Hebbian-type stimulation during robot-assisted training in patients with stroke

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Motor Control

Background:

• Motor function improvements post-training correlate with primary motor cortex (M1) plasticity.
• Hebbian-type transcranial magnetic stimulation (TMS) during movement enhances M1 plasticity in healthy individuals, outperforming random stimulation.

Purpose of the Study:

• To investigate if Hebbian-type M1 stimulation combined with training enhances M1 reorganization in stroke patients.
• To assess the effects of Hebbian-type M1 stimulation on motor maps and intracortical excitability in chronic stroke survivors.

Main Methods:

• Six chronic stroke patients performed robot-assisted wrist extension movements at 0.2 Hz.
• Subthreshold repetitive TMS was applied over M1 (contralateral or ipsilateral) at 0.1 Hz in a Hebbian-temporal relationship to movements.
• Changes in motor maps and intracortical excitability were evaluated using TMS.

Main Results:

• Training with Hebbian-type TMS (contralateral or ipsilateral M1) induced differential effects on motor maps and intracortical inhibition.
• Motor map shifts correlated with increased intracortical excitability.
• Unlike in healthy individuals, ipsilateral M1 stimulation did not show inhibition, and contralateral M1 stimulation's facilitatory effects were subtler in stroke patients.

Conclusions:

• Hebbian-type TMS is a feasible intervention for stroke patients, capable of inducing M1 map reorganization and reducing GABAergic inhibition.
• The effects of TMS on motor reorganization differ in the injured brain and are influenced by lesion location.
• Personalized TMS protocols are crucial for optimizing motor reorganization based on individual patient pathology.