Activation of the central serotonergic system in response to delayed but not omitted rewards.
Bottom Line: The forebrain serotonergic system is a crucial component in the control of impulsive behaviours.By contrast, during the intermittent reward condition, in which food was given on only about one-third of the site visits, the level of dopamine was lower than that during the immediate reward condition, whereas the level of serotonin did not change significantly.This is the first direct evidence that activation of the serotonergic system occurs specifically in relation to waiting for a delayed reward.
Affiliation: Neural Computation Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan. email@example.comShow MeSH
Related in: MedlinePlus
Mentions: To test whether there was any reciprocal interaction between 5-HT and DA, as predicted from the opponent theory, we examined the correlation between 5-HT and DA efflux every 5 min. There was no significant negative or positive correlation between 5-HT and DA efflux (r= −0.051, P=0.54) in any of the three reward conditions or in any of the conditions combined (Fig. 6A). We further checked whether the 5-HT and DA efflux correlated with the behavioural measures of food consumption and distance moved every 5 min. Although there was no significant correlation between 5-HT efflux and food consumption (r= −0.011, P=0.88) (Fig. 6B), DA efflux was significantly correlated with food consumption (r=0.30, P=0.0003) (Fig. 6C). 5-HT efflux had a significant negative correlation with distance moved during the task (r= −0.24, P=0.0011). However, a low level of 5-HT efflux would not be simply related to locomotion, as 5-HT efflux was lowest during the rest period (Fig. 4A and D). DA efflux had no significant correlation with distance moved (r= −0.14, P=0.09). Neither 5-HT nor DA efflux was significantly correlated with the time between the tone presentation at the home-base circle and the nose-poke at the food site (r=0.12, P=0.12 and r= −0.11, P=0.19, respectively).
Affiliation: Neural Computation Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan. firstname.lastname@example.org