Apthorp D, Bahrami B, Schwarzkopf D S, Kaul C, Alais D, Rees G, 2010, "Motion streaks in the brain: an fMRI study" Perception 39 ECVP Abstract Supplement, page 137
Motion streaks in the brain: an fMRI study
D Apthorp, B Bahrami, D S Schwarzkopf, C Kaul, D Alais, G Rees
Temporal integration in the visual system causes fast-moving objects to generate static, oriented traces (‘motion streaks’). While generally not seen, these might be used to help judge direction of motion (Geisler, 1999 Nature). Psychophysics and single-unit studies support this hypothesis, but no evidence from human brains has yet been provided. Here we use functional magnetic resonance imaging combined with univariate and multivariate pattern classification techniques to investigate the neural correlates of motion streaks. Observers viewed fast (‘streaky’) or slow-moving dot fields, moving at either 45 or 135 degrees, or static, oriented patterns (filtered noise) at the same orientations. Ten sessions, each with six blocks per session (randomized block design) gave ten blocks for each stimulus type. Univariate group analysis showed greater activation in early cortical areas when comparing fast to slow motion, but no increased activation in V5/MT+; the pattern of activity was similar to that seen when comparing static, oriented conditions to fixation rest. A multivariate pattern classifier trained on brain activity evoked by static, oriented patterns could successfully generalize to decoding brain activity evoked by fast but not slow motion sessions. These results suggest static, oriented ‘streak’ information is present in early visual cortex when viewing fast motion.
[Supported by the Australian Federation of University Women and the University of Sydney]
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