Cross-modal activation of visual cortices depends on auditory selective attention
Chrysa Retsa1, Pawel J. Matusz1, Jan Schnupp1,2, Micah Murray1,3,4,5; 11The Laboratory for Investigative Neurophysiology (The LINE), University Hospital Center and University of Lausanne, Lausanne, Switzerland, 2Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, 3EEG Brain Mapping Core, Center for Biomedical Imaging (CIBM) of Lausanne and Geneva, Switzerland, 4Vanderbilt University, Nashville, TN, USA, 5University of Lausanne, Jules-Gonin Eye Hospital, Lausanne, Switzerland
Laterally-presented sounds can activate visual cortices, despite the sounds being task-irrelevant. An auditory-evoked contralateral occipital positivity (ACOP) at ~250ms post-sound onset is postulated as the event-related potential (ERP) correlate of this effect. It has been suggested that the cross-modal process indexed by ACOP is automatic. Our group has used a passive auditory paradigm to demonstrate that ACOP is context-contingent. The ACOP was observed only when the sound’s location was unpredictable but was not present when location was predictable. As in prior studies the ACOP was elicited by task-irrelevant sounds, our present study examined to what extent task-relevance, and specifically, selective attention to a given feature of identical sounds modulates ACOP. To address this question, we employed an active auditory discrimination task and manipulated which one of four possible stimulus attributes (location, pitch, speaker identity, syllable) was task relevant in each block. Sound acoustics were held constant, and their location was always equiprobable (50% left, 50% right). The only manipulation was which sound dimension participants attended to. 128-channel ERP data from healthy participants were analyzed within an electrical neuroimaging framework. We show that presence of sound-elicited activations of visual cortices depended on the to-be-discriminated dimension. An ACOP was elicited only when participants were required to discriminate sound location, but not when they attended to any of the non-spatial features. These results further indicate that the ACOP is not automatic. Moreover, we extend these findings to show the interplay between task-relevance and spatial unpredictability in producing the cross-modal activation of visual cortices.
Topic Area: ATTENTION: Multisensory