Figure 2
Memory and fear learning in the Ahi knockout mouse. (a) Novel object recognition. In this low-stress task, Ahi1+/+ mice displayed better performance than their Ahi1+/− littermates, as manifested by their superior discrimination ability (ratio of time spent with the novel object out of total time spent with both objects). *P<0.05. n=7 (Ahi1+/+), n=9 (Ahi1+/−). (b, c) Pavlovian fear conditioning. In these fear-learning paradigms, Ahi1+/− exhibited a diminished ability to memorize the association between the shock and the context (b) or cue (c). Although baseline freezing (percentage of time freezing during 30 s) was similar across genotypes (habituation and pretone periods), as was the magnitude of freezing increment in the immediate postshock period (b), during the test, exposure to the preconditioned context (b) or cue (tone, c) resulted in freezing responses that were significantly lower in the Ahi1+/− mice compared with Ahi1+/+ littermates, leading to a significant conditioning state vs genotype interaction. ***P<0.001 compared with the same genotype’s freezing during the prior conditioning state. ++P<0.01 compared with Ahi1+/+ mice exposed to the conditioned stimulus. n=15 mice/group. Data are expressed as mean±s.e.m.
