Long-term working memory in the rat: Effects of hippocampally applied anisomycin.

Abstract

The extent to which protein synthesis is involved in working memory was investigated with the protein synthesis inhibitor anisomycin (ANI). Rats were trained to perform accurately on a 12-arm radial maze when delays of 240 min were interposed between choice 6 and choice 7. Bilateral hippocampal cannulas were then implanted. Accuracy on choices 7-12 was studied when ANI or saline was injected either 30 min before choice 1 or 5-10 min after choice 6 (Experiment 1). Pretrial injection of ANI significantly impaired performance following the 240-min delay, whereas ANI injected during the delay had no such effect. In Experiments 2 and 3, the ANI-induced amnesia was replicated, and the temporal course of development of the amnesia was determined. Pretrial administration of ANI did not significantly affect retention after a 2-min delay but did produce amnesia after delays of 15 min or longer. These data suggest that protein synthesis is important for the formation of temporary memories, provided the retention interval is long enough. It is suggested that working memory includes both short-term and long-term components. Protein synthesis appears to be important for formation of the long-term component, hut not the short-term component, of working memory.The current literature shows that there is no generally accepted theory describing the neurochemieal bases of learning and memory. An example is the lack of agreement on exactly what different forms of memory exist. Several dichotomies of memory have been proposed, for example, working and reference memory (Olton, 1983) and episodic and semantic memory (Tulving, 1972), most of which have been formulated from behavioral observations of humans or animals. Whether these behavioral distinctions actually represent quali-

Aspects of the Search for Neural Mechanisms of Memory

“…We also found that protein must be synthesized in the cortex soon after training if LTM is to be formed; neither short-term memory (STM) nor intermediateterm memory (ITM) required protein synthesis (e.g. Bennett et al 1972, Mizumori et al 1985, Mizumori et al 1987. Further studies were then designed to find the neurochemical processes that underlie formation of STM and ITM.…”

Rapid Consolidation to aradishand Protein Synthesis-Dependent Long-Term Memory after Single-Session Appetitive Olfactory Conditioning inDrosophila

“…A hallmark of LTM in all organisms is a requirement for new protein synthesis after training (McGaugh, 1966;Daniels, 1971;Jaffe, 1980;Davis and Squire, 1984;Mizumori et al, 1985;Montarolo et al, 1986;Rose and Jork, 1987;Castellucci et al, 1989;Tully et al, 1994;Schafe and LeDoux, 2000). The classic method to assess a role for new protein synthesis in memory is to feed animals the protein synthesis inhibitor CXM before or after training.…”

Heat shock disrupts long-term memory consolidation in Caenorhabditis elegans.

“…Work with both vertebrates and invertebrates has suggested that gene expression is necessary for the cellular processes of LTM (Flood et al 1977;Davis and Squire 1984;Mizumori et al 1985;Montarolo et al 1986;Frey et al 1988;Tully et al 1994;Ghirardi et al 1995). The use of invertebrate systems in which the physiology, anatomy, genetics, and development of the nervous system are accessible has been instrumental in furthering our understanding of the cellular processes underlying LTM (Montarolo et al 1986;Tully et al 1994;Ghirardi et al 1995).…”