CONTRIBUTIONS OF CELL-ADHESION MOLECULES TO ALTERED SYNAPTIC WEIGHTINGS DURING MEMORY CONSOLIDATION

The fundamental concept that synapse growth and change are associated with learning is considered a ''replay'' of early neurodevelopmental p rinciples that instruct neural connectivity pattern. Common mechanisms suggested to link the process of memory formation through synaptic el aboration are exemplified by the activity of cell adhesion molecules f ollowing learning and that center on waves of glycoprotein synthesis o ccurring in the 6- to 8-h and 10- to 12-h posttraining periods of cons olidation. These are associated with spatially clustered granule cells in the adult rat hippocampus that show a transient time-dependent inc rease in ribosome production and greater microtubular complexity and d endritic spine number 6 to 8 h following training. The elimination and /or selection of the synapses to be retained in the memory trace is pr oposed to be dependent on cell adhesion molecule glycosylation events in the 10- to 12-h posttraining period. The existence of similar cell adhesion molecule glycosylation mechanisms within a corticohippocampal pathway is used to contribute to a model of memory in which sensory r epresentations are eventually consolidated through relative change in synaptic weightings. (C) 1998 Academic Press.