Know thyself and you’ll know others better

Using functional MRI (fMRI) scanning, researchers have found that the region of the brain associated with introspective thought “lights up” when people infer the thoughts of others like themselves. However, this is not the case when we’re considering people we think of as different politically, socially, or religiously.

Published in the current issue of the Proceedings of the National Academy of Sciences, the study was led by Adrianna Jenkins, a graduate student in the Department of Psychology in the Faculty of Arts and Sciences at Harvard University, with Jason Mitchell, assistant professor of psychology at Harvard. Jenkins and Mitchell’s co-author was C. Neil Mcrae of the University of Aberdeen.

“Our research helps to explain how and when people draw on their own inner experiences to make inferences about the experiences of others,” says Jenkins. “The findings suggest that the part of the brain that is responsible for introspection also helps us to understand what other people might be thinking or feeling. But this primarily seems to be the case for people who we perceive to be similar to ourselves.”

Psychologists have not fully understood how it is that we make numerous, and often accurate, inferences about others’ thoughts and feelings. Some have guessed that we use aspects of our own experience to model the thoughts of others, while others posit that we acquire a knowledge base from observations and societal rules that guides our understanding of others’ mental states.

This study suggests that both processes may be used in different contexts. We may only use ourselves to understand others when we think our minds and experiences are sufficiently similar to those of the other person.

Previous research has shown that the region of the brain associated with introspection, the ventromedial prefrontal cortex (vMPFC), is also associated with understanding the thoughts and feelings of others.

Jenkins and colleagues tested whether individuals are more likely to access this self-referential region of the brain when considering the thoughts of a similar person or someone who is different. They used fMRI scans to examine brain activity when individuals were asked about their thoughts or feelings about an everyday experience, and what they imagine that another person might think or feel about a similar experience.

The study involved 13 students, both graduate and undergraduate, who, at the end of the study, all identified themselves as politically liberal.

At the beginning of the study, the subjects were shown photographs of two unfamiliar individuals, and then given a brief descriptive paragraph about each. One was described as a student with liberal political and social attitudes who attends a college in the Northeast, and the other as a conservative, fundamentalist Christian at a Midwestern university.

The subjects were asked a series of questions about their own thoughts or feelings, and the thoughts or feelings of the liberal or conservative individual. The questions were about everyday experiences such as “How much do you enjoy doing crossword puzzles?” or “How likely is it that he would get frustrated while sitting in traffic?”

By examining the brain’s activity in the vMPFC, the researchers saw that when the subjects considered the possible responses of the “liberal,” they employed the part of their brain that is active when they think about their own reactions. By contrast, the researchers did not see activity in this region of the brain when the subjects were considering the thoughts and preferences of the “conservative” student.

According to Jenkins, it’s possible that we rely on our own perspective to assess the potential thoughts and feelings of people who we think are similar, while we may make inferences regarding the thoughts of dissimilar others based on a different process.

Further research will examine whether it is possible to manipulate this effect and utilize the more introspective thought process when assessing the feelings of dissimilar others.

A forthcoming study in Psychological Science, led by Daniel Ames with Jenkins, Mitchell, and Mahzarin Banaji, the Richard Clarke Cabot Professor of Social Ethics and Carol K. Pforzheimer Professor at Radcliffe, considers whether or not the application of this self-referential thought process is immutable. In this study, the participants were asked to write a short essay from another person’s perspective. The results suggest that after an individual assumes another’s perspective (in this case by writing the essay), he or she is more likely to use the vMPFC region of the brain when later making inferences regarding that person’s thoughts or feelings.

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Neurologists Engineer First System of Human Nerve-Cell Tissue

Researchers at the University of Pennsylvania School of Medicine have demonstrated that living human nerve cells can be engineered into a network that could one day be used for transplants to repair damaged to the nervous system. They report their findings in the February issue of the Journal of Neurosurgery.

“We have created a three-dimensional neural network, a mini nervous system in culture, which can be transplanted en masse,” explains senior author Douglas H. Smith, MD, Professor, Department of Neurosurgery and Director of the Center for Brain Injury and Repair at Penn.

Although neuron transplantation to repair the nervous system has shown promise in animal models, there are few sources of viable neurons for use in the clinic and insufficient approaches to bridge extensive nerve damage in patients.

The Stretch Test
In previous work, Smith’s group showed that they could induce tracts of nerve fibers called axons to grow in response to mechanical tension. They placed neurons from rat dorsal root ganglia (clusters of nerves just outside the spinal cord) on nutrient-filled plastic plates. Axons sprouted from the neurons on each plate and connected with neurons on the other plate. The plates were then slowly pulled apart over a series of days, aided by a precise computer-controlled motor system, creating long tracts of living axons.

These cultures were then embedded in a collagen matrix, rolled into a form resembling a jelly roll, and then implanted into a rat model of spinal cord injury. After the four-week study period, the researchers found that the geometry of the construct was maintained and that the neurons at both ends and all the axons spanning these neurons survived transplantation. More importantly, the axons at the ends of the construct adjacent to the host tissue extended through the collagen barrier to connect with the host tissue as a sort of nervous tissue bridge.

The Next Step
Now, the researchers have taken the next step and are applying this technique to living human nerve cells. Smith and his team obtained human dorsal root ganglia neurons (due to their robustness in culture) to engineer into transplantable nervous tissue.

The root ganglia neurons were harvested from 16 live patients following elective ganglionectomies, and four thoracic neurons were harvested from organ donors. The neurons were purified and placed in a specially designed growth chamber. Using the stretch growth technique, the axons were slowly pulled in opposite directions over a series of days until they reached a desired length.

The neurons survived at least three months in culture while maintaining the ability to generate action potentials, the electrical signals transmitted along nerve fibers. The axons grew at about 1 millimeter per day to a length of 1 centimeter, creating the first engineered living human nervous tissue constructs.

“This study demonstrates the promise of adult neurons as an alternative transplant material due to their availability, viability, and capacity to be engineered,” says Smith. “We’ve also shown the feasibility of obtaining neurons from living patients as a source of neurons for autologous, or self, transplant as well as from organ donors for allografts.”

Penn co-authors are Jason H. Huang, Eric L. Zager, Jun Zhang, Robert G. Groff IV, Bryan J. Pfister, M. Sean Grady, and Eileen Maloney-Wilensky. Akiva S. Cohen from The Children’s’ Hospital of Philadelphia was also a co-author.
The authors thank the Gift of Life program and the family members of the organ donors for their support and selfless sacrifice. This work was funded by the National Institutes of Health.
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Short-term stress can affect learning and memory

Short-term stress lasting as little as a few hours can impair brain-cell communication in areas associated with learning and memory, University of California, Irvine researchers have found.

It has been known that severe stress lasting weeks or months can impair cell communication in the brain’s learning and memory region, but this study provides the first evidence that short-term stress has the same effect. The study appears in the March 12 edition of the Journal of Neuroscience.

“Stress is a constant in our lives and cannot be avoided,” said Dr. Tallie Z. Baram, the Danette Shepard Chair in Neurological Sciences in the UC Irvine School of Medicine and study leader. “Our findings can play an important role in the current development of drugs that might prevent these undesirable effects and offer insights into why some people are forgetful or have difficulty retaining information during stressful situations.”

In their study, Baram and her UC Irvine colleagues identified a novel process by which stress caused these effects. They found that rather than involving the widely known stress hormone cortisol, which circulates throughout the body, acute stress activated selective molecules called corticotropin releasing hormones, which disrupted the process by which the brain collects and stores memories.

Learning and memory take place at synapses, which are junctions through which brain cells communicate. These synapses reside on specialized branchlike protrusions on neurons called dendritic spines.

In rat and mouse studies, Baram’s group saw that the release of CRH in the hippocampus, the brain’s primary learning and memory center, led to the rapid disintegration of these dendritic spines, which in turn limited the ability of synapses to collect and store memories.

The researchers discovered that blocking the CRH molecules’ interaction with their receptor molecules eliminated stress damage to dendritic spines in the hippocampal cells involved with learning and memory.

In addition, the authors replicated the effects of stress on dendritic spines by administering low levels of synthetic CRH, and watching how the spines retracted over minutes. “Fortunately, once we removed the CRH, the spines seemed to grow back,” Baram said.

Baram also noted that there are compounds under development that show the ability to block CRH receptors, and that this study can play a role in the creation of therapies based on these compounds to address stress-related learning and memory loss.

Yuncai Chen, Celine Dubé and Courtney Burgdorff of UC Irvine also participated in the study, which was supported by the National Institutes of Health.
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Scientists determine structure of brain receptor implicated in epilepsy and PMT

Scientists funded by the Biotechnology and Biological Sciences Research Council (BBSRC) have published new research in the journal Molecular Pharmacology identifying the structure of a receptor in the brain implicated in conditions such as epilepsy and pre-menstrual tension. The same receptor has also been reported to be highly sensitive to alcohol.

The University of Cambridge team, in collaboration with colleagues at Aston University and the University of Alberta, have determined the arrangement of the constituent parts of an uncommon but important type of GABA receptor in the brain. GABAA receptors in the central nervous system play important roles in the body’s response to gamma-aminobutyric acid (GABA), a chemical used by the brain to control certain functions. By understanding how the receptors’ sub-units are arranged, scientists may now be able to develop drugs to block or stimulate them, providing hope for sufferers of a range of conditions.

Different types of GABAA receptor have been shown to play various roles in the body’s control of behaviour and development. The Cambridge scientists are the first to determine the structure of a type of GABAA receptor containing the so-called delta sub-unit. This receptor type is found in small numbers in the body but is thought to be disproportionately important in controlling our state of consciousness; it is highly sensitive to anaesthetics, and has been linked to epilepsy and pre-menstrual tension, and to the body’s response to alcohol.

The team used an atomic force microscope to detect the receptors. They applied tags to the receptors that bind to different sub-units. These can then be identified with the microscope, which scans a probe over the surface of a sample. By identifying the tags the team could identify where the various sub-units were located. Armed with this information, researchers can now build detailed models of the receptor which can be used to develop drugs to intervene in the signals that it receives.

Dr Mike Edwardson, who led the research team, said: “This type of GABA receptor plays a crucial role in the body’s response to a range of stimuli. Scientists think that when there is a problem in the signalling, conditions such as epilepsy and PMT can occur. Now we have identified the detailed structure of the receptor we are in a better position to design drugs that bind to it.”

Professor Nigel Brown, BBSRC Director of Science and Technology, commented: “Basic bioscience research has a crucial role to play in understanding conditions that affect the health and quality of life for millions of people. If we learn the detailed mechanisms by which the body functions, medical scientists and the pharmaceutical industry can develop treatments to intervene when it goes wrong.”

Via

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