The project activities centred around monitoring and manipulating the neurons of one of the main sources of serotoninergic neurons, the dorsal raphe nucleus (DRN). A series of behavioural experiments were carried out to probe reinforcement that is beneficial in the long term or reinforcement that is either deceiving in the long term or aversive and that subjects learn to refrain from repeating. We found that while serotoninergic neurons of the DRN (DRN5-HT) respond generally to reward and is necessary for the animals to repeat rewarded action, neighbouring dopaminergic neurons of the DRN (DRNDA) respond generally to aversive stimuli. We also found that the response of DRN5-HT neurons to reward is conserved in a structure involved in reinforcement that is the dorsolateral striatum, and that this signal is necessary for repeating the experience of reinforcement whether beneficial or deceiving. While this suggest that serotonin seems generally involved in reinforcement, we found that blocking one receptor of serotonin (5HT4) specifically reduced the repetition of deceiving reinforcement suggesting a selective role of serotonin receptors in restraint and reinforcement.
The results of FLEX5 were presented at four international conferences (European Brain and Behavioural Society forum 2021, Society For Neuroscience forum 2021, Basal Ganglia Gordon’s Conference 2022 and Federation of European Neuroscience Society 2022) and two further presentations are planned, after completion of the FLEX5 Project, at the Australasian neuroscience society forum 2022 and at the winter brain conference 2023. Furthermore, two scientific publications are in development and will be submitted to open access journals in 2023.
