Impaired stereoscopic detection thresholds after left or right temporal lobectomy.

ABSTRACT

The present study assessed global stereopsis as measured by random dot stereograms (RDS). Single stimuli were presented in order of increasing binocular correlation (40-100%) making it progressively easier to perceive the figures in depth, and then the same set of stimuli was presented in reverse order. The subjects tested included 50 patients with unilateral temporal-lobe lesions, 11 patients with right frontal-lobe lesions and 18 normal control subjects. Results indicate that either right or left temporal lobectomy leads to a higher than normal detection threshold for RDS. In contrast, right frontal lobectomy did not have a significant effect compared to the normal control subjects. All subjects were able to perceive correctly the figures at 100% binocular correlation. The results are interpreted in terms of a possible contribution of the inferior temporal cortex to global stereopsis.