Cerebellar direct current stimulation enhances motor learning in older adults.

Developing novel approaches to combat age related declines in motor function is key to maintaining health and function in older adults, a subgroup of the population that is rapidly growing. Motor adaptation, a form of motor learning, has been shown to be impaired in healthy older subjects compared with their younger counterparts. Here, we tested whether excitatory anodal transcranial direct current stimulation (tDCS) over the cerebellum could enhance adaptation in older subjects. Participants performed a "center-out" reaching task, adapting to the sudden introduction of a visual cursor rotation. Older participants receiving sham tDCS (mean age 56.3 ± 6.8 years) were slower to adapt than younger participants (mean age 20.7 ± 2.1 years). In contrast, older participants who received anodal tDCS (mean age 59.6 ± 8.1 years) adapted faster, with a rate that was similar to younger subjects. We conclude that cerebellar anodal tDCS enhances motor adaptation in older individuals. Our results highlight the efficacy of the novel approach of using cerebellar tDCS to combat age related deficits in motor learning.

Consensus: Can transcranial direct current stimulation and transcranial magnetic stimulation enhance motor learning and memory formation?

Noninvasive brain stimulation has developed as a promising tool for cognitive neuroscientists. Transcranial magnetic (TMS) and direct current (tDCS) stimulation allow researchers to purposefully enhance or decrease excitability in focal areas of the brain. The purpose of this article is to review information on the use of TMS and tDCS as research tools to facilitate motor memory formation, motor performance, and motor learning in healthy volunteers. Studies implemented so far have mostly focused on the ability of TMS and tDCS to elicit relatively short-lasting motor improvements and the mechanisms underlying these changes have been only partially investigated. Despite limitations, including the scarcity of data, work that has been already accomplished raises the exciting hypothesis that currently available noninvasive transcranial stimulation techniques could modulate motor learning and memory formation in healthy humans and potentially in patients with neurologic and psychiatric disorders.

Noninvasive brain stimulation in stroke rehabilitation.

Stroke is a common disorder that produces a major burden to society, largely through long-lasting motor disability in survivors. Recent studies have broadened our understanding of the processes underlying recovery of motor function after stroke. Bilateral motor regions of the brain experience substantial reorganization after stroke, including changes in the strength of interhemispheric inhibitory interactions. Our understanding of the extent to which different forms of reorganization contribute to behavioral gains in the rehabilitative process, although still limited, has led to the formulation of novel interventional strategies to regain motor function. Transcranial magnetic (TMS) and DC (tDCS) electrical stimulation are noninvasive brain stimulation techniques that modulate cortical excitability in both healthy individuals and stroke patients. These techniques can enhance the effect of training on performance of various motor tasks, including those that mimic activities of daily living. This review looks at the effects of TMS and tDCS on motor cortical function and motor performance in healthy volunteers and in patients with stroke. Both techniques can either enhance or suppress cortical excitability, and may move to the clinical arena as strategies to enhance the beneficial effects of customarily used neurorehabilitative treatments after stroke.