This proposal outlines a single year of research to examine the strength of neural signals within the lateral geniculate nucleus of awake behaving primates, in response to spatiotemporal edges. Human psychophysical studies using illusions of invisibility (such as forward and backward masking) have shown that it is the edges of masks in space, as well as the timing of their onset and termination (their temporal edges), that are most effective in rendering targets invisible. Neural signals important to masking are therefore most likely to be associated with the mask s spatiotemporal edge. The proposed experiments will examine the neural correlates of these edge effects (both spatial and temporal) in the lateral geniculate nucleus of primates by recording from single-units while displaying stimuli used in previous human psychophysical experiments. These experiments will segregate the spatial edge effects from the temporal edge effects and test them conveyed separately. The results should reveal the relative strength of neural inhibition from the spatiotemporal edge of the mask in comparison with the signal generated in the mask s spatial and temporal interior.
