Involvement of serotonin in cognitive flexibility in rats

BERNARDEZ MICAELA; RAPANELLI MAXIMILIANO; ZANUTTO SILVANO; FRICK LUCIANA ROMINA

Cordoba

Congreso; Reunion Anual de la SAN; 2012

Sociedad Argentina de Investigacion en Neurociencias

We have previously described the role of serotonin (5-HT) in the acquisition of an operant conditioning task. Here we studied the role of 5-HT in the reversal of this reward-dependent learning. First, animals were trained in an operant conditioning task, followed by several extinction sessions.  We found that Fluoxetine administration (a 5-HT reuptake inhibitor) improved the extinction of the rule, i.e., the animals needed fewer sessions to achieve a low number of incorrect responses. Instead, animals treated with Tianeptine (a 5-HT reuptake enhancer) had the opposite effect; rats had a higher number of incorrect responses even after several sessions of extinction. Then, we assayed the effect of Buspirone (a 5-HT1A receptor agonist). Buspirone did not have an overall effect on the extinction of the task, nevertheless, a slightly higher number of incorrect responses was observed in the last sessions. The 5-HT2A receptor antagonist Risperidone exerted a drastic effect on reversal learning; animals achieved a complete extinction after a few sessions. Finally, the 5-HT3 antagonist Ondansetron also improved the ability of the rats to learn the new rule faster than the controls. Taking into account our prior results, these data suggest that 5-HT plays an important role in cognitive flexibility, acting as a dual codifier of the reward and the lack of the same.