Figure 4.

Membranal ERK is activated 3 d after learning. A, Protein expression level of ERKII is not modified after olfactory learning. The protein level is normalized to the average value obtained from the naive animals. Summarized data are presented as mean OD ± SE; n = 9 rats for each experimental group. Above are representative immunoblots for ERKI/II protein prepared from the piriform cortex of naive, pseudo-trained, and trained animals. B, After learning the level of pERKII is increased. Summarized data are presented as the ratio of pERKII/total ERKII; n = 9 rats for each experimental group. Above are representative immunoblots for pERKII prepared from piriform cortex of each of the three groups. Values represent mean ± SE.