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Abstract:
We investigated whether parahippocampal cortex responds
selectively
and
automatically
to certain types of visual stimuli. Subjects were scanned with
fMRI while viewing photographs of scenes, houses, objects, and
faces, as well as scrambled versions of the same (Exp. 1); rooms
filled with furniture, the same rooms emptied of all furniture,
arrays of the furniture from these rooms on a white background, and
single objects (Exp. 2). Photographs were presented for 300 msec
each at a rate of 1.2/sec. Subjects either viewed the stimuli
passively or performed a 1-back repetition detection task. MR
signal intensity was greater when viewing scenes that when viewing
houses, objects, faces, or scrambled scenes in a bilateral region
of parahippocampal cortex we name the "parahippocampal place area",
or PPA (Exp. 1). The response in this region was just as strong to
scenes with spatial layout but no discrete objects (empty rooms) as
to scenes containing multiple objects (furnished rooms), and twice
as strong as the response to arrays of multiple objects without
three-dimensional spatial context (Exp. 2). These results were
found both for the 1-back task and for passive viewing (when no
explicit cognitive task was required). We conclude that the PPA
responds selectively and automatically to visual stimuli that
contain information about the shape of the local
environment.
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