Posts tagged science
Articles and news from the latest research reports.
Big Picture: Inside the Brain
The Spring 2013 issue of Big Picture, Inside the Brain, is now available online. This issue, explores the technologies that are helping us to understand the brain, including magnetic resonance imaging (MRI) and computed tomography (CT).
About the cover:
This photograph, taken by Robert Ludlow, shows the surface (cortex) of a human brain belonging to an epileptic patient. The image displays the bright red arteries that supply the brain with nutrients and oxygen and the purple veins that remove deoxygenated blood. This photograph was taken before an intracranial electrode recording procedure for epilepsy, in which electrical activity is measured from the exposed surface of the brain. To find out more about Robert’s image and its creation, view this video on the UCL Institute of Neurology’s website. (Wellcome Image Awards 2012)
What is déjà vu and why does it happen?
Have you ever experienced a sudden feeling of familiarity while in a completely new place? Or the feeling you’ve had the exact same conversation with someone before?
This feeling of familiarity is, of course, known as déjà vu (a French term meaning “already seen”) and it’s reported to occur on an occasional basis in 60-80% of people. It’s an experience that’s almost always fleeting and it occurs at random.
So what is responsible for these feelings of familiarity?
Despite coverage in popular culture, experiences of déjà vu are poorly understood in scientific terms. Déjà vu occurs briefly, without warning and has no physical manifestations other than the announcement: “I just had déjà vu!”
Many researchers propose that the phenomenon is a memory-based experience and assume the memory centres of the brain are responsible for it.
How The Memory Works In Learning
Teachers are the caretakers of the development of students’ highest brain during the years of its most extensive changes. As such, they have the privilege and opportunity to influence the quality and quantity of neuronal and connective pathways so all children leave school with their brains optimized for future success.
This introduction to the basics of the neuroscience of learning includes information that should be included in all teacher education programs. It is intentionally brief such that it can be taught in a single day of instruction. Ideally there would be additional opportunities for future teachers to pursue further inquiry into the science of how the brain learns, retrieves, and applies information.
Shakespeare and Wordsworth boost the brain, new research reveals
Scientists, psychologists and English academics at Liverpool University have found that reading the works of the Bard and other classical writers has a beneficial effect on the mind, catches the reader’s attention and triggers moments of self-reflection.
Using scanners, they monitored the brain activity of volunteers as they read works by William Shakespeare, William Wordsworth, T.S Eliot and others.
They then “translated” the texts into more “straightforward”, modern language and again monitored the readers’ brains as they read the words.
Scans showed that the more “challenging” prose and poetry set off far more electrical activity in the brain than the more pedestrian versions.
Scientists were able to study the brain activity as it responded to each word and record how it “lit up” as the readers encountered unusual words, surprising phrases or difficult sentence structure.
This “lighting up” of the mind lasts longer than the initial electrical spark, shifting the brain to a higher gear, encouraging further reading.
The research also found that reading poetry, in particular, increases activity in the right hemisphere of the brain, an area concerned with “autobiographical memory”, helping the reader to reflect on and reappraise their own experiences in light of what they have read. The academics said this meant the classics were more useful than self-help books.
Philip Davis, an English professor who has worked on the study with the university’s magnetic resonance centre, will tell a conference this week: “Serious literature acts like a rocket-booster to the brain.
"The research shows the power of literature to shift mental pathways, to create new thoughts, shapes and connections in the young and the staid alike."
FDA Approves Magnetic Helmet For Treating Depression
The United States Food and Drug Administration approved a device that treats depression using… magnets. About 14.8 million American adults, or 6.7 percent of the U.S. adult population, are diagnosed with major depression in a given year, and antidepressant medications often don’t help.
The technology, known as deep Transcranial Magnetic Stimulation or TMS, involves placing a helmet filled with electromagnetic coils very close to the scalp and zapping them with pulses of electricity, which causes neurons to fire in very specific areas of the brain.
Magnets, How Do They Work?
First the machine is calibrated by placing it over a part of the brain that causes the subject’s hand to move. Then the coils are aimed at the brain region under treatment. The treatment lasts about 15 to 30 minutes, repeated over several weeks, and is noninvasive—all the person feels is a slight buzzing, and there are no side effects. This makes it a more palatable relative of other treatments that also target the brain directly, such as electroconvulsive therapy (formerly electroshock), or surgically implanted electrodes.
Brainsway, a publicly traded Israeli company, has an exclusive license for the technology from the National Institutes of Health, where its two Israeli scientific cofounders developed it. Their device is already approved in Europe for clinical depression, bipolar disorder, schizophrenia (negative symptoms), Parkinson’s diseases, and PTSD. Clinical trials are under way to test how well brain-zapping electromagnets could work to treat a huge range of ailments including cocaine addiction, Tourette’s syndrome, Alzheimer’s, stroke rehabilitation, multiple sclerosis, even ADHD.
(Credit: theloneliestgod)
New understanding of brain’s early spatial development
Researchers at the University of Bath have uncovered a new understanding of how the brain develops its sense of space by working with blind people.
The researchers from the University’s Department of Psychology found that people who lose their sight later in life use a different method of following directions to those who are born without sight. This means that the brain needs to have a visual experience early on in life in order to build a visual perspective, or frame of reference, to know what is where.
The researchers carried out a study with participants including those who were congenitally blind; those who became blind later in life; and others who were sighted, to learn which methods the different groups used to remember where things are.
The study revealed that people who have been sighted and then become blind use a ‘allocentric’ reference frame, meaning they remember locations as they are positioned relative to one another, and this is the same as sighted people who do this task, even when blindfolded.
In contrast congenitally blind participants preferred an ‘egocentric’ reference frame meaning they first remember a starting point at home and then store a memory of the locations from the home location. Dr Michael Proulx who led the study said the results help us to understand more about the role of a critical period for developmental vision on spatial cognition and brain organisation.
He said: “In our study we were curious as to whether having visual experience during child development was key to creating the structures in the brain to support such an allocentric reference frame. First we found an interesting difference between the congenitally blind and sighted people: although the sighted people preferred the allocentric, reference frame, the congenitally blind participants preferred the self-centred or egocentric reference frame for remembering locations.
“The important piece of the puzzle, however, was whether the late blind people would perform like the congenitally blind, showing that current visual experience matters, or like the sighted, showing the role of early visual experience. The results were clear: the late blind performed the same as the sighted participants. Therefore having the experience of vision early in life lays the groundwork in the brain for the representation of locations in a different reference frame than that found in people who never had visual experience.”
All of the participants of the study were blindfolded and then walked to the locations of objects in a large room. They were later tested on a computer with a virtual pointing task that asked them to remember objects in the room relative to the other object locations.
Dr Proulx and his colleagues are following up this finding with additional research to investigate how additional information, such as the texture or sound of the environment, might influence the frame of reference used.
This would allow for improved maps rendered in Braille or sound to be produced for visually impaired persons to use in public places, such as rail stations, or in new cities.
They are also examining the impact of visual experience on the neural basis for spatial learning and memory by examining how the congenitally blind and late blind brains represent spatial information in the absence of vision.
My mistake or yours? How the brain decides
Humans and other animals learn by making mistakes. They can also learn from observing the mistakes of others. The brain processes self-generated errors in a region called the medial frontal cortex (MFC) but little is known about how it processes the observed errors of others. A Japanese research team led by Masaki Isoda and Atsushi Iriki of the RIKEN Brain Science Institute has now demonstrated that the MFC is also involved in processing observed errors.
The team studied the brains of monkeys while the animals performed the same task. Two monkeys sat opposite each other and took turns to choose between a yellow and green button, one of which resulted in a liquid reward for both. Each monkey’s turn consisted of two choices.
After blocks of between 5 and 17 choices, the button that resulted in reward was switched unpredictably, usually causing an error on the next choice. The choices made by each monkey immediately after such errors, or errors that were random, showed that they used both their own errors and their partner’s to guide their subsequent choices. While the monkeys performed this task, the researchers recorded activity of single neurons in their brains.
In this way they were able to determine which behavioural aspect was most closely associated with each neuron’s activity, explains Isoda. “We found that many neurons in the medial frontal cortex were not activated when the monkey made an error itself, but they became active when their partner made an error.” This brain activity shows that it is the MFC which processes observations of another’s error, and the corresponding behavior shows that observing and processing such errors guides subsequent actions.
“Such error identification and subsequent error correction are of crucial importance for developing and maintaining successful social communities,” says Isoda. “Humans are tuned into other people’s mistakes not only for competitive success, but also for cooperative group living. If non-invasive techniques become available in humans, then we should be able to identify medial frontal neurons that behave similarly.”
Having identified the MFC as being involved, Isoda now wants to delve deeper into the process. “The next steps will be to clarify whether the inactivation of medial frontal cortex neurons reduces the ability to identify others’ errors, and to determine whether other brain regions are also involved in the processing of others’ errors.”
Banded mongooses structure monosyllabic sounds in a similar way to humans
Animals are more eloquent than previously assumed. Even the monosyllabic call of the banded mongoose is structured and thus comparable with the vowel and consonant system of human speech. Behavioral biologists from the University of Zurich have thus become the first to demonstrate that animals communicate with even smaller sound units than syllables.
When humans speak, they structure individual syllables with the aid of vowels and consonants. Due to their anatomy, animals can only produce a limited number of distinguishable sounds and calls. Complex animal sound expressions such as whale and bird songs are formed because smaller sound units – so-called “syllables” or “phonocodes” – are repeatedly combined into new arrangements. However, it was previously assumed that monosyllabic sound expressions such as contact or alarm calls do not have any combinational structures. Behavioral biologist Marta Manser and her doctoral student David Jansen from the University of Zurich have now proved that the monosyllabic calls of banded mongooses are structured and contain different information. They thus demonstrate for the first time that animals also have a sound expression structure that bears a certain similarity to the vowel and consonant system of human speech.
David A.W.A.M. Jansen, Michael A. Cant, and Marta B. Manser. Segmental concatenation of individual signatures and context cues in banded mongoose (Mungos mungo) close calls. BMC Biology
Epigenetic processes orchestrate neuronal migration
Neurobiologists at the Friedrich Miescher Institute for Biomedical Research (FMI) are the first to show that directional migration of neurons during brain development is controlled through epigenetic processes. In an elaborate study bridging epigenetics and neurobiology, the scientists found that the migratory pattern is orchestrated through epigenetic regulation of genes within neurons and spatial signals in the environment. Their study has been published in Science.
As the foundation for our mind is laid, 100 billion cells are formed and appropriately connected in the brain. Despite the huge number of cells, no aspect of this process is left entirely to chance. Neurons divide, take on defined identities, migrate to the correct nodes in the network and send out their connecting axons along predefined paths to make contact with specific target neurons. The blueprint for these arrangements is encoded in the genome. However, how coordinated transcription of genes is finely tuned to achieve the precision of these processes is not yet clear.
A study by the research group of Filippo Rijli, group leader at the FMI and Professor of Neurobiology at the University of Basel, shows now for the first time that long-distance neuronal migration in the developing brain is regulated through transcriptional programs that are epigenetically controlled.
In their study published in Science, the neurobiologists have looked at a part of the brain called the brain stem and, in particular, at the neuronal ensembles forming the so-called precerebellar pontine nuclei. These nuclei are particularly important for the relay of information from the sensory and motor cortex to the cerebellum. During development, neurons, which will gather to form the pontine nuclei, migrate a long way from a distant progenitor compartment to their final positions, where they form connections that are vital for coordinated movement. The migratory path of these cells is defined by the relative position of the neuron in the progenitor compartment and is controlled by its specific combinatorial expression of Hox genes. Hox genes encode transcription factors and play an important role in many developmental processes that rely on a body plan and confer cellular identity.
It has been known that neurons in the precerebellar pontine nuclei start to migrate in the wrong direction as soon as their Hox identity has been disrupted. The Rijli team has now shown that epigenetic processes control the maintenance of appropriate Hox expression during migration. The key player in this scenario is a major contributor to mammalian epigenetic control, the histone methyl-transferase Ezh2. Ezh2 methylates histones and silences specific stretches of DNA, thus maintaining certain Hox genes repressed, while allowing expression of others.
Ezh2 also regulates the appropriate response to environmental clues that direct neuronal migration. The cells in the brain stem bathe in a sea of attractants and repellants. They respond to these stimuli depending on their identity and adapt their migratory paths. Rijli and colleagues found that Ezh2 controls transcription of both environmental Netrin, a neuronal attractant molecule and of its repellant receptor Unc5b in migrating neurons, such that the appropriate balance between attraction and repulsion is maintained throughout migration to keep neurons on track.
“Being able to link epigenetic regulation with a complex process such as long-distance directional neuronal migration during brain development is extremely exciting,” comments Rijli. “All the more we were delighted to see that the migratory pattern is not only epigenetically maintained through an intrinsic program established in the progenitor, but is also coordinated with an Ezh2-dependent silencing program that regulates the spatial distribution of extrinsic signals in the migratory environment. The knowledge gained from our studies contributes as well to our understanding of certain neurological syndromes that are caused by faulty neuronal migration and are currently incurable.”
(Source: fmi.ch)
The pilot and autopilot within our mind-brain connection
Have you ever driven to work so deep in thought that you arrive safely yet can’t recall the drive itself? And if so, what part of “you” was detecting cars and pedestrians, making appropriate stops and turns? Although when you get to work you can’t remember the driving experience, you are likely to have exquisite memory about having planned your day.
How does one understand this common experience? This is the question posed by Professor of Biology, John Lisman and his former undergraduate student, Eliezer J. Sternberg, now in medical school, in a recent paper in the Journal of Cognitive Neuroscience. Lisman explains that once a task such as driving has become a habit, you can perform another task at the same time, such as planning your day. But looking closer at these two behaviors, driving and planning, one can see interesting differences. The Habit system that is driving you to work is non-flexible: if the new parking regulations at work require you to go left instead or right, the likelihood that you’ll go right is very high. On the other hand, if you heard yesterday that your boss has scheduled a group meeting for noon, the likehood that you’ll plan your day accordingly is high. In other words, your non-habit system is flexible.
What interests Lisman and Sternberg is the relationship of the habit/non-habit systems to concepts of conscious vs unconscious. These concepts were popularized by Freud, who posited a duality of the human mind. Behavior can be influenced by both the conscious system and unconscious system. Freud compared the mind to an iceberg——with the small conscious system above water and the larger unconscious system below. Modern cognitive neuroscience now accepts this duality.
The mind can be described as having an unconscious and conscious part. And the brain can be described as having both habit and non-habit systems. Lisman and Sternberg argue that these two views can be merged: there is a habit system of which we are unconscious and a non-habit system of which we are conscious.
This simple equation turns out to have enormous implications for research on the mind-brain connection. Experiments on consciousness are done in humans because you can ask them to report their awareness, something you can’t do with animals. On the other hand, there are many invasive procedures for studying what’s happening in the brain of animals. So how can you study consciousness in rats?
Lisman and Sternberg provide a simple answer — ask whether rats have habit and non-habits. Scientific literature demonstrates that rats indeed have both habits and non-habits. For instance, when a rat comes to a choice point on a maze (and the reward site is to left), rats display very different behavior depending on how much experience they’ve had with that maze. With relatively little experience, rats pause at the choice point and look both ways before making a decision; in contrast, a highly experienced rats zooms left without stopping. Experiments have shown that different parts of the brain are involved in these two phases. Lisman and Sternberg make two conclusions: first, that rats, like us, have conscious and unconscious parts of the brain and second, that from experiments on rats we can learn to identify the parts of the brain that mediate conscious vs unconscious processes.
In their paper, Lisman and Sternberg also discuss potential objections to their hypothesis, and suggest further tests.
(Photo: GETTY)