Stimulus-feature Specific Modulation of the Visual Processing by Audiovisual Intermodal Orientation of Attention
Sunao Iwaki and Mitsuo Tonoike
Affiliation: Human Technology Research Institute National Institute of Advanced Industrial Science and Technology Tsukuba Ibaraki 305-8566 Japan.
Keywords: Audio-visual attention, data analysis, magnetoencephalography (MEG), spatial filter, spatial visual/auditory discrimination
experiment, ventral visual system.
Here, we studied how the intermodal selective attention between vision and audition affects the sensory information
processing in the human auditory and visual cortical areas. Specifically, we investigated whether audio-visual intermodal
orientation of attention modulates neural activity in the human visual and auditory cortices. We used MEG to assess
the neural activity in both the primary auditory area and the extrastriate visual areas, where visual stimulus features
such as color and shape are processed, while subjects performed spatial and non-spatial discrimination tasks, as presented
by either visual or auditory modality, under three attentional conditions, namely a) selective attention to vision (V), b) selective
attention to audition (A), and c) divided attention between vision and audition as neutral condition (N). MEG signals
were analyzed by using linearly-constrained minimum-variance (LCMV) beamformer and the differences of the estimated
activities in the visual cortical areas between the conditions were statistically tested. Neural activity in the contralateral
occipitotemporal area (BA18) was significantly increased under the V condition in the spatial discrimination task
but not in the non-spatial (color) discrimination task. On the other hand, attention to vision significantly enhanced activity
in the posterior inferotemporal area (BA19, 37). The results support the hypothesis that the intermodal selective attention
between the visual and auditory modalities modulates the neural activities in the ventral visual system in the stimulusfeature
specific manner at different latencies.
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