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Functional connectivity of the anterior cingulate cortex predicts treatment outcome for rTMS in treatment-resistant depression at 3-month follow-up
Repetitive transcranial magnetic stimulation (rTMS) is a first-line treatment for treatment-resistant depression (TRD). The mechanisms of action of rTMS are not fully understood, and no biomarkers are available to assist in clinical practice to predict response to rTMS. This study aimed to demonstrate that after-rTMS clinical improvement is associated with functional connectivity (FC) changes of the subgenual cingulate cortex (sgACC) and rostral anterior cingulate (rACC), and FC of sgACC and rACC might serve as potential predictors for treatment response.Cortical modulation of nociception by galvanic vestibular stimulation: A potential clinical tool?
Vestibular afferents converge with nociceptive ones within the posterior insula, and can therefore modulate nociception. Consistent with this hypothesis, caloric vestibular stimulation (CVS) has been shown to reduce experimental and clinical pain. Since CVS can induce undesirable effects in a proportion of patients, here we explored an alternative means to activate non-invasively the vestibular pathways using innocuous bi-mastoid galvanic stimulation (GVS), and assessed its effects on experimental pain.A frontal-vagal network theory for Major Depressive Disorder: Implications for optimizing neuromodulation techniques
Major Depressive Disorder (MDD) is a psychiatric disorder characterized by high comorbidity with cardiovascular disease. Furthermore, a combination of high heart rate (HR) and low heart rate variability (HRV) has been frequently reported in depressed patients. The present review proposes a frontal-vagal (brain-heart) network that overlaps with functional nodes of the depression network. Moreover, we summarize neuromodulation studies that have targeted key nodes in this depression network, with subsequent impact on heart rate (HR) or heart-rate-variability (HRV), such as the dorsolateral prefrontal cortex (DLPFC), subgenual anterior cingulate cortex (sgACC), and the vagus nerve (VN).Cardiovascular differences between sham and active iTBS related to treatment response in MDD
Heart rate in MDD is often dysregulated, expressed in overall higher heart rates (HR) and lower heart rate variability (HRV). Interestingly, HR decelerations have been reported after stimulation of the DLPFC using rTMS, suggesting connectivity between the DLPFC and the heart. Recently, a new form of rTMS called theta burst stimulation (TBS) has been developed. One form of TBS, intermittent TBS (iTBS), delivers 600 pulses in just 3 min.Cost of focality in TDCS: Interindividual variability in electric fields
In transcranial direct current stimulation (TDCS), electric current is applied via two large electrodes to modulate brain activity. Computational models have shown that large electrodes produce diffuse electric fields (EFs) in the brain, which depends on individual head and brain anatomy. Recently, smaller electrodes as well as novel electrode arrangements, including high-definition TDCS (HD-TDCS) montages, have been introduced to improve the focality of EFs. Here, we investigated whether the EFs of focal montages are more susceptible to interindividual anatomical differences.Transcranial direct current stimulation reduces seizure frequency in patients with refractory focal epilepsy: A randomized, double-blind, sham-controlled, and three-arm parallel multicenter study
Transcranial direct current stimulation (tDCS) has been explored in epilepsy with limited samples, varied parameters, and inconclusive results. We aimed to study the efficacy of tDCS for patients with refractory focal epilepsy.Prefrontal delta oscillations during deep brain stimulation predict treatment success in patients with obsessive-compulsive disorder
Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) is a promising neurotherapeutic approach for severe and refractory cases of obsessive-compulsive disorder (OCD). Successful VC/VS-DBS treatment alters function in frontostriatal pathways important for the etiopathogenesis of OCD [1–3]. Monitoring changes in frontostriatal functioning resulting from active DBS can reveal signatures of DBS engagement with disease-relevant pathways [1,4]. In particular, modulation of the dorsal-medial prefrontal cortex (dmPFC) seems to be crucial for therapeutic success: symptomatic OCD patients demonstrate hyperconnectivity between the VC/VS and dmPFC, which is normalized following successful VC/VS-DBS [1,5,6].Transcranial focused ultrasound pulsation suppresses pentylenetetrazol induced epilepsy in vivo
Epilepsy is a neurological disorder characterized by abnormal neuron discharge, and one-third of epilepsy patients suffer from drug-resistant epilepsy (DRE). The current management for DRE includes epileptogenic lesion resection, disconnection, and neuromodulation. Neuromodulation is achieved through invasive electrical stimulus including deep brain stimulation, vagus nerve stimulation, or responsive neurostimulation (RNS). As an alternative therapy, transcranial focused ultrasound (FUS) can transcranially and non-invasively modulate neuron activity.Color perception matches selectivity in human early visual cortex
Where and how the color perception formed in the human brain remains one of the most intriguing topics in vision science. Color selective neurons could be found along the visual hierarchy [1,2], but which level contributes directly to color perception and behaviorally correlated processing is still under debate. Lesion [3] and functional magnetic resonance imaging [4,5] studies in human subjects suggested a group of color-selective areas in the ventral occipitotemporal cortex (VOTC), which labeled V4/V4α or V8, might be critical for color percepts.Dopamine depletion effects on cognitive flexibility as modulated by tDCS of the dlPFC
Recent evidence suggests that transcranial direct current stimulation (tDCS) may interact with the dopaminergic system to affect cognitive flexibility. Objective/hypotheses: We examined whether putative reduction of dopamine levels through the acute phenylalanine/tyrosine depletion (APTD) procedure and excitatory anodal tDCS of the dorsolateral prefrontal cortex (dlPFC) are causally related to cognitive flexibility as measured by task switching and reversal learning.Combination of lithium and electroconvulsive therapy (ECT) is associated with higher odds of delirium and cognitive problems in a large national sample across the United States
Lithium is a helpful adjunct to patients undergoing ECT. However, only case reports and limited data suggest increase risk of delirium. Thus, this continues to be a controversial issue.Direct current stimulation-induced synaptic plasticity in the sensorimotor cortex: structure follows function
Non-invasive direct current stimulation (DCS) of the brain induces functional plasticity in vitro and facilitates motor learning across species. The effect of DCS on structural synaptic plasticity is currently unknown.Safety of transcranial focused ultrasound stimulation: A systematic review of the state of knowledge from both human and animal studies
Low-intensity transcranial focused ultrasound stimulation (TFUS) holds great promise as a highly focal technique for transcranial stimulation even for deep brain areas. Yet, knowledge about the safety of this novel technique is still limited.Impact of prior treatment on remission with intermittent theta burst versus high-frequency repetitive transcranial magnetic stimulation in treatment resistant depression
Multiple prior treatment failures are associated with reduced rates of remission to subsequent antidepressant treatment, including rTMS. The degree of treatment resistance that is especially predictive of inferior outcome is uncertain. Intermittent theta burst stimulation (iTBS) is a newer form of rTMS where less is known regarding clinical predictors of remission. The THREE-D study demonstrated that iTBS is non-inferior to 10 Hz rTMS for the treatment of depression.After-effects of 10 Hz tACS over the prefrontal cortex on phonological word decisions
Previous work in the language domain has shown that 10 Hz rTMS of the left or right posterior inferior frontal gyrus (pIFG) in the prefrontal cortex impaired phonological decision-making, arguing for a causal contribution of the bilateral pIFG to phonological processing. However, the neurophysiological correlates of these effects are unclear. The present study addressed the question whether neural activity in the prefrontal cortex could be modulated by 10 Hz tACS and how this would affect phonological decisions.Real-time estimation of electric fields induced by transcranial magnetic stimulation with deep neural networks
Transcranial magnetic stimulation (TMS) plays an important role in treatment of mental and neurological illnesses, and neurosurgery. However, it is difficult to target specific brain regions accurately because the complex anatomy of the brain substantially affects the shape and strength of the electric fields induced by the TMS coil. A volume conductor model can be used for determining the accurate electric fields; however, the construction of subject-specific anatomical head structures is time-consuming.The effect of electroconvulsive therapy (ECT) on serum tryptophan metabolites
Prior studies suggest that activation of the tryptophan catabolism via the kynurenine pathway by proinflammatory cytokines may be involved in the pathophysiology of depression. Electroconvulsive therapy (ECT) is an effective treatment for major depression (MD) with immunomodulation as one of the proposed modes of action.Combining reward and M1 transcranial direct current stimulation enhances the retention of newly learnt sensorimotor mappings
Reward-based feedback given during motor learning has been shown to improve the retention of the behaviour being acquired. Interestingly, applying transcranial direct current stimulation (tDCS) during learning over the primary motor cortex (M1), an area associated with motor retention, also results in enhanced retention of the newly formed motor memories. However, it remains unknown whether combining these distinct interventions result in an additive benefit of motor retention.No trace of phase: Corticomotor excitability is not tuned by phase of pericentral mu-rhythm
The motor potentials evoked by transcranial magnetic stimulation (TMS) over the motor hand area (M1-HAND) show substantial inter-trial variability. Pericentral mu-rhythm oscillations, might contribute to inter-trial variability. Recent studies targeting mu-activity based on real-time electroencephalography (EEG) reported an influence of mu-power and mu-phase on the amplitude of motor evoked potentials (MEPs) in a preselected group with strong pericentral mu-activity. Other studies that determined mu-power or mu-phase based on post-hoc trial sorting according in non-preselected individuals were largely negative.Distilling the essence of TMS-evoked EEG potentials (TEPs): A call for securing mechanistic specificity and experimental rigor
Using realistic sham stimulation, we have shown that transcranial magnetic stimulation (TMS) produces significant off-target excitation of the peripheral nervous system, even when applying state-of-the-art procedures to attenuate peripheral co-activation [1]. The peripherally evoked potentials (PEPs) strongly resembled TMS-evoked potentials (TEPs) [1]. Our study prompted a letter to the editor in the Brain Stimulation journal, signed by many researchers using TEP recordings [2]. While Belardinelli et al.Consistent linear and non-linear responses to invasive electrical brain stimulation across individuals and primate species with implanted electrodes
Electrical neuromodulation via implanted electrodes is used in treating numerous neurological disorders, yet our knowledge of how different brain regions respond to varying stimulation parameters is sparse.Transcranial direct current stimulation in inflammatory bowel disease patients modifies resting-state functional connectivity: A RCT
Chronic pain is known to be associated with functional and structural changes in the brain. Inflammatory bowel disease (IBD) presents with chronic abdominal pain in almost 35% of all patients. This study investigates structural and functional changes in magnetic resonance imaging (MRI) after transcranial direct current stimulation (tDCS) applied to ameliorate pain in IBD.Decoding voluntary movements and postural tremor based on thalamic LFPs as a basis for closed-loop stimulation for essential tremor
High frequency Deep brain stimulation (DBS) targeting motor thalamus is an effective therapy for essential tremor (ET). However, conventional continuous stimulation may deliver unnecessary current to the brain since tremor mainly affects voluntary movements and sustained postures in ET.Direction of TDCS current flow in human sensorimotor cortex influences behavioural learning
Recent studies have shown that neurophysiological outcomes of transcranial direct current stimulation (TDCS) are influenced by current flow in brain regions between the electrodes, and in particular the orientation of current flow relative to the cortical surface.Reproducibility in TMS–EEG studies: A call for data sharing, standard procedures and effective experimental control
A recent study by Conde, Tomasevic et al. (2019) [1] puts a spotlight on the subtleties of experimental design and analysis of studies involving TMS-evoked EEG potentials (TEPs), specifically focusing on the challenge of disentangling genuine cortical responses to TMS from those resulting from concomitant sensory activation. This is a relevant topic that the TMS–EEG community has previously identified [2] and addressed with different strategies [3–6]. Based on the similarity of the evoked EEG responses they obtained in real TMS at different sites and in sham conditions (auditory and somatosensory scalp stimulation), the authors of [1] inferred that TEPs can be significantly contaminated by the effects of concurrent, non-transcranial stimulation.
