V. Walsh et al., The role of the parietal cortex in visual attention hemispheric asymmetries and the effects of learning: a magnetic stimulation study, NEUROPSYCHO, 37(2), 1999, pp. 245-251
Our previous studies of the role of the parietal cortex in visual learning
and attention showed that the right parietal cortex is required for normal
performance on conjunction visual search tasks but that its role depends on
whether subjects are naive or trained on the task. Here we extend these fi
ndings in two Experiments. Experiment I shows that magnetic stimulation of
the left parietal cortex also impairs performance (measured as reaction tim
e) on conjunction visual search tasks, but only when the target is present
in the right (contralateral) visual field. Stimulation of the same region o
n a feature detection task speeds up performance significantly when the tar
get is in the left (ipsilateral) visual field. Experiment 2 explores furthe
r the role of the right parietal cortex in learning conjunction search task
s. Stimulation of the right parietal cortex in subjects who had already tra
ined on some visual search tasks did not impair performance on a novel moti
on/form conjunction task even though the search was clearly serial. Stimula
tion of area V5, however, severely disrupted performance on the same task;
These data indicate that the role of the parietal cortex may change much ea
rlier in the course of training than initially thought. (C) 1999 Elsevier S
cience Ltd. All rights reserved.