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

Abstract

Since William James (1890) first distinguished primary from secondary memory, equivalent to short-and longterm memory, respectively, it has been assumed that short-term memory processes are in charge of cognition while long-term memory is being consolidated. From those days a major question has been 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 brain areas after one-trial avoidance learning can effectively cancel short-term memory without affecting long-term memory formation. This shows that short-term memory and long-term memory involve separate mechanisms and are independently processed. Other treatments, however, influence both memory types similarly, suggesting links between both at the receptor and at the post-receptor level, which should not be surprising as they both deal with nearly the same sensorimotor representations. This review examines recent advances in short-and long-term memory mechanisms based on the effect of intra-hippocampal infusion of drugs acting upon neurotransmitter and signal transduction systems on both memory types.

Drug enhancement of memory consolidation: historical perspective and neurobiological implications

“…Some evidence suggests that it is not reasonable to draw that conclusion. Some drugs appear to enhance long-term memory without influencing short-term or working memory Barros et al 2002;Vianna et al 2000). Additionally, and importantly, corticosterone, in doses that enhance memory consolidation, impairs shortterm or working memory as well as memory retrieval (de Quervain et al 1998;Roozendaal et al 2002Roozendaal et al , 2003Roozendaal et al , 2004aBarsegyan et al submitted).…”

Distinct single but not necessarily repeated tetanization is required to induce hippocampal late-LTP in the rat CA1: Figure 1.

“…Four or more trains induce a more persistent phase of LTP (called late LTP)" (Kandel et al 2000). There are also forms, however, of immediate permanent learning (for instance, distinct forms of one-trial avoidance learning Vianna et al 2000; and others]). Here, we show that LTP mechanistically could also underlie such learning at the cellular level.…”

Promnesic effects of Ptychopetalum olacoides in aversive and non-aversive learning paradigms

“…While some drugs equally influence STM and LTM (e.g., scopolamine, CNQX, AP5, MCPG, muscimol), others either affect STM but not LTM (e.g., intrahippocampal SCH23390, SKF 38393, 8-OH-DPAT) or LTM but not STM (e.g., norepinephrine) (Izquierdo et al, 1998b;Vianna et al, 2000b;Schroder et al, 2003). Differential effects are consistent with the idea that STM and LTM pertain to (and are regulated by) separate subsystems in the brain, some but not all times sharing a given brain structure (Rosenzweig et al, 1993;Izquierdo et al, 1999).…”

“…Additionally, memories are also classified according to their duration, as short-(STM) and long-term memory (LTM) (Vianna et al, 2000b). Assisting in establishing these memories as separate entities the main structures involved in STM and LTM were identified (Izquierdo et al, 1998a, as well as treatments that block STM without affecting LTM (Izquierdo et al, 1998b).…”