Greater superior than inferior parietal lobule activation with increasing rotation angle during mental rotation: an fMRI study.

Mental rotation is a task known to activate the parietal cortical regions. The present study aimed to investigate whether there is differential activation of regions within the parietal lobe and to reveal functional subspecialisation of this region by examining the effects of increasing angle of rotation. Functional magnetic resonance imaging was performed in nine healthy female subjects whilst undertaking a parametric mental rotation task. The task comprised 6 alphanumeric characters presented in their normal or mirror-reversed orientation. Behaviourally, subjects showed increased reaction times with increased angle of rotation, with differential effects between the alphanumeric characters; numbers having greater reaction times than letters. BOLD signal increase was observed bilaterally in the middle occipital gyrus and medial frontal gyrus, in the right superior and inferior parietal lobules and in the left superior temporal gyrus. Parametric increases in activation with increasing angle of rotation were observed bilaterally in the superior and inferior parietal lobules and in the right medial frontal gyrus, with greater parametric effects in the superior parietal lobules compared to the inferior parietal lobules. Our findings suggest subspecialisation of the posterior parietal lobules during mental rotation, with differential responses in the superior and inferior regions.