| |
Abstract:
A number of recent neuroimaging studies have examined the
role of the prefrontal cortex in retrieval and selection during
semantic processing tasks. One such task, covert picture naming,
has yielded inconsistent patterns of activity across studies. One
potential explanation of this inconsistency is that prefrontal
activity during picture naming depends on the extent that a given
picture evokes a single, reliable meaning. To test this hypothesis,
subjects were asked to name a series of pictures divided into "high
name agreement" or "low name agreement" based on norms reported by
Snodgrass and Vanderwart (1980). Subjects were instructed to
respond either verbally or manually (button press). Each subject
participated in both output modalities. We found no significant
motion effects while subjects were responding covertly versus
responding overtly. More left inferior frontal gyrus (LIFG)
activity was found when subjects engaged in the "low name
agreement" condition than in the "high name agreement" condition.
This is further evidence supporting the idea that the LIFG mediates
selection among competing semantic alternatives. Furthermore, the
pattern of data observed is consistent across the two response
modalities (i.e., verbal and manual).
|
