Figure 1. Mice with ablated neurogenesis due to focal X-irradiation show impaired spatial memory for similar, but not distinct, spatial locations in the radial arm maze.
(A) Mice were irradiated 2 months prior to behavioral testing. (B,C) Irradiation significantly reduced the total numbers of immature Dcx+ cells in irradiated (IR) mice (C, right, white arrows) compared to sham controls (C, left) (independent samples t-test, t(17)=29.82 , p<0.001). (D) Pattern separation was tested using a DNMP protocol in the RAM by varying the distance between sample and correct arms: S2/low, S3 and S4/high (S=start arm). (E) Each trial consisted of a sample phase (left) and a choice phase (right). The mouse had to non-match to the novel location. (F) IR mice were impaired at low (S2) but not high (S3+S4) separations in the DNMP task. Dashed line represents chance. Error bars represent SEM. Scale bars represent 25 μm. ** p<0.01, * p<0.05. GCL indicates granule cell layer; HL, hilus.