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Elizabeth Chrastil, Michael Hasselmo, Chantal Stern, Sam Ling; Signatures of egocentric location and speed processing in early visual cortex. Journal of Vision 2016;16(12):883. doi: 10.1167/16.12.883.
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© ARVO (1962-2015); The Authors (2016-present)
Although early visual cortex is typically associated with low level visual processing, a variety of higher-level processes, such as attention and memory, have been shown to modulate visuocortical responses. Interestingly, recent animal studies have found that responses in visual cortex are also substantially modulated by locomotion. Here, we use fMRI to examine whether navigational location and speed influence the magnitude of BOLD responses in human visual cortex. To test this hypothesis, we scanned 24 participants while they viewed simulated self-motion in a virtual environment. Specifically, participants viewed first-person travel along a path that looped in a circle (~5-25 sec) in a landmark-free virtual environment (Chrastil et al., JNeurosci, 2015). The traveled loops varied from trial-to-trial; some trials were traveled faster than others, some were of greater radii, and some could close, overshoot, or undershoot the start ('home') location. Participants were asked to perform a location-tracking task, whereby they indicated at the end of each trial whether the loop they were travelling on ended at the loop's home location, or at a different location. The results demonstrated substantially elevated visuocortical responses when a participant was close to the home location, suggesting a task-driven, egocentric distance-dependent modulation of visuocortical responses. Furthermore, preliminary analyses suggest that the amplitude of early visuocortical responses increased monotonically as a function of the angular speed of motion. Taken together, our results suggest that human early visual cortex bears signatures of processing self-motion information, potentially increasing the signal-to-noise ratio for behaviorally relevant visual signals during spatial navigation.
Meeting abstract presented at VSS 2016
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