The spatial and temporal dynamics of neural interactions underlying attention-related enhancement and suppression of visual processing - Attention is critical for filtering incoming sensory information; however, attentional function is often impaired in common neuropsychiatric disorders including ADHD or schizophrenia. Visuospatial attention in particular involves both the enhancement of attended information and the suppression of ignored information at locations across the visual field. Major theories of visuospatial attention propose an interdependent relationship between enhancement and suppression, arising from competitive interactions between neural populations representing different visual field locations. Furthermore, recent research demonstrates that visuospatial attention involves ‘rhythmic sampling’ of the environment, with periodic alternation (~4-6 Hz) between two functional states: one that promotes selective processing at an attended location and another in which attentional selection is relatively diminished and attentional shifts are more likely. To investigate the neural basis of rhythmic sampling during visuospatial attention, the proposed research will test the temporal dynamics of enhancement and suppression-related competitive interactions between neural populations in extrastriate visual cortex (i.e., V4) representing different visual field locations (Aim 1). The processing of sensory information in visual cortex can be modulated by top-down control from the frontal eye fields (FEF) and lateral intraparietal area (LIP), two cortical nodes of large-scale ‘attention network’ that have previously been linked with attention-related enhancement and suppression. Recently, rhythmic sampling during visuospatial attention has been shown to involve rhythmic changes in neural activity within FEF and LIP. Emerging evidence points to functional specialization between FEF and LIP with respect to enhancement and suppression. The proposed research will further test the temporal dynamics of enhancement and suppression-related functional interactions between these higher-order cortical areas and visual cortex during the deployment of visuospatial attention (Aim 2). Multisite laminar probes will be used to simultaneously record neural activity from FEF, LIP, and V4 in two to three monkeys. In a visuospatial detection task, cues will indicate the locations of upcoming targets and/or distractors which will be presented within the receptive fields of recorded neural populations. This approach will reveal the temporal dynamics of network-level interactions supporting enhancement and suppression across the visual field, including (i) functional interactions between V4 neural populations representing distinct visual field locations (Aim 1) and (ii) functional interactions between higher-order cortical areas (i.e., FEF and LIP) and V4 during the voluntary deployment of enhancement and/or suppression (Aim 2). Results from these complementary, yet independent aims will provide key insights into how visuospatial attention shapes perception via the enhancement and suppression of sensory processing. The proposed project could therefore uncover new pathways for therapeutic intervention that could ultimately increase quality of life for individuals experiencing attentional deficits.
