Abstract
In this study, the effective application of high-definition transcranial direct current stimulation (HD-tDCS) based on the whole brain hemodynamic response in stroke patients was investigated using functional near-infrared spectroscopy (fNIRS). The intrahemispheric and interhemispheric synchronization and cortical activity based on the time during 1 mA HD-tDCS were examined in 26 chronic cerebrovascular disease patients. At the beginning of HD-tDCS, the synchronization and brain activity in the whole brain increased rapidly and decreased after 5 min. In the middle of tDCS, the synchronization began to increase again, and strong synchronic connections were formed around the desired stimulation area. After tDCS, strong cortical activation was observed in the stimulation area, indicating that the baseline of the oxyhemoglobin (HbO) signal increased in the desired stimulation area. Therefore, the results of this study indicate that HD-tDCS can be applied efficiently to enhance the effect of tDCS. This stimulation method with tDCS can be explored clinically for more neurorehabilitation of patients with degenerative brain diseases.
Highlights
Neuronal plasticity is one of the key factors influencing motor recovery after stroke [1].Numerous stroke rehabilitation schemes have been developed to promote neuronal plasticity, but few among such treatments have sufficiently improved motor functions [2,3]
There was no activation in the pre-rest stage, and cortical activation is shown in the regions with significant contrast with the functional near-infrared spectroscopy (fNIRS) signal of pre-rest stage
After a few minutes of stimulation, strong cortical activation was noticed in wide brain areas such as medial pre-frontal (MPF), Fr, M1, temporal lobe (Tm), supplementary motor area (SMA), and pre-motor cortex (PM), which was lasted for 5 min
Summary
Neuronal plasticity is one of the key factors influencing motor recovery after stroke [1].Numerous stroke rehabilitation schemes have been developed to promote neuronal plasticity, but few among such treatments have sufficiently improved motor functions [2,3]. Many results of previous studies indicate that tDCS induces a network and activation changes in the brain, detailed effects of tDCS based on the time and effective method to improve rehabilitation treatments are less well known. This is because the neuroimaging equipment used in previous studies is an offline method that cannot measure during tDCS, cannot observe the whole brain, or prohibits synchrony analysis because of low temporal resolution. HD-tDCS contains five small ring-based electrodes which are approximately the same size as standard EEG electrodes or fNIRS optodes They can produce focused stimulation and be simultaneously integrated with fNIRS system [25,26]
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