The effects of mesial temporal and cerebellar hypometabolism on learning and memory

The effects of mesial temporal (MT) and cerebellar hypometabolism were stud ied using measures of verbal, visual and motor skill learning. Twelve patie nts with refractory temporal lobe epilepsy who showed asymmetrical mesial t emporal lobe hypometabolism on [F-18] fluoro-2-deoxy-glucose positron emiss ion tomography (FDG-PET) were given tests involving 4 consecutive learning trials and a 30-min delayed recall trial. Delayed recognition was also asse ssed for the words and designs, and skill transfer was evaluated for mirror drawing. Compared to 9 normal control participants, patients with more mar ked MT hypometabolism on the left had impaired delayed recall of words and patients with more marked MT hypometabolism on the right showed impaired le arning of novel designs, but normal retention over delay. Patients were not impaired in their minor-drawing performance. The findings for MT hypometab olism correspond well to those obtained in other studies where patients hav e been classified on the basis of side of hippocampal atrophy or temporal l obe excision.