http://jneuroengrehab.biomedcentral.com/articles/10.1186/s12984-017-0242-1
- Irma N. Angulo-Sherman,
- Marisol Rodríguez-Ugarte,
- Nadia Sciacca,
- Eduardo IáñezEmail author and
- José M. Azorín
Journal of NeuroEngineering and Rehabilitation201714:31
DOI: 10.1186/s12984-017-0242-1
© The Author(s) 2017
Received: 14 November 2016
Accepted: 8 April 2017
Published: 19 April 2017
Abstract
Background
Transcranial direct current stimulation
(tDCS) is a technique for brain modulation that has potential to be used
in motor neurorehabilitation. Considering that the cerebellum and motor
cortex exert influence on the motor network, their stimulation could
enhance motor functions, such as motor imagery, and be utilized for
brain-computer interfaces (BCIs) during motor neurorehabilitation.
Methods
A new tDCS montage that influences
cerebellum and either right-hand or feet motor area is proposed and
validated with a simulation of electric field. The effect of current
density (0, 0.02, 0.04 or 0.06 mA/cm2) on
electroencephalographic (EEG) classification into rest or
right-hand/feet motor imagery was evaluated on 5 healthy volunteers for
different stimulation modalities: 1) 10-minutes anodal tDCS before EEG
acquisition over right-hand or 2) feet motor cortical area, and 3)
4-seconds anodal tDCS during EEG acquisition either on right-hand or
feet cortical areas before each time right-hand or feet motor imagery is
performed. For each subject and tDCS modality, analysis of variance and
Tukey-Kramer multiple comparisons tests (p
<0.001) are used to detect significant differences between
classification accuracies that are obtained with different current
densities. For tDCS modalities that improved accuracy, t-tests (p <0.05) are used to compare μ and β band power when a specific current density is provided against the case of supplying no stimulation.
Results
The proposed montage improved the
classification of right-hand motor imagery for 4 out of 5 subjects when
the highest current was applied for 10 minutes over the right-hand motor
area. Although EEG band power changes could not be related directly to
classification improvement, tDCS appears to affect variably different
motor areas on μ and/or β band.
Conclusions
The proposed montage seems capable of
enhancing right-hand motor imagery detection when the right-hand motor
area is stimulated. Future research should be focused on applying higher
currents over the feet motor cortex, which is deeper in the brain
compared to the hand motor cortex, since it may allow observation of
effects due to tDCS. Also, strategies for improving analysis of EEG
respect to accuracy changes should be implemented.
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