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Abstract

Our experience with a dynamic environment has tuned our visual system to use form
and motion as complementary sources of information for object recognition. To identify the
neural systems involved in integrating form and motion information during dynamic object
processing, we used an fMRI adaptation paradigm which factorially manipulated form and
motion repetition. Observers were sequentially presented with pairs of rotating novel objects
in which the form or rotation direction in depth could be repeated. They were required to
discriminate either dimension of the second target object, while the first object served as a
form or motion prime. At the behavioural level, observers were faster to recognize the target
or discriminate its direction when primed by the same form. Importantly, this form priming
effect was enhanced when prime and target objects rotated in the same direction. At the neural
level, the two priming effects (i.e., the main effect of form repetition and the interaction
between form and motion repetition) were associated with reduced activations in distinct
brain regions. Bilateral lateral occipital regions exhibited reduced activation when form was
repeated irrespective of rotation direction. In contrast, bilateral anterior fusiform and posterior
middle temporal regions (overlapping with hMT+/V5) regions showed an adaptation effect
that depended on both form and motion direction. Thus, the current results reveal a visual
processing hierarchy with lateral occipito-temporal cortex representing an object’s 3D
structure, and anterior fusiform and posterior middle temporal regions being involved in
spatio-temporal integration of form and motion during dynamic object processing.