Tag Archives: research

Have Excellent Autobiographical Memory? Your Brain is Differently Wired.

Do you remember what happened on the 6th June, 1999? Or 19 September 2000? Well, if you can effortlessly reel off the answers, and in general recollect events in your life with remarkable accuracy, you don’t just have good memory—you’d be pleased to know that you have what is called “Highly Superior Autobiographical Memory”.

This is a newly described ability of individuals to recall events from their personal past, including the days and dates of occurrence, with high accuracy. People with strong memories don’t necessarily have HSAM. They use certain mnemonics and strategies to perfect the art of memory, and this often doesn’t extend to autobiographical memories. In a case of one of the most famous mnemonists, the patient described living his life “in a haze”. Conversely, intense rehearsal of memories does not seem to be the primary means by which people with HSAM store their rich repertoire of memories.

Having excellent autobiographical memory could be a result of your brain being structured differently. [Image Credit: flickr.com/digitalshotgun]
Having excellent autobiographical memory could be a result of your brain being structured differently. [Image Credit: flickr.com/digitalshotgun]

How Are they “Highly Superior”?

Researchers at the University of California, Irvine tried to see if this difference between high autobiographical memory and good memory was also reflected in the way these are stored in the brain. They recruited people who claimed to have extremely good autobiographical memories and performed routine memorization tests on them. They identified 11 people who had vastly superior abilities to remember events in their past. However, these people performed no better than normal individuals on these tests. Yet when it came to public or private events that occurred after age 10½, “they were remarkably better at recalling the details of their lives,” said McGaugh, senior author on the new work.

They found that HSAM participants also had obsessive tendencies, though it remains unclear if the two are linked, and if so, how. Furthermore, they found that the brains of these participants were anatomically different from the brains of normal participants in 9 structures. Using MRI, some of these regions are shown to be active while autobiographical memories are being recalled.

Cause or Effect?

It must be noted, however, that these structural differences could either be a cause of HSAM or an effect. Our brains are remarkably plastic and embody the saying ‘we are what we do’. The wiring of our brains is subject to change upon repeated patterns of activity. Thus, the difference in certain brain regions of people with HSAM could simply arise as a result of different thought patterns in these people. Either way, this research does give us more information about the intricate workings of the brain and how it resolves the details of the world we live in.

You can read about this work here. It was published in the journal Neuroscience.

 

How does the Brain Distinguish Between Old and New? It is Biased.

Last weekend, I went to a cinema in the USA for the first time. I was conscious of two things—taking in the cine-going experience in a new country, and reminiscing about the last time I was at a theatre with my friends a year ago.

Is This Memory Already Stored Inside Me?

When we come across a situation, there are two conflicting processes that can take place- a new memory can be formed, or an old memory can be retrieved. Both these processes involve a common region of the brain called the hippocampus. However, despite the effortlessness with which we form memories and simultaneously recall old ones, the two processes themselves involve very different networks. Recalling a memory involves maximizing overlap with existing memories. On the contrary, forming a new memory involves minimizing the overlap with other memories. These are two conflicting requirements; how, then, does the brain decide what to do?

Recent experiments by researchers at Columbia University and New York University are showing that this decision is influenced by incidents prior to the decision. That is, prior incidents bias our brain either towards forming a new memory or towards recalling an existing one.

The brain is not very objective in its decision making. [Image Credit: Wikimedia Commons]
Participants were presented with pictures of novel and familiar objects and asked to classify them into one of three classes— identical, different, or similar but not identical to a previously encountered object. The ‘test’ objects were very similar to previous objects, but had subtle differences. It was found that participants who had been primed with a series of new objects tended to classify these as not identical, whereas participants who had been primed with familiar objects tended to classify them as identical. In another experiment, participants were found to form links between overlapping memories better if these overlapping memories had been formed after a retrieval of a memory, and their ability to form links between memories was less if the memories had been formed after a new memory had been formed. That is, a preceding experience definitely affects how a memory is stored in the brain with respect to other memories.

Biased by Our Environment

“We’ve all had the experience of seeing an unexpected familiar face as we walk down the street and much work has been done to understand how it is that we can come to recognize these unexpected events,” said Lila Davachi, an associate professor in NYU’s Department of Psychology and the study’s senior author. “However, what has never been appreciated is that simply seeing that face can have a substantial impact on your future state of mind and can allow you, for example, to notice the new café that just opened on the corner or the new flowers in the garden down the street.”
This is behavioral evidence that memory encoding and retrieval can evoke biases which influence subsequent memory processing. The production of this bias may be an adaptive mechanism. Making the decision about retrieval or creation of memory uses up resources, and it is very rarely that our experiences rapidly switch between the familiar and the novel. It could thus be advantageous for our nervous system to be more receptive to change in new environments and less sensitive to irregularities in familiar environments.
You can read more about this research here.

Ancient Snake Fossil Identifies Snake Ancestry

Biologically, snakes are just glorified lizards. Glorified, they are, for a reason. There are around 3000 species of snakes in a variety of habitats. Together, they form one of the most successful groups in the animal kingdom.

Did Snakes Evolve on the Land or in the Sea?

Where did snakes evolve from? Did they arise from marine environments, as their bodies became more slender in an adaptation for swimming, or did they arise from terrestrial environments, in which case their bodies would have become adapted for burrowing? Also, snakes have remarkably flexible jaws which allow them to devour prey much larger than themselves. Chances are that you haven’t come across any pictures of lizards ingesting huge animals. This is because lizards have inflexible jaws. How, then, did snakes get these jaws when their cousins don’t have them?

We don’t know the answers to these questions because of the incomplete fossil records in the serpent lineage. There haven’t been any fossils that connect snakes and lizards. Now, a snake fossil forming the missing link between these two classes of reptiles has been found.

Jaws of lizards (a), Coniophis (b) and modern snakes (c). Coniophis has hooked teeth like modern snakes, but its skull is still fixed. [Image Credit: Nicholas Longrich: taken from the publication in Nature]

New Snake Fossil Provides Perfect Snapshot of Evolution

Coniophis precedens from the plains of North America represents one of the most primitive snakes. Based on species comparison (also called ‘phylogenetic analysis’) with other snakes, it has been found to be amongst the most ancient. In what is a perfect snapshot in the evolutionary process, it has a snake-like body and a lizard-like head with snake-like teeth. Its small size and reduced spines both point to it being fossorial—adapted for digging. This points us towards snakes having evolved from burrowing lizards, and not from marine environments. Its hooked teeth, like those of its contemporary kin, are suitable for chewing on relatively large, soft-bodied prey, but like lizards, its jaw remains relatively fixed. Its slender body enabled it to slither, and according to Professor Nicolas Longrich, who headed this study, it could have slithered “beneath the feet of the dinosaur Tyrannosaurus rex”.

The picture that emerges is that Coniophis was a small carnivorous land snake that preyed upon small vertebrates. Snakes that followed it evolved flexible jaws in a series of adaptations that enabled them to feed on a greater variety to prey. Coniophis thus represents a stage in the stepwise accumulation of adaptations.

The bones of this ancient and important connecting link in the evolution of snakes are in museum collections in the United States of America.You can read more about this research here.

Researchers Build First Complete Computer Model of an Organism

Researchers at Stanford University have completed the world’s first complete computer model of an organism. Using research from 900 publications and accounting for over 1900 parameters, they were able to completely simulate the human pathogen, Mycoplasma genitalium. This pathogen is often found in the urinary or respiratory tracts of humans and is known to have the simplest genome of any free-living organism.

Phenotype Model
This image represents the many processes it takes to build a complex phenotype as was done in this study. (Courtesy Science Direct Journal Cell)

The study was partly funded by the NIH Director’s Pioneer Award. “This achievement demonstrates a transforming approach to answering questions about fundamental biological processes,” said James M. Anderson, director of the National Institutes of Health Division of Program Coordination, Planning and Strategic Initiatives. “Comprehensive computer models of entire cells have the potential to advance our understanding of cellular function and, ultimately, to inform new approaches for the diagnosis and treatment of disease.”

The study consisted of vast amounts of data and took a lot of computing power to pull off. But you may ask, “Why are we so interested in simulating an organism?” That is a good question. In the simplest of terms, what these scientists are building is called a phenotype, which basically means they are building a model based on observed behaviors or expressions in this organism. Using data from more than 900 scientific papers to account for every molecular interaction that takes place in the life cycle of Mycoplasma genitalium, the scientists were able to observe things in the computer model that would be hard to see in the real thing. They were also able to reexamine experimental data.

This study opens wide the possibilities of computer aided bio-engineering. If you’ve been around any construction or architectural firms, you know the impact that computer aided design (think AutoCAD) has contributed to the process of planning and engineering a building. In the same way, being able to simulate entire organisms and be able to predict what certain genes will do under certain conditions has so much potential for future applications such as pharmaceuticals and even personalized medicine. However, the study authors are cautious to note that it will be a while before this is possible.

This study was published in the journal Cell. For more information, see Stanford University’s website.

Our Skin Can Tell Time

That our body has ‘clocks’ is known. The best known is the circadian ‘day-night’ clock that regulates our sleep patterns and allows to anticipate environmental changes between day and night. Scientists have now found that skin cells also have an internal ‘clock’.

Skin as a Protective Barrier

Because the skin is the outermost layer of the body, it is most affected by environmental variations in conditions such as temperature, UV and sunlight. In fact, one of its main functions is to protect the body by forming a barrier to harsh environmental conditions. Wouldn’t it thus make sense for the skin to ‘sense’ changes in the environment and respond accordingly?

Some Skin Genes are Time-Dependent

Researchers in Hamburg measured the expressions of various genes in skin cells at different times of the day, and found a whole bunch of genes that were expressed differently depending on the time of the day. This means that the skin adapts to the current environment and regulates itself on the current need. Just as our clothes very with the weather, the suite of proteins and fats expressed by the skin vary according to the time of day.

[Image Credit: Getty Images]

They also found that many of these daytime-regulated genes were regulated by one other gene. This gene is a transcription factor, which means it doesn’t directly produce a protein, but regulates the expression of other proteins, either by inhibiting them or activating them. That is, the gene called Klf9 is a parent regulator—it is affected by the environment, and in turn, it affects the expression of other genes. However, we don’t yet know how these changes lead to differences in the activity of the skin at different times and that remains to be studied.

The job of the biological clock is to control the exact timing of various processes like cell division and DNA repair in skin. Prof. Achim Kramer, who headed this research, is already looking to the future: “If we understand these processes better, we could target the use of medication to the time of day in which they work best and have the fewest side effects.”

New Species Named After Bob Marley

A recent study, funded by the National Science Foundation, has resulted in the discovery of a new coral reef species which was given the name Gnathia marleyi as a tribute to the late reggae legend, Bob Marley.

Bob Marley
Bob Marley (Courtesy Wikimedia Commons)

Paul Sikkel, an assistant professor of marine ecology and a field marine biologist at Arkansas State University initially discovered the species 10 years ago in the  U.S. Virgin Islands, but they were so common, Sikkel assumed the species had been named already. It turns out he had a hunch and decided to consult fellow researchers and the next thing you know, he’s naming a brand new species. Gnathia marleyi is a gnathiid isopod and is a parasitic blood feeder in its juvenile stages. It infests certain fish that inhabit the coral reef and is the first new species to be named out of the Caribbean for years.

Juvenile Gnathiids
Juvenile gnathiids that have recently fed on fresh blood. Only juvenile gnathiids are parasitic.
Credit: Ann Marie Coile, Department of Biology, Arkansas State University

Sikkel’s research is primarily focused on the health of the reef. Recent reports say the reef is degrading in the Caribbean. According to the NSF press release, Sikkel says,”we are currently researching the relationships between the health of coral reef communities and gnathiid populations”. It appears that as the reef degrades the parasites that infest them gain ground. Sikkel likens the gnathiids to mosquitoes, which are known to carry blood born diseases. “Our current work is focused on how changes in coral reef environments, such as coral bleaching, influences interactions between hosts and parasites,” said Sikkel. “We’re including in our studies any effects on cleaning organisms that remove parasites from hosts.” As it turns out, there are “cleaner fish” that rely heavily on these parasites as food. Sikkel believes these little guys may be playing a large role in transmitting disease in the reef.

As to why these little guys were named for Marley, Sikkel said,”I named this species, which is truly a natural wonder, after Marley because of my respect and admiration for Marley’s music. Plus, this species is as uniquely Caribbean as was Marley”. The study was published in the June 6th issue of Zootaxia.

 

Researchers Create “MRI” of the Sun’s Interior Motions

A team of researchers from NYU’s Courant Institute of Mathematical Sciences and its Department of Physics, Princeton University, the Max Planck Institute, and NASA have created an “MRI” of the sun’s interior motions.

MRI of Sun
Image of the sun’s surface taken by the Helioseismic and Magnetic Imager (HMI) onboard NASA’s Solar Dynamics Observatory (courtesy NASA)

Looking for Some Hot Stuff

The sun’s inner core creates heat through a process called nuclear fusion. The heat moves to the outer surface of the sun through convection. Since the sun is opaque, not much has been learned about how the process works. Scientists have had to rely on studies of fluid models and then try to apply those observations to the sun.

The sun is primarily composed of hydrogen, helium, and plasma. Plasma according to Princeton’s website is “a fourth state of matter distinct from solid or liquid or gas and present in stars and fusion reactors; a gas becomes a plasma when it is heated until the atoms lose all their electrons, leaving a highly electrified collection of nuclei and free electrons”. It is also the primary contributor to the sun’s magnetic fields. This study sought to grasp a better understanding of phenomenon such as sun spots and magnetic fields. A fantastic NASA video showing activity on the surface of the sun is embedded below.

http://www.youtube.com/watch?v=f7K1Ig0Kemw

Smile! Say Cheese

To get their “MRI” the researchers relied on NASA’s Solar Dynamics Observatory to get a high definition picture of the sun’s surface. The Helioseismic and Magnetic Imager measures the effects of convection on the sun’s surface using a 16 million pixel camera. No hiding any sun spots or blemishes with a camera like that!

The end result of the research showed that many of our assumptions about the sun were incorrect. Current theory about the sun’s magnetic field rely on assumptions about the speed and magnitude of the sun’s inner motions. According to an NYU press release, study author Shravan Hanasoge, an associate research scholar in geosciences at Princeton University and a visiting scholar at NYU’s Courant Institute of Mathematical Sciences said, “our results suggest that convective motions in the Sun are nearly 100 times smaller than these current theoretical expectations” Hanasoge continued saying “If these motions are indeed that slow in the Sun, then the most widely accepted theory concerning the generation of solar magnetic field is broken, leaving us with no compelling theory to explain its generation of magnetic fields and the need to overhaul our understanding of the physics of the Sun’s interior.”

As so often happens in science, further research sometimes opens more questions and challenges the theories of the day. This research has been published in the Proceedings of the National Academy of Sciences.

Athletes Used to Study Climbing Habits of Orangutans

Research presented to the Society for Experimental Biology’s meeting in Salzburg, Austria used street athletes to measure the energy expenditure of different modes of navigating a forest. What they discovered was swaying from tree to tree was the most efficient mode of travel for the orangutan.

Orangutan
(Courtesy Wikimedia Commons)

Orangutans, sometimes referred to as the “old man of the forest”, primarily dwell high in the tree canopy. They are the largest of the tree dwelling animals. Dr. Lewis Halsey of the University of Roehampton set out find out why it is they get about the forest the way they do. Using Parkour athletes, which are athletes that specialize in efficient movement around obstacles, they measured the energy it takes to move from tree to tree using different modes of locomotion. They outfitted the athletes with masks that measured their oxygen levels while performing various tasks similar to what the orangutans would do. Using humans as stand-ins was the only logical way as orangutans are not likely to cooperate with masks as they climbed about an obstacle course. In the BBC footage embedded below, you can see the athletes performing the various exercises.

[Video Link]

Parkour Research from University of Roehampton on Vimeo.

According to Dr. Halsey, the Parkour athletes were the perfect stand-in for they are “professional parkour practitioners (free runners) who display elite gymnastic and athletic abilities.” They used the athletes to measure 3 types of locomotion: swaying, climbing, and leaping. What the team discovered is that swaying through the trees is the most efficient way for these large animals to travel about. This also explains how the orangutans are able to live on a diet of mostly fruit which is not a significant source of energy.

These studies will provide more information about the habitat necessary to maintain the highly endangered species. For more information about the study visit the University of Roehampton’s website.