title: The question shapes the answer: the neural correlates of task differences reveal dynamic semantic processing.
abstract: Task effects in semantic processing were investigated by contrasting the neural activation associated with two semantic categorization tasks (SCT) using event-related fMRI. The two SCTs involved different decision categories: is it an animal? vs. is it a concrete thing? Participants completed both tasks and, across participants, the same core set of items were presented in both tasks. Results showed task differences in the neural activation associated with these items: in the animal SCT there was greater activation in a number of frontal and temporal regions, including left superior and middle temporal gyri, while in the concrete SCT there was greater activation in left medial frontal gyrus and bilaterally in the precentral gyri. These results are interpreted as evidence of top-down modulation of semantic processing; participants make adjustments to optimize performance in a given task and these adjustments have consequences for the activation observed.
authors.affiliation: Department of Psychology, University of Calgary, 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada. ishargre@ucalgary.ca
authors.forename: Ian S
authors.initials: IS
authors.lastname: Hargreaves
authors.forename: Michelle
authors.initials: M
authors.lastname: White
authors.forename: Penny M
authors.initials: PM
authors.lastname: Pexman
authors.forename: Dan
authors.initials: D
authors.lastname: Pittman
authors.forename: Brad G
authors.initials: BG
authors.lastname: Goodyear
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology; D006801:Humans; D012660:Semantics