Researchers Identify Genetic Marker Linked to OCD

A group of researchers led by Johns Hopkins scientists say they have identified a genetic marker that may be associated with the development of obsessive-compulsive disorder (OCD), whose causes and mechanisms are among the least understood among mental illnesses.

The results of the research are published online May 13 by the journal Molecular Psychiatry.

“If this finding is confirmed, it could be useful,” says study leader Gerald Nestadt, M.D., M.P.H., a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and director of Johns Hopkins’ Obsessive-Compulsive Disorder Program. “We might ultimately be able to identify new drugs that could help people with this often disabling disorder, one for which current medications work only 60 to 70 percent of the time.”

Nestadt and his team conducted what is known as a genome-wide association study, scanning the genomes of more than 1,400 people with OCD and more than 1,000 close relatives of people with the mental disorder. A significant association was identified in OCD patients near a gene called protein tyrosine phosphokinase (PTPRD).

OCD is a condition marked by thoughts and images that chronically intrude in the mind and by repetitive behaviors aimed at reducing the associated anxiety. Some of the least disabling forms of the disorder can add an extra hour to the day’s routine, causing distress and interfering with daily life. Some people are so disabled that they can’t leave their homes.

Experts say OCD affects an estimated 1 to 2 percent of the U.S. population, and the World Health Organization has called it one of the more disabling medical conditions worldwide. Antidepressants known as SSRIs work for some people, but not everyone; the same is true of behavioral therapy.

Nestadt says the genome-wide association study findings of a PTRPD-OCD link add to evidence that the genetic region they identified is important. The gene has already been shown in animals to be possibly involved in learning and memory, traits influenced by OCD in humans. Moreover, some cases of attention-deficit hyperactivity disorder (ADHD) have been associated with the gene, and OCD and ADHD have some symptoms in common. He says the gene also works with another gene family, SLITRK, which has also been associated with OCD in animals.

“OCD research has lagged behind other psychiatric disorders in terms of genetics,” Nestadt says. “We hope this interesting finding brings us closer to making better sense of it — and helps us find ways to treat it.”

(Image credit: Jennifer Soo)

Alternative pathways let right and left communicate in early split brains

During the last century, many patients have undergone a variety of brain surgeries in an attempt to alleviate all sorts of psychiatric maladies, from hysteria and depression (mainly in women) to schizophrenia and epilepsy. Early on, doctors believed that psychiatric patients suffered from aberrant wiring among different brain areas and that cutting the connections between these areas would help patients regain normal brain circuits as well as their mental health. For instance, since the 1940s, several patients with intractable epilepsy have been treated with callosotomy, a surgical procedure that severs part or most of the corpus callosum. Curiously, some individuals are already born without the corpus callosum, a condition known as callosal dysgenesis (CD).

In 1968, the neurobiologist Roger Sperry confirmed that both callosotomized and CD patients have either absent or massively diminished connections between brain hemispheres. However, these two types of patients show a paradoxical difference concerning the transfer of information between the two sides of their brains. While typical callosotomized patients suffer from a disconnection syndrome in which there is minor or no communication between the left and right brain hemispheres, in CD patients, the two hemispheres are in fact able to communicate with each other.

For instance, when an unseen object is held in the right hand and thus recognized by the left hemisphere, both callosotomized and CD individuals can easily name that object verbally, because it is the left hemisphere that most often dominates verbal language. However, when an object is held in the left hand and thus recognized by the right hemisphere, callosotomized patients fail to verbally name the object because the missing corpus callosum prevents the right hemisphere from communicating with the left hemisphere. Conversely, CD patients have no difficulties in naming an unseen object regardless of the hand holding it.

The observation that the corpus callosum is the main connector between brain hemispheres earned Roger Sperry the Nobel Prize in 1981, but his own paradoxical discovery that CD patients do not present the classical disconnection syndrome observed in callosotomized patients remained unexplained until now.

In an article entitled “Structural and functional brain rewiring clarifies preserved inter-hemisphere transfer in humans born without the corpus callosum” and published in the Proceedings of the National Academy of Sciences (PNAS), a group of scientists from Rio de Janeiro and Oxford puts an end to Sperry’s paradox.

Previous work had led to the hypothesis that a defect in callosal formation would cause the brains of CD patients to create alternative pathways early on in life, but little was known about these potential pathways. The group led by Fernanda Tovar-Moll and Roberto Lent at the D’Or Institute for Research and Education and the Institute of Biomedical Sciences in Rio de Janeiro, Brazil, tested the brains of patients with CD using state of the art functional neuroimaging methods. The researchers were able to identify, morphologically describe and establish the function of two alternative pathways that help compensate for the lack of the corpus callosum. These pathways enable the transfer of complex tactile information between hemispheres, an ability missing in surgically callosotomized patients. Furthermore, by comparing six CD patients with 12 normal individuals, the group was able to demonstrate that CD patients present tactile recognition abilities similar to those observed in controls, indicating a functional role for these newly discovered brain pathways.

The authors believe that the development of alternative pathways results from the brain’s ability for long-distance plasticity and occurs in the utero during embryo development, which indicates that connections formed in the human brain early in development can be greatly modified, and most likely by environmental or genetic factors.

These findings will change the way we perceive the mechanisms of brain plasticity and may pave the way for a better understanding of a number of human disorders resulting from abnormal neuronal connections during embryonic development.

Electrical stimulation of brain alters dreams

Nighttime dreams in which you show up at work naked, encounter an ax-wielding psychopath or experience other tribulations may become a thing of the past thanks to a discovery reported on Sunday.

Applying electrical current to the brain, according to a study published online in Nature Neuroscience, induces “lucid dreaming,” in which the dreamer is aware that he is dreaming and can often gain control of the ongoing plot.

The findings are the first to show that inducing brain waves of a specific frequency produces lucid dreaming.

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Regulate brain boosting devices so everyone can have a go

Gamers around the world are snapping up a new device that promises to give them an edge on competitors by boosting their gaming focus. It is certainly easy to see the appeal of being able to improve your levels of attention at the push of a colourful, glowing button.

The foc.us device works by electrically stimulating the brain to increase the activity of neurons. More neuron activity, more focus, more winning – or so the manufacturers claim. It is just one product in a growing market of cognitive enhancement devices. All these devices affect the brain in some way, be it by improving your memory, attention, learning speed or another mental process.

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'Killer robots' to be debated at UN

Killer robots will be debated during an informal meeting of experts at the United Nations in Geneva.

Two robotics experts, Prof Ronald Arkin and Prof Noel Sharkey, will debate the efficacy and necessity of killer robots.

The meeting will be held during the UN Convention on Certain Conventional Weapons (CCW).

A report on the discussion will be presented to the CCW meeting in November.

This will be the first time that the issue of killer robots, or lethal autonomous weapons systems, will be addressed within the CCW.

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Study of neurogenesis in mice may have solved mystery of childhood amnesia in humans

A team of researchers working at the University of Toronto in Canada may have found the answer to the question of why we humans tend to have little to no memory of the first few years of our lives. In their paper published in the journal Science, the team describes several experiments they ran on mice and other small mammals that revealed the impact of neurogenesis on memory and how what they learned might be applied to memory retention in people. Lucas Mongiat and Alegandro Schinder offer a review of memory studies and how the research by the team in Toronto fits in with what has already been learned in a Perspective piece in the same journal edition.

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Experiencing letters as colours: new insights into synaesthesia

Scientists studying the bizarre phenomenon of synaesthesia – best described as a “union of the senses” whereby two or more of the five senses that are normally experienced separately are involuntarily and automatically joined together – have made a new breakthrough in their attempts to understand the condition.

V.S. Ramachandran and Elizabeth Seckel from the University of San Diego studied four synaesthetes who experience colour when seeing printed letters of the alphabet. Their aim was to determine at what point during sensory processing these ‘colours’ appeared.

To do this, the researchers asked their synaesthetes – as well as a control group – to complete three children’s picture puzzles in which words were printed backwards or were not immediately visible.  

When the results were processed, Ramachandran and Seckel discovered that the synaesthetes were able to complete the puzzles three times faster than the control subjects, and with fewer errors. The synaesthetes also revealed that they saw the obscured letters in the puzzles in the same colour as they would the ‘normal’ letters. This process effectively clued them in to what the letters were, and allowed them to read the distorted words much more quickly than the controls could.

Although it was just a small study, Ramachandran and Seckel’s work, published in the current issue of Neurocase, ‘strongly supports the interpretation that the synthetic colours are evoked preconsciously early in sensory processing’. The four synaesthetes had an advantage in completing the puzzles because the ‘extra’ information they received when looking at the letters was then sent up to ‘higher levels of sensory processing, providing additional insight for reading the distorted and backwards text’: a fascinating and important insight into a condition those of us who see letters as just letters find simply baffling.

From the Phenomenology to the Mechanisms of Consciousness: Integrated Information Theory 3.0

This paper presents Integrated Information Theory (IIT) of consciousness 3.0, which incorporates several advances over previous formulations. IIT starts from phenomenological axioms: information says that each experience is specific – it is what it is by how it differs from alternative experiences; integration says that it is unified – irreducible to non-interdependent components; exclusion says that it has unique borders and a particular spatio-temporal grain. These axioms are formalized into postulates that prescribe how physical mechanisms, such as neurons or logic gates, must be configured to generate experience (phenomenology). The postulates are used to define intrinsic information as “differences that make a difference” within a system, and integrated information as information specified by a whole that cannot be reduced to that specified by its parts. By applying the postulates both at the level of individual mechanisms and at the level of systems of mechanisms, IIT arrives at an identity: an experience is a maximally irreducible conceptual structure (MICS, a constellation of concepts in qualia space), and the set of elements that generates it constitutes a complex. According to IIT, a MICS specifies the quality of an experience and integrated information Φ^Max its quantity. From the theory follow several results, including: a system of mechanisms may condense into a major complex and non-overlapping minor complexes; the concepts that specify the quality of an experience are always about the complex itself and relate only indirectly to the external environment; anatomical connectivity influences complexes and associated MICS; a complex can generate a MICS even if its elements are inactive; simple systems can be minimally conscious; complicated systems can be unconscious; there can be true “zombies” – unconscious feed-forward systems that are functionally equivalent to conscious complexes.

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