A visual event can often go unnoticed, even though it can be readily detected at other times. What are the neural mechanisms that determine whether or not we are aware of a visual event? In the proposed set of experiments we plan to investigate the neural underpinnings of visual awareness. In particular, we propose a novel combination of neuroimaging with high temporal and spatial resolution and direct perturbation of cortical activity to understand the interactions between frontoparietal and occipitotemporal cortex in the service of visual awareness. Because the interactions among cortical areas responsible for our final percept happen on a short time scale, they have been inherently difficult to map out. The high spatial and temporal resolution of the event-related optical signal (EROS) allows us to measure these fast interactions between areas. Furthermore, by combining EROS with single-pulse transcranial magnetic stimulation (TMS) we can not only measure the neural response to stimuli but also observe the response of the system to perturbations (via TMS) of specific nodes in the network. These methods will allow us to determine whether awareness depends on feedback from frontoparietal cortex as well as contribution of frontoparietal activity to ongoing oscillatory brain activity and its influnce on awareness. Across all the experiments proposed here, we will gain valuable insight into the interactions of frontoparietal and occipitotemporal mechanisms responsible for our visual experience. Such knowledge can have implications for normal vision and a range of visual disorders that are cortical in their origin, such as hemianopia and the visual agnosias, as well as provide valuable information for designing visual prostheses. A deeper understanding of the frontoparietal network and its interaction with ongoing processing in visual cortex could also provide insight to a variety of attention-related brain disorders such as Attention Deficit / Hyperactivity Disorder (ADHD), unilateral neglect syndrome, Alzheimer's disease, autism and schizophrenia.
Across all the experiments proposed here, we will gain valuable insight into the interactions of frontoparietal and occipitotemporal mechanisms responsible for our visual experience. Such knowledge can have implications for normal vision and a range of visual disorders that are cortical in their origin, such as hemianopia and the visual agnosias, as well as provide valuable information for designing visual prostheses. A deeper understanding of the frontoparietal network and its interaction with ongoing processing in visual cortex could also provide insight to a variety of attention-related brain disorders such s Attention Deficit / Hyperactivity Disorder (ADHD), unilateral neglect syndrome, Alzheimer's disease, autism and schizophrenia.
