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Abstract:
Abstract: We investigated the time course of inferior
temporal activity during object-recognition. 6 healthy joung adults
participated in a combined whole-head magnetoencephalographic (MEG)
and electroencephalographic (ERP) study. Coloured pictures of
nameable objects were presented at a rate of 2 seconds and repeated
after 8 to 12 intervening stimuli. Participants were instructed to
perform a recognition judgment on each picture. When compared to
new pictures, recognized repeated pictures elicited a long-lasting
and widespread positive shift in the ERPs that started at 240 ms
and lasted until 900 ms. In the MEG this repetition/recognition
effect was recorded with the same time-course but fragmented into
spatially separable waveforms. These were two bilateral posterior
inferior temporal effects from 280 to 320 ms and 460 to 500 ms.
Between 520 to 600 ms the inferior temporal activity lateralized to
the left hemisphere and shifted anteriorly. This
repetition/recognition pattern was very similar to that reported
for MEG indices of words recognition. However, at 720 ms a
prominent and strongly lateralized right anterior, inferior
temporal activity emerged that was not described previously for
word recognition. The data suggest that when compared to word
recognition the recognition of nameable objects differentially
involves right inferior temporal cortex in a late time
window.
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