The search for a biochemistry of memory

The search for a biochemistry of memory may be divided into two consecutive periods: the search for molecular memory coding in the brain (1960-1975), and the ongoing search for biochemical correlates of learning or memory. During the first period, three main methods were used: chemical analysis of macromolecules after learning, studying the effects on learning of compounds (antibiotics) impairing macromolecule synthesis, and attempting chemical transfer of information items acquired by the brain ("memory transfers"). None of the three methods succeeded in clearly demonstrating that memory is chemically encoded. Subsequent modern work has focused on the search for correlates between brain chemical mechanisms and memory processes: the role of protein synthesis in memorization, peptide modulation of learning, and the role of the main neurotransmitter systems (particularly acetylcholine, catecholamines, GABA and glutamic acid). The correlates, which are to be interpreted with caution, are based on both pharmacological results in animals and clinical data in man.