Visual half-field testing of memory functions in patients considered for surgical treatment of intractable complex partial epilepsy

The present research employed the visual half-field (VHF) technique to assess memory functions in normal subjects and in patients with unilateral temporal lobe epilepsy prior to surgery. Two studies were conducted. In Study 1, concrete and abstract words were presented to the left (LVF) or the right visual half field (RVF), and measures were made of response latencies, naming, free recall, and recognition. In Study 2, pictures depicting random shapes with low verbal association values were presented, and measures were made of latencies for identification and recognition of the shapes. Overall, the results showed a RVF advantage for words, but no lateralization for shapes. A selective hemisphere memory deficit was obtained for abstract words in patients with left temporal lobe lesions. Otherwise, no obvious lesion-related differences were found in the preoperative analyses. It is concluded that VHF testing of verbal information, but not abstract visuo-spatial information, is discriminative in assessing hemispheric functions in normal subjects and patients with temporal-lobe epileptic lesions.