The neural basis underlying the generation of nouns and verbs is still not completely
understood. In classical generation tasks, specific features of the produced words
can hardly be controlled. Therefore, the observed neural correlates of noun and verb
production cannot be directly related to differences in specific features of the generated
words. The present study seeks to address this issue by using a "minimal-phrase context"
to elicit the activation of specific nouns and verbs. With this context, the to-be-generated
words were highly constrained, and thus their semantic and other features (visual/action
relatedness, word frequency, cloze probability, etc.) are well controlled. Thus, the
present paradigm combines the advantages of classical word generation tasks (i.e.,
active semantic processing) with the advantages of tasks that allow for a high control
of the experimental stimuli, such as passive viewing, reading, or lexical decision
tasks. In an fMRI study, 17 participants generated verbs with strong motor and nouns
with strong visual associations. Both noun and verb generation, compared to a rhyme
generation baseline, elicited stronger activation in perisylvian language areas of
the temporal and parietal cortex. In addition, stronger activation for nouns was found
in the right middle/inferior temporal cortex. This activation supports the claim that
noun generation is mediated by visual processing areas. Stronger activation for verb
generation was found in the left superior temporal gyrus. Since this area is involved
in motion perception, the results suggest that perceptual representations of movements
mediate the generation of action verbs.
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