Study reveals potential role of 'love hormone' oxytocin in brain function

In a loud, crowded restaurant, having the ability to focus on the people and conversation at your own table is critical. Nerve cells in the brain face similar challenges in separating wanted messages from background chatter. A key element in this process appears to be oxytocin, typically known as the "love hormone" for its role in promoting social and parental bonding.

In a study appearing online August 4 in Nature, NYU Langone Medical Center researchers decipher how , 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," says Richard W. Tsien, DPhil, the Druckenmiller Professor of Neuroscience and director of the Neuroscience Institute at NYU Langone Medical Center. "It not only quiets background activity, but also increases the accuracy of stimulated impulse firing. Our experiments show how the activity of can be sharpened, and hint at how this re-tuning of brain circuits might go awry in conditions like autism."

Children and adults with (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 gene predispose people to autism. Recent brain recordings from people with ASD show impairments in the transmission of even simple .

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 – called inhibitory – 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."

To resolve this paradox, Dr. Tsien and his Stanford graduate student Scott Owen collaborated with Gord Fishell, PhD, the Julius Raynes Professor of Neuroscience and Physiology at NYU Langone Medical Center, and NYU graduate student Sebnem Tuncdemir. They identified the particular type of inhibitory interneurons responsible for the effects of oxytocin: "fast-spiking" inhibitory interneurons.

The mystery of how oxytocin drives these fast-spiking inhibitory cells to fire, yet also increases signaling to pyramidal neurons, was solved through studies with rodent models. The researchers found that continually activating the fast-spiking inhibitory neurons – good for lowering background noise – also causes their GABA-releasing synapses to fatigue. Accordingly, when a stimulus arrives, the tired synapses release less GABA and excitation of the pyramidal neuron is not dampened as much, so that excitation drives the pyramidal neuron's firing more reliably.

"The stronger signal and muffled background noise arise from the same fundamental action of oxytocin and give two benefits for the price of one," Dr. Fishell explains. "It's too early to say how the lack of oxytocin signaling is involved in the wide diversity of autism-spectrum disorders, and the jury is still out about its possible therapeutic effects. But it is encouraging to find that a naturally occurring neurohormone can enhance brain circuits by dialing up wanted signals while quieting background noise."

More information: Oxytocin enhances hippocampal spike transmission by modulating fast-spiking interneurons, DOI: 10.1038/nature12330

Related Stories

No oxytocin benefit for autism

Jul 18, 2013

The so-called trust hormone, oxytocin, may not improve the symptoms of children with autism, a large study led by UNSW researchers has found.

Oxytocin improves brain function in children with autism

May 21, 2012

(Medical Xpress) -- Preliminary results from an ongoing, large-scale study by Yale School of Medicine researchers shows that oxytocin — a naturally occurring substance produced in the brain and throughout ...

Could nasal spray of 'love hormone' treat autism?

May 16, 2012

(HealthDay) -- Children with autism given a squirt of a nasal spray containing the hormone oxytocin showed more activity in brain regions known to be involved with processing social information, a small study ...

Recommended for you

'Trigger' for stress processes discovered in the brain

6 hours ago

At the Center for Brain Research at the MedUni Vienna an important factor for stress has been identified in collaboration with the Karolinska Institutet in Stockholm (Sweden). This is the protein secretagogin ...

New research supporting stroke rehabilitation

Nov 26, 2014

Using world-leading research methods, the team of Dr David Wright and Prof Paul Holmes, working with Dr Jacqueline Williams from the Victoria University in Melbourne, studied activity in an area of the brain ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.