Our memories of social interactions

Where in the brain do we form memories of our social interactions? Researchers from both France and Canada have identified the internal part of the prefrontal cortex as an essential region for the memory formation of social information. They used fMRI imaging on 17 volunteers as they performed memory tasks. These memory tasks contained social scenes and nonsocial scenes. From these scans they identified the medial prefrontal cortex as the area that is important for the encoding of our social interactions in an image.

Previous research performed by the same researcher identified the same prefrontal region as being the key structure for processes of thinking about oneself and others. This research will serve to be important in the understanding of social and personality disorders like antisocial personality disorder. The antisocial behavior that these people engage in could be a result of some deficiency in the medial prefrontal cortex.

The article can be found here:
http://www.emaxhealth.com/7/11177.html

Twin Brains

An article called, Genetic Influences on Human Brain Structures: A Review of Brain Imaging Studies in Twins was published last week by researchers in the Netherlands. This journal article is very interesting because it focuses on the genetic basis of brain structures based on a MARI study performed on twins. Imaging studies done on twins has helped researchers conclude that the genetic influences on the brain vary depending on the structure. The regions that are highly heritable are the grey matter in the medial prefrontal cortex, Herschl's gyrus, and the postcentral gyrus as well as large regions of white matter. Moderate to high heritabilities were found in Broca's area, anterior cingulate, hippocampus, amygdala, gray matter of the parahippocampal gyrus, and white matter of the superior occipitofrontal fasciculus.

The study described above is significant for various reasons. Firstly, it suggests that there is a genetic basis to brain development. Secondly, many of the areas that have high heritability are involved in common memory conditions, which helps conclude that these condition have a genetic correlation. Lastly, this study may lead to future studies that focus on these high heritable regions develop throughout life.

The abstract of the journal article can be found here:
http://www3.interscience.wiley.com/cgi-bin/abstract/114207464/ABSTRACT

Trying to make sense of the role of the medial temporal lobe structures in memory through research articles

This week we read three journal articles that all focused on the role of medial temporal lobe structures in memory. The role of the medial temporal lobe structures in memory has been extensively debated and researched. One article presented research by Chun and Phelps conducted the first study. They wanted to see the role of the hippocampus and adjacent medial temporal lobe structures in the encoding of implicit contextual information. Amnesiac patients were the subjects of this study and their performance in a visual search task was analyzed. To examine contextual learning in this task, the experimenters repeated old displays throughout the session. Their performance on old displays (context dependent) was then compared to their performance on new displays (context independent). The results of this study showed that the amnesiac patients with MTL damage showed normal implicit perceptual learning but were impaired in implicit contextual learning. These findings are consistent with the fact that the hippocampus and adjacent medial temporal structures are necessary for encoding and learning conceptual information.

The second article we read presented the results of a study conducted by Professor Davachi, Jason P. Mitchell and Anthony D. Wagner. This study looked at the role of various medial temporal lobe structures on source and item memory or recognition by using event related functional MRI. They wanted to look at the differences in activation in different areas of the MTL during the formation of the memory, the recognition of an item that was previously seen, and the recollection of the context or source of the previous encounter. The subjects of this study were healthy adults with no medial temporal damage. The participants’ scans showed that encoding activation in the parahippocampal and hippocampal areas were correlated with later source recollection. This activation was absent in item recognition. Increased activation was also seen in the perirhinal cortex but it was correlated with later item recognition and not source recognition. These results indicates the role of different parts of the MTL in different types of memory.

The third article presented the research findings of a study performed by Eldridge and her colleagues. This study discussed the hippocampus’s role in episodic memory retrieval by using event related functional MRI. The subjects in this study were healthy individuals and they were required to memorize a list of words. They then underwent fMRI scans while they were presented with previously studied and new items. During this test, they were asked to determine if the item was old or new and they were given a remember-know task. The results of this were consistent with present theories that state that the hippocampus is necessary for the retrieval of episodes. This activation of the hippocampus required conscious awareness or recollection of the event. Researchers propose that the hippocampus might help put together the features and context of the event.

All of these journal articles show how complex the role of the medial temporal lobe’s in memory really is. Even though these structures all have their distinct purposes, they all complement each other and contribute to our memory of events and items. One problem I had with these studies was that none had an equal amount of men and women and the amount of subjects used was small. The amount of subjects used could be explained by the price tag of conducting these studies and the amount of amnesiac patients that are available to researchers. I do not understand why researchers did not use a close to equal amount of male and female subjects because some research has shown sex differences in activation of brain regions. My guess is that this difference was not taken into account because it is probably not significant.

While I was reading the article on the hippocampus and the retrieval of episodic memories all I kept thinking about are the times that I forgot where the car was parked after a long day of shopping and forgetting where I put my keys after I put them in a “safe place” the day before. How was the encoding of the object location flawed?

I found an article that tries to explain how we remember locations whether it be where we put our keys or the directions to our favorite restaurant.The hippocampus is important in the formation of these types of memories because it contains place cells. These cells become active in response to a specific location. In a study done on rats, they put them in maze and the activity of the place cells was measured while the rats worked their way around the maze. The results of this study were that the activity of the place cells while they were looking for food in the maze, signaled location. However, other cells were sensitive to recent or impending events, which showed that the rats planned their movements prior to making them.

The implications of this study are that the hippocampus’ neurons fire in a way that helps express location and is very goal oriented. This firing can be in response to external cues (i.e. street name, stores, restaurants, etc…) that guide us to our desired location. So the reason why I did not remember where I parked my car was that the place cells did not fire properly, which could be caused by failure to encode the spatial information successfully. Failure to encode the information properly then leads to flawed storage of the location.

So why is it that when we intentionally place something in a safe place that we sometimes forget what this place is? Is it that the association of the object with this “safe place” is weak?

Does ginkgo biloba really help improve memory?

Ginkgo biloba is an herbal supplement that is mainly used to aid memory. Studies have concluded that this herb improves the memory of those suffering from dementia. New research published in the Journal of American Dietetic Association has revealed that ginkgo biloba may not have much short tem effects on the memory of healthy older adults. Among the 90 men and women ages 65-84 who participated in this study, those who took ginkgo biloba every day for a period of 4 months did not display any improvement in performance on tests on memory, attention and other cognitive function when compared to those who received the placebo. Even though the intake of ginkgo biloba did not have any short-term benefits, there might be some long-term benefits. A study conducted by the National Institute of Health that looks at the long-term effects of ginkgo biloba intake will be published soon.

After reading this article, I wonder if ginkgo biloba has the same effects on younger individuals. I took it for about 4 months and I really did not see any difference. I felt that just sleeping and taking my daily multi vitamin pill was more helpful.

The entire article can be found here:
http://www.nlm.nih.gov/medlineplus/news/fullstory_46591.html

Lacuna Inc. in a drug

Last week I wrote my blog about a woman known as AJ who could not forget. This week I want to write about a drug that has been tested on rats, which selectively erases memories or causes limited amnesia. Clementine from the film Eternal Sunshine of a Spotless Mind did this by enlisting the help of Lacuna Inc. This company erased all the memories good and bad that she had of her relationship with Joel.

According to research done by Joseph LeDoux of the Center for Neural Science at New York University and his colleagues, the drug called U0126 can selectively erase memories in rats while keeping other memories intact. The study took rats and trained them to fear two musical tones by playing either one at the same time the experimenters gave the rats an electric shock. They then gave half of the rats the drug, replayed only one of the tones, and shocked the rats. A day later, the rats were exposed to the tone that was replayed and the untreated rats continued to show signs of fear. The rats that were given the drug were not afraid of the tone because somehow the drug caused them to forget the relation between that specific tone and the electric shock. These results also shows the role of the amygdala in the formation of frightening memories because the rats that were treated with the drug showed decreased communication between the neurons in this region. An increased activity in this area is only seen when fearful memories are formed which led researchers to infer that the memory of the fearful tone was deleted.

A difficult break-up is a minor reason for erasing a memory but imagine if a person could erase the memory of a traumatic experience like sexual abuse or war experience. For many people who go through these experiences, large amounts of therapy sessions and the intake of anti-anxiety medication or antidepressants are needed. These experiences can also affect a person’s daily life and impede them from doing every day things like getting up in the morning. For people who have tried everything from drugs to hypnosis, this drug could me their last and only option. Taking this memory-erasing drug if it is ever approved by the FDA would allow these people to regain control of their lives.

This research is very promising but it is not going to be approved by the FDA anytime soon because a rat’s brain is nothing like the human brain in terms of complexity and the amount of information stored. It is also very hard to pinpoint the exact location of a traumatic memory. If only our brains were an organized filing cabinet, this drug can give individuals suffering from post-traumatic stress disorder an endless amount of possibilities and opportunities.

This article can be found here:
http://ezproxy.library.nyu.edu:2368/news/2007/070305/full/070305-17.html

I also found a website for the “Lacuna Inc.” the fictional memory erasing company from the movie.

http://www.lacunainc.com/

Have you been abducted by aliens???

Have you ever come across a person who claimed to have been abducted by aliens? Do you know anyone who believes that they had a past life? If the answer is yes to any of these question then a new study has the answer to why these people may feel this way. This new study conducted by Maarten Peters of Maastrcht University in the Netherlands showed that people who have memories of their past lives are more susceptible to misremembering or misattributing the source of any given information.

In this study, Peters tested patients of “reincarnation therapist” who used hypnosis in order to remember the details of their past lives. These subjects were given a memory test called a false fame paradigm, which asked the subjects to recite a list of unfamiliar names. The day after their exposure to names, they were shown a list that included the unfamiliar names, new names, and the names of famous people. The result of this test was that those who believed they had a previous life were more likely to believe that that the unfamiliar names belonged to famous people. This means that they are more likely to make a source monitoring error, which is an error in determining the original source of memory. In terms of this test, the subjects are “misremembering the source-themselves- of non-famous names. Psychologists believe that making this error is one of the things that lead to the formation false memories, which may explain why these people may believe that they were abducted by aliens. Peters states “Once familiarity of an event is achieved, this can relatively easily be converted into a belief that the event did take place. A next possible step is that individuals interpret their thoughts and fantasies about the fictitious event as real memories”

Jim Tucker, a psychiatrist from the University of Virginia Medical Center is skeptical about these findings because he believes that people who are getting help from a reincarnation therapist may have psychological problems and may be more susceptible to hypnosis. I agree with Tucker because “Earth Angel” a man that I saw on the 6 train who claimed that he came from the heavens and is now on Earth to warn us, seemed to have a couple of screws loose. I also feel like this study does not take into account the reasons the subjects might have these memories. They might be using these memories as a defense mechanism for something traumatic that happened in their lives.

The article can be found here:

http://www.sciam.com/article.cfm?articleId=A430214C-E7F2-99DF-3EEED6B0410A5114&chanId=sa013&modsrc=most_popular