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Abstract:
Large neurocognitive networks such as the spatial attentional
network are formed by interconnected transmodal areas that show
relative specialization for specific behavioral components of the
relevant domain. Manipulating the behavioral components of one
domain should modulate the connectivity between the epicenters of
the concerned network. We used the dichotic listening paradigm to
conduct a PET study on auditory spatially selective and divided
attention. Ten subjects were studied using a Siemens ECAT HR+
scanner. Eight experimental and four control H215O scans were
acquired for each subject. For experimental scans, two different
syllables were presented simultaneously, one to each ear (dichotic
presentation). Subjects performed an identification task and were
asked to attend to the left, to the right or to both sides. For
control scans, two identical syllables were presented
simultaneously, thus drastically reducing the attentional load.
Based on literature and our activation data (Lipschutz et
al.(2000), NeuroImage, 11(5,2)) we studied attention-dependent
changes in functional connectivity between defined cortical regions
such as the parietal or the anterior cingulate cortices and the
rest of the brain by means of a psychophysiological interaction
analysis. Our data show enhanced cortico-cortical interactions,
driven by the attentional demand of a dichotic listening paradigm,
mainly between the different epicenters of the spatial attentional
network in the right hemisphere.
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