Neuronal and Perceptual Effects of Selective Attention in the Primate Visual System

Abstract

The work included in this thesis examines cognitive influences on the processing of visual information both on the neural and the behavioral level. A prominent mechanism for the selection and modulation of behaviorally relevant sensory information in the brain is selective attention. Recording single unit activity and local field potentials (LFPs) in middle temporal area (MT) of the macaque monkey, we have gained deeper insights into the neural mechanisms of various aspects of selective attention that, so far, had been unexplored. Specifically, we demonstrated that attention individually enhances representations of multiple moving objects. Furthermore, we showed that attention modulates the input signals of MT neurons, and that these effects are reflected in certain frequency bands of LFP oscillations. Finally, we showed that spike timing is a source of information likely used by the brain for encoding different features of visual stimuli. Complementing the electrophysiological studies, our behavioral experiments investigated consequences of dividing attention between stimuli represented in two different reference frames and the influence of feature-based attention on the processing of information from non-overlapping spatial locations. Collectively, these studies show that cognitive factors strongly modulate the processing of sensory information in primate visual cortex.