Device-based non-invasive brain stimulation (NIBS) techniques show promise for the treatment of neurological and psychiatric disorders, although inconsistencies in protocol designs and study findings can make the field difficult to navigate. In this Review, we discuss applications of NIBS for enhancing cognitive and motor function in people with various neurological diseases that are characterized by disruption of large-scale brain networks, including neurodegenerative diseases and brain lesion disorders such as stroke and traumatic brain injury. In particular, we focus on repetitive transcranial magnetic stimulation and transcranial electrical stimulation, as these techniques have been widely used in clinical settings and randomized controlled trials. We summarize and synthesize current knowledge, and highlight gaps and shortcomings in the existing research that make it difficult to draw firm conclusions, including small sample sizes, heterogeneous patient populations and variations in stimulation protocols. We believe that a rapid evolution of NIBS techniques from state-dependent, network-informed, multifocal and subcortical paradigms to individualized electric field modelling and accelerated NIBS protocols will improve the management of neurological disorders. However, realizing this potential will require us to address crucial challenges and acquire deeper mechanistic insights, with the aim of developing adaptive, biomarker-driven protocols to optimize target engagement, dosing and timing for each patient.

• Publication type
• Journal Article MeSH
• Review MeSH

Aging populations face significant cognitive challenges, particularly in working memory (WM). Transcranial alternating current stimulation (tACS) offer promising avenues for cognitive enhancement, especially when inspired by brain physiology. This study (NCT04986787) explores the effect of multifocal tACS on WM performance in healthy older adults, focusing on fronto-parietal network modulation. Individualized physiology-inspired tACS applied to the fronto-parietal network was investigated in two blinded cross-over experiments. The first experiment involved monofocal/bifocal theta-tACS to the fronto-parietal network, while in the second experiment cross-frequency theta-gamma interactions between these regions were explored. Participants have done online WM tasks under the stimulation conditions. Network connectivity was assessed via rs-fMRI and multichannel electroencephalography. Prefrontal monofocal theta tACS modestly improved WM accuracy over sham (d = 0.30). Fronto-parietal stimulation enhanced WM task processing speed, with the strongest effects for bifocal in-phase theta tACS (d = 0.41). Cross-frequency stimulations modestly boosted processing speed with or without impairing task accuracy depending on the stimulation protocol. This research adds to the understanding of physiology-inspired brain stimulation for cognitive enhancement in older subjects.

• Keywords
• Cognition, Electric field modelling, Healthy aging, Multifocal, Neuroimaging, Orchestrated brain stimulation, Systems neuroscience, Working memory, tACS,
• Publication type
• Journal Article MeSH

• MeSH
• Alzheimer Disease * therapy   MeSH
• Cognitive Dysfunction * therapy   etiology   MeSH
• Humans MeSH
• Transcranial Direct Current Stimulation methods   MeSH
• Transcranial Magnetic Stimulation methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH
• News MeSH

Transcranial direct current stimulation combined with cognitive training (tDCS-cog) represents a promising approach to combat cognitive decline among healthy older adults and patients with mild cognitive impairment (MCI). In this 5-day-long double-blinded randomized trial, we investigated the impact of intensified tDCS-cog protocol involving two trains of stimulation per day on working memory (WM) enhancement in 35 amnestic and multidomain amnestic MCI patients. Specifically, we focused to improve WM tasks relying on top-down attentional control and hypothesized that intensified tDCS would enhance performance of visual object matching task (VOMT) immediately after the stimulation regimen and at a 1-month follow-up. Secondarily, we explored whether the stimulation would augment online visual working memory training. Using fMRI, we aimed to elucidate the neural mechanisms underlying the intervention effects by analyzing BOLD activations during VOMT. Our main finding revealed no superior after-effects of tDCS-cog over the sham on VOMT among individuals with MCI as indicated by insignificant immediate and long-lasting after-effects. Additionally, the tDCS-cog did not enhance online training as predicted. The fMRI analysis revealed brain activity alterations in right insula that may be linked to tDCS-cog intervention. In the study we discuss the insignificant behavioral results in the context of the current evidence in tDCS parameter space and opening the discussion of possible interference between trained cognitive tasks.

• MeSH
• Dorsolateral Prefrontal Cortex MeSH
• Double-Blind Method MeSH
• Cognitive Dysfunction * therapy   MeSH
• Memory, Short-Term physiology   MeSH
• Humans MeSH
• Brain diagnostic imaging   MeSH
• Prefrontal Cortex physiology   MeSH
• Transcranial Direct Current Stimulation * methods   MeSH
• Aged MeSH
• Check Tag
• Humans MeSH
• Aged MeSH
• Publication type
• Journal Article MeSH
• Randomized Controlled Trial MeSH