TEMPORAL DYNAMICS OF LOCAL FIELD POTENTIALS IN THE MACAQUE VISUAL ATTENTION NETWORK

Abstract

The visual system is a complex network of visual areas that are responsible for processing diverse visual information and mediating various cognitive activities such as attention. Anatomical studies suggest that it is organized in a hierarchical manner, which assumes that information processing is driven sequentially within the visual system. However, this aspect has been contradicted by some previous studies of neurological activity. In this study, I calculated the onset latencies of four areas known to be involved in the primate visual attention network, V4, TEO, LIP and the pulvinar, using two different components of the local field potential (LFP), a signal that represents the population activity of nearby neurons. I found that V4 had the earliest latencies in both the first significant positive deflection and the second significant negative deflection, whereas the other areas had simultaneous onset latencies. I also found a significant effect of the component I used, which led me to hypothesize that the first positive deflection reflects the feed forward “driver” signal and the second negative deflection is the feedback “modulator” signal. My onset latency results fit well with the established anatomical connectivity of these areas with each other, but conflict with the suggested hierarchical organization of the visual system. I also investigated the attentional effects on onset latency but I failed to find any significant changes. Overall this study provides valuable information about the information processing between V4, LIP, TEO and the pulvinar and organization within the visual system.