The Journal of Neuroscience, March 1, 2000, 20(5):1975-1981
Conscious and Unconscious Processing of Nonverbal Predictability
in Wernicke's Area
Amanda
Bischoff-Grethe1,
Shawnette M.
Proper2,
Hui
Mao3,
Karen A.
Daniels4, and
Gregory S.
Berns2, 5
1 Department of Neurology, 2 Department of
Psychiatry and Behavioral Sciences, and 3 Department of
Radiology, Emory University School of Medicine, Atlanta, Georgia 30322, 4 School of Psychology, Georgia Institute of Technology,
Atlanta, Georgia 30332, and 5 Georgia Tech/Emory Biomedical
Engineering Department, Atlanta, Georgia 30322
The association of nonverbal predictability and brain activation
was examined using functional magnetic resonance imaging in humans.
Participants regarded four squares displayed horizontally across a
screen and counted the incidence of a particular color. A repeating
spatial sequence with varying levels of predictability was embedded
within a random color presentation. Both Wernicke's area and its right
homolog displayed a negative correlation with temporal predictability,
and this effect was independent of individuals' conscious awareness of
the sequence. When individuals were made aware of the underlying
sequential predictability, a widespread network of cortical regions
displayed activity that correlated with the predictability. Conscious
processing of predictability resulted in a positive correlation to
activity in right prefrontal cortex but a negative correlation in
posterior parietal cortex. These results suggest that conscious
processing of predictability invokes a large-scale cortical network,
but independently of awareness, Wernicke's area processes
predictive events in time and may not be exclusively associated
with language.
Key words:
functional imaging; Wernicke's area; predictability; sequences; nonverbal grammar; awareness; entropy
Copyright © 2000 Society for Neuroscience 0270-6474/00/2051975-07$05.00/0