Search

Bidirectional interactions coordinate activity throughout the visual system, prioritizing some inputs and suppressing others based on behavioral context and past experience. Though the mechanisms involved in selecting features and locations for processing are well studied, the role of functional network reorganization in goal directed vision is unclear. This dissertation integrates theoretical perspectives on temporal coding with my empirical work, which demonstrates that task context modulates the time course of visual detection, the quality of encoding, and functional connectivity between visual cortical regions and the hippocampus. In three interocular suppression studies, I found that configuration, predictability, and relevance can influence detection performance. Suppressed line segments that completed a visible shape surrounding them were detected more frequently than orthogonal segments and those presented without a surround. Enhanced detection and localization were observed for stimuli that warranted a button press. Invalid predictive cues impaired visibility reports but not localization. Predictability modulated orientation recognition response sensitivity and reaction times. Thus, contour integration and motor relevance impact processing pre-detection, whereas predictability primarily affects post-detection factors such as response readiness and confidence. Detecting relevant stimuli can also enhance the processing of concurrently-presented, unrelated stimuli—the attentional boost effect. In a neuroimaging study, I found that pictures accompanied by a target tone, as opposed to a distractor or no tone, were decoded more accurately from multivoxel patterns in the ventral visual cortex. Critically, this enhancement coincided with increased functional connectivity between those visual regions and the hippocampus, stronger locus coeruleus responses, and higher recognition confidence for images that were correctly identified in a subsequent memory test. This suggests that functional network reorganization contributes to visual episodic memory encoding during relevant events. My findings are compatible with the view that the detection, maintenance, and encoding of visual information are mediated by the transient stabilization of coordinated population firing patterns. Spike timing regulation and oscillatory synchronization in the visual thalamocortical network enable precise control of the duration and depth of stimulus processing. Generalizing further, the core thesis of my Dynamical Emergence Theory is that conscious neural representations correspond to quasi-discrete functional connectivity states lying on a relatively low-dimensional manifold.