Aug 28, 2007 12:00 AM | 1
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We've long accepted that hormones can make you amorous, aggressive, or erratic. But lately neuroscience has been abuzz with evidence that the hormone oxytocin -- which also acts as a neuromodulator -- can enhance at least one cognitive power: the ability to understand the gist of what others are thinking. In this week's Mind Matters, Jennifer Bartz and Eric Hollander, two leading researchers in this area, review the many and surprising ways in which oxytocin seems to influence both our openness to others and our understanding of them.
For inherently social creatures such as humans, the ability to identify the motives, intentions, goals, desires, beliefs and feelings of others is not a nicety but an essential skill. We must understand "where others are coming from" not only to pursue our individual goals but also to facilitate social harmony more generally. Specifically, we need to recognize that other people can have thoughts, beliefs, desires and feelings that differ from our own -- and that those thoughts, ideas, and desires can drive their behavior. This understanding in turn allows us to predict how others will behave. Cognitive and social neuroscientists call this vital skill "theory of mind," or ToM, and they see it as fundamental to success in a species as social as ours. As researcher Simon Baron-Cohen put it, "In the heat of a social situation, it pays to be able to come up with a sensible interpretation of the causes of actions quickly if one is to survive to socialize for another day." How does the brain produce this vital ability to read the minds of others? A recent paper by the University of Germany's Gregor Domes and colleagues sheds light on this question, linking a much-researched hormone, oxytocin, with this complicated and important social cognitive skill. The paper, "Oxytocin Improves 'Mind-Reading' in Humans," suggests much about both normal social understanding and the grave deficits in social interaction that seem to underlie conditions such as autism. Motherhood, Memory, and Mind Reading Oxytocin is a peptide hormone composed of nine amino acids. It is produced in the brain (specifically, in the magnocellular neurosecretory cells within the supraoptic nucleus and paraventricular nucleus of the hypothalamus) and is released into the blood stream. Oxytocin acts on the mammary glands to cause milk let-down during breast feeding, as well as on the uterus during contractions during labor and delivery. It is also projected to other parts of the brain and to the spinal cord, where it acts as a neuromodulator, influencing the activity of other neurons in the brain. Research with rodents and non-human primates has shown that oxytocin, as well as the structurally similar peptide vasopressin, plays an important role in attachment and affiliative behaviors including pair-bond formation, maternal behavior, sexual behavior and separation distress. Oxytocin has also been found to enable social memory in rodents -- that is, the ability to recognize a novel rodent over time. In normal mice this social memory is enhanced by low doses of oxytocin but is impaired if the mouse is given agents that block the oxytocin receptor. In addition, mice that have been genetically manipulated so that oxytocin has been eliminated from their system are unable to recognize a previously encountered mouse. If these same genetically modified mice are given oxytocin before meeting a new mouse, however, they gain the ability to acquire such social memories. Other studies have suggested that oxytocin may be involved in human social behavior and cognition. For example, synthetic oxytocin administered nasally has been found to promote trust [pdf download] (in the context of making investment decisions) and to regulate how the brain responds to fearful stimuli. Now, in this study by Domes and colleagues, it appears to facilitate theory of mind. Is It My Hormones, or Am I Reading Your Mind? Domes and colleagues administered a synthetic form of oxytocin (Syntocinon) or placebo (each participant received both at some point) through the nose to 30 healthy male adults (aged 21-30). After each dose, the participants would complete a task assessing the ability to infer other peoples' mental states. Specifically, they viewed pictures of actors conveying a number of different emotional expressions such as shame, alarm and bewilderment. These pictures showed only the eye region, which is thought to be required for the identification of more complex emotions. Each picture was accompanied by four descriptive words, and participants were asked to choose the word that best described what the actor was thinking or feeling. (Editor's note: You can take a similar test online.) Participants performed significantly better on this task following oxytocin administration than they did after receiving the placebo. These findings have implications for understanding not only the neurobiological processes underlying healthy human social cognition but also for understanding disorders marked by deficits in social functioning, such as autism. Individuals with autism spectrum disorders often show impairments in processing social information, and they have particular difficulty identifying the emotions of others through facial expression and other modalities such as tone of voice or posture. It's generally thought that these deficits in understanding -- and perhaps a more global failure in theory of mind -- may in part underlie autism's more general deficits in social functions such as reciprocity and empathy. Indeed, a number of researchers over the years have suggested that oxytocin (and vasopressin) may be involved in autism's etiology -- and that oxytocin may have potential in treating it. Our lab, for instance, found that giving adults with autism spectrum disorders synthetic oxytocin (Pitocin) reduced repetitive behaviors (a core symptom of autism) over a 4-hour period and seemed to facilitate performance retention on an auditory social information processing task. Mechanics Both our lab and the Domes lab have found that oxytocin facilitates the processing of social information gathered through at least two different sensory modalities -- that is, through both hearing and vision. This raises questions about just how oxytocin actually facilitates social cognition and theory of mind. Previous research indicates that oxytocin plays a role in regulating stress and fear reactivity. Thus oxytocin may facilitate theory of mind by reducing the social anxiety that is inherent in many social encounters -- and which is felt keenly by many individuals with autism. Another possibility is that oxytocin may increase motivation to attend to social cues by reinforcing social information processing. Compared to their less social cousins the montane voles, for instance,prairie voles have more oxytocin and vasopressin receptors in brain regions associated with reinforcement and motivation, such as the nucleus accumbens (see Insel and Shapiro 1992 and Lim and Young 2006). Just how oxytocin improves theory of mind remains an open question. Answering it, however, may shed light on the pathophysiology of such disorders as autism and suggest targets for intervention. Given that oxytocin and vasopressin have been found to affect males and females differently in animal studies, another area ripe for research is whether and how gender influences how oxytocin and vasopression affect theory of mind. Domes and colleagues studied men; would oxytocin similarly enhance women's theory of mind? The breadth of these questions suggests just how much there is to learn and gain by studying how one's brain knows another's mind. Jennifer Bartz is a social psychologist and assistant professor in the Department of Psychiatry at the Mount Sinai School of Medicine in New York, where her research focuses on attachment processes in close relationships and the biological factors -- oxytocin in particular -- underlying attachment, social cognition and prosocial behavior. Eric Hollander is the chair of the Department of Psychiatry at Mount Sinai, where he researches the biological causes and treatment approaches to autism and other developmental disorders.
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