title: A functional magnetic resonance imaging study of overt letter verbal fluency using a clustered acquisition sequence: greater anterior cingulate activation with increased task demand.
abstract: Regional cerebral activation during a cognitive task can vary with task demand and task performance. In a functional magnetic resonance imaging study, we examined the effect of manipulating task demand on activation during verbal fluency by using "easy" and "hard" letters. A "clustered" image acquisition sequence allowed overt verbal responses to be made in the absence of scanner noise which facilitated "on-line" measurement of task performance. Eleven right-handed, healthy male volunteers participated. Twice as many errors were produced with hard as with easy letters (20.8 +/- 13.6 and 10.1 +/- 10.7% errors, respectively). For both conditions, the distribution of regional activation was comparable to that reported in studies of covert verbal fluency, but with greater engagement of subcortical areas. The hard condition was associated with greater dorsal anterior cingulate activation than the easy condition. This may reflect the greater demands of the former, particularly in terms of arousal responses with increased task difficulty and the monitoring of potential response errors.
authors.affiliation: Institute of Psychiatry, King's College London, London SE5 8AF, United Kingdom.
authors.forename: Cynthia H Y
authors.initials: CH
authors.lastname: Fu
authors.forename: Kevin
authors.initials: K
authors.lastname: Morgan
authors.forename: John
authors.initials: J
authors.lastname: Suckling
authors.forename: Steve C R
authors.initials: SC
authors.lastname: Williams
authors.forename: Chris
authors.initials: C
authors.lastname: Andrew
authors.forename: Goparlen N
authors.initials: GN
authors.lastname: Vythelingum
authors.forename: Philip K
authors.initials: PK
authors.lastname: McGuire
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D006179:Gyrus Cinguli / Q000502:physiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010865:Pilot Projects; D011597:Psychomotor Performance / Q000502:physiology; D014705:Verbal Behavior / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology*
chemical_list: D010100:Oxygen