Spaced stimuli stabilize MAPK pathway activation and its effects on dendritic morphology

Memory storage in mammalian neurons probably depends on both biochemical ev ents and morphological alterations in dendrites. Here we report an activity -dependent stabilization of the MAP kinase (MAPK) pathway, prominent in hip pocampal dendrites. The longevity of the signal in these dendrites was incr eased to hours when multiple spaced stimuli were used. Likewise, spaced sti muli and MAPK activation were critical for protrusion of new dendritic filo podia that also remained stable for hours. Our experiments define a new rol e for stimulus-specific responses of MAPK signaling in activity-dependent n euronal plasticity. The local biochemical signaling in dendrites complement s MAPK signaling in gene expression. Together, these processes may support long-lasting behavioral changes.