Written by | Bob Holmes
Translated by | Muchun
Proofreading | Things off
Edit | Pheasant
What's going on in the brain when love is infested? For years, biologists will tell you, "Oxytocin!" This tiny protein, which is only nine amino acids long, is sometimes called the "love hormone" — it is involved in male-female pairing, maternal care, and other positive, love-related social behaviors.
However, neuroscientists have recently revised their understanding of oxytocin. Experiments on mice and other laboratory animals have shown that oxytocin is not the "trigger" that triggers prosocial behavior. It simply enhances the mice's perception of social cues, so they learn how to focus more precisely on specific social behaviors. Gül D len, a neuroscientist at Johns Hopkins University, puts it this way: "It turns out that this is not as straightforward as 'oxytocin equals love.'" "If a similar situation is present for people, it may add new difficulties to treat interpersonal communication disorders such as autism by improving people's oxytocin system."
Neuroscientists have long believed that the release of oxytocin in the brain may be triggered by social interactions with specific individuals who may be offspring or mates important to humans or other animals. When the researchers blocked oxytocin activity in the experiment, the mice were no longer able to identify important individuals in social relationships. This suggests that oxytocin plays a central role in social learning — but researchers have yet to come to terms with how oxytocin works. With advances in neuroscience and technology, this situation is changing. In recent years, researchers have been able to identify and record the activity of individual neurons that produce oxytocin deep within the brain. These records tell a story that differs from traditional belief, small but crucial.
Studies have shown that in the main olfactory center of the mouse brain, oxytocin is able to inhibit the random, chaotic discharge of nerve cells, which makes the nerve signal of the actual target odor more prominent (this is done indirectly by exciting nerve cells called granulocytes, which are able to inhibit other nerve cells) [1].
The mother mouse is able to discern the cries of the mice she feeds. The researchers found that oxytocin kept other noises in the mother mouse's auditory system silent, making it easier for her to hear the mice's cries. 丨SHARI E. ROSS
Larry Young, a behavioral neuroscientist at Emory University, and her collaborator, Robert Froemke, published an article last year in the Annual Review of Neuroscience exploring our new understanding of oxytocin.[2] Yang said: "There is a lot of noise in the brain, but when oxytocin is released, it can reduce noise interference, so the signal will become clearer." ”
Yevgenia Kozorovitskiy, a neuroscientist at Northwestern University, says oxytocin also enhances the brain's reward system response. This effect can transform the animal's behavior in searching for something new in its environment, focusing its attention on social rewards.
For pastoral voles, this shift facilitates their pairing. The Tahara voles follow monogamy, which is rare among rodents [3-4]. In the brains of such voles, some cells sensitive to oxytocin associate the smell of their partners with the reward system. "Pairing is in a sense an obsession with a partner, and a partner is a natural reward." Yang said. Non-monogamous species such as mice and meadow voles lack receptors for these oxytocins. Interestingly, such receptors are found in the human brain. This means that our response is more like a Tahara vole than a mouse (the molecular cousin antidiuretic hormone on oxytocin also plays a role in paired binding behavior).
This new understanding of oxytocin's ability to increase attention to significant signals in social interaction may help explain the universal experience of love making the world sparkle. "When you look into your partner's eyes, oxytocin makes the world more vivid." Yang said so.
This is more complex than imagined, and it's important to note that if oxytocin works to make socially relevant sensory perceptions clearer, rather than just social, it means that these chemicals may have different effects in different contexts. For example, Yang noted that oxytocin enhances maternal care in mice, which is undoubtedly a prosocial behavior, but it also enhances maternal aggression towards strange individuals.
Unlike most rodents, Tahara voles are lifelong dependent on their partners. The oxytocin-sensitive cells present in the reward centers of their brains make them feel better when their partners are present. 丨COURTESY OF LARRY YOUNG
In addition, Yang and his colleagues found that female Tahara voles respond differently to oxytocin [5], depending on whether they have a mate. In female Tahara voles without a mate, oxytocin reduces noise in the reward system, allowing them to better smell the smell of potential partners. In the case of companion voles, these molecules expand the capacity of the reward system, making the partner more rewarding, thereby reducing aggressive behavior towards the partner.
Some similar phenomena also appear in human groups. In a 2012 study, 30 men with a spouse who received nasal sprays of oxytocin maintained greater social distancing from an attractive strange woman compared to placebo spray [6]. This effect was not found in another experimental group of 27 single-person men.
The contextual dependence of oxytocin complicates the use of oxytocin to treat autism spectrum disorder. Some therapists have treated autistic patients with nasal sprays of oxytocin, based on the theory that oxytocin enhances people's response to social stimuli. However, a recent large clinical trial found no significant effect [7].
Yang said there was no need to be surprised because the experiment did not control the situation in which patients were sprayed with oxytocin. For example, if a child is bullied at school, this treatment will not only not help, but will exacerbate the negative experience. Yang argues that any oxytocin-based therapy needs to be carefully conducted in a safe environment during the treatment process [8].
Neuroscientists also emphasize that while oxytocin plays an important role in regulating social behaviors such as male-female pairing and parenting, it is by no means the only influencing factor. Kozorovicki said: "Falling in love is an experience in which the whole brain and body are involved, involving sensory and cognitive elements, and memory is also crucial. Is oxytocin one of the many regulators influencing these changes? Absolutely. But can oxytocin explain everything? This is undoubtedly an oversimplification. ”
bibliography
[1] Oettl, Lars-Lennart, et al. "Oxytocin enhances social recognition by modulating cortical control of early olfactory processing." Neuron 90.3 (2016): 609-621.
[2] Froemke, Robert C., and Larry J. Young. "Oxytocin, neural plasticity, and social behavior." Annual Review of Neuroscience 44 (2021): 359-381.
[3] Mice, meadow voles, and prairie voles are all rodents, with tahara voles monogamous and mice and meadow voles not monogamous.
[4] Walum, Hasse, and Larry J. Young. "The neural mechanisms and circuitry of the pair bond." Nature Reviews Neuroscience 19.11 (2018): 643-654.
[5] Borie, Amélie M., et al. "Social experience alters oxytocinergic modulation in the nucleus accumbens of female prairie voles." Available at SSRN 3891068 (2021).
[6] Scheele, Dirk, et al. "Oxytocin modulates social distance between males and females." Journal of Neuroscience 32.46 (2012): 16074-16079.
[7] Sikich, Linmarie, et al. "Intranasal oxytocin in children and adolescents with autism spectrum disorder." New England Journal of Medicine 385.16 (2021): 1462-1473.
[8] Ford, Charles L., and Larry J. Young. "Refining oxytocin therapy for autism: context is key." Nature Reviews Neurology (2021): 1-2.
This article is reprinted with permission from the WeChat public account "Neural Reality".
original:
https://www.discovermagazine.com/mind/what-the-two-halves-of-your-brain-dont-say-about-you
Special mention
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