Cognitive changes after tDCS and escitalopram treatment in major depressive disorder: Results from the placebo-controlled ELECT-TDCS trial

BACKGROUND

Cognitive deficits in major depressive disorder (MDD) are associated with low quality of life and higher suicide risk. Antidepressant drugs have modest to null effects in improving such deficits. Therefore, we investigated the cognitive effects of transcranial direct current stimulation (tDCS), which is a promising antidepressant non-pharmacological intervention, in MDD.

METHODS

An exploratory analysis on cognitive performance was conducted in 243 depressed patients from the Escitalopram vs. Electric Current Therapy for Treating Depression Clinical Study (ELECT-TDCS), a sham-controlled study comparing the efficacy of tDCS vs. escitalopram. A neuropsychological battery was applied at baseline and endpoint (10 weeks of treatment) to create composite cognitive scores (processing speed, working memory, and verbal fluency). Linear mixed regression models were used to evaluate changes according to intervention groups, adjusted for confounding variables (age, years of schooling, gender, and benzodiazepine use) and depression improvement.

RESULTS

No cognitive deterioration was observed in any group. Patients receiving tDCS presented reduced practice gains compared to placebo in processing speed. In patients receiving escitalopram vs. placebo and in the subgroup of clinical responders (>50% depression improvement from baseline), those receiving tDCS vs. placebo presented increased performance in verbal fluency. No significant differences between tDCS and escitalopram groups were detected.

LIMITATIONS

Absence of healthy controls.

CONCLUSION

Prefrontal tDCS did not lead to cognitive deficits in depressed patients, although it reduced practice effects in processing speed. tDCS responders presented increased performance in verbal fluency. Further investigation of tDCS cognitive effects in depression is warranted.

Schizophrenia-associated MicroRNA-Gene Interactions in the Dorsolateral Prefrontal Cortex

Schizophrenia-associated anomalies in gene expression in postmortem brain can be attributed to a combination of genetic and environmental influences. Given the small effect size of common variants, it is likely that we may only see the combined impact of some of these at the pathway level in small postmortem studies. At the gene level, however, there may be more impact from common environmental exposures mediated by influential epigenomic modifiers, such as microRNA (miRNA). We hypothesise that dysregulation of miRNAs and their alteration of gene expression have significant implications in the pathophysiology of schizophrenia. In this study, we integrate changes in cortical gene and miRNA expression to identify regulatory interactions and networks associated with the disorder. Gene expression analysis in post-mortem prefrontal dorsolateral cortex (BA 46) (n = 74 matched pairs of schizophrenia, schizoaffective, and control samples) was integrated with miRNA expression in the same cohort to identify gene-miRNA regulatory networks. A significant gene-miRNA interaction network was identified, including miR-92a, miR-495, and miR-134, which converged with differentially expressed genes in pathways involved in neurodevelopment and oligodendrocyte function. The capacity for miRNA to directly regulate gene expression through respective binding sites in BCL11A, PLP1, and SYT11 was also confirmed to support the biological relevance of this integrated network model. The observations in this study support the hypothesis that miRNA dysregulation is an important factor in the complex pathophysiology of schizophrenia.

Impaired hemodynamic activity in the right dorsolateral prefrontal cortex is associated with impairment of placebo analgesia and clinical symptoms in postherpetic neuralgia

The dorsolateral prefrontal cortex (dlPFC) is functionally linked to the descending pain modulation system and has been implicated in top down pain inhibition, including placebo analgesia. Therefore, functions of the dlPFC may be impaired in patients with chronic pain. Postherpetic neuralgia (PHN) is one of several syndromes with chronic neuropathic pain. In the present study, we investigated possible dysfunction of the dlPFC in chronic pain using patients with PHN. In a conditioning phase, heathy controls (n = 15) and patients with PHN (n = 7) were exposed to low (LF) and high (HF) frequency tones associated with noxious stimuli: weak (WS) and strong (SS) electrical stimulation, respectively. After the conditioning, cerebral hemodynamic activity was recorded from the bilateral dlPFC while the subjects were subjected to the cue tone-noxious electrical stimulation paradigm, in which incorrectly cued noxious stimuli were sometimes delivered to induce placebo and nocebo effects. The results indicated that hemodynamic responses to the LF tone in the right dlPFC was significantly lower in patients with PHN compared to the healthy controls. Furthermore, the same hemodynamic responses in the right dlPFC were correlated with placebo effects. In addition, clinical symptoms of PHN were negatively correlated to cerebral hemodynamic responses in the right dlPFC and magnitudes of the placebo effects. The results suggest that the right dlPFC, which is closely associated with the descending pain modulation system, is disturbed in PHN.

A systematic review and meta-analysis of rTMS effects on cognitive enhancement in mild cognitive impairment and Alzheimer's disease

Repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation technique, has emerged as a promising treatment for mild cognitive impairment (MCI) and Alzheimer's disease (AD). Currently, however, the effectiveness of this therapy is unclear because of the low statistical power and heterogeneity of previous trials. The purpose of the meta-analysis was to systematically characterize the effectiveness of various combinations of rTMS parameters on different cognitive domains in patients with MCI and AD. Thirteen studies comprising 293 patients with MCI or AD were included in this analysis. Random-effects analysis revealed an overall medium-to-large effect size (0.77) favoring active rTMS over sham rTMS in the improvement of cognitive functions. Subgroup analyses revealed that (1) high-frequency rTMS over the left dorsolateral prefrontal cortex and low-frequency rTMS at the right dorsolateral prefrontal cortex significantly improved memory functions; (2) high-frequency rTMS targeting the right inferior frontal gyrus significantly enhanced executive performance; and (3) the effects of 5-30 consecutive rTMS sessions could last for 4-12 weeks. Potential mechanisms of rTMS effects on cognitive functions are discussed.

Elevated expression of unfolded protein response genes in the prefrontal cortex of depressed subjects: Effect of suicide

BACKGROUND

Major Depressive Disorder (MDD) is a leading cause of mental disability worldwide. Despite many studies, the pathophysiology associated with MDD brain is not very clear. It is reported that cellular stress is related to depressive symptoms. Under stressful conditions, intracellular homeostasis processes can be disrupted, which can induce a process of unfolded protein response (UPR) in the subcellular lumen of endoplasmic reticulum (ER). The purpose of this study is to elucidate whether UPR is active in the depressed brain.

METHODS

The dorsolateral prefrontal cortex (dlPFC) was used from 23 non-psychiatric controls and 43 MDD subjects. The expression levels of UPR associated genes (GRP78, GRP94, XBP-1, CHOP, ATF4C, and ATF6C) were measured by qRT-PCR.

RESULTS

The level of mRNA expression in MDD subjects was significantly higher for GRP78 (p = 0.008), GRP94 (p = 0.018), and ATF4C (p = 0.03) compared to non-psychiatric controls. Further analysis suggested that changes in the expression of these genes were specifically higher only in those MDD subjects who died by suicide but not in those who died by causes other than suicide when compared with non-psychiatric controls (GRP78, p = 0.007; GRP94, p = 0.041; ATF4C, p = 0.037).

LIMITATIONS

This study was performed only in MDD subjects who had died by suicide. Suicide subjects with other psychiatric illnesses need to be included.

CONCLUSIONS

Given that UPR is involved in many physiological processes in the brain, including inflammatory response as well as apoptosis, increased expression of UPR genes indicates that ER stress and mediated UPR may be critical factors in suicidality among depressed patients.

A systematic review and meta-analysis of rTMS effects on cognitive enhancement in mild cognitive impairment and Alzheimer's disease

Repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation technique, has emerged as a promising treatment for mild cognitive impairment (MCI) and Alzheimer's disease (AD). Currently, however, the effectiveness of this therapy is unclear because of the low statistical power and heterogeneity of previous trials. The purpose of the meta-analysis was to systematically characterize the effectiveness of various combinations of rTMS parameters on different cognitive domains in patients with MCI and AD. Thirteen studies comprising 293 patients with MCI or AD were included in this analysis. Random-effects analysis revealed an overall medium-to-large effect size (0.77) favoring active rTMS over sham rTMS in the improvement of cognitive functions. Subgroup analyses revealed that (1) high-frequency rTMS over the left dorsolateral prefrontal cortex and low-frequency rTMS at the right dorsolateral prefrontal cortex significantly improved memory functions; (2) high-frequency rTMS targeting the right inferior frontal gyrus significantly enhanced executive performance; and (3) the effects of 5-30 consecutive rTMS sessions could last for 4-12 weeks. Potential mechanisms of rTMS effects on cognitive functions are discussed.

Abnormal functional connectivity of habenula in untreated patients with first-episode major depressive disorder

Major depressive disorder (MDD) is associated with abnormalities in emotional/cognitive processing and low reward sensitivity. The habenula has a pivotal role in these processes that may contribute to depression. However, there has been little research on the abnormal connectivity between the habenula and whole brain of first-onset MDD. We aimed to explore the differences of functional connectivity between patients and healthy controls using functional magnetic resonance imaging. We used seed-based resting-state fMRI to examine functional connectivity between the habenula and whole-brain in 49 first-episode depressive patients and 25 healthy controls. Compared to controls, patients with MDD demonstrated significant increases in functional connectivity between the habenula and the dorsolateral prefrontal cortex (dlPFC). Furthermore, the receiver operating characteristic (ROC) curve proved that connectivity between the habenula and dlPFC was highly predictive. Additionally, there was a positive correlation between Hamilton Rating Scale for Depression (HAMD) score and functional connectivity between the habenula and right dlPFC. We found that the aberrant functional connectivity to the habenula and dlPFC can distinguish MDD patients from the normal.

The effect of neurostimulation applied to the left dorsolateral prefrontal cortex on post-stress adaptation as a function of depressive brooding

Depressive brooding following a stressful event predicts negative affect and neuroendocrine responses related to psychological stress. The dorsolateral prefrontal cortex (DLPFC) has been associated with the top-down regulation of thoughts and emotions, and abnormal neural activity within this region has been associated with increased psychological stress and ruminative thinking. The aim of this study was to investigate whether the modulation of the DLPFC could have beneficial effects on ruminative thoughts and the endocrine response following a self-relevant stressor. Using a sham-controlled within-subjects crossover-design, two sessions of intermittent theta-burst stimulation (iTBS) were administered over the left DLPFC to thirty-eight healthy-volunteers after they were confronted with a social-evaluative stressor, the Trier Social Stress Test. To assess stress recovery, momentary rumination was measured before and after a resting period subsequent to the encounter with the stressor. In addition, cortisol levels were measured between and after the two iTBS sessions that were applied during the stress recovery phase. Overall, iTBS did not significantly influence ruminative thinking and cortisol secretion during the stress recovery phase. However, taking into account participants ruminative tendencies, our results revealed that for participants with higher levels of brooding ruminative thinking remained stable after iTBS, whereas in the sham condition there was a marginal significant increase in ruminative thinking. Moreover, only after iTBS, there was a significant reduction in cortisol secretion (i.e. a faster return to baseline as compared to sham) for high brooders during the recovery from the stressor. These results show that the prefrontal cortex plays a role in stress recovery mechanisms in individuals who are more vulnerable for psychopathology.

The safety and efficacy of adjunctive 20-Hz repetitive transcranial magnetic stimulation for treatment of negative symptoms in patients with schizophrenia: A double-blinded, randomized, sham-controlled study

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a promising treatment strategy for negative symptoms. However, the evidence for its efficacy is mixed, with contradictory results between studies due to lack of consensus about the optimal stimulation parameters.

AIM

The present study was planned to assess the safety and efficacy of 20-Hz rTMS over left dorsolateral prefrontal cortex (Lt-DLPFC) with more robust stimulation parameters for adjunctive treatment of negative symptoms in patients with schizophrenia.

MATERIALS AND METHODS

Thirty patients with negative symptoms of schizophrenia (Positive and Negative Syndrome Scale [PANSS] negative subscore ≥15) were randomized to receive a 4-week treatment with either real-rTMS (n = 15) or sham-rTMS (n = 15). The study outcomes were assessed at baseline, after 5^th and 20^th rTMS sessions with PANSS, Scale for the Assessment of Negative Symptoms (SANS), Calgary Depression Scale for Schizophrenia, Clinical Global Impressions-Severity of illness scale, and rTMS side-effect checklist.

RESULTS

There was significantly greater reduction in negative symptoms assessed by SANS score in the real rTMS group, compared with the sham rTMS group. There was no significant difference in the rate of side-effects reported between the two groups. The rTMS treatment was well-tolerated by all the patients, except one seizure episode reported in the active group.

CONCLUSION

The high-frequency rTMS protocol was safe and well-tolerated, provided patients prone to developing seizure were excluded by baseline electroencephalography prior to starting of the treatment. The 20-Hz rTMS over Lt-DLPFC with more robust stimulation parameters (100% motor threshold and 40,000 pulses) might be an effective augmentation strategy for the treatment of negative symptoms in schizophrenia.

Multiple Sessions of High-Frequency Repetitive Transcranial Magnetic Stimulation as a Potential Treatment for Gambling Addiction: A 3-Month, Feasibility Study

Gambling disorder (GD) is a behavioral addiction, in which dysfunctions in prefrontal activity have been proposed as relevant pathophysiological correlates. The aim of the present study was to preliminarily investigate the feasibility of a noninvasive neuromodulation intervention targeting the prefrontal cortex to treat GD in an open-label setting. We included 8 treatment-seeking patients with GD (7 males; 1 female; mean age: 40.6 ± 11.2). The study consisted of 3 phases: (1) outpatient screening phase, (2) 2-week intensive repetitive transcranial magnetic stimulation (rTMS) treatment phase (twice daily, 5 days/week for 2 weeks); and (3) 3-month maintenance follow-up phase (twice daily, once a week). Each high-frequency (15 Hz) rTMS session was delivered targeting the left dorsolateral prefrontal cortex. GD severity and treatment response were assessed at the baseline and during the follow-up. No relevant side effect was reported. We found a 71.2% Gambling Symptom Assessment Scale mean score reduction after 2 weeks of rTMS treatment; the days spent gambling decreased from 19.63 ± 7.96 to 0.13 ± 0.35 days. Clinical improvements were maintained throughout the study period. The lack of a control group limits the interpretation of these results. In conclusion, these results consolidate the rationale that rTMS interventions deserve further investigation as a potential treatment for GD. These protocols should be tested in larger randomized controlled studies, to determine the real benefits of neuromodulation in the clinical course of patients with GD. Registration Number: ClinicalTrials.gov Identifier NCT03336879.

Disruption of gamma-delta relationship related to working memory deficits in first-episode psychosis

Working memory (WM) deficits constitute a core symptom of schizophrenia. Inadequacy of WM maintenance in schizophrenia has been reported to reflect abnormalities in the excitation/inhibition (E/I) balance between pyramidal neurons and parvalbumin basket cells, which may explain alterations of the dynamics of gamma and delta oscillations. To address this issue, we assessed event-related gamma (35-45 Hz) and delta (0.5-4 Hz) oscillatory responses in a visual n-back WM task in patients with first-episode psychosis (FEP) and healthy controls (HC). Periodicity analyses of oscillations were computed to explore the relationship between the psychiatric status and the WM load-related processes reflected by each frequency range. The correspondence between nested delta-gamma oscillations was estimated to assess the strength of the frontal E/I balance. In HC, gamma oscillations were synchronized by the stimulus in a 50-150 ms time range for all tasks, and periodicity of the delta cycle was comparable between the tasks. In addition, synchronization of gamma oscillations in HC occurred at the maximal descending phase of the delta cycle half-period, supporting the coexistence of delta-nested gamma oscillations. Compared with controls, FEP patients showed a lack of gamma synchronization independently of the nature of the task, and the period of delta oscillation increased significantly with the difficulty of the WM task. We thus demonstrated in FEP an inability to encode multiple items in short-term memory associated with abnormalities in the relationship between oscillations related to the difficulty of the WM task. These results argue in favor of a dysfunction of the E/I balance in psychosis.

Acute moderate-intensity exercise improves 24-h sleep deprivation-induced cognitive decline and cerebral oxygenation: A near-infrared spectroscopy study

We evaluated the effects of moderate-intensity exercise in improving the decline in cognitive performance induced by a 24-h period of acute sleep deprivation (SD). We hypothesized that the positive effect of exercise is mediated by increased oxygenation (measured using near-infrared spectroscopy) of the dorsolateral prefrontal cortex (DLPFC). Cognitive performance was measured using the reaction time and interference scores of the Stroop colour and word test, in 12 healthy adults (eight males, 21.1 ± 0.3 years-old), at pre- and post-exercise. Cognitive scores were compared under two conditions: rested wakefulness (RW) and 24-h SD. The exercise consisted of 20-min of ergometer cycling at an intensity of 60 % VO_2peak. Oxygenation to the DLPFC increased, at 12 min after exercise onset, compared to the baseline and was maintained until the end of the exercise in both RW and SD conditions (P < 0.01). The change in RT correlated with sleepiness (P < 0.05), with no correlation for the interference score and oxygenation. Taken together, moderate-intensity exercise reverses SD-induced cognitive decline.

Transcranial direct current stimulation for the treatment of generalized anxiety disorder: A randomized clinical trial

BACKGROUND

Generalized anxiety disorder (GAD) is a common condition with current treatments being only moderately effective. Non-invasive brain stimulation techniques might provide a novel approach for treating GAD. Transcranial direct current stimulation (tDCS) has shown promising efficacy and tolerability for major depression but has not been investigated for GAD yet. Thus, we investigated the effects of tDCS on patients with GAD.

METHODS

We conducted a pilot, double-blind, randomized, sham-controlled trial on 30 GAD patients. Five sessions of tDCS (2 mA, 20 min, anode over the left dorsolateral prefrontal cortex and cathode over the right supraorbital cortex) were performed. Anxiety was the primary outcome and it was measured by the Hamilton Anxiety Rating Scale and the Beck Anxiety Inventory. Secondary outcomes were accessed by the Lipp Inventory of Stress Symptoms for Adults, Positive and Negative Affect Schedule, and the Beck Depression Inventory (BDI). Data were examined at baseline, after the 5th day of intervention, and at 1-week follow-up.

RESULTS

Thirty patients finished the study. There were no significant improvements in anxiety, mood symptoms of stress, affectivity or depression. Anodal stimulation of the left DLPFC showed significant improvements in physical symptoms of stress in GAD patients.

LIMITATIONS

Additional tDCS sessions could have resulted in larger tDCS effects.

CONCLUSION

Five sessions of anodal tDCS over the DLPFC did not improve the main outcomes for GAD patients, although physical symptoms of stress were improved. The role of tDCS in GAD should be explored in larger patient samples using different parameters.

Twice-daily neuronavigated intermittent theta burst stimulation for bipolar depression: A Randomized Sham-Controlled Pilot Study

The safety and efficacy of neuronavigated intermittent theta burst stimulation (iTBS) in patients with bipolar depression has not yet been investigated. We hypothesized the superiority of active iTBS over sham. Twenty-six patients were randomly allocated to receive either active (n=12) or sham (n=14) iTBS. Response and remission rates according to changes in depression MADRS score were high following active iTBS (72% and 42% for response and remission rates, respectively), but no significant difference was found after sham stimulation (42%and 25%). No adverse events were observed. This study revealed the safety and tolerability of twice daily iTBS in patients with bipolar depression. Larger controlled studies are warranted to prove iTBS superiority in treatment-resistant bipolar depression.

Focal left prefrontal lesions and cognitive impairment: A multivariate lesion-symptom mapping approach

Despite network studies of the human brain have brought consistent evidence of brain regions with diverse functional roles, the neuropsychological approach has mainly focused on the functional specialization of individual brain regions. Relatively few neuropsychological studies try to understand whether the severity of cognitive impairment across multiple cognitive abilities can be related to focal brain injuries. Here we approached this issue by applying a latent variable modeling of the severity of cognitive impairment in brain tumor patients, followed by multivariate lesion-symptom methods identifying brain regions critically involved in multiple cognitive abilities. We observed that lesions in confined left lateral prefrontal areas including the inferior frontal junction produced the most severe cognitive deficits, above and beyond tumor histology. Our findings support the recently suggested integrated albeit modular view of brain functional organization, according to which specific brain regions are highly involved across different sub-networks and subserve a vast range of cognitive abilities. Defining such brain regions is relevant not only theoretically but also clinically, since it may facilitate tailored tumor resections and improve cognitive surgical outcomes.

Effects of repetitive transcranial magnetic stimulation on nicotine consumption and craving: A systematic review

We performed a systematic review of the studies employing repetitive transcranial magnetic stimulation (rTMS) in subjects with smoking addiction. High-frequency (HF) rTMS over the prefrontal cortex (PFC), in particular the left dorsolateral PFC (DLPFC), might represent a save and innovative treatment tool for tobacco consumption and craving in nicotine-dependent otherwise healthy people. rTMS can be effective for this indication also in patients with schizophrenia, but the results are conflicting and sufficient evidence from large-scale trials is still lacking. Promising results have been obtained using particular techniques for brain stimulation, such as deep rTMS and theta burst stimulation. Multiple-target HF rTMS can also have a potential in smoking cessation. fMRI and EEG recordings have proven to be useful for objectively assessing the treatment effects. TMS is likely to be most effective when paired with an evidence-based self-help intervention, cognitive-behavioral interventions and nicotine replacement therapy. However, the most recent studies employed different protocols and yielded heterogeneous results, which should be replicated in further controlled studies with larger sample sizes and rigorous standards of randomization. To date, no recommendation other than that a possible efficacy of HF-rTMS of the left DLPFC can be made for alternative rTMS procedures in nicotine craving and consumption.

Brain oscillation-synchronized stimulation of the left dorsolateral prefrontal cortex in depression using real-time EEG-triggered TMS

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (DLPFC) is an effective treatment for major depressive disorder (MDD), but response rates are low and effect sizes small. Synchronizing TMS pulses with instantaneous brain oscillations can reduce variability and increase efficacy of TMS-induced plasticity.

OBJECTIVE

To study whether brain oscillation-synchronized rTMS is feasible, safe and has neuromodulatory effects when targeting the DLPFC of patients with MDD.

METHODS

Using real-time EEG-triggered TMS we conducted a pseudo-randomized controlled single-session crossover trial of brain oscillation-synchronized rTMS of left DLPFC in 17 adult patients with antidepressant-resistant MDD. Stimulation conditions in separate sessions were: (1) rTMS triggered at the negative EEG peak of instantaneous alpha oscillations (alpha-synchronized rTMS), (2) a variation of intermittent theta-burst stimulation (modified iTBS), and (3) a random alpha phase control condition.

RESULTS

Triggering TMS at the negative peak of instantaneous alpha oscillations by real-time analysis of the electrode F5 EEG signal was successful in 15 subjects. Two subjects reported mild transient discomfort at the site of stimulation during stimulation; no serious adverse events were reported. Alpha-synchronized rTMS, but not modified iTBS or the random alpha phase control condition, reduced resting-state alpha activity in left DLPFC and increased TMS-induced beta oscillations over frontocentral channels.

CONCLUSIONS

Alpha-synchronized rTMS of left DLPFC is feasible, safe and has specific single-session neuromodulatory effects in patients with antidepressant-resistant MDD. Future studies need to further elucidate the mechanisms, optimize the parameters and investigate the therapeutic potential and efficacy of brain oscillation-synchronized rTMS in MDD.

Preliminary findings of four-week, task-based anodal prefrontal cortex transcranial direct current stimulation transferring to other cognitive improvements in schizophrenia

Most transcranial Direct Current Stimulation (tDCS) trials of schizophrenia administer few sessions and do not assess transfer effects to other cognitive domains. In a randomized, double-blind, sham-controlled, parallel groups trial, we determined the extent to which 4-weeks of 2 mA tDCS at 20 min/day totalling 20 tDCS sessions administered during a spatial working memory test, with anodal right dorsolateral prefrontal cortex (DLPFC) and cathodal left tempo-parietal junction (TPJ) placement, as an adjunct to antipsychotics reduced auditory hallucinations and improved cognition in 12 outpatients with schizophrenia. Anodal tDCS significantly improved language-based working memory after 2 weeks and verbal fluency after 2 and 4 weeks. Thus, four weeks of tDCS appears to be safe and elicits transfer benefits to other prefrontal-dependent cognitive abilities in schizophrenia.

Appetite effects of prefrontal stimulation depend on COMT Val158Met polymorphism: A randomized clinical trial

The regulation of appetite is supported by dopamine-modulated brain circuits. Recent studies have shown that transcranial direct current stimulation (tDCS) aimed at increasing the excitability of the dorsolateral prefrontal cortex can reduce appetite, but the underlying mechanisms remain unknown, and response variability is large. The aim of this study was to determine whether individual differences in Catechol-O-methyl transferase (COMT) Val158Met polymorphism can influence tDCS effects on appetite. Thirty-eight adult women with obesity, classified as carriers or non-carriers of the Met allele, underwent a randomized, double-blind, sham-controlled tDCS intervention involving three phases: Phase I, target engagement (immediate effects of tDCS on working memory performance), Phase II, tDCS only (10 sessions, two weeks), and Phase III, tDCS + hypocaloric diet: (6 sessions, two weeks, 30% energy intake reduction, inpatient). Data were analyzed using linear mixed-effects models and mixed ANCOVA. Appetite was evaluated using visual analogue scales. We found that Met-carriers receiving active tDCS were the only participants who experienced a significant reduction of appetite over time. Conversely, Met non-carriers maintained high levels of appetite during the intervention; this effect was driven by a delayed paradoxical rise in appetite after stimulation. Working memory task performance at phase I correlated with subsequent appetite change in a COMT-dependent manner: speed improvements during the task predicted appetite increase in Met carriers and appetite reduction in Met non-carriers. Our findings suggest that genotype differences impacting dopamine levels influence prefrontal tDCS effects on appetite. This source of variability should be considered in the design of future studies.

Promising Neuroimaging Biomarkers in Depression

The neuroimaging has been applied in the study of pathophysiology in major depressive disorder (MDD). In this review article, several kinds of methodologies of neuroimaging would be discussed to summarize the promising biomarkers in MDD. For the magnetic resonance imaging (MRI) and magnetoencephalography field, the literature review showed the potentially promising roles of frontal lobes, such as anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC). In addition, the limbic regions, such as hippocampus and amygdala, might be the potentially promising biomarkers for MDD. The structures and functions of ACC, DLPFC, OFC, amygdala and hippocampus might be confirmed as the biomarkers for the prediction of antidepressant treatment responses and for the pathophysiology of MDD. The functions of cognitive control and emotion regulation of these regions might be crucial for the establishment of biomarkers. The near-infrared spectroscopy studies demonstrated that blood flow in the frontal lobe, such as the DLPFC and OFC, might be the biomarkers for the field of near-infrared spectroscopy. The electroencephalography also supported the promising role of frontal regions, such as the ACC, DLPFC and OFC in the biomarker exploration, especially for the sleep electroencephalogram to detect biomarkers in MDD. The positron emission tomography (PET) and single-photon emission computed tomography (SPECT) in MDD demonstrated the promising biomarkers for the frontal and limbic regions, such as ACC, DLPFC and amygdala. However, additional findings in brainstem and midbrain were also found in PET and SPECT. The promising neuroimaging biomarkers of MDD seemed focused in the fronto-limbic regions.

Testing the role of cognitive inhibition in physical endurance using high-definition transcranial direct current stimulation over the prefrontal cortex

The aim of this study was to clarify the role of the prefrontal cortex (PFC) in physical effort regulation. We hypothesized that the PFC would be progressively involved in physical endurance through the engagement of cognitive inhibition, which would be necessary to maintain effort by inhibiting fatigue-related cues. This hypothesis was examined using a double-blind, sham-controlled, within-subjects study (N = 20) using high-definition (HD) transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (dlPFC). Participants had to maintain a knee extensor contraction at 30% of their maximal force while simultaneously performing an Eriksen flanker task to evaluate their inhibition performance during the task. Anodal stimulation of the dlPFC influenced response to the cognitive task during exercise, as seen by slower response times and better accuracy. However, it did not lead to any measureable improvement in cognitive inhibition and did not influence endurance time. There was no correlation between cognitive inhibition and the maintenance of physical effort. This result does not indicate a relationship between cognitive inhibition and endurance performance. The contribution of the PFC in physical endurance could be explained through its involvement on decisional processes.

Temporal dynamic changes of intrinsic brain activity in schizophrenia with cigarette smoking

Mounting evidence from multimodal neuroimaging studies has supported a neurobiological basis for schizophrenia-nicotine dependence comorbidity. However, this evidence comes exclusively from studies measuring static intrinsic activity/connectivity of the brain, while the dynamic effects of this comorbidity remain poorly understood. The current study therefore sought to examine whether temporal dynamic intrinsic brain activity interacted with diagnosis (schizophrenics vs. healthy controls) and smoking status (smokers vs. non-smokers). We used a mixed sample design and included the following four groups: i) schizophrenic smokers (n = 22), ii) schizophrenic non-smokers (n = 27), iii) healthy control smokers (n = 22), and iv) healthy control non-smokers (n = 21). All subjects underwent functional magnetic resonance imaging during the resting state. The temporal variability in intrinsic brain activity among the four groups was compared using a novel dynamic amplitude of low-frequency fluctuation (dALFF) method. A significant main effect of diagnosis was found in the left superior parietal gyrus (SPG; F_{(1, 88)} = 142.1, P < 0.0001). Moreover, the dALFF strength in the SPG was positively correlated with disease duration in patients with schizophrenia (Rho₍₄₆₎ = 0.43, P = 0.002). In addition, a significant interaction between diagnosis and smoking status was observed in the left dorsolateral prefrontal cortex (DLPFC; F_{(1, 88)} = 7.39, P = 0.008), which was consistent with the self-medication hypothesis. Together, this study has demonstrated for the first time that nicotine restores dynamic intrinsic brain activity in the left DLPFC in patients with schizophrenia. This interaction may be a clinical neuromarker for increased comorbid smoking in schizophrenia.

Brain activation and adaptation of deception processing during dyadic face-to-face interaction

Though deception is consistently characterized by the slippery-slope effect, i.e., the escalation of small lies over time, differing interactive situations and interacting processes may influence the trajectories of deception. To explore this influence, we investigated naturalistic face-to-face (FF) and computer-mediated face-blocked (FB) interactions using functional near-infrared spectroscopy (fNIRS). Pairs of participants acted as deceivers and receivers in an adapted ultimatum game while brain activity in the right dorsolateral prefrontal cortex (rDLPFC) and temporoparietal junction (rTPJ) was recorded. Comparison of deception in the two types of interactions showed that the FF interactions resulted in more successful deception, as well as acceptance of deception, and prompted more neural activation in the rDLPFC than the FB interactions. We found that the deception magnitude escalated in both FF and FB interactions, but rDLPFC activity during deception diminished over time only in the FF interactions but not in FB interactions, suggesting that the deceivers behaviourally adapted to deception over time in both types of interactions, but the neural adaptation occurred only in the FF interactions. Furthermore, neural adaptation in FF interactions was associated with behavioural switching after deception, indicating that the rDLPFC contributes to deception adaptation and the control of switching between deception and honesty. The FF interactions were also characterized by activity in the rTPJ, which showed an adaptation to deception. These findings highlight the importance of interactive situations in dyadic naturalistic settings for deception and the role of the rDLPFC and rTPJ in the slippery-slope effect in deception.

Differential levels of prefrontal cortex glutamate+glutamine in adults with antisocial personality disorder and bipolar disorder: A proton magnetic resonance spectroscopy study

As the main excitatory neurotransmitter in the central nervous system, glutamate, as measured in combination with glutamine (Glx), is implicated in several psychopathologies when levels are aberrant. One illness that shows heightened Glx levels is bipolar disorder (BD), an illness characterized by high impulsivity. In addition, although animal studies have reported elevated levels of Glx in aggressive and impulsive phenotypes, no study, to our knowledge, has reported Glx in the human cortex in relation to aggression. Here, we addressed the question of whether elevated levels of Glx would be present in patients with BD and antisocial personality disorder (ASPD), a condition associated with aggression and, like BD, also presents high impulsivity. We recruited individuals with ASPD (n = 18), individuals with BD (n = 16), and a healthy control group (n = 24). We used proton magnetic resonance spectroscopy to measure relative neurometabolite concentrations in the left dorsolateral prefrontal cortex (dlPFC) and supra-genual anterior cingulate cortex (ACC), two brain regions associated with impulsivity and behavior control. We found significantly elevated levels of Glx in the ASPD group relative to the BD and healthy control groups in the dlPFC (p = .014), and a positive correlation between Glx levels and aggression in the dlPFC in the ASPD group alone (r = .59, p = .026). These findings suggest a link between aggression in ASPD and Glx levels.

Virtual Brain Projection for Evaluating Trans-skull Beam Behavior of Transcranial Ultrasound Devices

Focused ultrasound single-element piezoelectric transducers constitute a promising method to deliver ultrasound to the brain in low-intensity applications, but are subject to defocusing and high attenuation because of transmission through the skull. Here, a novel virtual brain projection method is used to superimpose a magnetic resonance image of the brain in ex vivo human skulls to provide targets during trans-skull focused ultrasound single-element piezoelectric transducer pressure field mapping. Positions of the transducer, skull and hydrophone are tracked in real time using a stereoscopic navigation camera and 3-D Slicer software. Virtual targets of the left dorsolateral prefrontal cortex, left hippocampus and cerebellar vermis were chosen to illustrate the method's flexibility in evaluating focal-zone beam distortion and attenuation. The regions are of interest as non-invasive brain stimulation targets in the treatment of neuropsychiatric disorders via repeated ultrasound exposure. The technical approach can facilitate the assessment of transcranial ultrasound device operator positioning reliability, intracranial beam behavior and computational model validation.