Behavioral training-induced c-Fos expression in the rat nucleus basalis ofMeynert during aging

The present study investigated the behavioral training-induced c-Fos expres sion in the nucleus basalis of Meynert (nbM) in differently aged rats. This study demonstrated that the c-Fos expression in nbM was significantly incr eased and the peak occurred at 2 h after dark-avoidance training. Although the increase of c-Fos expression was also observed after pseudotraining, th e number of Fos-like immunoreactive neurons in pseudotrained rats was signi ficantly less than that in dark-avoidance trained rats at each time-point. This result suggested that c-Fos expression might be involved in learning a nd memory processes. In addition, all the pseudotraining-, training- and me mory arousing-induced c-Fos expression was decreased with increasing age, a nd the decrease was more notable in trained and memory aroused rats. This s uggested that the total number of nbM neurons and/or the sensitivity of nbM neurons to experimental manipulations, especially learning and memory perf ormance, might reduce during aging. (C) 2000 Elsevier Science B.V. All righ ts reserved.