Mushroom spine dynamics in medium spiny neurons of dorsal striatum associated with memory of moderate and intense training

Significance Interference with activity of cerebral structures, including the dorsal striatum, produces amnesia after moderate levels of training; such interference, nonetheless, becomes ineffective when animals are subjected to intense training procedures. The mechanisms that mediate the protective effect of intense training are unknown. This report shows an increase in relative density of mushroom spines in medium spiny neurons (MSNs) of the dorsal striatum, which depends upon the intensity of training; relative density of mushroom spines in MSNs of nucleus accumbens, on the other hand, is augmented after noncontingent administration of a foot-shock alone. These findings suggest that increased mushroom spinogenesis produced by intense training strengthens memory consolidation and facilitates transfer of information from the dorsal striatum to other cerebral structures.