The ability to predict future events based on environmental cues and to subsequently choose appropriate actions is important for gaining benefits and avoiding stress. Dopamine signaling in the cerebral cortex and basal ganglia plays a crucial role in associative learning. In addition, there is a close relationship between exercise and dopamine activity. This study examined the effects of various exercise habits on associative learning as a preliminary test of the hypothesis that exercise habits enhance associative learning activating dopamine signaling. Four-week-old rats were housed in cages with rotating wheels for one month. Subsequently, they underwent surgery to attach a head fixation frame and implant a telemetry transmitter to measure blood pressure. In a cue-reward association task, one tone cue (CS+) was associated with reward delivery (US+; 10% sucrose, 0.08 mL), while another tone cue (CS−) was associated with no reward (US−). The LED was turned on as a GO signal 15 s after CS presentation. Rats received a reward if they licked the tube in front of them within 2 s of the GO signal in CS+ trials, but not in CS− trials. Changes in licking behavior and blood pressure responses were analyzed as indicators of learning performance. The mean (± s.d.) number of wheel rotations driven by the rats was 78,172 ± 34,174 (n = 8, range: 49,527-137,026). We observed that the predictive pressor response to CS+ (calculated as the difference between CS+ and CS−) tended to occur earlier in individuals with higher locomotor activity compared to those with lower locomotor activity (n = 5). These results suggest the existence of large individual differences in motivation for exercise, and that individuals with high exercise motivation may have accelerated cue-reward association learning.
Yamanaka et al. (Thu,) studied this question.