Does 10-Hz cathodal oscillating current of the parieto-occipital lobe modulate target detection?

Abstract

The phase of alpha (8-12 Hz) brain oscillations have been associated with moment to moment changes in visual attention and awareness. Previous work has demonstrated that endogenous oscillations and subsequent behavior can be modulated by oscillating transcranial current stimulation (otCS). The purpose of the current study is to establish the efficacy of cathodal otCS for modulation of the ongoing alpha brain oscillations, allowing for modulation of individuals visual perception. Thirty-six participants performed a target detection with sham and 10-Hz cathodal otCS. Each participant had two practice and two experimental sets composed of three blocks of 128 trials per block. Stimulating electrodes were small square sponges (20 cm2) placed on the participants head with the anode electrode at Cz and the cathode electrode at Oz. A 0.5 mA current was applied at the cathode electrode every 100 ms (10 Hz frequency) during the otCS condition. The same current and frequency was applied for the first 10-20 s of the sham condition, after which the current was turned off. Target detection rates were separated into ten 10-ms bins based on the latency between the stimulation/sham pulse and target onset. Target detection rates were then compared between the sham and otCS experimental conditions across the ten bins in order to test for effects of otCS phase on target detection. We found no significant difference in target detection rates between the sham and otCS conditions, and discuss potential reasons for the apparent inability of cathodal otCS to effectively modulate visual perception.