Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.21.213538v1?rss=1 Authors: Eom, K., Lee, H. R., Hyun, J. H., Ryu, H.-H., Lee, Y.-S., Lee, I., Ho, W.-K., Lee, S.-H. Abstract: Kv1.2 expression in rodent CA3 pyramidal cells (CA3-PC) is polarized to distal apical dendrites, and regulate the synaptic responses to perforant pathway (PP) inputs. Accordingly, Kv1.2 haploinsufficiency (Kcna2+/-) in CA3-PCs, but not Kv1.1 (Kcna1+/-), lowered the threshold for long-term potentiation at PP-CA3 synapses. The Kcna2+/- mice, but not Kcna1+/-, displayed impairments in contextual fear discrimination task. The size and overlap of CA3 ensembles activated by the first visits to slightly different contexts were not different between wildtype and Kcna2+/- mice, but these ensemble parameters diverged over training days between genotypes, suggesting abnormal plastic changes in the CA3 network of Kcna2+/- mice. Eventually, the Kcna2+/- mice exhibited larger ensemble size and overlap upon retrieval of two contexts, compared to wildtype or Kcna1+/- mice. These results suggest that Kv1.2 subunits prevent promiscuous plastic changes at PP-CA3 synapses, and contribute to sparse representation of memories and pattern separation in the CA3 network. Copy rights belong to original authors. Visit the link for more info