Competition between visual stimuli in the monkey parietal cortex

We live in a complicated visual world where stimuli are constantly clamoring for our limited attentional resources. We use our eyes to explore the world and our brain must make moment-to-moment decisions about which points of space contain the most information or which points are associated with rewarding outcomes. In our neural representation of the visual world, stimuli are locked in a constant battle for spatial priority and a single winner must emerge each time an eye movement is to be made, though the mechanisms by which this winner emerges are unclear. In this thesis we explore how competition between neural representations of visual stimuli in the parietal cortex may be implemented by changes in the activity and reliability of neural signals. The macaque lateral intraparietal area (LIP) is part of an oculomotor attentional network and its activity represents the relative priority of spatial locations. We demonstrate how neurons in LIP use surround suppressive mechanisms to resolve conflict between spatial locations and explore the role of shared variability in the priority map network. We manipulate the cognitive state of the monkey by changing his expected reward and show that the activity, reliability, and noise correlation are affected by the context of the monkeys' choice. Finally, we demonstrate how behavioral variables such as the monkeys' performance and saccade latency are modulated during competitive choice.