Dynamics of Dendritic Spines in Dorsal Striatum after Retrieval of Moderate and Strong Inhibitory Avoidance Learning

In marked contrast to the ample literature showing that the dorsal striatum is engaged in memory consolidation, little is known about its involvement in memory retrieval. Recent findings demonstrated significant increments in dendritic spine density and mushroom spine counts in dorsal striatum after memory consolidation of moderate inhibitory avoidance (IA) training; further increments were found after strong training. Here, we provide evidence that in this region spine counts were also increased as a consequence of retrieval of moderate IA training, and even higher mushroom spine counts after retrieval of strong training; by contrast, there were fewer thin spines after retrieval. Similar changes in mushroom and thin spine populations were found in the ventral striatum (nucleus accumbens), but they were related to the aversive stimulation and not to memory retrieval. These results suggest that memory retrieval is a dynamic process which produces neuronal structural plasticity that might be necessary for maintaining or strengthening assemblies that encode stored information. This article is part of a Special Issue entitled: In memory of Ivan Izquierdo South American pioneer of the Neuroscience of Memory Temporal dynamics and molecular mechanisms. (C) 2021 IBRO. Published by Elsevier Ltd. All rights reserved.

Automated summary

In contrast to previous literature, this study demonstrates the involvement of the dorsal striatum in memory consolidation and its role in memory retrieval remains less understood. The results show an increase in spine counts in the dorsal striatum after moderate inhibitory avoidance (IA) training, with further increments after strong training. Retrieval of IA training also leads to increased spine counts and higher mushroom spine counts, while there is a decrease in thin spines. Similar changes are observed in the ventral striatum, but they are related to aversive stimulation rather than memory retrieval.