Timing is Important for Learning

The timing of brain stimulation during movements can benefit neuroplasticity – the brain’s ability to change from experience. If researchers could tweak neuroplasticity in stroke patients, this would considerably improve their chances of rehabilitation. Therefore, researcher George F. Wittenberg and colleagues stimulated the brains of 16 participants, while a robotic arm eased their arm movements when the participants reached for an object.. The team collaborates across University of Maryland Schools of Medicine, Moss Rehabilitations Research Institute along with Veterans Affairs Medical Center in USA.

Stroke is a leading cause of long term disability worldwide. To come to grips with rehabilitation of stroke patients, focus lies on jogging their neuroplasticity in a particular region of the brain involved with carrying out movements – the motor cortex – in combination with carrying out the movements themselves.

Notably, a stream of research unveiled that training movements in combination with brain stimulation indeed tweaks plasticity. One such form of stimulation is transcranial magnetic stimulation (TMS), where a coil, placed near the head, produces small electrical currents in the region of the brain just below the coil.

TMS enhances neuroplasticity while training movements isolated to small body parts, like the thumb. To ease movements of an entire arm, robotics is increasingly being used. However, it is still unclear how the timing of brain stimulation during, for example, a reaching task influences the extent and type of neuroplasticity. The timing could show an effect, since the motor cortex triggers a signal to move the arm before the muscles in the arm actually start to contract.

To find out, Wittenberg and his team studied 16 healthy participants. While the participants were moving their arm to reach for, say a glass, a robot eased their movements. This particular movement is called reaching. At the same time, the researchers stimulated the participants ́ motor cortex, using TMS. They either stimulated before the actual reaching, during the reaching or randomly. They then evaluated the brain signals.

The researchers found that the timing of TMS during robotic reaching indeed affects plasticity. Strikingly, the effect was positive when the researchers stimulated the brain before the muscle activity of reaching started. Stimulations during the reaching task showed negative effect. And stimulating randomly showed no change.

These new findings show that the sensitivity of the motor cortex is dynamic during the stimulation exercise. And they open up promising avenues for rehabilitating stroke survivors.
The paper was published in Clinical Neurophysiology.

About the author:

Tanja_Jensen_Getty_ScienceDr. Tanja Jensen is a neuroscientist and a writer. Although she works at Novo Nordisk, a global pharmaceutical company, she also does science writing on a regular basis at the science park Medicon Village in Lund, Sweden. In her work she writes about medical safety along with the awe-inspiring world of life science. In her spare time, this awe circles around the brain, which you can read more about in her blog. Tanja is also a triathlete and truly enjoys exercising – especially when the weather is nice.

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