| |
Abstract:
Functional brain imaging studies have implicated parietal
cortex (PC) in mediating spatial shifts of visual attention. One
discovery is a hemispheric asymmetry: whereas left PC deals with
contralateral space, right PC deals with both sides. Little is
known about the role of PC in auditory attention. Two experiments
were conducted that suggest a role for PC in shifting spatial
auditory attention. Tones were presented to listeners while
event-related potentials (ERPs) were recorded from 64 electrodes.
In experiment 1, on some trials listeners disengaged attention from
one side of space and reoriented to a tone on the opposite side.
Other trials required no reorienting. ERPs to tones on reorient
trials were more positive than no-reorient trials beginning 150 ms
post-target. This difference was located over parietal cortex and
matched the asymmetry found in vision: reorienting toward left
hemispace produced a positive shift over right PC, but reorienting
to right hemispace produced a positive shift over both hemispheres.
Experiment 2 was similar to experiment 1 except listeners
reoriented in both conditions. As predicted, differences between
ERPs in the two conditions were reduced or eliminated when both
conditions involved re-orienting. We interpret these data to
suggest that, like visual attention, spatial shifts of auditory
attention involve parietal cortex.
|
