Figure 1.

(A) Schematic representation of the monkey fMRI set-up. The animal sits in a sphinx position within the primate chair, in the bore of the scanner, head restrained by the head-post, with the 8 channel, phase array coil located on top of the head. The animal is involved in a passive fixation task, i.e., maintaining the gaze on a green fixation target back-projected on a stimulation screen by a video-projector. Eye position is monitored by an infrared video-based eye-tracker. Correct fixation triggers the delivery of fluid rewards during the runs. (B) Illustration of the stimuli and experimental design. The EC stimulus consisted of a square field of dots moving in a coherent optic flow pattern containing expansion/contraction and rotation components that varied over time, consistent with self-motion on a varying spiral trajectory. The EI stimulus consisted of a 3 × 3 array of 9 identical panels, each containing a smaller version of the EC stimulus. Recordings were performed using a block-design, with the alternation of EC and EI flow stimuli, separated by blank periods. Each run contained 7 repetitions of such blocks (112 TR in total). EC conditions were shown first in half of the runs and EI conditions appeared first in the other half of the runs.