Johnson Center, #333 D
April 12, 2019, 02:30 PM to 04:30 PM
Vision supplies the central nervous system a vast majority of its information about the surrounding environment. The central nervous system then understands and organizes that information using perception and cognition. Finally, it produces the output: adaptive motor control. A consistent and precise representation of physical space is necessary for the perceptual, cognitive, and motor systems to coordinate and inform each other. Healthy brains synchronize both bottom-up and top-down signals from all three of the above systems, producing a seamless transition between input and output. When speaking specifically about vision, our most dominant sense, this involves the complex transition of retinal space to physical space. The following studies investigate visual perception, cognitive capabilities including spatial memory and motor planning, and how both bottom-up perception top-down cognition are influenced by and discretely influence motor action. Study 1 examines whether making eye movements in a specific direction interferes with the cognitive organization of physical space. We found evidence that oculomotor systems and spatial memory may share common spatial frames of reference. Study 2 reports a novel paradigm to measure precise spatial and temporal properties of fast eye movements called saccades. Here we report that when the saccade target unexpectedly jumps to a new location, the direction of the saccade begins to compensate for the displacement with as little as 60 ms of preparation time. However, we found that the timecourse of this compensation qualitatively changes as the displacement size increases. Study 3 extends the paradigm established in Study 2, but we manipulated the perceptual input afforded by the saccade target. When stimuli have a different brightness compared to their surrounding, this information is simultaneously processed by two visual systems: the magnocellular (reflexive) and parvocellular (perceptual) pathways. In contrast, if stimuli in the foreground have the same brightness as the background but differ in color, the perceptual system must rely on the parvocellular pathway. We introduced a condition where the saccade targets were isoluminant with the background, removing a significant portion of magnocellular information. We found that oculomotor planning was delayed by a consistent span when deprived of this perceptual input even across increasing target displacements.