Abstract
Stimulation using weak electrical direct currents has shown to be capable of inducing polarity-dependent diminutions or elevations in motor and visual cortical excitability. The aim of the present study was to test if reading during transcranial direct current stimulation (tDCS) is able to modify stimulation-induced plasticity in the visual cortex. Phosphene thresholds (PTs) in 12 healthy subjects were recorded before and after 10 min of anodal, cathodal, and sham tDCS in combination with reading. Reading alone decreased PTs significantly, compared to the sham tDCS condition without reading. Interestingly, after both anodal and cathodal stimulation there was a tendency toward smaller PTs. Our results support the observation that tDCS-induced plasticity is highly dependent on the cognitive state of the subject during stimulation, not only in the case of motor cortex but also in the case of visual cortex stimulation.
Highlights
Over the last 15 years transcranial direct current stimulation has become a promising tool in neuroplasticity research with perspectives in clinical neurophysiology (Nitsche and Paulus, 2011; Miniussi and Ruzzoli, 2013; Kuo et al, 2014)
The most common way to evaluate cortical excitability changes induced by transcranial direct current stimulation (tDCS) is by applying single-pulse transcranial magnetic stimulation (TMS) to the motor cortex (M1), since it allows the quantifiable measurements of its effects through the analysis of motor-evoked potentials (MEPs)
TDCSinduced neuronal plasticity over V1 was modified by reading: instead of showing the previously observed bidirectional response of anodal and cathodal stimulations on Phosphene thresholds (PTs) (Antal et al, 2003a,b), application of both stimulation polarities resulted in a tendency toward an increase in cortical excitability that was significant after cathodal stimulation compared to sham
Summary
Over the last 15 years transcranial direct current stimulation (tDCS) has become a promising tool in neuroplasticity research with perspectives in clinical neurophysiology (Nitsche and Paulus, 2011; Miniussi and Ruzzoli, 2013; Kuo et al, 2014). The most common way to evaluate cortical excitability changes induced by tDCS is by applying single-pulse transcranial magnetic stimulation (TMS) to the motor cortex (M1), since it allows the quantifiable measurements of its effects through the analysis of motor-evoked potentials (MEPs). Later human studies confirmed these results, demonstrating that the tDCS aftereffects are relatively short lasting in the visual areas compared to those of the M1, when using the same stimulation intensities and durations. The efficacy of tDCS over visual areas can be demonstrated by measuring phosphene thresholds (PTs). We have elicited phosphenes by applying short trains of 5-Hz repetitive TMS delivered over the primary visual cortex (V1; Antal et al, 2003a). Anodal stimulation resulted in the opposite effect, probably via induction of cortical hyperexcitability
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
