In recent years, there was numerous well-documented research on the relationship between serotonin and social & emotional behaviors and brain fitness. Now in a recent study, some scientists found that serotonin acts on specific areas of the brain to promote patience. Hence the neural computation unit at the Okinawa Institute of Science and Technology Graduate University (OIST) did a study on mice with the co-authors, Dr. Katsuhiko Miyazaki and Dr. Kayoko Miyazaki.


Dr. Kayoko Miyazaki says that “Serotonin is one of the most famous neuromodulators of behavior, helping to regulate mood, sleep-wake cycles, and appetite,” and “Our research shows that the release of this chemical messenger also plays a crucial role in promoting patience, increasing the time that mice are willing to wait for a food reward.”


In the previous study, the researchers focused on the three regions of the brain, where the damage to serotonin leads to impulsive behavior, and the three regions are nucleus accumbens (NAc), orbitofrontal cortex (OFC), and the medial prefrontal cortex (mPFC).


“Impulse behaviors are intrinsically linked to patience -— the more impulsive an individual is, the less patient — so these brain areas were prime candidates.” says the co-author Dr. Katsuhiko Miyazaki.


Now, the researchers trained mice to perform a waiting task where after the training the mice were supposed to poke their nose inside the hole known as “Nose Poke” and wait for its food until it is delivered. In order to observe how much area corresponds to serotonin stimulation, the mice went under surgery to implant optic fibers in either of their NAc, OFc, or mPFC.


After their recovery from the implantation surgery, the researchers once again activated serotonin release through the light stimulation procedure in 75% of the animals and the remaining 25% of the mice went into the omission group where they received no serotonin stimulation.


When they activated the Serotonergic neurons in the DRN, the mice showed improved impatience while waiting for their food rewards. When OFC was stimulated, it was almost effective as DRN which promotes prolonged waiting in the mice. Whereas triggering NAc had no effects, but interestingly stimulating the mPFC enhanced the mice’s waiting ability as they were not aware of their food arrival time.


These results show that serotonin in the mPFC triggers and affect the mice’s ability in evaluating its time required to wait for its food, while the OFC plays an assistant role in delaying the reward situation. Dr. Miyazaki concludes that


“This confirmed the idea that these two brain areas are calculating the probability of a reward independently from each other and that these independent calculations are then combined to ultimately determine how long the mice will wait.”