Contributed Session II: Attentional Modulation of Early Cortical Chromatic Responses

Abstract

Prior research demonstrates that attention can modulate the amplitude of achromatic (black and white) pattern reversal stimuli. Similarly, MRI research has shown attentional modulation of BOLD responses to both chromatic and achromatic stimuli. However, prior research has also demonstrated that the chromatic onset visual evoked potential (VEP) is robust to attentional modulation (e.g., Highsmith & Crognale, 2010; Wang & Wade, 2011) with either spatially contiguous or spatially disparate manipulations. It is possible that more demanding attentional tasks than those that have been used previously, may reveal attentional modulation of the chromatic VEP. Here we report the results of experiments in which we recorded chromatic and achromatic VEPs while subjects performed multiple object tracking (MOT) tasks with several levels of difficulty. Steady-state onset responses were recorded at 3hz for stimuli modulated along the chromatic and achromatic axes. Our preliminary results suggest that the increased attentional demand provided by MOT can reveal a clear, but idiosyncratic modulation of chromatic VEP responses. The question remains whether or not chromatic and achromatic mechanisms share similar attentional gain processes as reflected in the VEP. We are currently characterizing the nature of these attentional gain mechanisms.