The Neural Control of Vision
P. Ongoing Research

Figure 16-13 shows images obtained from a normal and a stereoblind subject demonstrating the differences in brain activation. The images are a maximum intensity projections showing a sagittal view of the two brains. For each display shown in Figure 7, the scans collected for condition 1 (no depth) were contrasted with the scans obtained with either condition 2 or 3 (disparity cues only and motion parallax cues only). The top two figures show brain activation for motion parallax under binocular viewing conditions. The second two show the activation that occurs with disparity cues. There was no activation in the brain of the stereoblind subject specific for stereopsis. The bottom figure displays the control condition for the normal subject showing no activation under monocular viewing conditions using the displays with disparity. Figure 16-13 establishes that the procedures we have devised work extremely well in specifically activating the brain for stereopsis and motion parallax in the normal subjects and not activating the brain in the stereoblind subjects. We have obtained similar results in several other subjects.