NemoImage
11, Number
5, 2000,
Part 2 of 2 Parts 1 DE
bl@
COGNITION
(OTHER)
Mental rotation of 3D, verbal and non-verbal visual objects: An fMR1 study Kirsten Jordan*,
Torsten Wuestenberg *, Kai Lutz*, Hans-Jocben Heinzej3, Lutz Janeke*
*Inst. $ General iDepartment
of Neurology
Psychology, II, Faculty
Otto-von-Guericke of Medicine,
University
Otto-von-Guericke
Magdeburg, University
Germany Magdeburg,
Germany
Several
recent experiments have investigated the cortical areas involved in mental rotation of objects. It is known to date that parietal lobule is active during this taskl-3. However different strategies and thus different neural systems may be evoked using different stimuli4. This could be due to different reference frames used for rotation or due to more fundamental differences in stimulus processing. To test for effects of different stimuli on mental rotation, we used 3 types of stimuli: A) pictures rendered from 3-dimensional objects similar to the ones used by Sheperd & Metzler5, B) 2-dimensional drawings of abstract figures taken from the mental rotation task of Hochberg & Gellmann6 (nonverbal material) and C) 2-dimensional drawings of the letters K and F (verbal material). Pairs of stimuli of the same type were presented for 2.5s and subjects (8 female. 1 male. mean age 21 lr I .2 years) had to judge whether one stimulus can be rotated onto the other. 2 Control conditions were introduced in which the Ss had to D) categorically judge whether a pair of stimuli consisted of two identical stimuli or of two stimuli from different types (described in A-C), and E) judge from a pair of dot patterns, whether the left one consisted of more dots that the right one. Behavioral data confirm the well known finding of a linear increase of reaction time with angle of rotation, however with a more pronounced increase of RT with angle of rotation for the 3-dimensional stimuli. Error rates were highest for 3d stimuli, followed by nonverbal and verbal stimuli. Imaging data show an increase in activity with all three types of rotation stimuli compared to the control conditions in the following regions: bilateral superior and inferior parietal cortex, right Hemodynamic responses for the three mental middle occipital gyms. When comparing the three rotation conditions, only one rotation conditions relative to the control comparison (nonverbal vs. 3-dimensional stimuli) shows two areas (left and right condition lingual gyms and left precentral gyrus) which are significantly more activated during rotation of nonverbal stimulus material. A region of interest (ROI) analysis confined to a space with rectangular borders was performed covering the superior and inferior parietal lobe, pars opercularis of the inferior frontal gyms. The maximal T-value in right LPs was highest when rotating 3-dimensional objects, smaller when rotating the nonverbal stimuli and smallest when rotating verbal stimuli. Individual maximal T-values in right LPi significantly correlated with the corresponding reaction times. Also, maximal T-values derived from the ROI analysis are higher in the right LPi (for 3-dimensional stimuli), and pars opercularis of the inferior frontal gyms (all conditions) than in their left homologues. The areas shown by others to be involved in mental rotation tasks are contirmed in this study using different stimuli. Regarding the clear differences in behavioral data it is somehow surprisingly, however, that there were only slight differences in activation patterns between the stimuli. It seems, that Sa have used the same strategies for rotating the different stimuli and also used the same neural structures. The fact that those tasks with longest reaction times evoked strongest T-values in right LPi can be taken as support for as further evidence that greater task demands evoke stronger BOLD responses with mental rotation tasks.
the superior
Literature: 1. 2. 3. 4.
Cohen. M. S., Kosslyn, S. M.. Breiter. H. C.. et al. Brain 119, 1996, 89-100 Tagaris, G. A., Kim, S. G. Stmpp. P. A., et al., Journal of Cognitive Neuroscience 9:4, 1997. 419-432 Richter W. et al. Neuroreport 8, 1997. 1257 Kosslyn, S.M., Digirolamo, G.J.. Thompson, W.L., Alpert, N.M. Mental rotation of objects versus hands: Neural mechanisms revealed by positron emission tomography. Psychophysiology, 35. 1998, 151-161. S. Shepard. RN., Metzler, J. Science 171, 1971, 701-703 6. Ho&berg. J.. & Gellman, 1.. The effect of landmark features on mental rotation times. Memory and Cognition, 5. 1977, 23-26.