Neural Basis of Unconscious Attentional Processing in Hemianopic Patient
Dr. Javier Sánchez López
Department of Neuroscience, Biomedicine and Movements Sciences, University of Verona
The relation between visual attention and visual awareness has been a topic of interest in the field of cognitive neurosciences. Some previous studies have disentangled this relation by studying the visual attention to unseen stimuli in healthy participants and blindsight patients suggesting the existence of dissociation between these two processes. However, to our knowledge no studies have investigated the neural mechanisms of visual attention without awareness. Therefore, here we will discuss the last findings regarding these mechanisms. In a first study we monitored with steady-state visual evoked potentials (SSVEPs) the neurophysiological correlates of endogenous spatial attention to unseen stimuli presented to the blind field of hemianopic patients. The results provided evidence that the neural correlates of spatial attention are present regardless of visual awareness and this is in accord with the general hypothesis of a possible dissociation between attention and awareness. In a second study we investigated the behavioral and neurophysiological correlates of visual orientation to unseen stimuli presented to the blind hemifield of hemianopic patients, and the existence of hemispheric differences for this kind of unconscious attention. Results confirmed (behaviorally) and extend to neurophysiological mechanisms the existence of unconscious visual orienting and are in keeping with a right hemisphere dominance for unconscious as well as conscious attention.