Selective right parietal lobe activation during mental rotation

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.

Motor imagery ability in children with congenital hemiplegia: Effect of lesion side and functional level

“…Post-hoc tests were conducted using Tukey's HSD procedure and partial eta squared (η 2 ) was calculated to determine effect size. To analyse RT and accuracy overall, a commonly used technique in mental rotation studies to increase reliability of estimates by increasing the number of trials at each angle was employed (see, for example, Harris, et al, 2000;Roelofs, van Galen, Keijsers, & Hoogduin, 2002). This involved combining data from the same angular rotation, regardless of direction.…”

“…combining responses to 45 and 315 ) to allow sufficient responses at each angle for analysis. This is a common technique when analysing such data (Harris, et al, 2000;Roelofs, et al, 2002;Williams, Thomas, Maruff, Butson, & Wilson, 2006). However, this technique could be criticised given our findings that responses to left and right hands differed when presented in CW compared to CCW directions.…”

Human motor cortex activity during mental rotation

“…Although it is generally agreed that the parietal cortex is involved in the mental rotation process, there is considerable disagreement about interhemispheric activation differences. For Shepard-Metzler-like stimuli most studies have reported bilateral parietal activation (Cohen et al, 1996;Richter et al, 1997Richter et al, , 2000Jordan et al, 2001), while experiments using other stimuli demonstrated predominance of either the left (Alivisatos and Petrides, 1997) or the right hemisphere (Harris et al, 2000;Yoshino et al, 2000) or no distinct difference (Tagaris et al, 1998;Lamm et al, 2001).…”

“…From these results it was hypothesized that subjects "mentally rotated" the mental image of one object along a trajectory until it had the same orientation as the other object and then compared both for congruency. Based on this study, a number of experiments investigating the brain responses underlying mental rotation processes have been performed, using electrophysiological methods, positron emission tomography and functional magnetic resonance imaging (fMRI) (Cohen et al, 1996;Alivisatos and Petrides, 1997;Tagaris et al, 1997Tagaris et al, , 1998Richter et al, 1997Richter et al, , 2000Kosslyn et al, 1998;Carpenter et al, 1999;Harris et al, 2000;Yoshino et al, 2000;Jordan et al, 2001;Lamm et al, 2001;Vingerhoets et al, 2001Vingerhoets et al, , 2002. Although it is generally agreed that the parietal cortex is involved in the mental rotation process, there is considerable disagreement about interhemispheric activation differences.…”

“…Imaging studies have, however, shown inconclusive results. Some found activity in the premotor (PM) cortex (Cohen et al, 1996;Richter et al, 2000), while others did not report PM involvement during mental rotation of both two-dimensional and threedimensional objects Harris et al, 2000;Jordan et al, 2001). Concerning the primary motor cortex, Richter et al (2000) reported that activation in contralateral primary motor (M1) cortex seems to be related to the button press at the end of each task, but could not rule out that M1 is also involved in another aspect of the task.…”