Short- and long-term memory: Differential involvement of neurotransmitter systems and signal transduction cascades

Since William James (1890) first distinguished primary from secondary memor y, equivalent to short- and lung term memory, respectively, it has been ass umed that short-term memory processes are in charge of cognition while long -term memory is being consolidated. From those days a major question has be en whether shortterm memory is merely a initial phase of long-term memory, or a separate phenomena. Recent experiments have shown that many treatments with specific molecular actions given into the hippocampus and related bra in areas after one-trial avoidance learning can effectively cancel short-te rm memory without affecting long-term memory formation. This shows that sho rt-term memory and long-term memory involve separate mechanisms and are ind ependently processed. Other treatments, however, influence both memory type s similarly, suggesting links between both at the receptor and at the post- receptor level, which should not be surprising as they both deal with nearl y the same sensorimotor representations. This review examines recent advanc es in short and long-term memory mechanisms based on the effect of intra-hi ppocampal infusion of drugs acting upon neurotransmitter and signal transdu ction systems on both memory types.