The study, recently published in the journal Social Cognitive and Affective Neuroscience, found that individuals who identified themselves as inhibited may experience habituation failure -- or the inability to adapt to new stimuli -- in the amygdala and the hippocampus regions of the brain.
The researchers used functional magnetic resonance imaging (fMRI) to examine adults with either an inhibited or uninhibited temperament. Study participants were shown pictures of unfamiliar faces multiple times.
Individuals with an uninhibited temperament demonstrated habituation in both the amygdala and hippocampus. Their brain response increased when the faces were new but declined as they became familiar.
In contrast, individuals with an inhibited temperament failed to habituate across repeated presentations of faces, meaning familiar faces triggered the same brain response as the unfamiliar.
"This failure to habituate provides a novel neural mechanism for understanding the shy and cautious behavior that is characteristic of inhibited individuals," said Jennifer Urbano Blackford, Ph.D., assistant professor of Psychiatry and Psychology and lead author of the study.
"Individuals who familiarize more slowly may find encounters with new people overwhelming and thus avoid new social experiences, whereas those who adjust more quickly may be more likely to seek novel social experiences."
Blackford and colleagues think that this failure to habituate may be a key cause of social anxiety disorder, the persistent, chronic fear of a specific social situation. Social anxiety disorder is the second most common anxiety disorder and affects approximately one in 10 adults in the United States.
She is continuing her research by studying inhibited children to see if this brain deficit is present early in development.
Blackford conducted this research with Amil Allen, fourth-year Vanderbilt University School of Medicine student; Ronald Cowan, M.D., Ph.D., associate professor of Psychiatry; and Suzanne Avery, third-year Neuroscience doctoral student.
Overcome your anxiety
Sunday, 25 March 2012
Thursday, 15 March 2012
Mechanism Sheds Light On How the Brain Adapts to Stress
ScienceDaily (Jan. 25, 2012) — Scientists now have a better understanding of the way that stress impacts the brain. New research, published by Cell Press in the January 26 issue of the journal Neuron, reveals pioneering evidence for a new mechanism of stress adaptation and may eventually lead to a better understanding of why prolonged and repeated exposure to stress can lead to anxiety disorders and depression.
Most stressful stimuli cause the release of corticotropin-releasing hormone (CRH) from neurons in the brain. This is typically followed by rapid changes in CRH gene expression. In more practical terms, as soon as the CRH-containing neurons run out of CRH, they are already receiving directions to make more. CRH controls various reactions to stress, including immediate "fight-or-flight" responses as well as more delayed adaptive responses in the brain. Regulation of CRH activity is critical for adaptation to stress, and abnormal regulation of CRH is linked with multiple human psychiatric disorders.
"Despite the wealth of information regarding the physiological role of CRH in mediating the response to stress, the molecular mechanisms that regulate expression of the CRH gene, and thereby CRH synthesis, have remained largely elusive," explains senior study author, Dr. Gil Levkowitz, from the Weizmann Institute of Science in Israel. "In our study, we used mouse and zebrafish model systems to identify a novel intracellular signaling pathway that controls stress-induced CRH gene expression."
Dr. Levkowitz and colleagues discovered that the protein Orthopedia (Otp), which is expressed in parts of the brain associated with stress adaptation, modulated CRH gene expression and was required for stress adaptation. The researchers went on to show that Otp regulates production of two different receptors on the neurons' surface. The receptors, which receive and relay CRH production instructions, essentially function as "ON" and "OFF" switches.
"This regulation of the CRH gene is critical for neuronal adaptation to stress. Failure to activate or terminate the CRH response can lead to chronic over- or under-activation of stress-related brain circuits, leading to pathological conditions," concludes Dr. Levkowitz. "Taken together, our findings identify an evolutionarily conserved biochemical pathway that modulates adaptation to stress."
Most stressful stimuli cause the release of corticotropin-releasing hormone (CRH) from neurons in the brain. This is typically followed by rapid changes in CRH gene expression. In more practical terms, as soon as the CRH-containing neurons run out of CRH, they are already receiving directions to make more. CRH controls various reactions to stress, including immediate "fight-or-flight" responses as well as more delayed adaptive responses in the brain. Regulation of CRH activity is critical for adaptation to stress, and abnormal regulation of CRH is linked with multiple human psychiatric disorders.
"Despite the wealth of information regarding the physiological role of CRH in mediating the response to stress, the molecular mechanisms that regulate expression of the CRH gene, and thereby CRH synthesis, have remained largely elusive," explains senior study author, Dr. Gil Levkowitz, from the Weizmann Institute of Science in Israel. "In our study, we used mouse and zebrafish model systems to identify a novel intracellular signaling pathway that controls stress-induced CRH gene expression."
Dr. Levkowitz and colleagues discovered that the protein Orthopedia (Otp), which is expressed in parts of the brain associated with stress adaptation, modulated CRH gene expression and was required for stress adaptation. The researchers went on to show that Otp regulates production of two different receptors on the neurons' surface. The receptors, which receive and relay CRH production instructions, essentially function as "ON" and "OFF" switches.
"This regulation of the CRH gene is critical for neuronal adaptation to stress. Failure to activate or terminate the CRH response can lead to chronic over- or under-activation of stress-related brain circuits, leading to pathological conditions," concludes Dr. Levkowitz. "Taken together, our findings identify an evolutionarily conserved biochemical pathway that modulates adaptation to stress."
Monday, 12 March 2012
Stress Levels Affected By Amount Of Green Space In The Area
Stress levels of unemployed people are linked more to their surroundings than their age, gender, disposable income, and degree of deprivation, a study shows.
The presence of parks and woodland in economically deprived areas may help people cope better with job losses, post traumatic stress disorder, chronic fatigue and anxiety, researchers say.
They found that people's stress levels are directly related to the amount of green space in their area - the more green space, the less stressed a person is likely to be.
Researchers measured stress by taking saliva samples from a group of 35-55 year olds in Dundee and gauging levels of cortisol - a hormone released in response to stress. They found that if less than 30 per cent of a person's surrounding area was green space, its population showed unhealthy levels of cortisol.
The study shows that for every one per cent increase in green space there was a corresponding steeper decline in stress levels. Where there is more green space, people tend to respond better to disruptive events, either by not getting as stressed in the first place or by coping better.
Participants were also asked to self-diagnose their stress levels and these results directly related to the percentage of local green space. People with more green space had lower levels of self-reported stress.
The research was led by the University of Edinburgh and Heriot-Watt's OPENspace research centre, working with the Universities of Glasgow and Westminster. The James Hutton Institute was the project manager. The findings have been published in the journal Landscape and Urban Planning.
Catharine Ward Thompson, director of OPENspace research centre said: "Given the increasing levels of stress and poor mental health suffered by people in Scotland, this is an exciting breakthrough. For the first time, researchers have worked with unemployed people from deprived areas and used scientific tests to show that, where there is more green space around, people's stress levels were measurably lower, while less green space was linked with signs of the body's hormones not working properly."
Exercise was another factor found to reduce stress, but it may not be related to exercising in park land. People reported feeling less stressed if they lived in areas with more green space, regardless of how much exercise they did.
Published by: MNT
The presence of parks and woodland in economically deprived areas may help people cope better with job losses, post traumatic stress disorder, chronic fatigue and anxiety, researchers say.
They found that people's stress levels are directly related to the amount of green space in their area - the more green space, the less stressed a person is likely to be.
Researchers measured stress by taking saliva samples from a group of 35-55 year olds in Dundee and gauging levels of cortisol - a hormone released in response to stress. They found that if less than 30 per cent of a person's surrounding area was green space, its population showed unhealthy levels of cortisol.
The study shows that for every one per cent increase in green space there was a corresponding steeper decline in stress levels. Where there is more green space, people tend to respond better to disruptive events, either by not getting as stressed in the first place or by coping better.
Participants were also asked to self-diagnose their stress levels and these results directly related to the percentage of local green space. People with more green space had lower levels of self-reported stress.
The research was led by the University of Edinburgh and Heriot-Watt's OPENspace research centre, working with the Universities of Glasgow and Westminster. The James Hutton Institute was the project manager. The findings have been published in the journal Landscape and Urban Planning.
Catharine Ward Thompson, director of OPENspace research centre said: "Given the increasing levels of stress and poor mental health suffered by people in Scotland, this is an exciting breakthrough. For the first time, researchers have worked with unemployed people from deprived areas and used scientific tests to show that, where there is more green space around, people's stress levels were measurably lower, while less green space was linked with signs of the body's hormones not working properly."
Exercise was another factor found to reduce stress, but it may not be related to exercising in park land. People reported feeling less stressed if they lived in areas with more green space, regardless of how much exercise they did.
Published by: MNT
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