Mental rotation and object categorization share a common network of prefrontal and dorsal and ventral regions of posterior cortex
Section snippets
Methods
The mental rotation task was followed by the object-decision task, or vice versa, counterbalanced across participants. The saccade task was last. Standard blocked designs were used to maximize activation and signal to noise ratio. The tasks were administered on a MacIntosh G3 Powerbook computer. Stimuli were projected via a magnetically shielded video projector onto a translucent screen placed behind the head of each subject. A front-surface mirror mounted on the head coil allowed participants
Object-decision task
Object-decision accuracy was the same (99.9%) on average in both Intact and Scrambled conditions.
Mental rotation task
Nine rotation angles were collapsed into three levels of rotation: low (20°, 40°, 60°), medium (80°, 100°, 120°), and high (140°, 160°, 180°), as in our prior work (Amick et al., 2006). For response times (RTs), to remove outliers, a cut-off of the mean ± 2.5 SDs was applied to each of the three rotation levels and the control condition, separately. RT and accuracy measures were subjected to repeated
Discussion
Our neuroimaging results provide clear and direct anatomical support for a key prediction of the MVPT variant of object model verification theories, namely, that regions along the dorsal stream critical for mental rotation can be recruited for visual object cognition (Bülthoff et al., 1995). We found that, during both mental rotation of objects in-depth and a simple object categorization task (and not during a saccade task), the same regions are activated in the ventral caudal IPS (vcIPS) and
Conclusions
It is well-established that the ventral visual pathway supports object analysis and representation, whereas the dorsal pathway supports spatial analysis, but both ventral occipitotemporal and more dorsal areas have been found to be object-sensitive, suggesting a role for the dorsal pathway in object analysis. Our neuroimaging findings clearly support a key prediction of the MVPT variant of object model verification theories: the dorsal object-sensitive areas of vcIPS and DF1, as well as parts
Acknowledgments
Research was supported by grants F32 AG05914 and Tufts University Faculty start-up funds to H.E.S who was also supported by a Faculty Research Award Committee (FRAC) Research Semester Fellowship from Tufts University and NINDS Grant 9R01 NS052914 during preparation of this manuscript. Brain scanning was conducted at and supported by pilot funding to H.E.S. from the MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, which is supported by NCRR grant P41RR14075 and the MIND
References (98)
- et al.
An area within human ventral cortex sensitive to “building” stimuli: evidence and implications
Neuron
(1998) - et al.
Similar cortical correlates underlie visual object identification and orientation judgment
Neuropsychologia
(2005) - et al.
Frontostriatal circuits are necessary for visuomotor transformation: mental rotation in Parkinson's disease
Neuropsychologia
(2006) Neural coding of behavioral relevance in parietal cortex
Curr. Opin. Neurobiol.
(2003)- et al.
Cortical activity during rotational and linear transformations
Neuropsychologia
(2000) - et al.
A parametric fMRI study of overt and covert shifts of visuospatial attention
NeuroImage
(2001) - et al.
Parallel visual motion processing streams for manipulable objects and human movements
Neuron
(2002) Mental rotation and the right hemisphere
Brain Lang.
(1997)- et al.
Cortical surface-based analysis. I. Segmentation and surface reconstruction
NeuroImage
(1999) - et al.
Time-resolved fMRI of mental rotation revisited—Dissociating visual perception from mental rotation in female subjects
NeuroImage
(2006)