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Abstract:
Neural basis of visual gestural analysis was investigated
with Positron Emission Tomography (PET) during naming and
orientation tasks performed on pictures either of static gestures
or tridimensional objects. To prevent automatic object-related
activation during the visual processing of gestures, only
intransitive gestures were selected, that is symbolic or
meaningless gestures that do not imply handling of objects.
Conversely, only intransitive objects that cannot be handled were
selected to prevent gesture-related activation during object visual
processing. Conjunction analysis (SPM96, Wellcome Institute)
results clearly demonstrate segregation between the processing of
intransitive gestures and the processing of intransitive objects.
Visual processing of objects elicited mainly a fusiform gyrus
activity, while visual processing of gestures activated the lateral
occipito-temporal junction, encroaching upon the motion analysis
area MT/V5. These findings suggest that the lateral
occipito-temporal junction, in association with area MT/V5, plays a
prominent role in the high-level perceptual analysis of gesture,
that is the construction of its visual representation, suitable for
subsequent recognition or imitation.
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