CONICET | Buscador de Institutos y Recursos Humanos

The medial pre frontal cortex (mPFC) has been involved several higher order functions including behavioral flexibility, attention, inhibitory control, decision making, goal-directed behaviors, interference and response selection. The interference theory refers to the idea that forgeting ocurrs because the recall of certain items interfere with the recall of other items. Under this theory, two memories traces that require the same neuronal mechanisms will trigger the activation of the PFC with the subsequent forgetting of one of the traces. The PFC activity is heavily modulated by different neurotransmitters pathways, including the serotoninergic system. Serotonin (5-HT) modulates different physiological responses including mood, impulsivity, aggression and cognition among others. It works through the activation of 14 different receptors. In particular, the mPFC expressed high levels of the excitatory 5-HT2a receptor (5-HT2aR), which have been the focus of intense study as a key player in the modulation of cortical activity. Particularly, changes in cortical 5-HT2aR have been associated with psychiatric disorders like anxiety, stress and schizophrenia. However it is not clear which is the role of the serotoninergic system and the 5-HT2aR in particular during response selection and interference processes. We studied the possible role of the 5-HT system and the 5-HT2aR in interference processes using different versions of the novel object recognition task (NOR). In all the experiments rats received local injections of the selective 5-HT2aR antagonist, MDL 11,939, 15 minutes before the test phase. Animals injected with MDL 11, 939 showed deficits in a mPFC-dependent version of the NOR (temporal order) with no changes in attention or a hippocampal dependent NOR. To support our hypothesis that activity of mPFC is important for selection of the correct response when there is competition of memory traces, we did an object in context recognition test (OIC). We found that also in this case, blockage of the cortical 5-HT2aR avoid the ability of the mPFC to make a response selection, suggesting that the activity of the mPFC is important when there is competition of memory traces to select the correct response.