Conditional spatial discrimination in humans with hypoxic brain injury

Abstract

Hypoxic brain injury can cause severe anterograde amnesia with intact intelligence and attention in select patients. This neuropsychological profile is similar among a broad class of etiologies resulting in damage to the hippocampus and associated medial temporal structures. Several recent studies have demonstrated that subjects with anterograde amnesia can nonetheless acquire simple associative tasks. In the present study, the performance of subjects with anterograde memory impairments resulting from hypoxic brain injury on a conditional spatial discrimination was examined. Quantitative magnetic resonance imaging revealed significant hippocampal atrophy in the hypoxic subjects. The hypoxic subjects were able to acquire and reverse the discrimination, although they were slower relative to matched control subjects. Hypoxic subjects also showed a tendency to perseverate after reward contingencies were reversed.