It is suggested that tES may enhance attentional functions and the left vDLPFC may be a potential target for future tES studies aiming to improve attention.
Abstract
Non-invasive brain stimulation techniques, such as transcranial electric stimulation (tES), are increasingly promoted as methods to enhance attention. However, their efficacy and optimal stimulation targets remain uncertain. We conducted a preregistered meta-analysis of randomized controlled trials in healthy adults (58 trials, 295 outcomes) examining the effects of tES on attentional functions (PROSPERO: CRD42023487035), complemented by a performance-electric field correlation (PEC) analysis to identify brain regions most strongly linked to tES-induced behavioral improvements. In general, tES produced a small but significant improvement in attentional functions compared to control conditions (standardized mean difference [SMD] = 0.24, 95% confidence interval [CI] = 0.12-0.36, I2 = 61%). Small but consistent benefits were observed in trials assessing attentional functions after stimulation (40 trials, SMD = 0.23, 95% CI = 0.12-0.33, I2 = 39%) and in trials applying anodal transcranial direct current stimulation (tDCS) targeting prefrontal regions (vs sham; 31 trials, SMD = 0.26, 95% CI = 0.12-0.39, I2 = 46%) with no evidence of publication bias or serious imprecision. The PEC analysis further revealed that tDCS-induced electric fields in the ventral subregion of the left dorsolateral prefrontal cortex (left vDLPFC) were most strongly associated with improvements in attentional functions following tDCS. Taken together, these findings suggest that tES may enhance attentional functions and the left vDLPFC may be a potential target for future tES studies aiming to improve attention.
Objective. Non-invasive brain stimulation (NIBS) techniques are increasingly used to modulate brain activity in basic and translational research. Kilohertz transcranial magnetic perturbation (kTMP) is a recently developed NIBS approach that uses magnetic induction to generate subthreshold electric fields in the brain. kTMP has been shown to modulate cortical excitability while producing no perceptible sensation at the stimulation site. However, its safety and tolerability have not yet been systematically evaluated—a gap this study aims to address. Approach. We conducted sham-controlled experiments, within-subject comparisons, and patient feasibility studies with kTMP, entailing 433 sessions across 143 individuals. Participants rated annoyance, muscle activation, and pain on a 0–10 scale after each session. With primary motor cortex (M1) as the target, we compared active stimulation (∼8 V m−1 cortical field) to sham (0 V m−1) in healthy adults and chronic stroke patients. In healthy adults, we compared active vs. sham stimulation applied to dorsolateral prefrontal cortex, superior temporal gyrus, and cerebellum. Additional datasets examined tolerability across active kTMP parameters and multi-session feasibility in stroke patients. Safety monitoring included continuous observation for abnormal motor activity and EMG recording in initial experiments. Main results. No device-related adverse reactions occurred across 433 sessions. EMG monitoring revealed no artifacts, and no participants exhibited involuntary muscle contractions or signs of abnormal cortical excitation. kTMP was well tolerated, with mean ratings for active and sham stimulation remaining below 1.5 (where ‘2’ indicates just-noticeable sensation). Permutation tests showed no significant active–sham differences and bootstrapped 95% confidence intervals consistently fell within the ±1 equivalence margin. When auditory masking was used, participants could not distinguish active from sham stimulation. Significance. kTMP achieves cortical E-fields an order of magnitude higher than conventional subthreshold tES while maintaining robust safety margins and tolerability indistinguishable from sham, supporting its use for rigorous double-blind studies and translational settings. Trial Registration: ClinicalTrials.gov Identifier: NCT06317194.
Christina M. Merrick, Guy Avraham, Philipp Reber et al.· Journal of Neural Engineerin...· 0 citations
BACKGROUND
Impulsivity is a multidimensional construct comprising motor and cognitive components, subserved by partially dissociable prefrontal networks. Transcranial direct current stimulation (tDCS) has emerged as a promising tool to modulate these circuits, yet its domain-specific effects remain poorly defined.
METHODS
A systematic review of studies published up to March 2025 was conducted. Eligible studies assessed tDCS effects on impulsivity-related outcomes, including response inhibition, delay discounting, risk taking, planning, and impulsive behaviour. Results were synthesised according to stimulation parameters, cortical targets, population characteristics, and impulsivity domains.
RESULTS
Across studies, 156 positive, 28 negative, and 133 non-significant outcomes were identified. Converging evidence indicates that tDCS most reliably enhances motor impulsivity, particularly response inhibition, following stimulation of right-lateralised prefrontal regions such as the inferior frontal gyrus and dorsolateral prefrontal cortex. In contrast, effects on cognitive impulsivity domains were inconsistent and highly context-dependent, influenced by task demands, stimulation protocols, and inter-individual variability. Evidence for improvements in planning remains limited but promising.
CONCLUSIONS
tDCS exerts positive effects on inhibitory control but shows limited reliability for higher-order decision-making processes. These findings underscore the need for circuit-specific targeting and methodological standardisation to advance precision neuromodulation approaches in psychiatry.
Alexandre Chouk, JulianaTeti Mayer, M. Nicolier et al.· Progress in Neuro-psychophar...· 0 citations
Transcranial alternating current stimulation (tACS) is a promising noninvasive intervention for modulating pathological brain oscillations in Parkinson's disease (PD). To evaluate its clinical and neurophysiological efficacy, we searched five databases (Web of Science, PubMed, Scopus, Google Scholar and APA PsycInfo) up to August 31, 2025, for trials employing tACS in patients with idiopathic PD. Risk of bias was assessed using the RoB 2 and ROBINS-I tools. Random-effects meta-analyses were used to calculate standardized (SMD) and unstandardized mean differences (MD) with 95% confidence intervals (CIs). We included 10 studies (184 patients with PD, mean age: 64.9, mean disease duration: 5.2 years) in the qualitative review and seven trials (146 patients with PD, mean age: 65.6, mean disease duration: 5 years) in the meta-analysis. No statistically significant differences favoring active tACS over control were found in overall motor severity (UPDRS: SMD = 0.21, 95% CI [-0.10, 0.52], p = 0.097), tremor (SMD = -0.40, 95% CI [-1.97, 1.17], p = 0.478), or a neurophysiological marker of inhibitory response, represented by short intracortical inhibition (MD = 0.00, 95% CI [-0.40, 0.41], p = 0.971). The prediction intervals indicated substantial uncertainty, and significant between-study heterogeneity was observed, particularly for tremor outcomes (I2 = 86.1%). This variability and limitation in evidence quality is largely driven by small sample sizes, highly heterogeneous stimulation protocols, and varying outcome assessments. Systematically, tACS was generally well-tolerated, with no serious adverse events reported across the included studies; however, formal safety assessment was beyond the scope of this review. Current exploratory evidence shows a lack of consistent improvements in motor symptoms or functions in PD largely due to protocol-level heterogeneity. Future studies should consistently assess the MDS-UPDRS III post-tACS and report its specific subscores alongside neurophysiological measures to enable robust meta-analyses.
T. T. Mai, T. Gjishti, K. Witt et al.· medRxiv· 0 citations
Objective This meta-analysis investigated the effects of functional magnetic resonance imaging neurofeedback (fMRI-NF) on inattention and cognitive dysfunctions. Methods Using the keywords “fMRI neurofeedback” and “attention,” randomized controlled trials were identified from major electronic databases from inception to June 2024. Outcomes were expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). Results Five studies including 214 participants (mean age = 16.8 years) were analyzed. The median number of fMRI-NF sessions was four (range 3−15), and the median follow-up duration was three weeks (range 1−10 weeks). Stimulation sites included the right inferior frontal gyrus (n = 2), right anterior insular cortex (n = 1), dorsal anterior cingulate cortex (n = 1), and an individualized approach (n = 1). The primary analysis showed no significant difference in inattention improvement between the fMRI-NF and control groups (SMD = 0.17, 95% CI −0.15 to 0.49, p = 0.30; four studies, 153 participants). Secondary outcomes also showed no significant intergroup differences, including vigilance (SMD = 0.08, 95% CI −0.49 to 0.65, p = 0.79), inhibition (SMD = −0.68, 95% CI −2.11 to 0.74, p = 0.35), and processing speed (SMD = −0.56, 95% CI −1.38 to 0.27, p = 0.19). Heterogeneity was greater for the secondary outcomes than for the primary outcome, with I2 values of 49% for vigilance, 90% for inhibition, and 79% for processing speed, compared with 0% for the primary outcome. Conclusion Given the limited evidence available to date, current evidence remains insufficient to draw robust conclusions regarding the therapeutic effectiveness of fMRI-NF.
Ying-Hsin Chen, Shun-Chin Liang, Cheuk-Kwan Sun et al.· Clinical Psychopharmacology...· 0 citations
Introduction Spatial memory relies on distributed hippocampal–cortical networks that are highly sensitive to modulation of excitability, connectivity, and synaptic plasticity. Transcranial magnetic stimulation (TMS) has emerged as a promising tool to experimentally probe and therapeutically modulate these networks, although its effects on spatial memory remain heterogeneous. Methods We conducted a PRISMA-guided systematic review synthesizing evidence from rodent and human studies examining the effects of TMS on spatial memory. A total of 35 studies (23 animal, 12 human) identified through searches of Scopus, Web of Science, and PubMed were included, encompassing a broad range of stimulation protocols, behavioral paradigms, and neurophysiological outcomes. Results In animal models, TMS consistently improved spatial learning and memory under pathological conditions, including neurodegenerative, vascular, stress-related, and injury models. These effects were associated with convergent mechanisms, including restoration of hippocampal long- term potentiation, modulation of neurotrophic signaling, reduced apoptosis and neuroinflammation, enhanced synaptic plasticity, and recovery of hippocampal network function. In contrast, findings in healthy animals were mixed and strongly dependent on stimulation parameters. Human findings were similarly variable. Improvements were observed in some clinical populations, whereas results in healthy individuals were inconsistent and task dependent. Neurophysiological evidence indicated modulation of oscillatory activity and hippocampal–cortical connectivity, although these changes did not always translate into measurable behavioral effects. Discussion Overall, TMS effects on spatial memory appear to be strongly state-dependent, reflecting interactions between stimulation parameters and underlying circuit integrity. Further research should prioritize multimodal approaches integrating behavioral and neurophysiological measures, particularly in clinical populations, to improve mechanistic understanding and translational applicability. Systematic review registration https://osf.io/, identifier 10.17605/OSF.IO/32VWN.
J. C. Lobo, A. Gutiérrez-Menéndez, Marta Mendez et al.· Frontiers in Behavioral Neur...· 0 citations
Repetitive transcranial magnetic stimulation (rTMS) is a subcategory of non-invasive brain stimulation (NIBS), used to modulate brain plasticity and improve post-stroke recovery. Neuronavigation is used to improve the accuracy of stimulation with the aim of achieving a superior clinical outcome than with conventional targeting. The objective of this review is to evaluate the efficacy of navigated rTMS in subacute and chronic stroke patients in comparison to sham stimulation. We conducted a systematic-review and meta-analysis of randomized controlled trials (RCTs) identified from Pubmed, Scopus and Cochrane CENTRAL. Trials employing neuronavigated rTMS were included of these five types; high and low frequency rTMS, intermittent and continuous theta-burst stimulation (TBS) and Hebbian-type stimulation. 13 RCTs were included after a screening of 1900 studies. 606 patients receiving either active (n = 360) or sham stimulation (n = 246) were assessed. The pooled standardized mean difference (SMD) favored rTMS over sham SMD = 0.4 (95 %CI: 0.11-0.69), with moderate heterogeneity I2 = 55 %. Among stimulation modalities, continuous TBS showed the largest pooled effect. rTMS was also associated with significant improvements in disability-related outcomes, SMD = 0.61 (95 % CI 0.14-1.08). Navigated rTMS is associated with modest but significant improvements in motor and disability outcomes in subacute and chronic stroke. Large comparative trials are required to clarify the potential added value over conventional targeting approaches.
E. Beris, Parmenion P. Tsitsopoulos, A. Katsanos et al.· Journal of clinical neurosci...· 0 citations
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