Adult neurogenesis mediates forgetting of multiple types of memory in the rat

Molecular Brain

John G. Howland¹  Kelsea A. Gorzo²  Alex P. Vu²  Jonathan R. Epp²  Gavin A. Scott²  Dylan J. Terstege²  Andrew J. Roebuck³ 

[1] Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, 107 Wiggins Road, S7N 5E5, Saskatoon, SK, Canada;Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, HMRB 162, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, T2N 4N1, Calgary, AB, Canada;Yukon University, 500 University Drive, Y1A 5K4, Whitehorse, YT, Canada;

关键词: Neurogenesis;    Forgetting;    Hippocampus;    Morris Water Task;    Contextual fear conditioning;    Paired Associates Learning;    Touchscreens;   

DOI  :  10.1186/s13041-021-00808-4

来源: Springer

【 摘 要 】

The formation and retention of hippocampus-dependent memories is impacted by neurogenesis, a process that involves the production of new neurons in the dentate gyrus of the hippocampus. Recent studies demonstrate that increasing neurogenesis after memory formation induces forgetting of previously acquired memories. Neurogenesis-induced forgetting was originally demonstrated in mice, but a recent report suggests that the same effect may be absent in rats. Although a general species difference is possible, other potential explanations for these incongruent findings are that memories which are more strongly reinforced become resilient to forgetting or that perhaps only certain types of memories are affected. Here, we investigated whether neurogenesis-induced forgetting occurs in rats using several hippocampus-dependent tasks including contextual fear conditioning (CFC), the Morris Water Task (MWT), and touchscreen paired associates learning (PAL). Neurogenesis was increased following training using voluntary exercise for 4 weeks before recall of the previous memory was assessed. We show that voluntary running causes forgetting of context fear memories in a neurogenesis-dependent manner, and that neurogenesis-induced forgetting is present in rats across behavioral tasks despite differences in complexity or reliance on spatial, context, or object memories. In addition, we asked whether stronger memories are less susceptible to forgetting by varying the strength of training. Even with a very strong training protocol in the CFC task, we still observed enhanced forgetting related to increased neurogenesis. These results suggest that forgetting due to neurogenesis is a conserved mechanism that aids in the clearance of memories.

【 授权许可】

CC BY