PT  - JOURNAL ARTICLE
AU  - Anne Albrecht
AU  - Iris Müller
AU  - Aliće Weiglein
AU  - Evangelia Pollali
AU  - Gürsel Çalışkan
AU  - Oliver Stork
TI  - Choosing memory retrieval strategies: a critical role for inhibition in the dentate gyrus
AID  - 10.1101/2022.05.02.490267
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.05.02.490267
4099  - http://biorxiv.org/content/early/2022/06/28/2022.05.02.490267.short
4100  - http://biorxiv.org/content/early/2022/06/28/2022.05.02.490267.full
AB  - Remembering the location of food is essential for survival. Rodents and humans employ mainly hippocampus-dependent spatial strategies, but when being stressed they shift to striatum-mediated stimulus-based strategies. To investigate underlying brain circuits, we tested mice with a heightened stress susceptibility due to a lack of the GABA-synthetizing enzyme GAD65 (GAD65-/- mice) in a dual solution task. Here, GAD65-/- mice preferred to locate a food reward in an open field via a proximal cue, while their wildtype littermates preferred a spatial strategy. The analysis of cFos co-activation across brain regions and of stress-induced mRNA expression changes of GAD65 pointed towards the hippocampal dorsal dentate gyrus (dDG) as a central structure for mediating stress effects on strategy choices via GAD65. Reducing the GAD65 expression locally in the dDG by a shRNA mediated knock down was sufficient to replicate the phenotype of the global GAD65 knock out and to increase dDG excitability. Using DREADD vectors to specifically interfere with dDG circuit activity during dual solution retrieval but not learning confirmed that the dDG modulates strategy choices and that a balanced excitability of this structure is necessary to establish spatial strategy preference. These data highlight the dDG as a critical hub for choosing between spatial and non-spatial foraging strategies.Competing Interest StatementThe authors have declared no competing interest.ACCanterior cingulate cortexBLAbasolateral amygdalaCACornu ammonisCeAcentral amygdalaCNOclozapine-N-oxideCORTcorticosteronedDGdorsal dentate gyrusDREADDdesigner receptors exclusively activated by designer drugsfEPSPfield postsynaptic potentialsGAD65glutamic acid decarboxylating enzyme, 65 kDa isoformGRglucocorticoid receptorsLAlateral amygdalamPFCmedial prefrontal cortexMRmineralocorticoid receptorsPL/ILPre-/ Infralimbic cortex