title: Selective right parietal lobe activation during mental rotation: a parametric PET study.
abstract: Regional cerebral blood flow (rCBF) was measured with PET in seven healthy subjects while they carried out a mental rotation task in which they decided whether alphanumeric characters presented in different orientations were in their canonical form or mirror-reversed. Consistent with previous findings, subjects took proportionally longer to respond as characters were rotated further from the upright, indicating that they were mentally rotating the characters to the upright position before making a decision. We used a parametric design in which we varied the mental rotation demands in an incremental fashion while keeping all other aspects of the task constant. In four different scanning conditions, 10, 40, 70 or 100% of the stimuli presented during the scan required mental rotation while the rest were upright. The statistical parametric mapping technique was used to identify areas where changes in rCBF were correlated with the rotational demands of the task. Significant activation was found in only one area located in the right posterior parietal lobe, centred on the intraparietal sulcus (Brodmann area 7). The experimental literature on monkeys and humans suggests that this area is involved in a variety of spatial transformations. Our results contribute evidence that such transformations are recruited during mental rotation and add to a body of evidence which suggests that the right posterior parietal lobe is important for carrying out visuospatial transformations.
authors.affiliation: Department of Medicine, University of Sydney, Neuropsychology Unit, Royal Prince Alfred Hospital, Sydney, Australia. irinah@npsych.rpa.cs.nsw.gov.au
authors.forename: I M
authors.initials: IM
authors.lastname: Harris
authors.forename: G F
authors.initials: GF
authors.lastname: Egan
authors.forename: C
authors.initials: C
authors.lastname: Sonkkila
authors.forename: H J
authors.initials: HJ
authors.lastname: Tochon-Danguy
authors.forename: G
authors.initials: G
authors.lastname: Paxinos
authors.forename: J D
authors.initials: JD
authors.lastname: Watson
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D004292:Dominance, Cerebral; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D008875:Middle Aged; D010104:Oxygen Radioisotopes; D010296:Parietal Lobe / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000502:physiology*; D012039:Regional Blood Flow; D013850:Thinking; D014055:Tomography, Emission-Computed
chemical_list: D010104:Oxygen Radioisotopes