Oxytocin, also known as the "love hormone" keeps social and parental bonds active in a crowded environment.
In the study, NYU Langone Medical Center researchers decipher how oxytocin, acting as a neurohormone in the brain, not only reduces background noise, but more importantly, increases the strength of desired signals.
These findings may be relevant to autism, which affects one in 88 children in the United States.
"Oxytocin has a remarkable effect on the passage of information through the brain," Richard W. Tsien, DPhil, the Druckenmiller Professor of Neuroscience and director of the Neuroscience Institute at NYU Langone Medical Center, said.
"It not only quiets background activity, but also increases the accuracy of stimulated impulse firing. Our experiments show how the activity of brain circuits can be sharpened, and hint at how this re-tuning of brain circuits might go awry in conditions like autism," he said.
Children and adults with autism-spectrum disorder (ASD) struggle with recognizing the emotions of others and are easily distracted by extraneous features of their environment.
Previous studies have shown that children with autism have lower levels of oxytocin, and mutations in the oxytocin receptor gene predispose people to autism.
Recent brain recordings from people with ASD show impairments in the transmission of even simple sensory signals.
The current study built upon 30-year old results from researchers in Geneva, who showed that oxytocin acted in the hippocampus, a region of the brain involved in memory and cognition.
The hormone stimulated nerve cells - called inhibitory interneurons - to release a chemical called GABA.
This substance dampens the activity of the adjoining excitatory nerve cells, known as pyramidal cells.
"From the previous findings, we predicted that oxytocin would dampen brain circuits in all ways, quieting both background noise and wanted signals," Dr. Tsien explains.
"Instead, we found that oxytocin increased the reliability of stimulated impulses - good for brain function, but quite unexpected," he said.
The study is published in the journal Nature.