Rare form of temporary amnesia highlights role of CA1 neurons in accessing memories

 Neuroscience 

(Medical Xpress) -- German researchers working out of the Institute of Neuroradiology, University Hospital Schleswig-Holstein, University of Kiel, have found through the study of a rare form of temporary amnesia, that impairment of the CA1 neuron clusters in the Hippocampus appears to cause a loss of so-called autobiographical memories. The team has published its results in this week's issue of the Proceedings of the National Academy of Sciences.

Autobiographical memories are those that are built up over a lifetime and serve to provide a means of self identification and are thought to be a part of self-awareness. The loss of such memories tends to leave people with a limited ability to understand who they are which quite obviously makes understanding the world around them very difficult.

To find out what causes loss of autobiographical memories, the research team looked at patients afflicted with “acute transient global amnesia” a rare but debilitating condition that results in almost a total loss of short term memory in conjunction with a variety of problems associated with long term memory. Such patients are also incapable of forming new memories. Because it is so rare and because it generally only lasts for two to eight hours it has been notoriously difficult to study and until now, the condition has been little understood.

Because the team was working out of a major hospital they were able to have patients with the condition undergo an MRI while still experiencing symptoms. In so doing, they found that of sixteen patients examined, fourteen exhibited lesions in the CA1 cell clusters. One of the researchers, Gunther Deuschl, notes that this indicates that proper functioning of the CA1 cells appears to be a necessary component in memory activation and retention.

This association could mean big news for the millions of people who suffer from dementia, particularly those with Alzheimer’s disease, as the Hippocampus in general and the CA1 cluster in particular, appears to be one of the first to be affected in such people. By narrowing down which parts of the brain are impacted when memory loss occurs and how, new drugs might be developed that can target specific brain cells, thus helping to ward off nerve degeneration while minimizing side effects.

More information: CA1 neurons in the human hippocampus are critical for autobiographical memory, mental time travel, and autonoetic consciousness, PNAS, Published online before print October 10, 2011, doi:10.1073/pnas.1110266108

 

Abstract 
Autobiographical memories in our lives are critically dependent on temporal lobe structures. However, the contribution of CA1 neurons in the human hippocampus to the retrieval of episodic autobiographical memory remains elusive. In patients with a rare acute transient global amnesia, highly focal lesions confined to the CA1 field of the hippocampus can be detected on MRI. We studied the effect of these lesions on autobiographical memory using a detailed autobiographical interview including the remember/know procedure. In 14 of 16 patients, focal lesions in the CA1 sector of the hippocampal cornu ammonis were detected. Autobiographical memory was significantly affected over all time periods, including memory for remote periods. Impairment of episodic memory and autonoetic consciousness exhibited a strong temporal gradient extending 30 to 40 y into the past. These results highlight the distinct and critical role of human hippocampal CA1 neurons in autobiographical memory retrieval and for re-experiencing detailed episodic memories.

© 2011 Medical Xpress

"Rare form of temporary amnesia highlights role of CA1 neurons in accessing memories." October 11th, 2011. http://medicalxpress.com/news/2011-10-rare-temporary-amnesia-highlights-role.html

 

Posted by
Robert Karl Stonjek

Neuroscientists pinpoint specific social difficulties in people with autism

 Neuroscience 
Credit: Caltech/Lance Hayashida

(Medical Xpress) -- People with autism process information in unusual ways and often have difficulties in their social interactions in everyday life. While this can be especially striking in those who are otherwise high functioning, characterizing this difficulty in detail has been challenging. Now, researchers from the California Institute of Technology (Caltech) have isolated a very specific difference in how high-functioning people with autism think about other people, finding that—in actuality—they don’t tend to think about what others think of them at all.

This finding, described online this week in the Proceedings of the National Academy of Sciences, sheds light on what researchers call "theory of mind" abilities—our intuitive skill for figuring out what other people think, intend, and believe. One key aspect of such abilities in terms of social interactions is to be able to figure out what others think of us—in other words, to know what our social reputation is. It is well known that social reputation usually has a very powerful influence on our behavior, motivating us to be nice to others.

The Caltech team capitalized on this strong effect by asking people to make real money donations to UNICEF under two conditions: alone in a room or while being watched by a researcher. 

"What we found in control participants—people without autism—basically replicated prior work. People donated more when they were being watched by another person, presumably to improve their social reputation," explains Keise Izuma, a postdoctoral scholar at Caltech and first author on the study. "By contrast, participants with autism gave the same amount of money regardless of whether they were being watched or not. The effect was extremely clear."

To be certain that the subjects with autism really were not thinking about their social reputation in the presence of the other person—as opposed to simply ignoring that onlooker—the researchers showed that everyone, both controls and people with autism, do better on simple math tasks when being watched than when alone.

"This check was important," says Ralph Adolphs, Bren Professor of Psychology and Neuroscience and professor of biology at Caltech and the principal investigator on the paper, "because it showed us that in people with autism, the presence of another person is indeed registered, and can have general arousal effects. It tells us that what is missing is the specific step of thinking about what another person thinks about us. This is something most of us do all the time—sometimes obsessively so—but seems to be completely lacking in individuals with autism."

The findings provide a much more precise picture of how people with autism process social information, says Adolphs, and is important not only for use in diagnostic and interventional therapies, but also for educating the general public about the psychology of autism.

Next up for the team: MRI studies to investigate what occurs in the brain during such social interactions, as well as other investigations into the biology and psychology of autism.

Other authors on the PNAS paper, "Insensitivity to social reputation in autism," are Colin Camerer, Robert Kirby Professor of Behavioral Economics at Caltech and Kenji Matsumoto, a neuroscientist at Tamagawa University in Japan. The work was supported by a Simons Foundation Autism Research Initiative, the National Institute of Mental Health, a fellowship from the Japan Society for the Promotion of Science Fellows, and a Global Centers of Excellence collaborative grant from the Japanese government to Caltech and Tamagawa University.

Provided by California Institute of Technology

"Neuroscientists pinpoint specific social difficulties in people with autism." October 11th, 2011. http://medicalxpress.com/news/2011-10-neuroscientists-specific-social-difficulties-people.html

 

Posted by
Robert Karl Stonjek

The perils of polite misunderstandings

 Psychology & Psychiatry 

Your friend debuts a questionable haircut and asks what you think of it. Brutal honesty would definitely hurt his feelings, so what do you say? Most people in this situation would probably opt for a vague or evasive response, along the lines of "It's really unique!" or "It's so you!" Politeness helps us get through awkward social situations like these and makes it easier for us to maintain our relationships. But a new article published in the October issue of Current Directions in Psychological Science, a journal of the Association for Psychological Science, suggests that this kind of politeness can have disastrous consequences, especially in high-stakes situations.

According to authors Jean-François Bonnefon and Wim de Neys of CNRS and Université de Toulouse and Aidan Feeney of Queen's University, we resort to politeness strategies when we have to share information that might offend or embarrass someone or information that suggests someone has made a mistake or a bad choice. The more sensitive an issue is, the more likely we are to use these kinds of politeness strategies.

Politeness can become problematic, however, when it causes us to sacrifice clarity. Existing research suggests that politeness strategies can lead to confusion about the meaning of statements that, under other circumstances, would be clear. And this confusion is especially likely to occur in high-stakes situations, the very situations in which we are most likely to use politeness strategies.

Even worse, say the authors, it takes more of our cognitive resources to process these kinds of polite statements. Thus, "[w]e must think harder when we consider the possibility that people are being polite, and this harder thinking leaves us in a greater state of uncertainty about what is really meant."

This confusion and uncertainty can have particularly negative consequences when safety and security are on the line – such as for pilots trying to fly a plane in an emergency or for a doctor trying to help a patient decide on a treatment. Politeness can also have serious consequences within corporate culture – people don't want to embarrass their bosses or their co-workers, so they hesitate to point out when something looks amiss, even when potential fraud or misconduct might be involved.

So how can we make sure to get around the confusion of politeness? One option is to encourage people to be more assertive in high-stakes situations. Some companies, including airlines, have even instituted assertiveness training programs, but it's not yet clear whether these programs really work.

Another option is to try to make the interpretation of polite statements easier for people. "Say that there is a tone, a prosodic feature which typically signals that politeness is at work," says Bonnefon. If we can identify this tone, we could "train pilots or other professionals to react intuitively to that tone in order to treat it as a warning signal."

While politeness can be detrimental in certain situations, Bonnefon takes pains to point out that the goal of this research is not to encourage or license general impoliteness – "politeness is obviously a very positive behavior in most cases," he concludes.

Provided by Association for Psychological Science

"The perils of polite misunderstandings." October 11th, 2011. http://medicalxpress.com/news/2011-10-perils-polite.html

 

Posted by
Robert Karl Stonjek