Lower levels of TRAF1 in Brodmann's area 24, but not 46, in bipolar disorders are not detectable in major depressive disorders

INTRODUCTION

Multiple lines of research implicate inflammation-related pathways in the molecular pathology of mood disorders, with our data suggesting a critical role for aberrant cortical tumour necrosis factor α (TNF)-signaling in the molecular pathology of bipolar disorders (BPD) and major depressive disorders (MDD).

METHODS

To extend our understanding of changes in TNF-signaling pathways in mood disorders we used Western blotting to measure levels of tumour necrosis factor receptor associated factor 1 (TRAF1) and transmembrane TNF receptor superfamily member 1B (tmTNFRSF1B) in Brodmann's areas (BA) 24 and 46 from people with BPD and MDD. These proteins are key rate-limiting components within TNF-signaling pathways.

RESULTS

Compared to controls, there were higher levels of TRAF1 of large effect size (η = 0.19, Cohen's d = 0.97) in BA 24, but not BA 46, from people with BPD. Levels of TRAF1 were not altered in MDD and levels of tmTNFRSF1B were not altered in either disorder.

LIMITATIONS

The cases studied had been treated with psychotropic drugs prior to death which is an unresolvable study confound. Cohort sizes are relatively small but not untypical of postmortem CNS studies.

CONCLUSIONS

To facilitate post-synaptic signaling, TRAF1 is known to associate with tmTNFRSF1B after that receptor takes its activated conformation which occurs predominantly after it binds to transmembrane TNF (tmTNF). Simultaneously, when tmTNFRSF1B binds to tmTNF reverse signaling through tmTNF is activated. Hence our findings in BA 24 argues that bidirectional TNF-signaling may be an important component of the molecular pathology of BPD.

Brain stimulation over the left DLPFC enhances motivation for effortful rewards in patients with major depressive disorder

BACKGROUND

Amotivation is a typical feature in major depressive disorder (MDD), which produces reduced willingness to exert effort. The dorsolateral prefrontal cortex (DLPFC) is a crucial structure in goal-directed actions and therefore is a potential target in modulating effortful motivation. However, it remains unclear whether the intervention is effective for patients with MDD.

METHODS

We employed transcranial magnetic stimulation (TMS), computational modelling and event-related potentials (ERPs) to reveal the causal relationship between the left DLPFC and motivation for effortful rewards in MDD. Fifty patients underwent both active and sham TMS sessions, each followed by performing an Effort-Expenditure for Rewards Task, during which participants chose and implemented between low-effort/low-reward and high-effort/high-reward options.

RESULTS

The patients showed increased willingness to exert effort for rewards during the DLPFC facilitated session, compared with the sham session. They also had a trend in larger P3 amplitude for motivated attention toward chosen options, larger CNV during preparing for effort exertion, and larger SPN during anticipating a high reward. Besides, while behavior indexes for effortful choices were negatively related to depression severity in the sham session, this correlation was weakened in the active stimulation session.

CONCLUSIONS

These findings provide behavioral, computational, and neural evidence for the left DLPFC on effortful motivation for rewards. Facilitated DLPFC improves motor preparation and value anticipation after making decisions especially for highly effortful rewards in MDD. Facilitated DLPFC also has a potential function in enhancing motivated attention during cost-benefit trade-off. This neuromodulation effect provides a potential treatment for improving motivation in clinics.

Pilot study with randomised control of dual site theta burst transcranial magnetic stimulation (TMS) for methamphetamine use disorder: a protocol for the TARTAN study

BACKGROUND

Transcranial magnetic stimulation (TMS) (including the theta burst stimulation (TBS) form of TMS used in this study) is a non-invasive means to stimulate nerve cells in superficial areas of the brain. In recent years, there has been a growth in the application of TMS to investigate the modulation of neural networks involved in substance use disorders. This study examines the feasibility of novel TMS protocols for the treatment of methamphetamine (MA) use disorder in an ambulatory drug and alcohol treatment setting.

METHODS

Thirty participants meeting the criteria for moderate to severe MA use disorder will be recruited in community drug and alcohol treatment settings and randomised to receive active TMS or sham (control) intervention. The treatment is intermittent TBS (iTBS) applied to the left dorsolateral prefrontal cortex (DLPFC), then continuous TBS (cTBS) to the left orbitofrontal cortex (OFC). Twelve sessions are administered over 4 weeks with opt-in weekly standardized cognitive behaviour therapy (CBT) counselling and a neuroimaging sub-study offered to participants. Primary outcomes are feasibility measures including recruitment, retention and acceptability of the intervention. Secondary outcomes include monitoring of safety and preliminary efficacy data including changes in substance use, cravings (cue reactivity) and cognition (response inhibition).

DISCUSSION

This study examines shorter TBS protocols of TMS for MA use disorder in real-world drug and alcohol outpatient settings where withdrawal and abstinence from MA, or other substances, are not eligibility requirements. TMS is a relatively affordable treatment and staff of ambulatory health settings can be trained to administer TMS. It is a potentially scalable and translatable treatment for existing drug and alcohol clinical settings. TMS has the potential to provide a much-needed adjuvant treatment to existing psychosocial interventions for MA use disorder. A limitation of this protocol is that the feasibility of follow-up is only examined at the end of treatment (4 weeks).

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry ACTRN12622000762752. Registered on May 27, 2022, and retrospectively registered (first participant enrolled) on May 23, 2022, with protocol version 7 on February 24, 2023.

Safety and efficacy of repetitive stimulation of the left dorsolateral prefrontal cortex using transcranial focused ultrasound in treatment-resistant depressed patients: A non-inferiority randomized controlled trial protocol

BACKGROUND

About 30% of patients diagnosed with major depressive disorder fail with the mainstream pharmacological treatment. Patients who do not achieve clinical remission of symptoms, even with two different antidepressants, are classified with treatment-resistant depression (TDR). This condition imposes an additional burden with increased Disability Adjusted Life Years. Therefore, complementary treatments, such as neuromodulation, are necessary. The transcranial focused ultrasound (tFUS) has emerged in the past few years as a reliable method for non-invasive neuromodulation in humans and may help treat TRD. This study aims to propose a research protocol for a non-inferiority randomized clinical trial of TDR with tFUS.

METHODS

Patients with documented TRD will be screened upon entering the TRD outpatient clinic at UFMG (Brazil). One hundred patients without a clinical history of other psychiatric illness, anatomical abnormalities on magnetic resonance imaging (MRI), or treatment with electroconvulsive therapy will be invited to participate. Patients will be randomized (1:1) into two groups: 1) treatment with a previously established protocol of transcranial magnetic stimulation; and 2) treatment with a similar protocol using the stimulation. Besides regular consultations in the outpatient clinic, both groups will attend 7 protocolled spaced days of brain stimulation targeted at the left dorsolateral prefrontal cortex. They will also be submitted to 4 sessions of image studies (2 MRIs, 2 positron-emission tomography), 3 of neuropsychological assessments (at baseline, 1 week and 2 months after treatment), the Montgomery-Åsberg Depression Rating Scale to analyze the severity of depressive symptoms.

DISCUSSION

This clinical trial intends to verify the safety and clinical efficacy of tFUS stimulation of the dorsolateral prefrontal cortex of patients with TRD, compared with a previously established neuromodulation method.

'Nip it in the bud': Low-frequency rTMS of the prefrontal cortex disrupts threat memory consolidation in humans

It is still unclear how the human brain consolidates aversive (e.g., traumatic) memories and whether this process can be disrupted. We hypothesized that the dorsolateral prefrontal cortex (dlPFC) is crucially involved in threat memory consolidation. To test this, we used low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) within the memory stabilization time window to disrupt the expression of threat memory. We combined a differential threat-conditioning paradigm with LF-rTMS targeting the dlPFC in the critical condition, and occipital cortex stimulation, delayed dlPFC stimulation, and sham stimulation as control conditions. In the critical condition, defensive reactions to threat were reduced immediately after brain stimulation, and 1 h and 24 h later. In stark contrast, no decrease was observed in the control conditions, thus showing both the anatomical and temporal specificity of our intervention. We provide causal evidence that selectively targeting the dlPFC within the early consolidation period prevents the persistence and return of conditioned responses. Furthermore, memory disruption lasted longer than the inhibitory window created by our TMS protocol, which suggests that we influenced dlPFC neural activity and hampered the underlying, time-dependent consolidation process. These results provide important insights for future clinical applications aimed at interfering with the consolidation of aversive, threat-related memories.

Validation of real-time fMRI neurofeedback procedure for cognitive training using counterbalanced active-sham study design

Investigation of neural mechanisms of real-time functional MRI neurofeedback (rtfMRI-nf) training requires an efficient study control approach. A common rtfMRI-nf study design involves an experimental group, receiving active rtfMRI-nf, and a control group, provided with sham rtfMRI-nf. We report the first study in which rtfMRI-nf procedure is controlled through counterbalancing training runs with active and sham rtfMRI-nf for each participant. Healthy volunteers (n = 18) used rtfMRI-nf to upregulate fMRI activity of an individually defined target region in the left dorsolateral prefrontal cortex (DLPFC) while performing tasks that involved mental generation of a random numerical sequence and serial summation of numbers in the sequence. Sham rtfMRI-nf was provided based on fMRI activity of a different brain region, not involved in these tasks. The experimental procedure included two training runs with the active rtfMRI-nf and two runs with the sham rtfMRI-nf, in a randomized order. The participants achieved significantly higher fMRI activation of the left DLPFC target region during the active rtfMRI-nf conditions compared to the sham rtfMRI-nf conditions. fMRI functional connectivity of the left DLPFC target region with the nodes of the central executive network was significantly enhanced during the active rtfMRI-nf conditions relative to the sham conditions. fMRI connectivity of the target region with the nodes of the default mode network was similarly enhanced. fMRI connectivity changes between the active and sham conditions exhibited meaningful associations with individual performance measures on the Working Memory Multimodal Attention Task, the Approach-Avoidance Task, and the Trail Making Test. Our results demonstrate that the counterbalanced active-sham study design can be efficiently used to investigate mechanisms of active rtfMRI-nf in direct comparison to those of sham rtfMRI-nf. Further studies with larger group sizes are needed to confirm the reported findings and evaluate clinical utility of this study control approach.

Neurofeedback training of executive function in autism spectrum disorder: distinct effects on brain activity levels and compensatory connectivity changes

BACKGROUND

Deficits in executive function (EF) are consistently reported in autism spectrum disorders (ASD). Tailored cognitive training tools, such as neurofeedback, focused on executive function enhancement might have a significant impact on the daily life functioning of individuals with ASD. We report the first real-time fMRI neurofeedback (rt-fMRI NF) study targeting the left dorsolateral prefrontal cortex (DLPFC) in ASD.

METHODS

Thirteen individuals with autism without intellectual disability and seventeen neurotypical individuals completed a rt-fMRI working memory NF paradigm, consisting of subvocal backward recitation of self-generated numeric sequences. We performed a region-of-interest analysis of the DLPFC, whole-brain comparisons between groups and, DLPFC-based functional connectivity.

RESULTS

The ASD and control groups were able to modulate DLPFC activity in 84% and 98% of the runs. Activity in the target region was persistently lower in the ASD group, particularly in runs without neurofeedback. Moreover, the ASD group showed lower activity in premotor/motor areas during pre-neurofeedback run than controls, but not in transfer runs, where it was seemingly balanced by higher connectivity between the DLPFC and the motor cortex. Group comparison in the transfer run also showed significant differences in DLPFC-based connectivity between groups, including higher connectivity with areas integrated into the multidemand network (MDN) and the visual cortex.

CONCLUSIONS

Neurofeedback seems to induce a higher between-group similarity of the whole-brain activity levels (including the target ROI) which might be promoted by changes in connectivity between the DLPFC and both high and low-level areas, including motor, visual and MDN regions.

Differential effects of high-definition transcranial direct current stimulation (HD-tDCS) on attentional guidance by working memory in males with substance use disorder according to memory modality

Information stored in working memory can guide perception selection, and this process is modulated by cognitive control. Although previous studies have demonstrated that neurostimulation over the left dorsolateral prefrontal cortex (lDLPFC) contributes to restore cognitive control among individuals with substance use disorder (SUD), there remains an open question about the potential stimulation effects on memory-driven attention. To address this issue, the present study adopted a combined working memory/attention paradigm while employing high-definition transcranial direct current stimulation (HD-tDCS) to stimulate the lDLPFC. Observers were asked to maintain visual or audiovisual information in memory while executing a search task, while the validity of the memory contents for the subsequent search task could be either invalid or neutral. The results showed a faint memory-driven attentional suppression effect in sham stimulation only under the audiovisual condition. Moreover, anodal HD-tDCS facilitated attentional suppression effect in both the strength and temporal dynamics under the visual-only condition, whereas the effect was impaired or unchanged under the audiovisual condition. Surprisingly, cathodal HD-tDCS selectively improved temporal dynamics of the attentional suppression effect under the audiovisual condition. The present study revealed the differential enhancement of HD-tDCS on cognitive control over visual and audiovisual memory-driven attention among individuals with SUD.

Repetitive transcranial magnetic stimulation as a treatment for Alzheimer's disease: A randomized placebo-controlled double-blind clinical trial

We report results of a large multisite double-blind randomized trial investigating the short and long-term efficacy of repetitive transcranial magnetic stimulation (rTMS) applied to patients with Alzheimer's disease (AD) at mild to moderate stages, in doses of either 2 or 4 weeks of treatment (5 days/week), whilst compared with 4 weeks of sham rTMS. Randomization to treatment group was stratified based on age and severity. The objectives of this study were to: 1) investigate the efficacy of active rTMS versus sham, 2) investigate the effect of dose of treatment (2 or 4 weeks), and 3) investigate the length of benefits from treatment. The rTMS pulses (20 ​Hz, 30 pulses/train, 25 trains, 10-s intertrain interval) were applied serially to the left and right dorsolateral prefrontal cortex using neuro-navigation. We compared the primary outcome measure's (ADAS-Cog) score changes from pre- to post-treatment, with assessments at baseline and 4 more times up to 6 months post-treatment. Data of 135 patients were analyzed. The mean total ADAS-Cog score at baseline did not differ between the active and sham treatment groups, nor across the three study sites. The overall results show significant cognitive improvement after treatment up to two months post-treatment with either sham or active coils. The results show both short and long-term benefits of active rTMS treatment but also show similar benefits for sham coil treatment of mild/moderate AD. We discuss this finding in the context of the existing literature on rTMS therapy for AD, as well as evidence of the sham coil's potential to induce a low-level current in the brain. TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT02908815.

Lack of effects of eight-week left dorsolateral prefrontal theta burst stimulation on white matter macro/microstructure and connection in autism

Whether brain stimulation could modulate brain structure in autism remains unknown. This study explored the impact of continuous theta burst stimulation (cTBS) over the left dorsolateral prefrontal cortex (DLPFC) on white matter macro/microstructure in intellectually able children and emerging adults with autism. Sixty autistic participants were randomized (30 active) and received active or sham cTBS for eight weeks twice per week, 16 total sessions using a double-blind (participant-, rater-, analyst-blinded) design. All participants received high-angular resolution diffusion MR imaging at baseline and week 8. Twenty-eight participants in the active group and twenty-seven in the sham group with good imaging quality entered the final analysis. With longitudinal fixel-based analysis and network-based statistics, we found no significant difference between the active and sham groups in changes of white matter macro/microstructure and connections following cTBS. In addition, we found no association between baseline white matter macro/microstructure and autistic symptom changes from baseline to week 8 in the active group. In conclusion, we did not find a significant impact of left DLPFC cTBS on white matter macro/microstructure and connections in children and emerging adults with autism. These findings need to be interpreted in the context that the current intellectually able cohort in a single university hospital site limits the generalizability. Future studies are required to investigate if higher stimulation intensities and/or doses, other personal factors, or rTMS parameters might confer significant brain structural changes visible on MRI in ASD.

Computational simulation of transcranial magnetic stimulation-induced electric fields in the dorsolateral prefrontal cortex of heavy cannabis using individuals

We aimed to investigate the influence of demographic and clinical modulators on the strength of transcranial magnetic stimulation (TMS)-induced electric fields (EFs) in the left dorsolateral prefrontal cortex (lDLPFC) in heavy cannabis using individuals. Structural T1-weighted magnetic resonance imaging scans of 20 heavy cannabis using individuals and 22 non-cannabis users (the controls) in the age range of 18-25 were retrieved. Computational simulations of TMS-induced EFs in the lDLPFC were performed. No significant difference in the strength of TMS-induced EFs was observed between heavy cannabis using individuals and the controls. A negative correlation between the scalp-to-cortex distance demonstrated and the strength of the induced EFs. The severity of cannabis use related problems did not correlate with the induced EFs in the lDLPFC of heavy cannabis using individuals. However, the severity of alcohol use related problems was negatively correlated with the induced EF in the lDLPFC localized by the 5-cm method in the whole sample. Early adulthood seems related to an increase in the induced EFs in the lDLPFC. In conclusion, the dominant factor influencing TMS-induced EFs was the scalp-to-cortex distance. In early adulthood, the interaction between age and comorbid substance use may influence with the magnitude of TMS-induced EFs, thereby complicating the treatment effect of TMS in young people with substance use disorders.

A miR-137-Related Biological Pathway of Risk for Schizophrenia Is Associated With Human Brain Emotion Processing

BACKGROUND

miR-137 is a microRNA involved in brain development, regulating neurogenesis and neuronal maturation. Genome-wide association studies have implicated miR-137 in schizophrenia risk but do not explain its involvement in brain function and underlying biology. Polygenic risk for schizophrenia mediated by miR-137 targets is associated with working memory, although other evidence points to emotion processing. We characterized the functional brain correlates of miR-137 target genes associated with schizophrenia while disentangling previously reported associations of miR-137 targets with working memory and emotion processing.

METHODS

Using RNA sequencing data from postmortem prefrontal cortex (N = 522), we identified a coexpression gene set enriched for miR-137 targets and schizophrenia risk genes. We validated the relationship of this set to miR-137 in vitro by manipulating miR-137 expression in neuroblastoma cells. We translated this gene set into polygenic scores of coexpression prediction and associated them with functional magnetic resonance imaging activation in healthy volunteers (n1 = 214; n2 = 136; n3 = 2075; n4 = 1800) and with short-term treatment response in patients with schizophrenia (N = 427).

RESULTS

In 4652 human participants, we found that 1) schizophrenia risk genes were coexpressed in a biologically validated set enriched for miR-137 targets; 2) increased expression of miR-137 target risk genes was mediated by low prefrontal miR-137 expression; 3) alleles that predict greater gene set coexpression were associated with greater prefrontal activation during emotion processing in 3 independent healthy cohorts (n1, n2, n3) in interaction with age (n4); and 4) these alleles predicted less improvement in negative symptoms following antipsychotic treatment in patients with schizophrenia.

CONCLUSIONS

The functional translation of miR-137 target gene expression linked with schizophrenia involves the neural substrates of emotion processing.

The two-back task leads to activity in the left dorsolateral prefrontal cortex in schizophrenia patients with predominant negative symptoms: a fNIRS study and its implication for tDCS

Transcranial direct current stimulation (tDCS) over left dorsolateral prefrontal cortex (DLPFC) has shown some potential as an adjunctive intervention for ameliorating negative symptoms of schizophrenia, but its efficacy requires optimization. Recently, 'functional targeting' of stimulation holds promise for advancing tDCS efficacy by coupling tDCS with a cognitive task where the target brain regions are activated by that task and further specifically polarized by tDCS.The study used 48-channel functional near infra-red spectroscopy (fNIRS) aiming to determine a cognitive task that can effectively induce a cortical activation of the left DLPFC in schizophrenia patients with predominant negative symptoms before running a tDCS trial. Sixty schizophrenia patients with predominant negative symptoms completed measures of clinical and psychosocial functioning characteristics and assessments across cognitive domains. Hemodynamic changes during n-back working memory tasks with different cognitive loads (1-back and 2-back) and verbal fluency test (VFT) were measured using fNIRS. For n-back tasks, greater signal changes were found when the task required elevated cognitive load. One sample t-test revealed that only 2-back task elicited significant activation in left DLPFC (t = 4.23, FDR-corrected p = 0.0007). During VFT, patients failed to show significant task-related activity in left DLPFC (one sample t-test, t = -0.25, FDR-corrected p > 0.05). Our study implies that 2-back task can effectively activate left DLPFC in schizophrenia patients with predominant negative symptoms. This neurophysiologically-validated task is considered highly potential to be executed in conjunction with high-definition tDCS for "functional targeting" of the left DLPFC to treat negative symptoms in a double-blind randomized sham-control trial, registered on ClinicalTrials.gov Registry (ID: NCT05582980).

Role of Repetitive Transcranial Magnetic Stimulation in Treatment of Fibromyalgia: A Randomized Controlled Trial

Background and Objective

Fibromyalgia syndrome (FMS) is a chronic disease characterized by widespread, persistent musculoskeletal pain in association with impaired health-related quality of life. Repetitive transcranial magnetic stimulation (rTMS) is an emerging tool for the management of fibromyalgia. There is no standardized protocol of rTMS for the treatment of FMS, and both low- and high-frequency stimulation of the dorsolateral prefrontal cortex (DLPFC) are described in the literature with variable efficacy. The objective of this study was to determine the effectiveness of rTMS in people with fibromyalgia and compare the response of low- and high-frequency stimulation with sham stimulation.

Materials and Methods

This study was a single-blinded, randomized, placebo-controlled trial. Ninety patients with the diagnosis of FMS were randomly allocated into one of the following three groups: low-frequency (1 Hz) group, high-frequency (10 Hz) group, and sham group. Pain, depression, anxiety, and quality of life were measured using the Numerical Pain Rating Scale (NPRS), Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Rating Scale (HDRS), and Revised Fibromyalgia Impact Questionnaire (FIQR) immediately following treatment as well as at 1 and 3 months after treatment. The data was statistically analyzed using Statistical Package for the Social Sciences version 23 software. P value < 0.05 was considered statistically significant.

Results

Intergroup analysis revealed a significant improvement in NPRS, HAM-A, HDRS, and FIQR scores in both low- and high- frequency groups immediately following treatment and for 3 months after treatment. No significant difference in the efficacy of low- and high-frequency stimulation was noticed.

Conclusions

rTMS is an effective mode of treatment in people with FMS. Both low and high frequencies of stimulation at DLPFC are equally effective in reducing pain and associated symptoms.

Transcranial alternating current stimulation does not affect microscale learning

A theory has been posited that microscale learning, which involves short intervals of a few seconds during explicit motor skill learning, considerably enhances performance. This phenomenon correlates with diminished beta-band activity in the frontal and parietal regions. However, there is a lack of neurophysiological studies regarding the relationship between microscale learning and implicit motor skill learning. In the present study, we aimed to determine the effects of transcranial alternating current stimulation (tACS) during short rest periods on microscale learning in an implicit motor task. We investigated the effects of 20-Hz β-tACS delivered during short rest periods while participants performed an implicit motor task. In Experiments 1 and 2, β-tACS targeted the right dorsolateral prefrontal cortex and the right frontoparietal network, respectively. The participants performed a finger-tapping task using their nondominant left hand, and microscale learning was separately analyzed for micro-online gains (MOnGs) and micro-offline gains (MOffGs). Contrary to our expectations, β-tACS exhibited no statistically significant effects on MOnGs or MOffGs in either Experiment 1 or Experiment 2. In addition, microscale learning during the performance of the implicit motor task was improved by MOffGs in the early learning phase and by MOnGs in the late learning phase. These results revealed that the stimulation protocol employed in this study did not affect microscale learning, indicating a novel aspect of microscale learning in implicit motor tasks. This is the first study to examine microscale learning in implicit motor tasks and may provide baseline information that will be useful in future studies.

Neural correlates of home-based intervention effects on value-based sequential decision-making in healthy older adults

Older adults demonstrate difficulties in sequential decision-making, which is partly attributed to under-recruitment of prefrontal networks. It is, therefore, important to understand the mechanisms that may improve this ability. This study investigated the effectiveness of an 18-sessions, home-based cognitive intervention and the neural mechanisms that underpin individual differences in intervention effects. Participants were required to learn sequential choices in a 3-stage Markov decision-making task that would yield the most rewards. Participants were assigned to better or worse responders group based on their performance at the last intervention session (T18). Better responders improved significantly starting from the fifth intervention session while worse responders did not improve across all training sessions. At post-intervention, only better responders showed condition-dependent modulation of the dorsolateral prefrontal cortex (DLPFC) as measured by fNIRS, with higher DLPFC activity in the delayed condition. Despite large individual differences, our data showed that value-based sequential-decision-making and its corresponding neural mechanisms can be remediated via home-based cognitive intervention in some older adults; moreover, individual differences in recruiting prefrontal activities after the intervention are associated with variations in intervention outcomes. Intervention-related gains were also maintained at three months after post-intervention. However, future studies should investigate the potential of combining other intervention methods such as non-invasive brain stimulation with cognitive intervention for older adults who do not respond to the intervention, thus emphasizing the importance of developing individualized intervention programs for older adults.

Functional connectivity via the dorsolateral prefrontal cortex in the late phase of rest periods predicts offline learning

The relationship between offline learning gains and functional connectivity (FC) has been investigated in several studies. They have focused on average motor task performance and resting-state FC across subjects. Generally, individual differences are seen in both offline learning gain and neurophysiological profiles in resting-state FC. However, few studies have focused on the relationship between individual differences in offline learning gain and temporal characteristics of resting-state FC. The present study aimed to clarify this relationship between the two profiles. Thirty-four healthy right-handed participants performed a force-controlled motor task. Electroencephalography was performed during the 15-minute wakeful rest period between tasks. The results revealed a significant correlation between offline learning gain and FC between the contralateral dorsolateral prefrontal cortex (DLPFC) and contralateral primary motor cortex (M1), and ipsilateral primary somatosensory cortex (S1) during late phase of the rest interval. These results are consistent with the findings of previous studies showing the FC between M1, which is necessary for awake offline learning, and DLPFC, which is related to motor control. Additionally, sensory feedback related to force control may be caused by the interaction between contralateral DLPFC and ipsilateral S1. Our study shed light on the temporal profiles of resting-state FC associated with individual differences in offline learning.

Theta Oscillations Support Prefrontal-hippocampal Interactions in Sequential Working Memory

The prefrontal cortex and hippocampus may support sequential working memory beyond episodic memory and spatial navigation. This stereoelectroencephalography (SEEG) study investigated how the dorsolateral prefrontal cortex (DLPFC) interacts with the hippocampus in the online processing of sequential information. Twenty patients with epilepsy (eight women, age 27.6 ± 8.2 years) completed a line ordering task with SEEG recordings over the DLPFC and the hippocampus. Participants showed longer thinking times and more recall errors when asked to arrange random lines clockwise (random trials) than to maintain ordered lines (ordered trials) before recalling the orientation of a particular line. First, the ordering-related increase in thinking time and recall error was associated with a transient theta power increase in the hippocampus and a sustained theta power increase in the DLPFC (3-10 Hz). In particular, the hippocampal theta power increase correlated with the memory precision of line orientation. Second, theta phase coherences between the DLPFC and hippocampus were enhanced for ordering, especially for more precisely memorized lines. Third, the theta band DLPFC → hippocampus influence was selectively enhanced for ordering, especially for more precisely memorized lines. This study suggests that theta oscillations may support DLPFC-hippocampal interactions in the online processing of sequential information.

Lateral Prefrontal Stimulation of Active Cortex With Theta Burst Transcranial Magnetic Stimulation Affects Subsequent Engagement of the Frontoparietal Network

BACKGROUND

A critical unanswered question about therapeutic transcranial magnetic stimulation is what patients should do during treatment to optimize its effectiveness. Here, we address this lack of knowledge in healthy participants, testing the hypotheses that stimulating the left dorsolateral prefrontal cortex (dlPFC) while participants perform a working memory task will provide stronger effects on subsequent activation, perfusion, connectivity, and performance than stimulating resting dlPFC.

METHODS

After a baseline functional magnetic resonance imaging session to localize dlPFC activation and the associated frontoparietal network (FPN) engaged by an n-back task, healthy participants (N = 40, 67.5% female) underwent 3 counterbalanced sessions, separated by several weeks, during which they received intermittent theta burst stimulation (iTBS) followed by magnetic resonance imaging scans as follows: 1) iTBS to the dlPFC while resting passively (passive), 2) iTBS to the dlPFC while performing the n-back task (active), and 3) iTBS to a vertex site, while not engaged in the n-back task and resting passively (control).

RESULTS

We found no difference in n-back performance between the 3 conditions. However, FPN activation was reduced while performing the n-back task in the active condition relative to the passive and control conditions. There was no differential activity in the FPN on comparing passive with control conditions, i.e., there was no effect of the site of stimulation. We found no effects of state or site of stimulation on perfusion or connectivity with the dlPFC.

CONCLUSIONS

In this study, the state of the brain while receiving iTBS affected FPN activation, possibly reflecting greater efficiency of FPN network activation when participants were stimulated while engaging the FPN.

Lateralization of self-control over the dorsolateral prefrontal cortex in decision-making: a systematic review and meta-analytic evidence from noninvasive brain stimulation

The dorsolateral prefrontal cortex (DLPFC) has been widely recognized as a crucial brain "control area." Recently, its causal role in promoting deliberate decision-making through self-control and the asymmetric performance of the left and right DLPFC in control functions have attracted the interest of many researchers. This study was designed to investigate the role of DLPFC in decision-making behaviors and lateralization of its control function by systematically examining the effects of noninvasive brain stimulation (NIBS) over the DLPFC on intertemporal choice, risk decision-making, and social fairness-related decision-making tasks. Literature searches were implemented at PubMed, Embase, Cochrane, Web of Science, Wanfang Data, China Science and Technology Journal Database, and China National Knowledge Infrastructure until May 10, 2022. Meta-analytic results for included studies were estimated by random-effect models. A total of 33 eligible studies were identified, yielding 130 effect sizes. Our results indicated that compared to sham group, excitatory NIBS over the left DLPFC reduced delay discounting rate (standardized mean differences, SMD = -0.51; 95% confidence interval, 95% CI: [-0.81, -0.21]) and risk-taking performance (SMD = -0.39, 95% CI [-0.68, -0.10]), and inhibitory NIBS over the right DLPFC increased self-interested choice of unfair offers (SMD = 0.50, 95% CI [0.04, 0.97]). Finding of current work indicated that neural excitement of the DLPFC activation improve individuals' self-control during decision-makings, whereas neural inhibition results in impaired control. In addition, our analyses furnish causal evidence for the presence of functional lateralization in the left and right DLPFC in monetary impulsive decision-making and social decision-making, respectively.

Relation between task-related activity modulation and cortical inhibitory function in schizophrenia and healthy controls: a TMS-EEG study

Schizophrenia has been associated with a reduced task-related modulation of cortical activity assessed through electroencephalography (EEG). However, to the best of our knowledge, no study so far has assessed the underpinnings of this decreased EEG modulation in schizophrenia. A possible substrate of these findings could be a decreased inhibitory function, a replicated finding in the field. In this pilot study, our aim was to explore the association between EEG modulation during a cognitive task and the inhibitory system function in vivo in a sample including healthy controls and patients with schizophrenia. We hypothesized that the replicated decreased task-related activity modulation during a cognitive task in schizophrenia would be related to a hypofunction of the inhibitory system. For this purpose, 27 healthy controls and 22 patients with schizophrenia (including 13 first episodes) performed a 3-condition auditory oddball task from which the spectral entropy modulation was calculated. In addition, cortical reactivity-as an index of the inhibitory function-was assessed by the administration of 75 monophasic transcranial magnetic stimulation single pulses over the left dorsolateral prefrontal cortex. Our results replicated the task-related cortical activity modulation deficit in schizophrenia patients. Moreover, schizophrenia patients showed higher cortical reactivity following transcranial magnetic stimulation single pulses over the left dorsolateral prefrontal cortex compared to healthy controls. Cortical reactivity was inversely associated with EEG modulation, supporting the idea that a hypofunction of the inhibitory system could hamper the task-related modulation of EEG activity.

Efficacy of Transcranial Direct Current Stimulation for Controlling of Food Craving in Subjects With Overweight or Obesity: A Pilot Study

OBJECTIVE

We aim to explore the effects of transcranial direct current stimulation (tDCS) on food craving improvement and changes in brain function associated with craving by conducting a total of 10 sessions of tDCS over a period of 2 weeks on overweight and obese subjects.

METHODS

A total of 15 patients who were overweight or obese (body mass index [BMI] ≥23 kg/m2) were included. Weight, BMI, neuropsychological variables, and food craving-related variables were assessed. We measured absolute and relative power in 19 channels and analyzed quantitative electroencephalography (qEEG) according to the following frequency ranges: delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-25 Hz), high beta (25-30 Hz), and gamma (30-80 Hz).

RESULTS

After the application of tDCS, there was no significant reduction observed in weight and BMI. However, all measures related to food and eating showed a decrease in the intensity of cravings, and there was also a significant reduction in depression, anxiety, and perceived stress. In qEEG analysis, an increase in theta waves was observed in the left frontal area (F7 and F3), an increase in alpha waves in the right parietal area (P4), and a decrease in beta waves in the frontal area (FP2) and occipital area (O1).

CONCLUSION

This study confirmed the beneficial effects of tDCS on food craving regulation in overweight or obese individuals and observed improved scores in psychological factors such as depression and anxiety. Furthermore, neurophysiological changes related to food craving were observed using qEEG.

Motor cortex repetitive transcranial magnetic stimulation in major depressive disorder - A preliminary randomized controlled clinical trial

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) at left dorsolateral prefrontal cortex (lDLPFC) is commonly used in major depressive disorder (MDD), even though its therapeutic efficacy is limited. Given that many MDD patients show psychomotor retardation, we aim to examine whether the left motor cortex (lMC) as a novel rTMS target would provide effective and well-tolerated treatment as being comparable to lDLPFC-rTMS.

METHODS

In this prospective double-blind randomized single-center study, 131 MDD patients were randomly assigned to the lDLPFC or lMC group and were treated with 10 Hz rTMS (90 % motor threshold) applied twice daily for 4000 pulses continuously over five days. The primary endpoint was the Hamilton Depression Scale (HAMD) total score change after treatment.

RESULTS

After the five-day rTMS treatment, there was no significant difference in both HAMD reduction rate (lDLPFC 59.3 % ± 20.4 %, lMC 51.3 % ± 26.3 %, P = 0.10) and adverse effects (P = 0.79) between 48 (73.8 %) lMC subjects and 51 (77.3 %) lDLPFC subjects. Furthermore, the lMC study group showed stable HAMD scores at follow-up compared to their endpoint scores (P = 0.08).

LIMITATIONS

Sham-control group was not included and the sample size was small. Therefore, our results should be seen as exploratory and preliminary.

CONCLUSIONS

The preliminary good therapeutic response, comparability, and tolerability of lMC-rTMS suggest lMC a potential and more easily accessible rTMS target. Together, our findings raise the possibility of symptom-specific rTMS in motor cortex (psychomotor retardation) or lDLPFC (cognitive deficits). This warrants larger clinical trials of rTMS in MDD with symptom-specific stimulation targets.

Evaluation of the separate and combined effects of anodal tDCS over the M1 and F3 regions on pain relief in patients with type-2 diabetes suffering from neuropathic pain

BACKGROUND

Neuropathic pain (NP) is a common complication of chronic diabetes that negatively affects the routine functioning and sleep of patients. The present study aimed to investigate the separate and combined effects of anodal transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) and left dorsolateral prefrontal cortex (F3) regions on pain relief in patients with type-2 diabetes suffering from NP.

METHODS

The statistical population of this double-blind randomized clinical trial consisted of all the members of the Bonab Diabetes Association in 2022 aged 45 to 65 years who were diagnosed with NP by a specialist. A total of 48 patients who met the inclusion criteria were selected as the sample through purposive sampling. The participants were then randomly assigned into 4 groups, each attending 12 sessions of a special intervention (three times a week). The Short Form-McGill Pain Questionnaire-2 (SF-MPQ-2) was used for data collection. Data were statistically analyzed using SPANOVA, analysis of covariance, and the Bonferroni test.

RESULTS

The results showed that tDCS had the potential to induce pain relief in patients with type-2 diabetes suffering from NP (F = 11.48, P < 0.001). The mean perceived pain intensity in the posttest was lower in the M1 stimulation group than in the F3 stimulation group. Nevertheless, there was no significant difference between the two groups in terms of perceived pain intensity in the one-month and two-month follow-up stages.

CONCLUSIONS

The tDCS approach (over both M1 and F3) showed promising effects for pain management in patients with type-2 diabetes suffering from NP and may be an effective add-on treatment. However, more trials with larger sample sizes are necessary to define clinically relevant effects.

Sex differences in bipolar disorder: The dorsolateral prefrontal cortex as an etiopathogenic region

Bipolar disorder (BD) is worldwide a prevalent mental illness and a leading risk factor for suicide. Over the past three decades, it has been discovered that sex differences exist throughout the entire panorama of BD, but the etiologic regions and mechanisms that generate such differences remain poorly characterized. Available evidence indicates that the dorsolateral prefrontal cortex (DLPFC), a critical region that controls higher-order cognitive processing and mood, exhibits biological disparities between male and female patients with psychiatric disorders, which are highly correlated with the co-occurrence of psychotic symptoms. This review addresses the sex differences in BD concerning epidemiology, cognitive impairments, clinical manifestations, neuroimaging, and laboratory abnormalities. It also provides strong evidence linking DLPFC to the etiopathogenesis of these sex differences. We emphasize the importance of identifying gene signatures using human brain transcriptomics, which can depict sexually different variations, explain sex-biased symptomatic features, and provide novel targets for sex-specific therapeutics.

Modulation effects of repeated transcranial direct current stimulation on the dorsal attention and frontal parietal networks and its association with placebo and nocebo effects

Literature suggests that attention is a critical cognitive process for pain perception and modulation and may play an important role in placebo and nocebo effects. Here, we investigated how repeated transcranial direct current stimulation (tDCS) applied at the dorsolateral prefrontal cortex (DLPFC) for three consecutive days can modulate the brain functional connectivity (FC) of two networks involved in cognitive control: the frontoparietal network (FPN) and dorsal attention network (DAN), and its association with placebo and nocebo effects. 81 healthy subjects were randomized to three groups: anodal, cathodal, and sham tDCS. Resting state fMRI scans were acquired pre- and post- tDCS on the first and third day of tDCS. An Independent Component Analysis (ICA) was performed to identify the FPN and DAN. ANCOVA was applied for group analysis. Compared to sham tDCS, 1) both cathodal and anodal tDCS increased the FC between the DAN and right parietal operculum; cathodal tDCS also increased the FC between the DAN and right postcentral gyrus; 2) anodal tDCS led to an increased FC between the FPN and right parietal operculum, while cathodal tDCS was associated with increased FC between the FPN and left superior parietal lobule/precuneus; 3) the FC increase between the DAN and right parietal operculum was significantly correlated to the placebo analgesia effect in the cathodal group. Our findings suggest that both repeated cathodal and anodal tDCS could modulate the FC of two important cognitive brain networks (DAN and FPN), which may modulate placebo / nocebo effects.

Top-down control of vestibular inputs by the dorsolateral prefrontal cortex

The vestibular apparatus provides spatial information on the position of the head in space and with respect to gravity. Low-frequency sinusoidal galvanic vestibular stimulation (sGVS), a means of selectively changing the firing of vestibular afferents, induces a frequency-dependent perception of sway and, in some individuals, induces nausea. Given that vestibular afferents project to the insular cortex-which forms part of the vestibular cortex-and that the insula receives inputs from the dorsolateral prefrontal cortex (dlPFC), we tested the hypothesis that electrical stimulation of the dlPFC can modulate vestibular inputs. Sinusoidal electrical stimulation (± 2 mA, 0.08 Hz, 100 cycles) was delivered via surface electrodes over (1) the mastoid processes alone (sGVS), (2) electroencephalogram (EEG) site F4 (right dlPFC) and the nasion or (3) to each site concurrently (sGVS + dlPFC) in 23 participants. The same stimulation protocol was used in a separate study to investigate EEG site F3 (left dlPFC) instead of F4 in 13 participants. During sGVS, all participants reported perceptions of sway and 13 participants also reported nausea, neither sensation of which occurred as a result of dlPFC stimulation. Interestingly, when sGVS and dlPFC stimulations were delivered concurrently, vestibular perceptions and sensations of nausea were almost completely abolished. We conclude that the dlPFC provides top-down control of vestibular inputs and further suggests that dlPFC stimulation may provide a novel means of controlling nausea.

Transcranial alternating current stimulation ameliorates emotional attention through neural oscillations modulation

Background

Numerous clinical reports have suggested that psychopathy like schizophrenia, anxiety and depression is accompanied by early attentional abnormalities in emotional processing. Recently, the efficacy of transcranial alternating current stimulation (tACS) in changing emotional functioning has been repeatedly observed and demonstrated a causal relationship between endogenous oscillations and emotional processing.

Aims

Up to now, tACS effects on emotional attention have not yet been tested. To assess such ability, we delivered active-tACS at individual alpha frequency (IAF), 10 Hz or sham-tACS for 7 consecutive days in the bilaterally dorsolateral prefrontal cortex (dlPFC) to totally 79 healthy participants.

Results

IAF-tACS group showed significant alpha entrainment at-rest, especially in open state around stimulation area and showed an obvious advantage compared to 10 Hz-tACS. Event-related potential revealed a significant larger P200 amplitude after active-tACS and IAF group showed wider range of emotions than 10 Hz-tACS, indicating the attentional improvement in facial emotion processing. A notable positive correlation between alpha power and P200 amplitude provided an electrophysiological interpretation regarding the role of tACS in emotional attention modulation instead of somatosensory effects.

Conclusion

These results support a seminal outcome for the effect of IAF-tACS on emotional attention modulation, demonstrating a feasible and individual-specific therapy for neuropsychiatric disorders related to emotion processing, especially regarding oscillatory disturbances.

Repetitive transcranial magnetic stimulation improves cardiovascular autonomic nervous system control: A meta-analysis

BACKGROUND

Cardiovascular autonomic system (ANS) may be affected by altered neural activations in the brain. This systematic review and meta-analysis investigated potential effects of repetitive transcranial magnetic stimulation (rTMS) protocols on cardiovascular ANS control.

METHODS

Through 19 qualified studies, we acquired 70 comparisons for data synthesis. Individual effect sizes were estimated by comparing changes in following cardiovascular ANS control variables between active and sham stimulation conditions: (a) blood pressure (BP), (b) heart rate (HR), and (c) heart rate variability (HRV). Moreover, two moderator variable analyses determined whether changes in cardiovascular ANS control were different based on (a) rTMS protocols (excitatory rTMS versus inhibitory rTMS) and (b) specific targeted cortical regions, respectively.

RESULTS

The random-effects model meta-analysis revealed significant improvements in cardiovascular ANS control after the rTMS protocols. Specifically, applying excitatory and inhibitory rTMS protocols significantly decreased values of BP and HR variables. For HRV variables, excitatory rTMS protocols showed significant positive effects. These improvements in cardiovascular ANS control were observed while applying either excitatory rTMS protocols to the left dorsolateral prefrontal cortex or inhibitory rTMS protocols to the right dorsolateral prefrontal cortex.

LIMITATIONS

Relatively small number of studies for inhibitory rTMS on the right dorsolateral prefrontal cortex were included in this meta-analysis.

CONCLUSION

These findings suggest that applying excitatory and inhibitory rTMS protocols on prefrontal cortical regions may be effective to improve cardiovascular ANS control.

Alterations of BDNF, mGluR5, Homer1a, p11 and excitatory/inhibitory balance in corticolimbic brain regions of suicide decedents

BACKGROUND

Developing biological based approaches for preventing suicide has become a priority. In recent years, there has been a surge in studies investigating the role of the glutamatergic system in suicide, although it remains unclear.

METHODS

We evaluated changes in the gene expression of the metabotropic glutamate receptor 5 (mGluR5) and its scaffolding proteins Homer1a and p11 in the dorsolateral prefrontal cortex (DLPFC), amygdala (AMY), and hippocampus (HIP) of 28 suicide decedents (S) (with no clinical psychiatric history or treatment with anxiolytics or antidepressants) and 26 controls (C) by real-time PCR (qPCR). Indeed, we measured BDNF gene expression and VGluT1 and VGAT immunoreactivities in the HIP by qPCR and immunohistochemistry, respectively. Cases and controls matched for age (C: 48.6 ± 11.6 years; S: 46.9 ± 14.5 years) and postmortem interval (PMI; C: 20.1 ± 13h; S: 16.9 ± 5h).

RESULTS

In DLPFC, S had lower p11 gene expression levels, but no differences were found in mGluR5 or Homer1a. In the AMY and HIP, mGluR5 and Homer1a were increased, p11 and BDNF were reduced. In the HIP, there were less VGAT-ir and more VGluT1-ir.

LIMITATIONS

Future studies are necessary to evaluate protein levels, and determine the cell types and potential compensatory mechanisms in a larger sample including S diagnosed with psychiatric disorders, females and different ethnicities.

CONCLUSIONS

This study identified significant alterations in mGluR5, Homer1a, p11, BDNF and excitatory/inhibitory balance in corticolimbic brain areas of S. These results further characterize the biological basis of suicide, contributing to the identification of potential biomarkers for suicide prevention.

The neuropsychology and neuroanatomy of reduplicative paramnesia

Reduplicative paramnesia refers to the delusional belief that there are identical places in different locations. In this case-control study we investigated the clinical, phenomenological, neuropsychological and neuroanatomical data of eleven patients with reduplicative paramnesia and compared them against a control group of eleven patients with severe spatial disorientation without signs of reduplicative paramnesia. We show that most patients with reduplicative paramnesia report that a current place is reduplicated and/or relocated to an other familiar place. Patients with reduplicative paramnesia show a higher prevalence of deficits in the executive functions compared to the control patients, while mnestic and visuo-spatial deficits were both frequent in patients with reduplicative paramnesia and the control group. Patients with reduplicative paramnesia mostly suffer from right hemispheric lesions with a maximal overlap in the dorsolateral prefrontal cortex. Using lesion network mapping we show that lesions causing reduplicative paramnesia are connected to bilateral anterior insula and the right cingulate cortex. We argue that patients with reduplicative paramnesia fail to integrate the actual context with visuo-spatial memories and personal relevant emotional information due to a disruption of the neural network within the anterior temporal lobe, the cingulate cortex and the anterior insula. Also patients with reduplicative paramnesia are not able to resolve this conflict due to the lesion of the dorsolateral prefrontal cortex and executive dysfunction.

Association of loneliness and grey matter volume in the dorsolateral prefrontal cortex: the mediating role of interpersonal self-support traits

As a social and public health concern, loneliness is associated with an abundance of negative life outcomes such as depressive symptomatology, mortality, and sleep disturbance. Nevertheless, the neural basis underlying loneliness remains elusive; in addition, previous neuroimaging studies about loneliness mainly focused on the elderly and were limited by small sample sizes. Here, utilizing the voxel-based morphometry (VBM) approach via structural magnetic resonance imaging, we investigated the association between brain GMV and loneliness in 462 young adults (67.7% females, age = 18.59 ± 1.14 years). Results from whole-brain VBM analyses revealed that individuals with higher loneliness tended to have greater GMV in the right dorsolateral prefrontal cortex (DLPFC), which was thought to be associated with emotional regulation deficits and executive dysfunction. Importantly, the GMV-based predictive models (a machine-learning method) demonstrated that the correlation between loneliness and GMV in the DLPFC was robust. Further, interpersonal self-support traits (ISS), a Chinese indigenous personality construct and pivotal personality factor for resisting negative life outcomes, mediated the relationship between the GMV in the right DLPFC and loneliness. Taken together, the present study reveals that the GMV in right DLPFC acts as an underlying neurostructural correlate of loneliness in the healthy brain, and further provides a brain-personality-symptom pathway for protection against loneliness in which GMV of DLPFC affects loneliness through ISS traits. Future intervention procedures aiming to decrease loneliness and enhance mental health levels among young adults should be developed through improving interpersonal relationships such as social skills training.

Layer-Specific Changes in the Prefrontal Glia/Neuron Ratio Characterizes Patches of Gene Expression Disorganization in Children with Autism

Autism spectrum disorder (ASD) is manifested by abnormal cell numbers and patches of gene expression disruption in higher-order brain regions. Here, we investigated whether layer-specific changes in glia/neuron ratios (GNR) characterize patches in the dorsolateral prefrontal cortex (DL-PFC) of children with ASD. We analyzed high-resolution digital images of postmortem human brains from 11 ASD and 11 non-ASD children obtained from the Autism Study of the Allen Human Brain Atlas. We found the GNR is overall reduced in the ASD DL-PFC. Moreover, layers II-III belonging to patches presented a lower GNR in comparison with layers V-VI. We here provide a new insight into how brain cells are arranged within patches that contributes to elucidate how neurodevelopmental programs are altered in ASD.

Sex hormones as correlates of oxidative stress in the adult brain

Oxidative stress, an imbalance between the production of reactive oxygen species and available antioxidant capacity, is implicated in multiple psychiatric disorders and neurodegenerative conditions. Peripheral and preclinical studies suggest oxidative stress differs by biological sex and covaries with estrogens. However, limited knowledge exists on the effect of circulating sex hormones on oxidative stress in the brain in humans in vivo. We aimed to examine the relationship of circulating estrogen with regional concentrations of brain glutathione (GSH) as a marker of oxidative stress. GSH was measured using magnetic resonance spectroscopy (MRS) at 7 Tesla in the dorsal anterior cingulate cortex (ACC), ventromedial prefrontal cortex (VMPFC), and left dorsolateral prefrontal cortex (DLPFC) in 34 individuals (18 females and 16 males). We observed an inverse correlation of estradiol with DLPFC GSH, as well as a trend inverse correlation of estrone with DLPFC GSH, in the combined sample of males and females and in females only. No significant sex differences were observed for GSH levels in the brain. Our study provides evidence of diminished DLPFC GSH in females with higher estradiol, suggesting circulating sex hormones may be important factors to consider in future studies examining brain GSH levels related to psychiatric and other disorders.

Cortical Morphology in Cannabis Use Disorder: Implications for Transcranial Direct Current Stimulation Treatment

Introduction

Transcranial direct current stimulation (tDCS) has been studied as an adjunctive treatment option for substance use disorders (SUDs). Alterations in brain structure following SUD may change tDCS-induced electric field (EF) and subsequent responses; however, group-level differences between healthy controls (HC) and participants with SUDs in terms of EF and its association with cortical architecture have not yet been modeled quantitatively. This study provides a methodology for group-level analysis of computational head models to investigate the influence of cortical morphology metrics on EFs.

Methods

Whole-brain surface-based morphology was conducted, and cortical thickness, volume, and surface area were compared between participants with cannabis use disorders (CUD) (n=20) and age-matched HC (n=22). Meanwhile, EFs were simulated for bilateral tDCS over the dorsolateral prefrontal cortex. The effects of structural alterations on EF distribution were investigated based on individualized computational head models.

Results

Regarding EF, no significant difference was found within the prefrontal cortex; however, EFs were significantly different in left-postcentral and right-superior temporal gyrus (P<0.05) with higher levels of variance in CUD compared to HC [F(39, 43)=5.31, P<0.0001, C=0.95]. Significant differences were observed in cortical area (caudal anterior cingulate and rostral middle frontal), thickness (lateral orbitofrontal), and volume (paracentral and fusiform) between the two groups.

Conclusion

Brain morphology and tDCS-induced EFs may be changed following CUD; however, differences between CUD and HCs in EFs do not always overlap with brain areas that show structural alterations. To sufficiently modulate stimulation targets, whether individuals with CUD need different stimulation doses based on tDCS target location should be checked.

The effects of transcranial electrical stimulation of the left dorsolateral prefrontal cortex on tactile spatial discrimination performance

The dorsolateral prefrontal cortex (DLPFC) plays a key role in tactile perceptual discrimination performance. Both transcranial random noise stimulation (tRNS) and anodal transcranial pulsed current stimulation (tPCS) have been shown to modulate neural activity in cortical regions. In this study, we aimed to determine whether tRNS and anodal tPCS over the left DLPFC would improve tactile perceptual discrimination performance of the right index finger in healthy neurological individuals. Subjects underwent a grating orientation task before, immediately after, and 30 min after applying tRNS in Experiment 1 or anodal tPCS in Experiment 2. tRNS application on the left DLPFC tended to enhance tactile perceptual discrimination performance. In contrast, the application of anodal tPCS over the left DLPFC did not affect tactile perceptual discrimination performance. These findings indicate that transcranial electrical stimulation to the left DLPFC may improve tactile perceptual discrimination performance, with effects that depend on stimulus modality.

The content-dependent effect of the N-back task on dual-task performance

Impaired task accuracy under dual-task conditions leads to issues such as falls and traffic accidents. Specific cognitive tasks (e.g., the N-back task) potentially improves dual-task performance. This study aims to establish an effective cognitive-task methodology for clinical practice and identify dual-task combinations in which the N-back task is likely to improve performance. Twenty-one young, healthy adults performed an intervention task (either N-back or control), followed by single- and dual tasks in the disappearing or dexterity condition, to assess its effect on different days. The participants performed force-control and calculation tasks in both disappearing and dexterity conditions. In the disappearing force-control task, target waveforms disappeared after a few practice trials, and the participants recalled them and adjusted their knee extension torque. The dexterity force-control task involved presenting complex waveforms. The participants carefully observed the waveforms, and adjusted their knee extension torque. We measured changes in the excitability of the dorsolateral prefrontal cortex (DLPFC) using near-infrared spectroscopy to determine whether the N-back-task-induced changes contributed to improving dual-task performance. For dual-task performance in the disappearing condition, the N-back task improved the performance of the disappearing force-control task, but the control task did not. The other results were the same regardless of the type of intervention task. The N-back task enhanced a portion of the DLPFC excitability. However, no correlation was observed between changes in dual-task performance and in DLPFC excitability. Our findings may contribute to establishing an effective method for improving dual-task performance using cognitive tasks.

Prolonged continuous theta burst stimulation increases motor corticospinal excitability and intracortical inhibition in patients with neuropathic pain: An exploratory, single-blinded, randomized controlled trial

OBJECTIVES

A new paradigm for Transcranial Magnetic Stimulation (TMS), referred to as prolonged continuous theta burst stimulation (pcTBS), has recently received attention in the literature because of its advantages over high frequency repetitive TMS (HF-rTMS). Clinical advantages include less time per intervention session and the effects appear to be more robust and reproducible than HF-rTMS to modulate cortical excitability. HF-rTMS targeted at the primary motor cortex (M1) has demonstrated analgesic effects in patients with neuropathic pain but their mechanisms of action are unclear and pcTBS has been studied in healthy subjects only. This study examined the neural mechanisms that have been proposed to play a role in explaining the effects of pcTBS targeted at the M1 and DLPFC brain regions in neuropathic pain (NP) patients with Type 2 diabetes.

METHODS

Forty-two patients with painful diabetic neuropathy were randomized to receive a single session of pcTBS targeted at the left M1 or left DLPFC. pcTBS stimulation consisted of 1,200 pulses delivered in 1 min and 44 s with a 35-45 min gap between sham and active pcTBS stimulation. Both the activity of the descending pain system which was examined using conditioned pain modulation and the activity of the ascending pain system which was assessed using temporal summation of pain were recorded using a handheld pressure algometer by measuring pressure pain thresholds. The amplitude of the motor evoked potential (MEP) was used to measure motor corticospinal excitability and GABA activity was assessed using short (SICI) and long intracortical inhibition (LICI). All these measurements were performed at baseline and post-pcTBS stimulation.

RESULTS

Following a single session of pcTBS targeted at M1 and DLPFC, there was no change in BPI-DN scores and on the activity of the descending (measured using conditioned pain modulation) and ascending pain systems (measured using temporal summation of pain) compared to baseline but there was a significant improvement of >13% in perception of acute pain intensity, increased motor corticospinal excitability (measured using MEP amplitude) and intracortical inhibition (measured using SICI and LICI).

CONCLUSION

In patients with NP, a single session of pcTBS targeted at the M1 and DLPFC modulated the neurophysiological mechanisms related to motor corticospinal excitability and neurochemical mechanisms linked to GABA activity, but it did not modulate the activity of the ascending and descending endogenous modulatory systems. In addition, although BPI-DN scores did not change, there was a 13% improvement in self-reported perception of acute pain intensity.

Neuronavigated repetitive transcranial magnetic stimulation improves depression, anxiety and motor symptoms in Parkinson's disease

Background

Repetitive transcranial magnetic stimulation (rTMS) is a potential treatment option for Parkinson's disease patients with depression (DPD), but conflicting results in previous studies have questioned its efficacy.

Method

To investigate the safety and efficacy of neuronavigated high-frequency rTMS at the left DLPFC in DPD patients, we conducted a randomized, double-blind, sham-controlled study (NCT04707378). Sixty patients were randomly assigned to either a sham or active stimulation group and received rTMS for ten consecutive days. The primary outcome was HAMD, while secondary outcomes included HAMA, MMSE, MoCA and MDS-UPDRS-III. Assessments were performed at baseline, immediately after treatment, 2 weeks, and 4 weeks post-treatment.

Results

The GEE analysis showed that the active stimulation group had significant improvements in depression, anxiety, and motor symptoms at various time points. Specifically, there were significant time-by-group interaction effects in depression immediately after treatment (β, -4.34 [95% CI, -6.90 to -1.74; P = 0.001]), at 2 weeks post-treatment (β, -3.66 [95% CI, -6.43 to -0.90; P = 0.010]), and at 4 weeks post-treatment (β, -4.94 [95% CI, -7.60 to -2.29; P < 0.001]). Similarly, there were significant time-by-group interaction effects in anxiety at 4 weeks post-treatment (β, -2.65 [95% CI, -4.96 to -0.34; P = 0.024]) and in motor symptoms immediately after treatment (β, -5.72 [95% CI, -9.10 to -2.34; P = 0.001] and at 4 weeks post-treatment (β, -5.43 [95% CI, -10.24 to -0.61; P = 0.027]).

Conclusion

The study suggested that neuronavigated high-frequency rTMS at left DLPFC is effective for depression, anxiety, and motor symptoms in PD patients.

Frontal tDCS reduces alcohol relapse rates by increasing connections from left dorsolateral prefrontal cortex to addiction networks

BACKGROUND

Brain-based interventions are needed to address persistent relapse in alcohol use disorder (AUD). Neuroimaging evidence suggests higher frontal connectivity as well as higher within-network connectivity of theoretically defined addiction networks are associated with reduced relapse rates and extended abstinence during follow-up periods.

OBJECTIVE

/Hypothesis: A longitudinal randomized double-blind sham-controlled clinical trial investigated whether a non-invasive neuromodulation intervention delivered during early abstinence can (i) modulate connectivity of addiction networks supporting abstinence and (ii) improve relapse rates.

HYPOTHESES

Active transcranial direct current stimulation (tDCS) will (i) increase connectivity of addiction networks known to support abstinence and (ii) reduce relapse rates.

METHODS

Short-term abstinent AUD participants (n = 60) were assigned to 5 days of either active tDCS or sham during cognitive training. Causal discovery analysis (CDA) examined the directional influence from left dorsolateral prefrontal cortex (LDLPFC, stimulation site) to addiction networks that support abstinence.

RESULTS

Active tDCS had an effect on the average strength of CDA-determined connectivity from LDLPFC to the incentive salience and negative emotionality addiction networks - increasing in the active tDCS group only. Active tDCS had an effect on relapse rates following the intervention, with lower probability of relapse in the active tDCS vs. sham. Active tDCS showed an unexpected sex-dependent effect on relapse rates.

CONCLUSION

Our results suggest that LDLPFC stimulation delivered during early abstinence has an effect on addiction networks supporting abstinence and on relapse rates. The unexpected sex-dependent neuromodulation effects need to be further examined in larger clinical trials.

Increased prefrontal cortical cells positive for macrophage/microglial marker CD163 along blood vessels characterizes a neuropathology of neuroinflammatory schizophrenia

Transcript levels of cytokines and SERPINA3 have been used to define a substantial subset (40%) of individuals with schizophrenia with elevated inflammation and worse neuropathology in the dorsolateral prefrontal cortex (DLPFC). In this study, we tested if inflammatory proteins are likewise related to high and low inflammatory states in the human DLFPC in people with schizophrenia and controls. Levels of inflammatory cytokines (IL6, IL1β, IL18, IL8) and a macrophage marker (CD163 protein) were measured in brains obtained from the National Institute of Mental Health (NIMH) (N = 92). First, we tested for diagnostic differences in protein levels overall, then we determined the percentage of individuals that could be defined as "high" inflammation using protein levels. IL-18 was the only cytokine to show increased expression in schizophrenia compared to controls overall. Interestingly, two-step recursive clustering analysis showed that IL6, IL18, and CD163 protein levels could be used as predictors of "high and low" inflammatory subgroups. By this model, a significantly greater proportion of schizophrenia cases (18/32; 56.25%; SCZ) were identified as belonging to the high inflammatory (HI) subgroup compared to control cases (18/60; 30%; CTRL) [χ2(1) = 6.038, p = 0.014]. When comparing across inflammatory subgroups, IL6, IL1β, IL18, IL8, and CD163 protein levels were elevated in both SCZ-HI and CTRL-HI compared to both low inflammatory subgroups (all p < 0.05). Surprisingly, TNFα levels were significantly decreased (-32.2%) in schizophrenia compared to controls (p < 0.001), and were most diminished in the SCZ-HI subgroup compared to both CTRL-LI and CTRL-HI subgroups (p < 0.05). Next, we asked if the anatomical distribution and density of CD163+ macrophages differed in those with schizophrenia and high inflammation status. Macrophages were localized to perivascular sites and found surrounding small, medium and large blood vessels in both gray matter and white matter, with macrophage density highest at the pial surface in all schizophrenia cases examined. A higher density of CD163+ macrophages, that were also larger and more darkly stained, was found in the SCZ-HI subgroup (+154% p < 0.05). We also confirmed the rare existence of parenchymal CD163+ macrophages in both high inflammation subgroups (schizophrenia and controls). Brain CD163+ cell density around blood vessels positively correlated with CD163 protein levels. In conclusion, we find a link between elevated interleukin cytokine protein levels, decreased TNFα protein levels, and elevated CD163+ macrophage densities especially along small blood vessels in those with neuroinflammatory schizophrenia.

The role of the dorsolateral prefrontal cortex in control of skin sympathetic nerve activity in humans

The dorsolateral prefrontal cortex (dlPFC) is primarily involved in higher order executive functions, with there being evidence of lateralization. Brain imaging studies have revealed its link to the generation of skin sympathetic nerve activity (SSNA), which is elevated in states of emotional arousal or anxiety. However, no studies have directly explored dlPFC influences on SSNA. Transcranial alternating current stimulation (-2 to 2 mA, 0.08 Hz, 100 cycles) was applied between the left or right dlPFC and nasion via surface electrodes. Spontaneous bursts of SSNA were recorded from the common peroneal nerve via a tungsten microelectrode in 21 healthy participants. The modulation index was calculated for each stimulation paradigm by constructing cross-correlation histograms between SSNA and the sinusoidal stimulus. Stimulation of the dlPFC caused significant modulation of SSNA, but there was no significant difference in the median modulation index across sides. Stimulation also caused cyclic modulation of skin blood flow and sweat release. We have shown for the first time that stimulation of the dlPFC causes modulation of SSNA, also reflected in the effector-organ responses. This supports a role for the dlPFC in the control of SSNA, which likely contributes to the ability of emotions to bring about cutaneous vasoconstriction and sweat release.

Transcranial direct current stimulation alters the process of reward processing in children with ADHD: Evidence from cognitive modeling

BACKGROUND

The ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are the neural underpinnings of reward processing, which is impaired in individuals with attention deficit hyperactivity disorder (ADHD). In the present study, we aimed to explore the impact of the vmPFC and the dlPFC regulation on reward processing.

METHODS

Twenty-six children with ADHD performed the balloon analogue risk-taking task (BART) and chocolate delay discounting task (CDDT) during five different sessions of transcranial direct current stimulation (tDCS), separated by a one-week interval: anodal left dlPFC/cathodal right vmPFC, the reversed electrode positioning, anodal left dlPFC stimulation with extracranial return electrode, anodal right vmPFC stimulation with extracranial return electrodes, and sham stimulation. Four-parameter and constant-sensitivity models were used to model the data.

RESULTS

In the BART, anodal dlPFC/cathodal vmPFC stimulation facilitated conservative decision making, anodal tDCS over dlPFC with extracranial return electrode increased positive beliefs about the explosion of a balloon, and anodal vmPFC/cathodal dlPFC stimulation reduced ongoing learning in the process of decision making. In the CDDT, anodal vmPFC stimulation with extracranial return electrode decreased impatience in the process of the task.

CONCLUSION

These results suggest a role of the left dlPFC and right vmPFC in the outcome of decision making and the process of risky decision making and delay discounting.

Effect of prefrontal transcranial direct current stimulation on sexual arousal: A proof of concept study

There is preliminary evidence that high-frequency repetitive transcranial magnetic stimulation targeting the right dorsolateral prefrontal cortex (DLPFC) could reduce cue-induced sexual arousal. Here, we aimed to replicate this finding by using transcranial direct current stimulation (tDCS). In a randomized, double-blind, sham-controlled crossover study design, 24 healthy male participants received anodal tDCS over right DLPFC, anodal tDCS over left DLPFC, and sham tDCS with exposure to neutral and sexual video cues before and after each intervention. None of the interventions significantly reduced subjective sexual arousal. Stimulation parameters should be varied in further studies to identify factors relevant to the intended effect.

Right dorsolateral prefrontal cortex volumetric reduction is associated with antidepressant effect of low-dose ketamine infusion: A randomized, double-blind, midazolam-controlled PET-MRI clinical trial

BACKGROUND

Evidence has shown a rapid antidepressant and antisuicidal effects of low-dose ketamine infusion among patients with treatment-resistant depression (TRD) and prominent suicidal ideation (SI). The dorsolateral prefrontal cortex (DLPFC) plays a crucial role in the TRD pathomechanisms.

OBJECTIVE

Whether the structural and functional changes of the DLPFC, particularly Brodmann area 46, are associated with the antidepressant and antisuicidal effects of ketamine infusion among such patients is unknown.

METHODS

We randomized 48 patients with TRD and SI into groups receiving a single infusion of 0.5 mg/kg ketamine or 0.045 mg/kg midazolam. The Hamilton Depression Rating Scale and the Montgomery-Asberg Depression Rating Scale were used to assess symptoms. Positron emission tomography (PET)-magnetic resonance imaging was conducted prior to infusion and on Day 3 postinfusion. We performed longitudinal voxel-based morphometry (VBM) analysis to evaluate the gray matter (GM) volume changes of the DLPFC. The standardized uptake value ratio (SUVr) of ¹⁸F-fluorodeoxyglucose PET images was calculated using the SUV of the cerebellum as a reference region.

RESULTS

The VBM analysis revealed a small but significant volumetric reduction in the right DLPFC in the ketamine group compared with that in the midazolam group. A greater reduction in depressive symptoms was associated with a smaller decrease in right DLPFC volumes (p = 0.025). However, we found no SUVr changes of the DLPFC between baseline and post-Day 3 ketamine infusion.

DISCUSSION

The optimal modulation of the right DLPFC GM volumes may play an essential role in the antidepressant neuromechanisms of low-dose ketamine.

Gray matter associations with extinction-induced neural activation in patients with anxiety disorders

The relationship between structural characteristics and extinction-induced brain activations in anxiety disorders (ANX) remains a space for greater exploration. In this study, we assessed gray matter volume (GMV) and its associated functional activations during fear extinction memory recall in an ANX cohort. We performed voxel-based morphometry analysis to examine GMVs from ANX (n = 92) and controls (n = 73). We further examined the correlation between GMVs and extinction-induced neural activations during recall across groups. In the patients' group, we observed decreased GMV in the anterior hippocampus and increased GMV in the dorsolateral prefrontal cortex (dlPFC). Hippocampal volume was positively correlated with ventromedial prefrontal cortex activation in healthy controls, while it was negatively correlated with dorsal anterior cingulate cortex (dACC) activation in ANX. The dlPFC volume was positively correlated with activations of dACC, pre- and post-central gyrus, and supramarginal gyrus only in healthy controls. Therefore, the link between structural and functional imbalance within the hippocampus and dlPFC might contribute to the pathophysiology of ANX. In the controls, the relationship between structural variance in the hippocampus and dlPFC and extinction-induced neural activations is consistent with a greater ability to regulate fear responding; associations that were absent in the ANX cohort. Furthermore, our findings of structure-function abnormalities within key nodes of emotional homeostasis in ANX point to dlPFC as a potential neural node to target using neuromodulation tools.

Stimulation of the dorsolateral prefrontal cortex modulates brain cue reactivity to reward (un)availability

Brain imaging studies have shown that stimulation of the left dorsolateral prefrontal cortex (dlPFC), which plays a pivotal role in high-order cognitive control processes, modulates brain reactivity to reward-related cues. Nevertheless, the impact of contextual factors such as reward availability (the reward that is depicted in the cue exposure task) on such modulation effect remains unclear. Here we tested whether a single session of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) over the left dlPFC differently impacts brain reactivity to cues signalling either availability or unavailability of a sports betting opportunity. Employing a within-subject design (verum versus sham HF-rTMS) among thirty-two frequent sports bettors, we first observed that, as compared to the sham condition, verum HF-rTMS modulated brain reactivity to game cues prior to being made (un)available for betting, through simultaneous increases (posterior insula and caudate nucleus) and decreases (occipital pole) in brain activation. Second, verum HF-rTMS led to increased ventral striatal activity towards cues available for betting but did not modulate brain response to cues unavailable for betting. Taken together, these findings demonstrate that transient stimulation of the left dlPFC led to a general modulation in brain activity in responses to cues, and that this effect is only partly dependent on cues signalling for reward (un)availability.

Dissociation and integration of outcome and state uncertainty signals in cognitive control

Signals related to uncertainty are frequently observed in regions of the cognitive control network, including anterior cingulate/medial prefrontal cortex (ACC/mPFC), dorsolateral prefrontal cortex (dlPFC), and anterior insular cortex. Uncertainty generally refers to conditions in which decision variables may assume multiple possible values and can arise at multiple points in the perception-action cycle, including sensory input, inferred states of the environment, and the consequences of actions. These sources of uncertainty are frequently correlated: noisy input can lead to unreliable estimates of the state of the environment, with consequential influences on action selection. Given this correlation amongst various sources of uncertainty, dissociating the neural structures underlying their estimation presents an ongoing issue: a region associated with uncertainty related to outcomes may estimate outcome uncertainty itself, or it may reflect a cascade effect of state uncertainty on outcome estimates. In this study, we derive signals of state and outcome uncertainty from mathematical models of risk and observe regions in the cognitive control network whose activity is best explained by signals related to state uncertainty (anterior insula), outcome uncertainty (dlPFC), as well as regions that appear to integrate the two (ACC/mPFC).

Transcranial direct current stimulation over the right dorsolateral prefrontal cortex increases oxyhemoglobin concentration and cognitive performance dependent on cognitive load

Transcranial direct current stimulation (tDCS) has been explored as a potential method for cognitive enhancement. tDCS may induce a cascade of neurophysiological changes including alterations in cerebral oxygenation. However, the effects of tDCS on the cognitive-cerebral oxygenation interaction remains unclear. Further, oxygenation variability across individuals remains minimally controlled for. The purpose of this sham-controlled study was to test the effects of anodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) on the interaction between working memory and cerebral oxygenation while controlling for individual oxygenation variability. Thirty-three adults received resting-state functional near-infrared spectroscopy (fNIRS) recordings over bilateral prefrontal cortices. Following this, working memory was tested using a Toulouse n-back task concurrently paired with fNIRS, with measurements taken before and after 20 min of anodal or sham tDCS at 1.5 mA. With individual oxygenation controlled for, anodal tDCS was found to increase the oxyhemoglobin concentration over the right DLPFC during the 2-back (q = .015) and 3-back (q = .008) conditions. Additionally, anodal tDCS was found to improve accuracy during the 3-back task by 13.4 % (p = .028) and decrease latency by 250 ms (p = .013). The increase in oxyhemoglobin was strongly correlated with increases in accuracy (p = .041) and decreases in latency during the 3-back span (p = .017). Taken together, anodal tDCS over the right DLPFC was found to regionally increase oxyhemoglobin concentrations and improve working memory performance in higher cognitive load conditions.