Abstract
Purpose :
Transcranial direct current stimulation (tDCS) has attracted attention as a non-invasive neuromodulation method. The purpose of this study is to investigate whether tDCS enhances the performance of retinal prosthsis.
Methods :
Four Long-Evans rats were anesthetized with urethane (1.75g/kg). Right visual cortex was exposed by craniotomy, and 2mm-diameter electrode for tDCS was placed on the skull adjacent to the exposed area. Anodal direct current (0.1 mA, 10 minutes) was applied to the electrode. Electrically evoked potentials (EEPs), evoked by suprachoroidal electrical stimulation to the retina, were recorded before and after the application of tDCS.
Results :
No significant increase of EEP amplitude was detected. However, the EEP slope (defined as the slope between first negative peak and second positive peak in EEP waveform) significantly increased at 5 and 60 minutes after the application of tDCS when 500 μA-amplitude 0.5 ms-duration current pulses were applied to the eye (paired t-test, p<0.05). The increase in averaged EEP slope was observed when 700 μA-amplitude pulses were applied, but this was not statistically significant.
Conclusions :
Results suggested that anodal tDCS to visual cortex increased cortical excitability, but the increase was significant only in EEP slope, not in EEP amplitude. We will try to improve the application method of tDCS to enhance its effect on neural response in the next step.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.