Figure 8

Activity, learning and memory of ArhGAP15^−/− mice.

(a–c) ArhGAP15^−/− mice show deficits in spatial learning, using the hidden platform version of the water maze test. During the acquisition phase the platform was placed always in the same position. On the fourth day the platform was moved to a different position in the reversal phase (2 days of 6 trials per day). In the reversal sessions there were significant differences between WT and ArhGAP15^−/− in the time required to reach the platform (*) (a), in the path travelled (*) and in the speed (*) (c). No change is observed in the time spent in each quadrant (b). (d–e) ArhGAP15^−/− mice show deficits in short-term working memory and procedural learning. Using the 8-arms radial maze test, ArhGAP15^−/− mice show a significantly slower acquisition, while the number of visits and the total number of errors (d) are higher (**). ArhGAP15^−/− mice differ significantly in the position of the first repetition (**), e.g. they make less correct arm choices before their first error (e). (f–h) ArhGAP15^−/− mice show deficit in associative memory and learning, assessed using an auditory fear-conditioning protocol. The animals exhibit an immobility response (freezing) after exposure to tones (conditioning stimulus, CS) paired with a foot shock (unconditioned stimulus US). During the training phase, freezing reactions was significantly fewer in the ArhGAP15^−/− (**) (f). In the recall session, significant differences were observed between genotypes when 24 hrs later the animals were tested for freezing reactions to the context (***) (g) or to the tone (***) (h). These results indicate that ArhGAP15^−/− mice are unpaired with respect to the fear-related memory formation. Experiments were conducted on 10 animals per genotype. *, ** and ***Indicate, respectively, p < 0.05, p < 0.01 and p < 0.001.