Serge O. Dumoulin
McGill Vision Research Unit,
Department of Ophthalmology,
McGill University,
Montréal, Canada
will speak on
Cortical specialization for processing first- and second-order motion
Abstract:
Distinct mechanisms underlying the visual perception of luminance-
(first-order) and contrast-defined (second-order) motion have been
proposed from electrophysiological, human psychophysical and neurological
studies; however a cortical specialization for these mechanisms
has proven elusive. Here human brain imaging (fMRI) combined with
psychophysical methods was used to assess cortical specializations for
processing these two kinds of motion. A common stimulus construction was
employed, controlling for differences in spatial and temporal properties,
psychophysical performance and attention. Distinct cortical regions have
been found preferentially processing either first- or second-order motion,
both in occipital and parietal lobes, producing the first physiological
evidence in humans to support evidence from psychophysical studies,
brain-lesion sites and computational models. These results provide
evidence for the idea that first-order motion is computed in V1 and
second-order motion in later occipital visual areas, and additionally
suggest a functional dissociation between these two kinds of motion
beyond the occipital lobe.
The lecture will take place in
Room 203, 44 Cummington St.
on Tuesday, May 13, 2003
at 12:00 pm
Hosted by the
Brain and Vision Research Laboratory