ON BRAIN-LESIONS, THE MILKMAN AND SIGMUNDA

Lesion studies have been of historical importance in establishing the brain systems involved in memory processes. Many of those studies, how ever, have been overinterpreted in terms of the actual role of each sy stem and of connections between systems. The more recent molecular pha rmacological approach has produced major advances in these two areas. The main biochemical steps of memory formation in the CAI region of th e hippocampus have been established by localized microinfusions of dru gs acting on specific enzymes of receptors, by subcellular measurement s of the activity or function of those enzymes and receptors at defini te times, and by transgenic deletions or changes of those proteins,The biochemical steps of long-term memory formation in CAI have been foun d to be quite similar to those of long-term potentiation in the same r egion, and of other forms of plasticity. Connections between the hippo campus and the entorhinal and parietal cortices in the formation and m odulation of short- and long-term memory have also been elucidated usi ng these techniques. Lesion studies, coupled with imaging studies, sti ll have a role to play; with regard to human memory, this role is in m any ways unique. But these methods by themselves are not informative a s to the mechanisms of memory processing, storage or modulation.