effective therapy for major depressive disorder; however, there is significant variability in therapeutic outcomes both within and across individuals, with approximately 50% of patients showing no response to rTMS treatment. Many studies have personalized the stimulation parameters of rTMS (e.g., location and intensity of stimulation) according to the anatomical and functional structure of the brain. In addition to these parameters, the internal states of the individual, such as circadian rhythm, behavior/cognition, neural oscillation, and neuroplasticity, also contribute to the variation in rTMS effects. In this review, we summarize the current literature on the interaction between rTMS and internal states. We propose two possible methods, multimodal treatment, and adaptive closed-loop treatment, to integrate patients' internal states to achieve better rTMS treatment for depression.

Four dimensions of individualization in brain stimulation for psychiatric disorders: context, target, dose, and timing

Non-invasive Brain Stimulation (NIBS) technologies, including transcranial electrical (tES) and magnetic (TMS) stimulation, have emerged as promising interventions for various psychiatric disorders. FDA-approved TMS protocols in depression, OCD and nicotine use disorder provide a meaningful improvement. Treatment efficacy however remains inconsistent across individuals, and one relevant reason is intervention effect variability based on individual factors. There is a growing effort to develop individualized interventions, reinforced recently by FDA approval of a new TMS protocol that includes individualized fMRI-based targeting along with other modifications with higher reported effect size than previous "one size fits all" protocols. This paper discusses the dimensions for individualizing tES/TMS protocols to enhance therapeutic efficacy. We propose a multifaceted approach to personalizing NIBS, considering four levels: (1) context, (2) target, (3) dose, and (4) timing. By addressing inter- and intra-individual variability, we highlight a path toward precision medicine using individualized Brain Stimulation to treat psychiatric diseases. Despite challenges and limitations, this approach encourages broader and more systematic adoption of personalized Brain Stimulation techniques to improve clinical outcomes.

Efficacy of CBT, intensified tDCS and their combination for reducing clinical symptoms and improving quality of life in social anxiety disorder with comorbid depression: a randomized controlled trial

BACKGROUND/AIM

Social anxiety disorder (SAD) is a common and disabling psychiatric disorder. It is generally treated with medication and psychotherapy such as cognitive-behavioral therapy (CBT). Due to the involvement of cortical and subcortical areas in the pathophysiology of SAD, non-invasive brain stimulation techniques such as transcranial Direct Current Stimulation (tDCS) are potential adjunctive treatment options for SAD. This study aims to assess comparable efficacy of CBT, intensified tDCS, and combined CBT/tDCS on clinical symptoms and quality of life of patients with SAD and comorbid depression.

METHODS

In this randomized controlled trial, 37 adults with SAD and comorbid depressive disorder were assigned into three groups: (1) CBT + active tDCS (n = 13), (2) active tDCS alone (n = 12), and (3) CBT + sham tDCS (n = 12). SAD symptoms, depressive states, quality of life and trait worry were assessed with the Liebowitz Social Anxiety Scale, Beck's Depression Inventory, QOL questionnaire (WHOQOL-BREF), and the Penn State Worry Questionnaire respectively. The active tDCS was an intensified stimulation protocol (20 min, twice-daily sessions with 20 min intervals, 5 consecutive days) and was applied over the left dorsolateral prefrontal cortex (F3) and medial prefrontal cortex (Fpz). The CBT was provided individually based on the exposure technique at 12-20 sessions, twice a week. All clinical measures were assessed at baseline, after the intervention, and at 3-month follow-up.

RESULTS

SAD symptoms significantly decreased after intervention and follow-up in all groups, with no significant differences between them. However, CBT + tDCS resulted in a numerically larger symptom reduction, significantly exceeding CBT + sham tDCS on the fear scale. Depressive states and trait worry significantly improved in all groups post-intervention and at the 3-month follow-up, with no between-group differences. Quality of life (total scores, physical, and psychological domains) significantly improved after the and at the 3-month follow-up only in the CBT + tDCS and tDCS-alone groups with no between-group differences.

CONCLUSION

Psychotherapeutic interventions​ with CBT, intensified tDCS targeting the prefrontal cortex, and the combined CBT-tDCS are effective for alleviating primary and secondary clinical symptoms in individuals with SAD. The combined CBT-tDCS intervention showed superior efficacy in reducing the primary symptoms of SAD.

TRIAL REGISTRATION ID

IRCT20220421054607N1, registration date: 19/05/2022, available at: https://irct.behdasht.gov.ir/trial/63119 .

Time-of-Day-Dependent Effects of Rehabilitation on Motor Recovery After Experimental Focal Cerebral Ischemia

BACKGROUND

Rehabilitation is an efficacious method to improve poststroke motor dysfunction. Various rehabilitative techniques have become popular in this field of research. However, it has not been reported whether better outcomes can be achieved if rehabilitation training is conducted at the optimal time of the day.

METHODS

A model of photothrombotic ischemic stroke was used in C57/BL6 mice, and poststroke 24-hour activity cycles were evaluated. We found an activity peak around Zeitgeber time (ZT)13 (21:00) and a trough around ZT20 (04:00) during the dark phase. In addition, we selected ZT6 (14:00) as the daytime training group (corresponding to the ZT13 training group, ZT20 training group, and ZT6 training group, respectively). The 3 groups underwent treadmill training for 4 weeks. Functional and histological recovery levels were compared among groups. In addition, bulk RNA sequencing analysis was used to explore the possible molecular mechanisms.

RESULTS

The results showed that stroke-induced mice maintained a regular nocturnal locomotor rhythm with reduced amplitude. Motor recovery was greater in the ZT13 training group than in the ZT6 group, with a trend toward better outcomes at ZT13 than ZT20. The ZT13 group also showed superior neuronal survival and neurogenesis compared with ZT6, while improvements between ZT13 and ZT20 were less pronounced. Bulk RNA sequencing suggested that synaptic plasticity, calcium signaling, cAMP signaling, and MAPK signaling pathways contributed to neural repair differences between ZT13 and ZT6. In addition, the results showed a similar pattern of motor recovery in female and aged mice trained at ZT13 compared with ZT6, reinforcing the benefits of time-of-day training.

CONCLUSIONS

In conclusion, rehabilitative training during the most active phase is beneficial for enhanced recovery outcomes. Our study suggests that rehabilitation should be conducted when the body is in an optimal physiological state-that is, a time-of-day-dependent rehabilitation strategy.

Theta-gamma transcranial alternating current stimulation enhances ballistic motor performance in healthy young and older adults

Theta-gamma transcranial alternating current stimulation (TG tACS) over primary motor cortex (M1) can improve ballistic motor performance in young adults, but the effect on older adults is unknown. This study investigated the effects of TG tACS on motor performance and M1 excitability in 18 young and 18 older adults. High-definition TG tACS (6 Hz theta, 75 Hz gamma) or sham tACS was applied over right M1 for 20 min during a ballistic left-thumb abduction motor training task performed in two experimental sessions. Motor performance was quantified as changes in movement acceleration during and up to 60 min after training. Transcranial magnetic stimulation (TMS) was used to assess changes in M1 excitability with motor-evoked potentials (MEP) and short-interval intracortical inhibition (SICI) before and after training. We found that TG tACS increased motor performance compared with sham tACS in young and older adults (P < 0.001), with greater effects for young adults (P = 0.01). The improved motor performance with TG tACS lasted at least 60 min after training in both age groups. Motor training was accompanied by greater MEP amplitudes with TG tACS compared to sham tACS in young and older adults (P < 0.001), but SICI did not vary between tACS sessions (P = 0.40). These findings indicate that TG tACS over M1 improves motor performance and alters training-induced changes in M1 excitability in healthy young and older adults. TG tACS may therefore be beneficial to alleviate motor deficits in the ageing population.

Multimodal population study reveals the neurobiological underpinnings of chronotype

The rapid shifts in society have altered human behavioural patterns, with increased evening activities, increased screen time and changed sleep schedules. As an explicit manifestation of circadian rhythms, chronotype is closely intertwined with physical and mental health. Night owls often exhibit unhealthier lifestyle habits, are more susceptible to mood disorders and have poorer physical fitness compared with early risers. Although individual differences in chronotype yield varying consequences, their neurobiological underpinnings remain elusive. Here we conducted a pattern-learning analysis with three brain-imaging modalities (grey matter volume, white-matter integrity and functional connectivity) and capitalized on 976 phenotypes in 27,030 UK Biobank participants. The resulting multilevel analysis reveals convergence on the basal ganglia, limbic system, hippocampus and cerebellum. The pattern derived from modelling actigraphy wearables data of daily movement further highlighted these key brain features. Overall, our population-level study comprehensively investigates chronotype, emphasizing its close connections with habit formation, reward processing and emotional regulation.

Outbalanced: The cross-cortical effects of prefrontal neuromodulation in posterior parietal cortex

Cognitive phenomena such as the Spatial-Numerical Association of Response Codes (SNARC) effect can arise in the fronto-parietal cortical network. Prior neuromodulation studies with cathodal transcranial direct current stimulation (tDCS) over the left prefrontal cortex (PFC) reduced the SNARC effect. Prior neuroimaging studies with functional near-infrared spectroscopy (fNIRS), however, showed signatures of the SNARC effect in the posterior parietal cortex (PPC). In this study, we investigated the distant neural effect of prefrontal neuromodulation on hemodynamic activity in the parietal cortex by combining cathodal tDCS with fNIRS. The SNARC effect and the numerical distance effect (NDE) were assessed in an event-related cross-over design (N = 45), when cathodal tDCS of 1 mA at the left PFC was applied simultaneously during the measurement of fNIRS covering the bilateral PPC. At the behavioral level, prefrontal tDCS did not significantly reduce the SNARC effect, indicating that the replication failed here. Crucially, at the neuronal level, prefrontal tDCS reduced left parietal activation associated with the SNARC effect but not with the NDE. This neuronal effect of tDCS in a remote site was shown in preregistered primary region-of-interest analyses and in secondary all-channel analyses. The results showed how the combination of neuromodulation and neuroimaging shed light on the fronto-parietal network responsible for numerical cognition, and how fNIRS can assess the distant neural effects of cathodal tDCS.

Association of chronotype pattern on the quality of sleep and anxiety among medical undergraduates - a cross-sectional study

OBJECTIVES

This study aims to explore the relationship between chronotypes, sleep quality, and anxiety among medical undergraduates, providing valuable insights for academic institutions seeking to enhance student well-being.

METHODS

A cross-sectional design was used, involving 200 medical undergraduates who were selected based on specific inclusion and exclusion criteria. Data collection included comprehensive clinical histories and the administration of three validated questionnaires: the Morningness-Eveningness Questionnaire Self-Assessment (MEQ-SA), the Pittsburgh Sleep Quality Index (PSQI), and the State-Trait Anxiety Inventory (STAI). Participants were recruited during class breaks, and informed consent was obtained prior to participation.

RESULTS

The majority of participants (76.5 %; n=152) exhibited a neutral chronotype, with a mean MEQ score of 50.18 (±7.781). No significant correlations were found between MEQ scores and variables such as sex, BMI, or electronic media use. However, individuals classified as evening types reported higher anxiety levels, with mean STAI-S and STAI-T scores of 56.09 (±4.566) and 49.09 (±6.202), respectively (ANOVA, F=31.798, p=0.001; F=30.294, p=0.001). The mean global PSQI score was 6.00 (±2.553), with 56 % of participants reporting poor sleep quality. Evening chronotypes had significantly poorer sleep quality, as evidenced by higher PSQI scores (8.14±1.670) (ANOVA, F=43.663, p=0.001).

CONCLUSIONS

The findings underscore the need for academic institutions to reconsider the alignment of academic schedules with students' chronotypes, potentially enhancing academic performance and reducing health risks. Despite these contributions, the study has limitations, including geographical and demographic constraints and reliance on self-reported data, suggesting the need for further research to provide more comprehensive insights.

Contribution of Glutamatergic and GABAergic Mechanisms to the Plasticity-Modulating Effects of Dopamine in the Human Motor Cortex

Dopamine, a key neuromodulator in the central nervous system, regulates cortical excitability and plasticity by interacting with glutamate and GABA receptors, which are affected by dopamine receptor subtypes (D1- and D2-like). Non-invasive brain stimulation techniques can induce plasticity and monitor cortical facilitation and inhibition in humans. In a randomized, placebo-controlled, double-blinded study, we investigated how dopamine and D1- and D2-like receptors impact transcranial direct current stimulation (tDCS)-induced plasticity concerning glutamatergic and GABAergic mechanisms. Eighteen healthy volunteers received 1 mA anodal (13 min) and cathodal tDCS (9 min) over the left motor cortex combined with the dopaminergic agents l-dopa (general dopamine activation), bromocriptine (D2-like receptor agonist), combined D2 antagonism via sulpiride and general dopaminergic activation via l-dopa to activate D1-like receptors, and placebo medication. Glutamate-related cortical facilitation and GABA-related cortical inhibition were monitored using transcranial magnetic stimulation techniques, including I-O curve, intracortical facilitation (ICF), short-interval intracortical inhibition (SICI), and I-wave facilitation protocols. Our results indicate that anodal tDCS alone enhanced the I-O curve and ICF while decreasing SICI. Conversely, cathodal tDCS decreased the I-O curve and ICF while increasing SICI. General dopamine and D2 receptor activation combined with anodal tDCS decreased the I-O curve and ICF, but enhanced SICI compared to tDCS alone. When paired with cathodal tDCS, general Dopamine and D2-like receptor activity enhancement prolonged the cathodal tDCS effect on excitability. After anodal tDCS, D1-like receptor activation increased the I-O curve and ICF while reducing SICI. These effects were abolished with cathodal tDCS. Dopaminergic substances combined with anodal and cathodal tDCS did not have a significant effect on I-wave facilitation. These results suggest that D1-like receptor activation enhanced LTP-like plasticity and abolished LTD-like plasticity via glutamatergic NMDA receptor enhancement, while global dopaminergic and D2-like receptor enhancement weakened LTP-like but strengthened LTD-like plasticity primarily via glutamatergic NMDA receptor activity diminution.

Cortical excitability on sleep deprivation measured by transcranial magnetic stimulation: A systematic review and meta-analysis

Sleep deprivation is a common public problem, and researchers speculated its neurophysiological mechanisms related to cortical excitatory and inhibitory activity. Recently, transcranial magnetic stimulation combined with electromyography (TMS-EMG) and electroencephalography (TMS-EEG) have been used to assess cortical excitability in sleep-deprived individuals, but the results were inconsistent. Therefore, we conducted a meta-analysis to summarize relevant TMS-evoked indices of excitability and inhibition for exploring the cortical effects of sleep deprivation. In TMS-EMG studies, short-interval cortical inhibition (SICI) significantly decreased in sleep-deprived subjects; while the intracortical facilitation (ICF), resting motor threshold (RMT), and cortical silent period (CSP) were not significant compared to healthy controls. In TMS-EEG studies, the amplitude and slope of TMS-evoked potential (TEP) increased in sleep-deprived subjects. This study indicated that cortical inhibition decreased following sleep deprivation based on the TMS-EMG results and cortical excitability enhanced in the TMS-EEG results, supporting the disturbance of cortical excitability in sleep-deprived individuals.

Transcranial direct-current stimulation of core language areas facilitates novel word acquisition

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that can alter the state of the stimulated brain area and thereby affect neurocognitive processes and resulting behavioural performance. Previous studies using tDCS to address the language function have shown disparate results, particularly with respect to language learning and word acquisition. To fill this gap, this study aimed at systematically addressing the effects of tDCS of core left-hemispheric language cortices on the brain mechanisms underpinning two main neurocognitive strategies of word learning: implicit inference-based Fast Mapping (FM) and direct instruction-based Explicit Encoding (EE). Prior to a word-learning session, 160 healthy participants were given 15 min of either anodal or cathodal tDCS of Wernicke's or Broca's areas, or a control sham (placebo) stimulation, in a between-group design. Each participant then learned sixteen novel words (eight through FM and eight through EE) in a contextual word-picture association session. Moreover, these words were learnt either perceptually via auditory exposure combined with a graphical image of the novel object, or in an articulatory mode, where the participants additionally had to overtly articulate the novel items. These learning conditions were fully counterbalanced across participants, stimuli and tDCS groups. Learning outcomes were tested at both lexical and semantic levels using two tasks: recognition and word-picture matching. EE and FM conditions produced similar outcomes, indicating comparable efficiency of the respective learning strategies. At the same time, articulatory learning produced generally better results than non-articulatory exposure, yielding higher recognition accuracies and shorter latencies in both tasks. Crucially, real tDCS led to global outcome improvements, demonstrated by faster (compared to sham) reactions, as well as some accuracy changes. There was also evidence of more specific tDCS effects: better word-recognition accuracy for EE vs. FM following cathodal stimulation as well as more expressed improvements in recognition accuracy and reaction times for anodal Broca's and cathodal Wernicke's stimulation, particularly for unarticulated FM items. These learning mode-specific effects support the notion of partially distinct brain mechanisms underpinning these two learning strategies. Overall, numerically largest improvements were observed for anodal Broca's tDCS, whereas the least expressed benefits of tDCS for learning were measured after anodal Wernicke stimulation. Finally, we did not find any inhibitory effects of either tDCS polarity in any of the comparisons. We conclude that tDCS of core language areas exerts a general facilitatory effect on new word acquisition with some limited specificity to learning protocols - the result that may be of potential applied value for future research aimed at ameliorating learning deficits and language disorders.

Investigating the Effects of Repetitive Paired-Pulse Transcranial Magnetic Stimulation on Visuomotor Training Using TMS-EEG

I-wave periodicity repetitive paired-pulse transcranial magnetic stimulation (iTMS) can modify acquisition of a novel motor skill, but the associated neurophysiological effects remain unclear. The current study therefore used combined TMS-electroencephalography (TMS-EEG) to investigate the neurophysiological effects of iTMS on subsequent visuomotor training (VT). Sixteen young adults (26.1 ± 5.1 years) participated in three sessions including real iTMS and VT (iTMS + VT), control iTMS and VT (iTMSControl + VT), or iTMS alone. Motor-evoked potentials (MEPs) and TMS-evoked potentials (TEPs) were measured before and after iTMS, and again after VT, to assess neuroplastic changes. Irrespective of the intervention, MEP amplitude was not changed after iTMS or VT. Motor skill was improved compared with baseline, but no differences were found between stimulus conditions. In contrast, the P30 peak was altered by VT when preceded by control iTMS (P < 0.05), but this effect was not apparent when VT was preceded by iTMS or following iTMS alone (all P > 0.15). In contrast to expectations, iTMS was unable to modulate MEP amplitude or influence motor learning. Despite this, changes in P30 amplitude suggested that motor learning was associated with altered cortical reactivity. Furthermore, this effect was abolished by priming with iTMS, suggesting an influence of priming that failed to impact learning.

Repeated prefrontal tDCS for improving mental health and cognitive deficits in multiple sclerosis: a randomized, double-blind, parallel-group study

BACKGROUND

Multiple Sclerosis (MS) is an autoimmune disease associated with physical disability, psychological impairment, and cognitive dysfunctions. Consequently, the disease burden is substantial, and treatment choices are limited. In this randomized, double-blind study, we conducted repeated prefrontal electrical stimulation in 40 patients with MS to evaluate mental health variables (quality of life, sleep difficulties, psychological distress) and cognitive dysfunctions (psychomotor speed, working memory, attention/vigilance), marking it as the third largest sample size tDCS research conducted in MS to date.

METHODS

The patients were randomly assigned (block randomization method) to two groups of sham (n = 20), or 1.5-mA (n = 20) transcranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex (F3) and right frontopolar cortex (Fp2) with anodal and cathodal stimulation respectively (electrode size: 25 cm2). The treatment included 10 sessions of 20 min of stimulation delivered every other day. Outcome measures were MS quality of life, sleep quality, psychological distress, and performance on a neuropsychological test battery dedicated to cognitive dysfunctions in MS (psychomotor speed, working memory, and attention). All outcome measures were evaluated at the pre-intervention and post-intervention assessments. Both patients and technicians delivering the stimulation were unaware of the type of stimulation being used.

RESULTS

Repeated prefrontal real tDCS significantly improved quality of life and reduced sleep difficulties and psychological distress compared to the sham group. It, furthermore, improved psychomotor speed, attention, and vigilance compared to the sham protocol. Improvement in mental health outcome variables and cognitive outperformance were interrelated and could predict each other.

CONCLUSIONS

Repeated prefrontal and frontopolar tDCS ameliorates secondary clinical symptoms related to mental health and results in beneficial cognitive effects in patients with MS. These results support applying prefrontal tDCS in larger trials for improving mental health and cognitive dysfunctions in MS.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT06401928.

Metaanalysis of Repetitive Transcranial Magnetic Stimulation (rTMS) Efficacy for OCD Treatment: The Impact of Stimulation Parameters, Symptom Subtype and rTMS-Induced Electrical Field

Background: Repetitive transcranial magnetic stimulation (rTMS) has recently demonstrated significant potential in treating obsessive-compulsive disorder (OCD). However, its effectiveness depends on various parameters, including stimulation parameters, OCD subtypes and electrical fields (EFs) induced by rTMS in targeted brain regions that are less studied. Methods: Using the PRISMA approach, we examined 27 randomized control trials (RCTs) conducted from 1985 to 2024 using rTMS for the treatment of OCD and conducted several meta-analyses to investigate the role of rTMS parameters, including the EFs induced by each rTMS protocol, and OCD subtypes on treatment efficacy. Results: A significant, medium effect size was found, favoring active rTMS (gPPC = 0.59, p < 0.0001), which was larger for the obsession subscale. Both supplementary motor area (SMA) rTMS (gPPC = 0.82, p = 0.048) and bilateral dorsolateral prefrontal cortex (DLPFC) rTMS (gPPC = 1.14, p = 0.04) demonstrated large effect sizes, while the right DLPFC showed a significant moderate effect size for reducing OCD severity (gPPC = 0.63, p = 0.012). These protocols induced the largest EFs in dorsal cognitive, ventral cognitive and sensorimotor circuits. rTMS protocols targeting DLPFC produced the strongest electrical fields in cognitive circuits, while pre-supplementary motor area (pre-SMA) and orbitofrontal cortex (OFC) rTMS protocols induced larger fields in regions linked to emotional and affective processing in addition to cognitive circuits. The pre-SMA rTMS modulated more circuits involved in OCD pathophysiology-sensorimotor, cognitive, affective, and frontolimbic-with larger electrical fields than the other protocols. Conclusions: While rTMS shows moderate overall clinical efficacy, protocols targeting ventral and dorsal cognitive and sensorimotor circuits demonstrate the highest potential. The pre-SMA rTMS appears to induce electrical fields in more circuits relevant to OCD pathophysiology.

Induction and stabilization of delta frequency brain oscillations by phase-synchronized rTMS and tACS

BACKGROUND

Brain oscillations in the delta frequency band have been linked with deep sleep and consolidation of declarative memory during sleep. However, the causal relationship of these associations remains not competely clarified, primarily due to constraints by technical limitations of brain stimulation approaches suited to induce and stabilize respective oscillatory activity in the human brain. The objective of this study was to establish a non-invasive brain stimulation protocol capable of reliably inducing, and stabilizing respective oscillatory activity in the delta frequency range.

HYPOTHESIS

We aimed to develop an efficient non-invasive brain stimulation (NIBS) protocol for delta frequency induction and stabilization via concurrent, phase-locked repetitive transcranial magnetic stimulation (rTMS) and transcranial alternating current stimulation (tACS). We hypothesized that rTMS induces oscillatory resting-state activity in the delta frequency and that tACS stabilizes this effect, as has been shown before for alpha and theta frequencies.

METHODS

19 healthy participants took part in a repeated-measures experimental protocol. We applied rTMS pulses synchronized with the peak or trough phase of 0.75Hz tACS over the bilateral prefrontal cortex. Resting state EEG in eyes-open (EO) and eyes-closed (EC) conditions was recorded before, immediately after and every 10 min for up to 1 h after intervention.

RESULTS

rTMS phase-synchronized to the trough of the tACS waveform significantly increased delta frequency activity for up to 60 min in both EO and EC conditions after stimulation. The effects extended from frontal to temporal regions and this enhancement of oscillatory activity was shown to be specific for the delta frequency range.

CONCLUSION

Concurrent, trough-synchronized 0.75 Hz rTMS combined with tACS may be a reliable protocol to induce long-lasting oscillatory activity in the delta frequency range. The results of the current study might perspectively be relevant for clinical treatment of sleep disturbances which are accompanied by pathologically altered brain oscillations, and enhancement of memory consolidation.

Circadian rhythm sleep loss impairs motor inhibition more than motor execution in continuous action

Under total sleep deprivation, both inhibitory and motor control are impaired. However, how circadian rhythm sleep loss caused by irregular sleep pattern affects motor inhibition and execution in continuous actions remains unknown. This study utilized a pointing task to investigate the question over 30 days. During regular trials, participants were instructed to tap on a specified location, while in countermanding trials, they were required to countermand their current action. Additionally, there was a control group performed the same task following a normal 24-h rhythm. The results indicated that the decrease in accuracy and the increase in movement time in countermanding trials were more prominent in the shift work group. In contrast, there was no significant difference in reaction time between the two groups. Notably, the shift work group outperformed the control group in terms of movement time in regular trials and radial displacement in countermanding trials. Overall, these results show that circadian rhythm sleep loss predominantly affects inhibitory control, rather than motor control, underscoring the nuanced impacts of sleep disruption on differential aspects of cognitive and motor functions.

Time me by the moon : The evolution and function of lunar timing systems

The moon has significant impact on the timing of organisms. Can the study of molecular timing mechanisms of marine animals and algae help to understand some of the “weird” correlations between human physiological/behavioral rhythms and the lunar cycle?

Diurnal cognitive functioning in patients with myasthenia gravis with the role of chronotype and depression: a pilot study

Purpose

Myasthenia gravis (MG) is an autoimmune disease manifested by fatigue and weakness of the skeletal muscles. Recent research has indicated that MG patients perform significantly worse than healthy controls in cognitive domains such as attention, verbal fluency, visual learning, and memory. This study aimed to investigate the diurnal fluctuations in cognitive performance in patients with myasthenia gravis in relation to selected clinical and socioeconomic parameters of the disease course, along with the role of chronotype and depression.

Methods

The participants were recruited from a neurology outpatient clinic. Patients' cognitive functions were assessed twice: in the morning and the evening of the same day. Neuropsychological diagnosis included attention, memory, executive, verbal, and visuospatial abilities. Mood was measured with the Beck Depression Inventory-II and Positive and Negative Affect Schedule. The Morningness-Eveningness Questionnaire was used to examine chronotype.

Results

The analyses performed showed no significant differences between subjects and within subjects, apart from semantic fluency. Patients receiving antidepressant treatment obtained better results on attention and working memory tasks.

Conclusions

The data obtained show that diurnal neuropsychological performance in MG patients is associated with depression. Routine assessment and treatment of mood disorders could significantly improve cognitive functioning in myasthenia gravis patients.

Zebrafish: A trending model for gut-brain axis investigation

Zebrafish (Danio rerio) has ascended as a pivotal model organism in the realm of gut-brain axis research, principally owing to its high-throughput experimental capabilities and evolutionary alignment with mammals. The inherent transparency of zebrafish embryos facilitates unprecedented real-time imaging, affording unparalleled insights into the intricate dynamics of bidirectional communication between the gut and the brain. Noteworthy are the structural and functional parallels shared between the zebrafish and mammalian gut-brain axis components, rendering zebrafish an invaluable model for probing the molecular and cellular intricacies inherent in this critical physiological interaction. Recent investigations in zebrafish have systematically explored the impact of gut microbiota on neurodevelopment, behaviour, and disease susceptibility, underscoring the model's prowess in unravelling the multifaceted influence of microbial communities in shaping gut-brain interactions. Leveraging the genetic manipulability inherent in zebrafish, researchers have embarked on targeted explorations of specific pathways and molecular mechanisms, providing nuanced insights into the fundamental functioning of the gut-brain axis. This comprehensive review synthesizes pivotal findings and methodological advancements derived from zebrafish-based gut-brain axis research, accentuating the model's potential to significantly advance our understanding of this complex interplay. Furthermore, it underscores the translational significance of these insights, offering promising avenues for the identification of therapeutic targets in neuro-gastroenterological disorders and psychiatric conditions intricately linked with gut-brain interactions.

Intensity-dependent effects of tDCS on motor learning are related to dopamine

Non-invasive brain stimulation techniques, such as transcranial direct current stimulation (tDCS), are popular methods for inducing neuroplastic changes to alter cognition and behaviour. One challenge for the field is to optimise stimulation protocols to maximise benefits. For this to happen, we need a better understanding of how stimulation modulates cortical functioning/behaviour. To date, there is increasing evidence for a dose-response relationship between tDCS and brain excitability, however how this relates to behaviour is not well understood. Even less is known about the neurochemical mechanisms which may drive the dose-response relationship between stimulation intensities and behaviour. Here, we examine the effect of three different tDCS stimulation intensities (1 mA, 2 mA, 4 mA anodal motor cortex tDCS) administered during the explicit learning of motor sequences. Further, to assess the role of dopamine in the dose-response relationship between tDCS intensities and behaviour, we examined how pharmacologically increasing dopamine availability, via 100 mg of levodopa, modulated the effect of stimulation on learning. In the absence of levodopa, we found that 4 mA tDCS improved and 1 mA tDCS impaired acquisition of motor sequences relative to sham stimulation. Conversely, levodopa reversed the beneficial effect of 4 mA tDCS. This effect of levodopa was no longer evident at the 48-h follow-up, consistent with previous work characterising the persistence of neuroplastic changes in the motor cortex resulting from combining levodopa with tDCS. These results provide the first direct evidence for a role of dopamine in the intensity-dependent effects of tDCS on behaviour.

Chronotype and emotional/behavioral problems mediate the association between leisure screen time and academic achievement in children

Leisure screen time is associated with poor academic achievement; however, the mechanism underlying this relationship is unclear. Chronotypes and emotional/behavioral problems may be linked to this association. This study aimed to examine the associations between leisure screen time, chronotype, emotional/behavioral problems, and academic achievement using mediation analysis. A total of 113 children aged 9-12 years participated in this study. All participants were assessed for leisure screen time, chronotype, emotional/behavioral problems, and academic achievement. Leisure screen time was evaluated using a self-reported questionnaire. Chronotypes were measured using The Japanese Children's Chronotype Questionnaire, and the morningness/eveningness (M/E) score was calculated. Emotional/behavioral problems were assessed using The Japanese Strengths and Difficulties Questionnaire, and the total difficulties score (TDS) was calculated. Academic achievement was assessed by the homeroom teacher for each of the seven school subjects. Partial correlation analysis adjusted for grade, sex, and sleep duration indicated that leisure screen time was associated with M/E scores and academic achievement (p < 0.05). There was a positive association between M/E score and TDS (p < 0.05) and a negative association between TDS and academic achievement (p < 0.05). A mediation analysis adjusted for grade, sex, and sleep duration was performed. There was a significant total effect of leisure screen time on academic achievement (p < 0.05). Additionally, the M/E score and TDS significantly mediated the association between leisure screen time and academic achievement (p < 0.05). Our findings suggest that the serial path between chronotype and emotional/behavioral problems weakly but significantly mediates the association of leisure screen time with academic achievement.

Exploring the Differential Effects of Transcranial Direct Current Stimulation: A Comparative Analysis of Motor Cortex and Cerebellar Stimulation

Background

Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique. Constant electric current is passed through the patient's scalp with the aim of modulating cortical excitability. Stroke is a cerebrovascular disease characterized by hemorrhage or cerebral ischemia. This systematic review and meta-analysis are aimed at comparing the efficacy of motor cortex stimulation with that of cerebellar stimulation by using transcranial direct current stimulation.

Method

Google Scholar, PubMed, EMBASE, Cochrane CENTRAL, and Physiotherapy Evidence Database (Pedro) databases were searched for studies. The extracted qualitative data was synthesized systematically. Cochrane RevMan software was used to conduct a meta-analysis of quantitative data. The fixed effects mean difference of the collected data was calculated at a 95% confidence interval (CI) for the changes in balance and side effects.

Results

This research included 10 articles with seven studies assessing changes in balance (outcome measured in CoP and FMA scores) and side effects (tingling and itching were the most prevalent). There was no significant difference between the efficacy levels of m1-tDCS versus ctDCS (P = 0.18), m1-tDCS versus sham (P = 0.92), and ctDCS versus sham (P = 0.19). Itching and tingling sensation were the most common and were significantly prevalent in sham interventions (P < 0.00001).

Conclusion

We found that motor cortex and cerebellar stimulations are both effective in improving motor function in stroke patients. There are no adverse effects to using the interventions besides mild itching and tingling experienced during the stimulation.

Effects of dry needling on spasticity, cortical excitability, and range of motion in a patient with multiple sclerosis: a case report

BACKGROUND

Dry needling is an intervention used by physiotherapists to manage muscle spasticity. We report the effects of three sessions of dry needling on ankle plantar flexor muscle spasticity and cortical excitability in a patient with multiple sclerosis.

CASE PRESENTATION

The patient was a 40-year-old Iranian woman with an 11-year history of multiple sclerosis. The study outcomes were measured by the modified modified Ashworth scale, transcranial magnetic stimulation parameters, and active and passive ankle range of motion. They were assessed before (T0), after three sessions of dry needling (T1), and at 2-week follow-up (T2). Our result showed: the modified modified Ashworth scale was improved at T2 from, 2 to 1. The resting motor threshold decreased from 63 to 61 and 57 at T1 and T2, respectively. The single test motor evokes potential increased from 76.2 to 78.3. The short intracortical inhibition increased from 23.6 to 35.4 at T2. The intracortical facilitation increased from 52 to 76 at T2. The ankle active and passive dorsiflexion ROM increased ~ 10° and ~ 6° at T2, respectively.

CONCLUSION

This case study presented a patient with multiple sclerosis who underwent dry needling of ankle plantar flexors with severe spasticity, and highlighted the successful use of dry needling in the management of spasticity, ankle dorsiflexion, and cortical excitability. Further rigorous investigations are warranted, employing randomized controlled trials with a sufficient sample of patients with multiple sclerosis. Trial registration IRCT20230206057343N1, registered 9 February 2023, https://en.irct.ir/trial/68454.

Circadian modulation of the time course of automatic and controlled semantic processing

We investigated whether chronotype and time-of-day modulate the time course of automatic and controlled semantic processing. Participants performed a category semantic priming task at either the optimal or non-optimal time of day. We varied the prime-target onset asynchrony (100-, 450-, 650-, and 850-ms SOAs) and kept the percentage of unrelated targets constant at 80%. Automatic processing was expected with the short SOA, and controlled processing with longer SOAs. Intermediate-types (Experiment 1) verified that our task was sensitive to capturing both types of processes and served as a reference to assess themin extreme chronotypes. Morning-type and evening-type participants (Experiment 2) differed in the influence of time of testing on priming effects. Morning-types applied control in all conditions, and no performance modulation by time-of-day was observed. In contrast, evening-types were most adversely affected by the time of day to shift from automatic-based to controlled-based responses. Also, they were considerably affected in successfully implementing controlled processing with long intervals, particularly at the non-optimal time of day, with inhibitory priming showing only a marginally significant effect at the longest SOA. These results suggest that extreme chronotypes may be associated with different styles of cognitive control. Morning-types would be driven by a proactive control style, whereas a reactive control style might be applied by evening-types.

Safety of noninvasive brain stimulation in children

PURPOSE OF REVIEW

Noninvasive brain stimulation (NIBS) is a promising method for altering cortical excitability with clinical implications. It has been increasingly used in children, especially in neurodevelopmental disorders. Yet, its safety and applications in the developing brain require further investigation. This review aims to provide an overview of the safety of commonly used NIBS techniques in children, including transcranial electrical stimulation (tES) and transcranial magnetic stimulation (TMS). Safety data for other NIBS methods is not reported in this review.

RECENT FINDINGS

In line with studies from the last decade, findings in the last 2 years (2022-2023) support the safety of NIBS in children and adolescents within the currently applied protocols. Both tES and TMS are well tolerated, if safety rules, including exclusion criteria, are applied.

SUMMARY

We briefly discussed developmental aspects of stimulation parameters that need to be considered in the developing brain and provided an up-to-date overview of tES/TMS applications in children and adolescents. Overall, the safety profile of tES/TMS in children is good. For both the tES and TMS applications, epilepsy and active seizure disorder should be exclusion criteria to prevent potential seizures. Using child-sized earplugs is required for TMS applications. We lack large randomized double-blind trialsand longitudinal studies to establish the safety of NIBS in children.

VIDEO ABSTRACT

http://links.lww.com/YCO/A78 .

Neurochemical mechanisms underlying serotonergic modulation of neuroplasticity in humans

BACKGROUND

Studies in animals and humans have shown that cortical neuroplasticity can be modulated by increasing serotonin levels by administering selective serotonin reuptake inhibitors (SSRI). However, little is known about the mechanistic background, especially the contribution of intracortical inhibition and facilitation, which depend on gamma-aminobutyric acid (GABA) and glutamate.

OBJECTIVE

We aimed to explore the relevance of drivers of plasticity (glutamate- and GABA-dependent processes) for the effects of serotonin enhancement on tDCS-induced plasticity in healthy humans.

METHODS

A crossover, partially double-blinded, randomized, and sham-controlled study was conducted in 21 healthy right-handed individuals. In each of the 7 sessions, plasticity was induced via transcranial direct current stimulation (tDCS). Anodal, cathodal, and sham tDCS were applied to the left motor cortex under SSRI (20 mg/40 mg citalopram) or placebo. Short-interval cortical inhibition (SICI) and intracortical facilitation (ICF) were monitored by paired-pulse transcranial magnetic stimulation for 5-6 h after intervention.

RESULTS

Under placebo, anodal tDCS-induced LTP-like plasticity decreased SICI and increased ICF. In contrast, cathodal tDCS-elicited LTD-like plasticity induced the opposite effect. Under 20 mg and 40 mg citalopram, anodal tDCS did not affect SICI largely, while ICF was enhanced and prolonged. For cathodal tDCS, citalopram converted the increase of SICI and decrease of ICF into antagonistic effects, and this effect was dosage-dependent since it lasted longer under 40 mg when compared to 20 mg.

CONCLUSION

We speculate that the main effects of acute serotonergic enhancement on tDCS-induced plasticity, the increase and prolongation of LTP-like plasticity effects, involves mainly the glutamatergic system.

Small effects of electric field on motor cortical excitability following anodal tDCS

The dose-response characteristics of transcranial direct current stimulation (tDCS) remain uncertain but may be related to variability in brain electric fields due to individual anatomical factors. Here, we investigated whether the electric fields influence the responses to motor cortical tDCS. In a randomized cross-over design, 21 participants underwent 10 min of anodal tDCS with 0.5, 1.0, 1.5, or 2.0 mA or sham. Compared to sham, all active conditions increased the size of motor evoked potentials (MEP) normalized to the pre-tDCS baseline, irrespective of anterior or posterior magnetic test stimuli. The electric field calculated in the motor cortex of each participant had a nonlinear effect on the normalized MEP size, but its effects were small compared to those of other participant-specific factors. The findings support the efficacy of anodal tDCS in enhancing the MEP size but do not demonstrate any benefits of personalized electric field modeling in explaining tDCS response variability.

Hybrid computational model depicts the contribution of non-significant lobes of human brain during the perception of emotional stimuli

Emotions are synchronizing responses of human brain while executing cognitive tasks. Earlier studies had revealed strong correlation between specific lobes of the brain to different types of emotional valence. In the current study, a comprehensive three-dimensional mapping of human brain for executing emotion specific tasks had been formulated. A hybrid computational machine learning model customized from Custom Weight Allocation Model (CWAM) and defined as Custom Rank Allocation Model (CRAM). This regression-based hybrid computational model computes the allocated tasks to different lobes of the brain during their respective executive stage. Event Related Potentials (ERP) were obtained with significant effect at P1, P2, P3, N170, N2, and N4. These ERPs were configured at Pz, Cz, F3, and T8 regions of the brain with maximal responses; while regions like Cz, C4 and F4 were also found to make effective contributions to elevate the responses of the brain, and thus these regions were configured as augmented source regions of the brain. In another circumstance of frequent -deviant - equal (FDE) presentation of the emotional stimuli, it was observed that the brain channels C3, C4, P3, P4, O1, O2, and Oz were contributing their emotional quotient to the overall response of the brain regions; whereas, the interaction effect was found presentable at O2, Oz, P3, P4, T8 and C3 regions of brain. The proposed computational model had identified the potential neural pathways during the execution of emotional task.

Targeting the prefrontal-supplementary motor network in obsessive-compulsive disorder with intensified electrical stimulation in two dosages: a randomized, controlled trial

Obsessive-compulsive disorder (OCD) is associated with a high disease burden, and treatment options are limited. We used intensified electrical stimulation in two dosages to target a main circuitry associated with the pathophysiology of OCD, left dorsolateral prefrontal cortex (l-DLPFC), and pre-supplementary motor area (pre-SMA) and assessed clinical outcomes, neuropsychological performance, and brain physiology. In a double-blind, randomized controlled trial, thirty-nine patients with OCD were randomly assigned to three groups of sham, 2-mA, or 1-mA transcranial direct current stimulation (tDCS) targeting the l-DLPFC (F3) and pre-SMA (FC2) with anodal and cathodal stimulation respectively. The treatment included 10 sessions of 20-minute stimulation delivered twice per day with 20-min between-session intervals. Outcome measures were reduction in OCD symptoms, anxiety, and depressive states, performance on a neuropsychological test battery (response inhibition, working memory, attention), oscillatory brain activities, and functional connectivity. All outcome measures except EEG were examined at pre-intervention, post-intervention, and 1-month follow-up times. The 2-mA protocol significantly reduced OCD symptoms, anxiety, and depression states and improved quality of life after the intervention up to 1-month follow-up compared to the sham group, while the 1-mA protocol reduced OCD symptoms only in the follow-up and depressive state immediately after and 1-month following the intervention. Both protocols partially improved response inhibition, and the 2-mA protocol reduced attention bias to OCD-related stimuli and improved reaction time in working memory performance. Both protocols increased alpha oscillatory power, and the 2-mA protocol decreased delta power as well. Both protocols increased connectivity in higher frequency bands at frontal-central areas compared to the sham. Modulation of the prefrontal-supplementary motor network with intensified tDCS ameliorates OCD clinical symptoms and results in beneficial cognitive effects. The 2-mA intensified stimulation resulted in larger symptom reduction and improved more converging outcome variables related to therapeutic efficacy. These results support applying the intensified prefrontal-SMA tDCS in larger trials.

Testing the modulation of self-related automatic and others-related controlled processing by chronotype and time-of-day

We assessed whether self-related automatic and others-related controlled processes are modulated by chronotype and time-of-day. Here, a shape-label matching task composed of three geometrical shapes arbitrarily associated with you, friend, and stranger was used. Twenty Morning-types, and twenty Evening-types performed the task at the optimal and non-optimal times of day (i.e., 8 AM, or 8:30 PM). Morning-types did not exhibit noticeable synchrony effects, thus proving the better adaptation of these participants to non-optimal moments of the day as compared to Evening-types. Contrary to our predictions regarding the absence of automatic-processing modulation and the presence of controlled-processing influences by time-of-day, we found an influence on self-related but not others-related processing only in Evening-type participants. Although brain structures are not directly tackled, we argue that such modulation may be due to the dependence of the activation of the ventromedial prefrontal cortex (VMPFC), an essential component of the self-attention network on circadian rhythms.

Circadian Rhythms, Chrononutrition, Physical Training, and Redox Homeostasis-Molecular Mechanisms in Human Health

A multitude of physiological processes, human behavioral patterns, and social interactions are intricately governed by the complex interplay between external circumstances and endogenous circadian rhythms. This multidimensional regulatory framework is susceptible to disruptions, and in contemporary society, there is a prevalent occurrence of misalignments between the circadian system and environmental cues, a phenomenon frequently associated with adverse health consequences. The onset of most prevalent current chronic diseases is intimately connected with alterations in human lifestyle practices under various facets, including the following: reduced physical activity, the exposure to artificial light, also acknowledged as light pollution, sedentary behavior coupled with consuming energy-dense nutriments, irregular eating frameworks, disruptions in sleep patterns (inadequate quality and duration), engagement in shift work, and the phenomenon known as social jetlag. The rapid evolution of contemporary life and domestic routines has significantly outpaced the rate of genetic adaptation. Consequently, the underlying circadian rhythms are exposed to multiple shifts, thereby elevating the susceptibility to disease predisposition. This comprehensive review endeavors to synthesize existing empirical evidence that substantiates the conceptual integration of the circadian clock, biochemical molecular homeostasis, oxidative stress, and the stimuli imparted by physical exercise, sleep, and nutrition.

The effect of time of day on Special Judo Fitness Test in active judokas: Evaluation in terms of chronotype

The present cross-sectional study aims to examine the effect of time of day on the judo-specific performance in judokas, considering their chronotypes. Twenty-four male judokas participated in the study where the Morningness-Eveningness Questionnaire was administered, and on it, they were divided into morning-type (MT:12-judokas) and evening-type groups (ET:12-judokas). Afterwards, the Special Judo Fitness Test (SJFT) was applied to both groups at three different times (morning: 09:00 h, afternoon: 13:00 h and evening: 17:00 h) with body temperature measured before and after every SJFT performance. As a result, the Group*Test Time interaction significantly affected overall throwing performance during SJFT [F(2,44) = 29.437, p = 0.001, η2p: .572]. Furthermore, a significant time effect was found for the SJFT index [F(2,44) = 5.118, p = 0.010, η2p: .189] and for the Group*Test Time interaction with the mean value of the index [F(2,44) = 24.424, p < 0.001, η2p: .526]. Furthermore, body temperature had a significant time effect [F(2,44) = 301.454, p < 0.001, η2p: .932] and the Group*Test Time interaction [F(2,44) = 5.802, p = 0.006, η2p: .209]. In conclusion, coaches and exercise experts should consider judo athletes' chronotype when planning special training programs to improve judo-specific anaerobic capacity. Furthermore, to minimize the impact of time of day and chronotype on athletes' performance in competitions, it is recommended that MT athletes develop their judo-specific anaerobic capacity in the evening hours, when their performance is lower, while ET athletes should do so in the morning hours when their performance is lower via randori training.

Disrupted synaptic homeostasis and partial occlusion of associative long-term potentiation in the human cortex during social isolation

Social isolation often occurs in the military mission of soldiers but has increased in the general population since the COVID-19 epidemic. Overall synaptic homeostasis along with associative plasticity for the activity-dependent refinement of transmission across single synapses represent basic neural network function and adaptive behavior mechanisms. Here, we use electrophysiological and behavioral indices to non-invasively study the net synaptic strength and long-term potentiation (LTP)-like plasticity of humans in social isolation environments. The theta activity of electroencephalography (EEG) signals and transcranial magnetic stimulation (TMS) intensity to elicit a predefined amplitude of motor-evoked potential (MEP) demonstrate the disrupted synaptic homeostasis in the human cortex during social isolation. Furthermore, the induced MEP change by paired associative stimulation (PAS) demonstrates the partial occlusion of LTP-like plasticity, further behavior performances in a word-pair task are also identified as a potential index. Our study indicates that social isolation disrupts synaptic homeostasis and occludes associative LTP-like plasticity in the human cortex, decreasing behavior performance related to declarative memory.

Efficacy of Transcranial Direct Current Stimulation on Pain Level and Disability of Patients with Fibromyalgia: A Systematic Review of Randomized Controlled Trials with Parallel-Group Design

Transcranial direct current stimulation (tDCS) has been increasingly applied in fibromyalgia (FM) to reduce pain and fatigue. While results are promising, observed effects are variable, and there are questions about optimal stimulation parameters such as target region (e.g., motor vs. prefrontal cortices). This systematic review aimed to provide the latest update on published randomized controlled trials with a parallel-group design to examine the specific effects of active tDCS in reducing pain and disability in FM patients. Using the PRISMA approach, a literature search identified 14 randomized controlled trials investigating the effects of tDCS on pain and fatigue in patients with FM. Assessment of biases shows an overall low-to-moderate risk of bias. tDCS was found effective in all included studies conducted in patients with FM, except one study, in which the improving effects of tDCS were due to placebo. We recommended tDCS over the motor and prefrontal cortices as "effective" and "probably effective" respectively, and also safe for reducing pain perception and fatigue in patients with FM, according to evidence-based guidelines. Stimulation polarity was anodal in all studies, and one single-session study also examined cathodal polarity. The stimulation intensity ranged from 1-mA (7.14% of studies) to 1.5-mA (7.14% of studies) and 2-mA (85.7% of studies). In all of the included studies, a significant improvement in at least one outcome variable (pain or fatigue reduction) was observed. Moreover, 92.8% (13 of 14) applied multi-session tDCS protocols in FM treatment and reported significant improvement in their outcome variables. While tDCS is therapeutically effective for FM, titration studies that systematically evaluate different stimulation intensities, durations, and electrode placement are needed.

Effects of multisession cathodal transcranial direct current stimulation with cognitive training on sociocognitive functioning and brain dynamics in autism: A double-blind, sham-controlled, randomized EEG study

BACKGROUND

Few treatment options are available for targeting core symptoms of autism spectrum disorder (ASD). The development of treatments that target common neural circuit dysfunctions caused by known genetic defects, namely, disruption of the excitation/inhibition (E/I) balance, is promising. Transcranial direct current stimulation (tDCS) is capable of modulating the E/I balance in healthy individuals, yet its clinical and neurobiological effects in ASD remain elusive.

OBJECTIVE

This double-blind, randomized, sham-controlled trial investigated the effects of multisession cathodal prefrontal tDCS coupled with online cognitive remediation on social functioning, information processing efficiency and the E/I balance in ASD patients aged 14-21 years.

METHODS

Sixty individuals were randomly assigned to receive either active or sham tDCS (10 sessions in total, 20 min/session, stimulation intensity: 1.5 mA, cathode: F3, anode: Fp2, size of electrodes: 25 cm2) combined with 20 min of online cognitive remediation. Social functioning, information processing efficiency during cognitive tasks, and theta- and gamma-band E/I balance were measured one day before and after the treatment.

RESULTS

Compared to sham tDCS, active cathodal tDCS was effective in enhancing overall social functioning [F(1, 58) = 6.79, p = .012, ηp2 = 0.105, 90% CI: (0.013, 0.234)] and information processing efficiency during cognitive tasks [F(1, 58) = 10.07, p = .002, ηp2 = 0.148, 90% CI: (0.034, 0.284)] in these individuals. Electroencephalography data showed that this cathodal tDCS protocol was effective in reducing the theta-band E/I ratio of the cortical midline structures [F(1, 58) = 4.65, p = .035, ηp2 = 0.074, 90% CI: (0.010, 0.150)] and that this reduction significantly predicted information processing efficiency enhancement (b = -2.546, 95% BCa CI: [-4.979, -0.113], p = .041).

CONCLUSION

Our results support the use of multisession cathodal tDCS over the left dorsolateral prefrontal cortex combined with online cognitive remediation for reducing the elevated theta-band E/I ratio in sociocognitive information processing circuits in ASD patients, resulting in more adaptive regulation of global brain dynamics that is associated with enhanced information processing efficiency after the intervention.

For Whom (and When) the Time Bell Tolls: Chronotypes and the Synchrony Effect

Circadian rhythms are powerful timekeepers that drive physiological and intellectual functioning throughout the day. These rhythms vary across individuals, with morning chronotypes rising and peaking early in the day and evening chronotypes showing a later rise in arousal, with peaks in the afternoon or evening. Chronotype also varies with age from childhood to adolescence to old age. As a result of these differences, the time of day at which people are best at attending, learning, solving analytical problems, making complex decisions, and even behaving ethically varies. Across studies of attention and memory and a range of allied areas, including academic achievement, judgment and decision-making, and neuropsychological assessment, optimal outcomes are found when performance times align with peaks in circadian arousal, a finding known as the synchrony effect. The benefits of performing in synchrony with one's chronotype (and the costs of not doing so) are most robust for individuals with strong morning or evening chronotypes and for tasks that require effortful, analytical processing or the suppression of distracting information. Failure to take the synchrony effect into consideration may be a factor in issues ranging from replication difficulties to school timing to assessing intellectual disabilities and apparent cognitive decline in aging.

Acute exercise performed before and after motor practice enhances the positive effects on motor memory consolidation

Performing a single bout of exercise can enhance motor learning and long-term retention of motor skills. Parameters such as the intensity and when the exercise bout is performed in relation to skill practice (i.e., timing) likely influence the effectiveness. However, it is still not fully understood how exercise should be administered to maximize its effects and how exercise interacts with distinct components of skill learning. Here, we expand this knowledge by investigating the potential synergistic effects of performing acute exercise both prior to and following motor practice. Sixty-four, able-bodied, young adult male participants practiced a sequential visuomotor accuracy tracking (SVAT) task requiring rapid and accurate force modulation and high levels of precision control using intrinsic hand muscles. The task also contained a repeated pattern of targets that allowed sequence-specific skill improvements. Sequential and non-sequential motor performance was assessed at baseline, immediately after motor practice, and again seven days later. One group performed moderate-intensity exercise before practice (PREMO), a second group performed high-intensity exercise after practice (POSTHI), a third group exercised both before and after practice (PREMO + POSTHI), and a fourth group did not exercise during these periods (CON). Regardless of the exercise condition, acute exercise improved long-term retention of the skill by countering performance decay between experimental sessions (i.e., a 7-day interval). Furthermore, exercising both before and after motor practice led to the greatest improvements in skilled performance over time. We found that the effects of exercise were not specific to the practiced sequence. Namely, the effects of exercise generalized across sequential and non-sequential target positions and orders. This suggests that acute exercise works through mechanisms that promote general aspects of motor memory (e.g., lasting improvements in fast and accurate motor execution). The results demonstrate that various exercise protocols can promote the stabilization and long-term retention of motor skills. This effect can be enhanced when exercise is performed both before and after practice.

Effects of Chronotype and Social Jet-Lag on Neurocognitive Functioning

The chronotype, which reflects the circadian rhythm preferences of individuals in their daily activities and sleep-wake cycles, can be considered on a dimension of extreme morningism and extreme eveningism. Individuals with extreme morning and extreme evening chronotypes face many physical and psychological dangers due to accumulated sleep debt, short total sleep time and insufficient sleep efficiency. In extreme chronotypes, especially in extreme evening people, the social jet-lag effect due to the mismatch between social and circadian clocks is thought to exacerbate these dangers. More recent studies have suggested that social jet-lag and chronotype have many negative effects on cognitive functioning. The aim of this article is to review the impact of social jet-lag and chronotype on cognitive functioning.

Transcranial random noise stimulation combined with cognitive training for treating ADHD: a randomized, sham-controlled clinical trial

Non-invasive brain stimulation has been suggested as a potential treatment for improving symptomology and cognitive deficits in Attention-Deficit/Hyperactivity Disorder (ADHD), the most common childhood neurodevelopmental disorder. Here, we examined whether a novel form of stimulation, high-frequency transcranial random noise stimulation (tRNS), applied with cognitive training (CT), may impact symptoms and neural oscillations in children with ADHD. We conducted a randomized, double-blind, sham-controlled trial in 23 unmedicated children with ADHD, who received either tRNS over the right inferior frontal gyrus (rIFG) and left dorsolateral prefrontal cortex (lDLPFC) or sham stimulation for 2 weeks, combined with CT. tRNS + CT yielded significant clinical improvements (reduced parent-reported ADHD rating-scale scores) following treatment, compared to the control intervention. These improvements did not change significantly at a 3-week follow-up. Moreover, resting state (RS)-EEG periodic beta bandwidth of the extracted peaks was reduced in the experimental compared to control group immediately following treatment, with further reduction at follow-up. A lower aperiodic exponent, which reflects a higher cortical excitation/inhibition (E/I) balance and has been related to cognitive improvement, was seen in the experimental compared to control group. This replicates previous tRNS findings in adults without ADHD but was significant only when using a directional hypothesis. The experimental group further exhibited longer sleep onset latencies and more wake-up times following treatment compared to the control group. No significant group differences were seen in executive functions, nor in reported adverse events. We conclude that tRNS + CT has a lasting clinical effect on ADHD symptoms and on beta activity. These results provide a preliminary direction towards a novel intervention in pediatric ADHD.

Acute effect of breathing exercises on muscle tension and executive function under psychological stress

Introduction

Intensive and long-lasting office work is a common cause of muscular and mental disorders due to workplace stressors. Mindful and slow breathing exercises decrease psychological stress and improve mental health, whereas fast breathing increases neuronal excitability. This study aimed to explore the influence of 5 min of mindful breathing (MINDFUL), slow breathing (SLOW), fast breathing (FAST), and listening to music (MUSIC) on muscle tension and executive function during an intensive psychological task.

Methods

Forty-eight participants (24 men and 24 women) were enrolled. Muscle tension was recorded using surface electromyography, and executive function was assessed using the Stroop Color and Word Test (Stroop Test). The respiration rate (RR), oxygen saturation (SpO₂), end-tidal carbon dioxide (EtCO₂), and the subjects' preferred method were also recorded. During the experiment, participants performed a one-time baseline test (watching a neutral video for 5 min) and then completed 5 min of MUSIC, MINDFUL, SLOW, and FAST in a random sequence. The Stroop Test was performed after each intervention, including the baseline test, and was followed by a 5 min rest before performing the next intervention.

Results

None of the methods significantly influenced muscular activity and performance of the Stroop Test in both men and women, based on the average 5 min values. However, at the fifth minute, men's accuracy rate in the Stroop Test was significantly higher after SLOW than after MUSIC and FAST, and the reaction time after the SLOW was the shortest. SpO₂ was significantly higher during SLOW than during MUSIC, and RR was relatively lower after SLOW than after MUSIC. Most men preferred SLOW, and most women preferred MUSIC, whereas FAST was the most unfavorable method for both men and women.

Conclusion

Brief breathing exercises did not substantially affect muscle tension under psychological stress. SLOW demonstrated greater potential for sustaining executive function in men, possibly via its superior respiration efficiency on SpO₂ and inhibition of RR.

Stimulation enhancement effect of the combination of exoskeleton-assisted hand rehabilitation and fingertip haptic stimulation

Introduction

Providing stimulation enhancements to existing hand rehabilitation training methods may help stroke survivors achieve better treatment outcomes. This paper presents a comparison study to explore the stimulation enhancement effects of the combination of exoskeleton-assisted hand rehabilitation and fingertip haptic stimulation by analyzing behavioral data and event-related potentials.

Methods

The stimulation effects of the touch sensations created by a water bottle and that created by cutaneous fingertip stimulation with pneumatic actuators are also investigated. Fingertip haptic stimulation was combined with exoskeleton-assisted hand rehabilitation while the haptic stimulation was synchronized with the motion of our hand exoskeleton. In the experiments, three experimental modes, including exoskeleton-assisted grasping motion without haptic stimulation (Mode 1), exoskeleton-assisted grasping motion with haptic stimulation (Mode 2), and exoskeleton-assisted grasping motion with a water bottle (Mode 3), were compared.

Results

The behavioral analysis results showed that the change of experimental modes had no significant effect on the recognition accuracy of stimulation levels (p = 0.658), while regarding the response time, exoskeleton-assisted grasping motion with haptic stimulation was the same as grasping a water bottle (p = 0.441) but significantly different from that without haptic stimulation (p = 0.006). The analysis of event-related potentials showed that the primary motor cortex, premotor cortex, and primary somatosensory areas of the brain were more activated when both the hand motion assistance and fingertip haptic feedback were provided using our proposed method (P300 amplitude 9.46 μV). Compared to only applying exoskeleton-assisted hand motion, the P300 amplitude was significantly improved by providing both exoskeleton-assisted hand motion and fingertip haptic stimulation (p = 0.006), but no significant differences were found between any other two modes (Mode 2 vs. Mode 3: p = 0.227, Mode 1 vs. Mode 3: p = 0.918). Different modes did not significantly affect the P300 latency (p = 0.102). Stimulation intensity had no effect on the P300 amplitude (p = 0.295, 0.414, 0.867) and latency (p = 0.417, 0.197, 0.607).

Discussion

Thus, we conclude that combining exoskeleton-assisted hand motion and fingertip haptic stimulation provided stronger stimulation on the motor cortex and somatosensory cortex of the brain simultaneously; the stimulation effects of the touch sensations created by a water bottle and that created by cutaneous fingertip stimulation with pneumatic actuators are similar.

Anodal stimulation of inhibitory control and craving in satiated restrained eaters

OBJECTIVES

Eating and weight disorders are severe and complex clinical conditions which, among other behaviors, include (attempts at) restrained eating, food avoidance, following dietary rules, and overeating. Comparable to women with obesity, restrained eaters (RE) without formal eating disorder diagnosis are worse at inhibiting their motor responses than unrestrained eaters (URE). According to neuroimaging studies, the right inferior frontal gyrus (rIFG) is involved in inhibitory control which, in turn, could be improved by neuromodulation such as anodal transcranial direct current stimulation (tDCS) across rIFG.

METHODS

This double-blind sham-controlled cross-over study was conducted after a standardized breakfast. Normal-weight female RE und URE performed a stop-signal task (SST) with food and non-food stimuli during sham or anodal tDCS. Food craving, hunger, and satiety were self-reported before and after tDCS. We employed a mixed between-subjects (group: RE vs. URE) and within-subjects factorial design (tDCS: anodal tDCS vs. sham; stimuli: food vs. control pictures).

RESULTS

Breakfast consumption was comparable for RE and URE, as well as craving, hunger, and thirst. Regarding inhibitory control, a significant two-way interaction between group and tDCS ermerged: RE had longer stop-signal reaction times (SSRTs) during sham tDCS, but they improved to the level of URE by application of anodal tDCS.

DISCUSSION

Results replicated an inhibitory control deficit in RE with longer SSRTs compared to URE without stimulation. During anodal tDCS to the rIFG, reduced SSRTs in RE indicated an improvement in inhibitory control. The findings suggest a specificity of rIFG stimulation in at-risk groups with regards to inhibitory control irrespective of craving.

Forgiving lark, resentful owl: Self-control mediates the relationship between chronotype and forgiveness

Considerable evidence shows that nocturnal chronotypes have increased odds of mental health problems, poor academic performance, and impairment in executive functions. Although the cognitive and health costs of evening-oriented preference are well-documented in the literature, little is known about its interpersonal costs. In this article, we propose that people with a preference for an evening chronotype show a lower tendency to forgive following an interpersonal offense because of their lower self-control ability. Three studies using independent samples and complementary measures reveal that morning-evening preference plays a role in the emergence of forgiveness, which provides support for our theoretical perspective. In Study 1, we found that evening-type students were less forgiving when responding to a transgression than morning-type students. Employing a longer measure of forgiveness and a more representative population, Study 2 replicated our initial findings and supported our hypothesis regarding the mediating role of self-control. To circumvent methodological issues associated with self-report data, Study 3 used a behavioral measure of forgiveness and revealed that chronotype can also predict actual forgiving behavior in a laboratory setting. Together, these findings suggest that diurnal preference towards eveningness not only imposes threats on people's health, but can also incur interpersonal costs.

Neural Mechanism Underlying Task-Specific Enhancement of Motor Learning by Concurrent Transcranial Direct Current Stimulation

The optimal protocol for neuromodulation by transcranial direct current stimulation (tDCS) remains unclear. Using the rotarod paradigm, we found that mouse motor learning was enhanced by anodal tDCS (3.2 mA/cm2) during but not before or after the performance of a task. Dual-task experiments showed that motor learning enhancement was specific to the task accompanied by anodal tDCS. Studies using a mouse model of stroke induced by middle cerebral artery occlusion showed that concurrent anodal tDCS restored motor learning capability in a task-specific manner. Transcranial in vivo Ca2+ imaging further showed that anodal tDCS elevated and cathodal tDCS suppressed neuronal activity in the primary motor cortex (M1). Anodal tDCS specifically promoted the activity of task-related M1 neurons during task performance, suggesting that elevated Hebbian synaptic potentiation in task-activated circuits accounts for the motor learning enhancement. Thus, application of tDCS concurrent with the targeted behavioral dysfunction could be an effective approach to treating brain disorders.

Emotional working memory training improves cognitive inhibitory abilities in individuals with borderline personality trait: A randomized parallel-group trial

BACKGROUND

Cognitive inhibition impairment is one of the causes of impulsive behaviors in individuals with borderline personality disorder (BPD). This study aimed to investigate the effect of emotional working memory training (EWMT) on cognitive inhibition in individuals with a clinically significant borderline personality trait.

METHODS

In a randomized, parallel-group trial, 40 individuals with borderline personality trait, were selected out of 1000 screened individuals and were randomly assigned to the experimental (N = 20) and waiting-list control (N = 20) groups based on the score on the Borderline Personality Scale and the follow-up Structured Clinical Interview for DSM-IV Personality Disorders. The experimental group underwent 10 sessions of EWMT and the control group did not receive any intervention (waiting list). Participants completed the Stroop Color and Word Test (SCWT) and Go/No-Go task Before and after the intervention.

RESULTS

EWMT significantly reduced reaction time of incongruent trials in the SCWT and commission errors in the Go/No-Go task after the intervention only in the experimental group. Furthermore, the interference score in SCWT and commission error rate at the post-intervention time were significantly lower for the experimental vs the waitlist group.

LIMITATIONS

The single-blind design and absence of follow-up measures.

CONCLUSIONS

EWMT can improve cognitive inhibition in individuals with borderline personality trait and could be used for therapeutic purposes of impulsivity behavior in BPD.

High-definition transcranial direct current stimulation (HD-tDCS) for the enhancement of working memory - A systematic review and meta-analysis of healthy adults

BACKGROUND

High-definition transcranial direct current stimulation (HD-tDCS) administers weak electric current through multiple electrodes, enabling focal brain stimulation. An increasing number of studies investigate the effects of anodal HD-tDCS on the enhancement of working memory (WM). The effectiveness of the technique is, however, still unclear.

OBJECTIVE/HYPOTHESIS

This systematic review analyzed the current literature on anodal HD-tDCS for WM enhancement, investigating its effectiveness and the influence of different moderators to allow for comparison with conventional tDCS.

METHODS

Following the Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines, a comprehensive literature review was conducted using PubMed, Web of Science, and Scopus. Sixteen single- or double-blind, sham-controlled studies were included in the review. Eleven studies were included in the meta-analysis, focusing solely on stimulation of the left prefrontal cortex (PFC).

RESULTS

No significant effect of anodal HD-tDCS on the left PFC for WM accuracy (g = 0.23, p = 0.08), and reaction time (g = 0.03, p = 0.75 after trim-and-fill) was found. Further analysis revealed heterogeneity in the accuracy results. Here, moderator analysis indicated a significant difference between studies that repeatedly used HD-tDCS enhanced WM training and studies with one-time use of HD-tDCS (p < 0.001), the latter having a smaller effect size. Another moderator was the research design, with differences between within-subjects-, and between-subjects designs (p < 0.05). Within-subject studies showed lower effect sizes and substantially lower heterogeneity. Qualitative analysis reinforced this finding and indicated that the motivation of the participant to engage in the task also moderates the effectiveness of HD-tDCS.

CONCLUSION

This review highlights the importance of inter-individual differences and the setup for the effectiveness of anodal, HD-tDCS augmented WM training. Limited evidence for increased sensitivity of HD-tDCS to these factors as compared to conventional tDCS is provided.

Chronotype and cognitive function: Observational study and bidirectional Mendelian randomization

BACKGROUND

Association has been found between chronotype and cognitive function in conventional observational studies but whether this association is causal and if so, its direction, is uncertain. There are also concerns among people with later chronotype that their habits may be detrimental to cognitive function.

METHODS

We analyzed the association between chronotype (measured as sleep midpoint) and cognitive function (measured by Mini-Mental Status Examination (MMSE) and Delayed Word Recall Test (DWRT)) using multivariable linear regression on 14,582 participants in the Guangzhou biobank cohort study (GBCS) from 2008 to 2012. Using bidirectional Mendelian randomization, we used 207 single nucleotide polymorphisms (SNPs) associated with chronotype from the combination of UK Biobank and 23andMe (n = 697,828), and 127 SNPs associated with cognitive function from the combination of UK Biobank and COGENT consortium (n = 257,841).

FINDINGS

Observationally in GBCS, later chronotype was associated with better cognitive function (MMSE scores: β = 0.14 per hour; 95% confidence interval (CI), 0.09-0.19; DWRT scores: β = 0.07 per hour; 95% CI, 0.04-0.11). Bidirectional MR showed genetic predisposition to early, versus later, chronotype was not associated with cognitive function using inverse-variance weighted (β = -0.02; 95% CI, -0.05 to 0.01). However, better cognitive function was associated with decreased odds of early chronotype (UK Biobank: odds ratio = 0.88 per standardized score; 95% CI, 0.83-0.93; 23andMe: 0.87 per standardized score; 95% CI, 0.80-0.95).

INTERPRETATION

It is a reassuring finding for adults with later chronotype who may be concerned if such a habit has a negative impact on cognitive function.

FUNDING

The National Natural Science Foundation of China; Natural Science Foundation of Guangdong; The University of Hong Kong Foundation for Educational Development and Research; The Health Medical Research Fund in Hong Kong; The University of Birmingham, UK.