SV3. Modulation of hemifield effects in visual-spatial attention by transcranial direct current stimulation

Abstract

Introduction A bilateral field advantage (BFA), that is enhanced visual processing when stimuli are aligned across both visual hemifields, corresponds to a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources for bilateral displays. Several studies have shown that the BFA extends beyond early stages of visual attentional processing. Visual-short-term-memory (VSTM) capacity was higher when stimuli are distributed bilaterally rather than unilaterally and repetitive transcranial magnetic stimulation (rTMS) over the right precuneus diminished the BFA (Kraft et al., 2014). Methods: Here we tested whether the BFA can be modulated by simultaneous anodal and cathodal transcranial direct current stimulation applied either over the left and right occipital cortex (O1/O2) or over the left and right parietal cortex (P3/P4). Twenty healthy subjects were tested using a whole report paradigm based on the Theory of Visual Attention (TVA; Bundesen, 1990). Results and Conclusion: This approach allowed us measuring VSTM capacity and visual processing speed variability in unilateral and bilateral displays. It is discussed how this approach can modulate the inter-hemispheric parietal and occipital balance and whether it can be used in therapeutic settings, e.g. in patients with visual deficits or spatial neglect.