Figure 3
Effects of GM-CSF deficiency on MWM performance.
(A,B) During acquisition, a main effect of genotype was noted as escape latencies (A) and swim path lengths (B) were greater in GMko mice compared to controls (genotype, p<0.001). However, learning progress between groups was comparable as reflected by a similar relative improvement over time for both parameters (genotype*day, both p>0.05). (C) Frequency density analysis of accumulated trajectories reveals thigmotactic behaviour of knock-outs during early training with an initial focus on pool entry sites. Platform-focused trajectories develop later and to a lesser extent compared to wildtypes. (D) Velocity profiles during training differed between groups (genotype, p<0.01, genotype*day, p<0.001). In contrast to controls, knock-outs displayed signs of an elevated stress response with initial hyper- and subsequent hypoactivity. (E) Only knock-outs displayed pronounced platform jump-off behaviour (genotype, p<0.001). This only subsided towards the end of the acquisition period. (F) Spatial memory was impaired in GMko mice which spent significantly less time in the target area during the probe trial (p<0.05). While performance at D12 clearly affected this parameter (p<0.01), genotype had an independent effect (p<0.05). (G) Representative probe trial trajectories illustrating reduced memory accuracy in GMko mice. (H) Frequency density maps illustrating inferior memory performance of GMko mice in the probe trial. (I) Occupancy of target area locations during the probe trial analyzed in bins of 10 seconds indicates differential platform search patterns between groups (genotype, p = 0.010; genotype*time, p<0.05). Controls initially perform a focused search at the former platform location (FPL) before screening other regions, while, at an overall lower rate, knock-outs keep constantly visiting the FPL. (J) Reversal learning was impaired in GMko mice (both genotype and genotype*time, p<0.05). Note that path lengths were indistinguishable at reversal training day 1. WT, n = 22; KO, n = 21 animals. Data is presented as mean ± SEM.
