E. Shikata et al., Surface orientation discrimination activates caudal and anterior intraparietal sulcus in humans: An event-related fMRI study, J NEUROPHYS, 85(3), 2001, pp. 1309-1314
Perception of surface orientation is an essential step for the reconstructi
on of the three-dimensional (3D) structure of an object. Human lesion and f
unctional neuroimaging studies have demonstrated the importance of the pari
etal lobe in this task. In primate single-unit studies, neurons in the caud
al part of the intraparietal sulcus (CIP) were found to be active during th
e extraction of surface orientation through monocular (two-dimensional) cue
s such as texture gradients and linear perspective as well as binocular (3D
) cues such as disparity gradient and orientation disparity. We used event-
related fMRI to study the functional neuroanatomy of surface orientation di
scrimination using stimuli with monocular depth cues in six volunteers. Bot
h posterior (CIP) and anterior (AIP) areas within the intraparietal sulcus
showed a stronger activation during surface orientation as compared with a
control (color discrimination) task using identical stimuli. Furthermore, t
he signal changes in CIP showed a greater performance effect than those in
AIP, suggesting that CIP is tightly linked to the discrimination task.