THE ROLE OF THE RIGHT MEDIAL TEMPORAL-LOBE IN THE CONTROL OF MEMORY-GUIDED SACCADES

The role of the hippocampal formation in the control of memory-guided saccades is unclear. We tested two types of memory-guided saccades wit h short memorization delay in three patients with a lesion affecting t he right medial temporal lobe and involving the hippocampal formation. In single memory-guided saccades, testing spatial working memory, the gain of the patient group did not differ from that of an age-matched control group. In contrast, in sequences of memory-guided saccades, te sting chronological working memory, then was a marked and significant increase in the percentage of erroneous sequences in patients, compare d to controls. These results suggest an important role of the hippocam pal formation in the memorization of the chronological order of saccad e sequences. In contrast. this structure does not appear to be crucial for spatial working memory, used in single memory-guided saccades.