Posts tagged brain

May 8th, 2012

Nanotechnology scientists and memory researchers at the Kiel University redesigned a mental learning process using electronic circuits.

The bell rings and the dog starts drooling. Such a reaction was part of studies performed by Ivan Pavlov, a famous Russian psychologist and physiologist and winner of the Nobel Prize for Physiology and Medicine in 1904. His experiment, nowadays known as “Pavlov’s Dog”, is ever since considered as a milestone for implicit learning processes. By using specific electronic components scientists form the Technical Faculty and the Memory Research at the Kiel University together with the Forschungszentrum Jülich were now able to mimic the behavior of Pavlov`s dog. The study “An Electronic Version of Pavlov’s Dog” is published in the current issue of Advanced Functional Materials (huwp 12012).

Digital and biological information processing are based on fundamentally different principles. Modern computers are able to work on mathematical-logical problems at an extremely high pace. In fact, procedures in the computer’s central processing unit and in the storage media run serially. While digital computers have shown immense success throughout the years in certain fields, they reveal weaknesses when it comes to pattern recognition and cognitive tasks. “However, to imitate biological information processing systems recognition and cognitive tasks are essential. Mammal brains – and therefore also the brains of humans – decode information in complex neuronal networks of synapses with up to 10¹⁴ (100 Trillion) connections. However, the connectivity between neurons is not fixed. “Learning means that new connections between neurons are created, or existing connections are reinforced or weakened”, says PD Dr. Thorsten Bartsch of the Clinic for Neurology. This is called neuronal plasticity.

Kiel scientists teach electronic circuits to memorize reactions. Source: Kohlstedt

Is it possible to design neural circuits with electronic devices to mimic learning? At this crossroad between neurobiology, material science and nanoelectronics, scientists from the University of Kiel are collaborating with their colleagues from the Research Center Jülich. Now, they have succeeded in electronically recreating the classical “Pavlov’s Dog” experiment. “We used memristive devices in order to mimic the associative behaviour of Pavlov’s dog in form of an electronic circuit”, explains Professor Hermann Kohlstedt, head of the working group Nanoelectronics at the University of Kiel.

Memristors are a class of electronic circuit elements which have only been available to scientists in an adequate quality for a few years. They exhibit a memory characteristic in form of hysteretic current-voltage curves consisting of high and low resistance branches.  In dependence on the prior charge flow through the device these resistances can vary.  Scientists try to use this memory effect in order to create networks that are similar to neuronal connections between synapses. “In the long term, our goal is to copy the synaptic plasticity onto electronic circuits. We might even be able to recreate cognitive skills electronically”, says Kohlstedt. The collaborating scientific working groups in Kiel and Jülich have taken a small step toward this goal.

The project set-up consisted of the following: two electrical impulses were linked via a memristive device to a comparator. The two pulses represent the food and the bell in Pavlov’s experiment. A comparator is a device that compares two voltages or currents and generates an output when a given level has been reached. In this case, it produces the output signal (representing saliva) when the threshold value is reached. In addition, the memristive element also has a threshold voltage that is defined by physical and chemical mechanisms in the nano-electronic device. Below this threshold value the memristive device behaves like any ordinary linear resistor. However, when the threshold value is exceeded, a hysteretic (changed) current-voltage characteristic will appear.

“During the experimental investigation, the food for the dog (electrical impulse 1) resulted in an output signal of the comparator, which could be defined as salivation. Unlike to impulse 1, the ring of the bell (electrical impulse 2) was set in such a way that the compartor’s output stayed unaffected – meaning no salivation”, describes Dr. Martin Ziegler, scientist at the Kiel University and the first-author of the publication. After applying both impulses simultaneously to the memristive device, the threshold value was exceeded. The working group had activated the memristive memory function. Multiple repetitions led to an associative learning process within the circuit – similar to Pavlov’s dogs. “From this moment on, we had only to apply electrical impulse 2 (bell) and the comparator generated an output signal, equivalent to salivation”, says Ziegler and is very pleased with these results. Electrical impulse 1 (feed) triggers the same reaction as it did before the learning. Hence, the electric circuit shows a behaviour that is termed classical conditioning in the field of psychology. Beyond that, the scientists were able to prove that the electrical circuit is able to unlearn a particular behaviour if both impulses were not longer applied simultaneously.

Information on “Pavlov’s dog”

In Behavioural Psychology, Pavlov’s experiments with dogs are considered as milestones to understand implicit learning in biological systems. In the early 20^th century, Ivan Pavlov was able to show that dogs reacted indifferently towards the impulse “bell” and “food” when these were presented separately. After combining those two impulses (food and bell) in multiple repetitions, the dogs associated both impulses with each other. As a result, the dogs produced a higher amount of saliva, now even hearing the bell alone. This method is called classical conditioning and can be generalized to various combinations of certain impulses.

Nanotechnology scientists and memory researchers have published research results concerning “Pavlov’s Dog”. Credit: Advanced Functional Materials (huwp 2012)

Source: Neuroscience News

ScienceDaily (May 8, 2012) — New research from the Royal College of Surgeons in Ireland (RCSI) published in Nature’s Neuropsychopharmacology has shown physical changes to exist in specific brain areas implicated in schizophrenia following the use of cannabis during adolescence. The research has shown how cannabis use during adolescence can interact with a gene, called the COMT gene, to cause physical changes in the brain.

The COMT gene provides instructions for making enzymes which breakdown a specific chemical messenger called dopamine. Dopamine is a neurotransmitter that helps conduct signals from one nerve cell to another, particularly in the brains reward and pleasure centres. Adolescent cannabis use and its interaction with particular forms of the COMT gene have been shown to cause physical changes in the brain as well as increasing the risk of developing schizophrenia.

Dr Áine Behan, Department of Physiology, RCSI and lead author on the study said ‘This is the first study to show that the combined effects of the COMT gene with adolescent cannabis use cause physical changes in the brain regions associated with schizophrenia. It demonstrates how genetic, developmental and environmental factors interact to modulate brain function in schizophrenia and supports previous behavioural research which has shown the COMT gene to influence the effects of adolescent cannabis use on schizophrenia-related behaviours.

The three areas of the brain assessed in this study were found to show changes in cell size, density and protein levels.

'Increased knowledge on the effects of cannabis on the brain is critical to understanding youth mental health both in terms of psychological and psychiatric well-being,' Dr Behan continued.

Source: Science Daily

ScienceDaily (May 8, 2012) — It is increasingly recognized that chronic psychotropic drug treatment may lead to structural remodeling of the brain. Indeed, clinical studies in humans present an intriguing picture: antipsychotics, used for the treatment of schizophrenia and psychosis, may contribute to cortical gray matter loss in patients, whereas lithium, used for the treatment of bipolar disorder and mania, may preserve gray matter in patients.

However, the clinical significance of these structural changes is not yet clear. There are many challenges in executing longitudinal, controlled, and randomized studies to evaluate this issue in humans, particularly because there are also many confounding factors, including illness severity, illness duration, and other medications, when studying patients.

It is therefore critical to develop animal models to inform the clinical research. To accomplish this, a group of researchers at King’s College London, led by Dr. Shitij Kapur, developed a rat model using clinically relevant drug exposure and matched clinical dosing in combination with longitudinal magnetic resonance imaging. They administered either lithium or haloperidol (a common antipsychotic) to rats in doses equivalent to those received by humans. The rats received this treatment daily for eight weeks, equivalent to 5 human years, and underwent brain scans both before and after treatment.

Dr. Kapur explained their findings, “Using this approach, we observed that chronic treatment with haloperidol leads to decreases in cortical gray matter, whilst lithium induced an increase, effects that were reversible after drug withdrawal.” Gray matter was decreased by 6% after haloperidol treatment, but increased by 3% after lithium treatment.

"These important observations clarify conflicting findings from clinical trials by removing many of the confounding effects," commented Dr. John Krystal, Editor of Biological Psychiatry. "Whether these changes in brain structure underlie the benefits or side effects of these medications remain to be seen. However, they point to brain effects of established medications that are not well understood, but which may hold clues to new treatment approaches."

"Whilst these intriguing findings are consistent with available clinical data, it should be noted these studies were done in normal rats, which do not capture the innate pathology of either schizophrenia or bipolar disorder," Kapur added. "Moreover, because the mechanism(s) of these drug effects remain unknown, further studies are required, and one should be cautious in drawing clinical inferences. Nevertheless, our study demonstrates a new and powerful model system for further investigation of the effects of psychotropic drug treatment on brain morphology."

Source: Science Daily

May 8, 2012

Researchers at the Medical Research Council (MRC) Toxicology Unit at the University of Leicester have identified a major pathway leading to brain cell death in mice with neurodegenerative disease. The team was able to block the pathway, preventing brain cell death and increasing survival in the mice.

In human neurodegenerative diseases, including Alzheimer’s, Parkinson’s and prion diseases, proteins “misfold” in a variety of different ways resulting in the build up of misshapen proteins. These form the plaques found in Alzheimer’s and the Lewy bodies found in Parkinson’s disease. 
  
The researchers studied mice with neurodegeneration caused by prion disease, as these mouse models currently provide the best animal representation of human neurodegenerative disorders, where it is known that the build up of misshapen proteins is linked with brain cell death. 
  
They found that the build up of misfolded proteins in the brains of these mice activates a natural defence mechanism in cells, which switches off the production of new proteins. This would normally switch back ‘on’ again, but in these mice the continued build-up of misshapen protein keeps the switch turned ‘off’. This is the trigger point leading to brain cell death, as those key proteins essential for nerve cell survival are not made. 
  
By injecting a protein that blocks the ‘off’ switch of the pathway, the scientists were able to restore protein production, independently of the build up of misshapen proteins, and halt the neurodegeneration. The brain cells were protected, protein levels and synaptic transmission (the way in which brain cells signal to each other) were restored and the mice lived longer, even though only a very small part of their brain had been treated. 
  
Misshapen proteins in human neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases, also over-activate this fundamental pathway controlling protein synthesis in the brains of patients, which represents a common target underlying these different clinical conditions. The scientists’ results suggest that treatments focused on this pathway could be protective in a range of neurodegenerative disease in which misshapen proteins are building up and causing neurons to die. 
  
Professor Giovanna Mallucci, who led the team, said: “What’s exciting is the emergence of a common mechanism of brain cell death across a range of different neurodegenerative disorders and activated by the different misfolded proteins in each disease. The fact that in mice with prion disease we were able to manipulate this mechanism and protect the brain cells means we may have a way forward in how we treat other disorders. Instead of targeting individual misfolded proteins in different neurodegenerative diseases, we may be able to target the shared pathways and rescue brain cell degeneration irrespective of the underlying disease.” 
  
Professor Hugh Perry, chair of the MRC’s Neuroscience and Mental Health Board, said: “Neurodegenerative diseases such as Alzheimer’s and Parkinson’s are debilitating and largely untreatable conditions. Alzheimer’s disease and related disorders affect over seven million people in Europe, and this figure is expected to double every 20 years as the population ages across Europe. The MRC believes that research such as this, which looks at the fundamental mechanisms of these devastating diseases, is absolutely vital. Understanding the mechanism that leads to neuronal dysfunction prior to neuronal loss is a critical step in finding ways to arrest disease progression.”

Provided by Medical Research Council 

Source: medicalxpress.com

May 8, 2012

(Medical Xpress) — Having a fat head may not be a bad thing, according to new findings at The Johns Hopkins University. As reported in the February 9 issue of Neuron, Hopkins researchers have made a significant discovery as to how adding fat molecules to proteins can influence the brain circuitry controlling cognitive function, including learning and memory.

“When you learn something, you strengthen and inhibit certain transmissions and sculpt a particular circuit. Recall [or memory] is using that circuit again,” says Richard L. Huganir, Ph.D., professor and director of the Solomon H. Snyder Department of Neuroscience at Johns Hopkins. His team’s latest finding describes for the first time how one protein chemically alters another in this circuit strengthening process and represents another step toward understanding a key part of how memories are made and maintained within the brain, something researchers believe could provide a pathway toward treating disorders like Alzheimer’s and schizophrenia.

In studying the molecular underpinnings of learning and memory, Huganir and his team have focused on one of several processes in which a molecule is tagged by another molecule of fat. Tagging sends the molecules to a particular destination within a cell. Specifically, the team has studied DHHC5, which is known to add a fat molecule to other proteins. Until now it was not known which proteins receive this tag.

The scientists suspected a target molecule would need to bind DHHC5, which would then transfer fat onto it. To determine what DHHC5 could bind, they used it as bait in a large pool of rat brain proteins to fish for those that stuck to DHHC5. Within that pool, DHHC5 bound four different proteins, researchers found. Using a computer program, they compared these with other proteins implicated in learning and memory. All four shared similarity with the brain protein known as GRIP1, mutations of which have been linked to disorders such as autism. The scientists then tested GRIP1 and DHHC5 directly and found that they bound each other as well. Next, they put GRIP1 into human kidney cells, either by itself or with DHHC5, and analyzed each group of cells to see what happened. They found that only the GRIP1 proteins that were added to cells with DHHC5 were tagged with fat. From this they concluded that DHHC5 does indeed tag GRIP1 with fat.

The researchers then wanted to know if this process happens in a brain. However, they needed a way to look into a living cell and be able to tell apart GRIP1 that had a fat tag and GRIP1 that didn’t. They designed two distinct GRIP1 proteins: one permanently tagged with fat, and another mutated so that it could never be tagged. They added color markers to both proteins so they could track them under a microscope, and then added one type or the other to living brain cells. The fat-tagged proteins seemed to form clusters extending to the cell’s edges in a pattern resembling that of cellular recycling-center proteins. The untagged proteins, in contrast, seemed to diffuse around the center of the cell. From this, the team concluded that DHHC5 tags proteins like GRIP1 with fat to send them to be recycled.

According to Huganir, protein recycling is critical for strengthening and maintaining memory circuits. Since GRIP1 is involved with recycling, it may be important in this critical aspect of memory formation. Huganir believes some day researchers could learn how to control this mechanism and reverse the disease process for disorders like Alzheimer’s and schizophrenia.

“Some day we may be able to inhibit or activate these molecules,” Huganir says. “These molecules are involved in mediating everything in the brain, all behaviors.”

Provided by Johns Hopkins University

Source: medicalxpress.com

May 7th, 2012

New research provides the strongest evidence to date that psychopathy is linked to specific structural abnormalities in the brain.

The study, published in Archives of General Psychiatry and led by researchers at King’s College London is the first to confirm that psychopathy is a distinct neuro-developmental sub-group of anti-social personality disorder (ASPD).

Most violent crimes are committed by a small group of persistent male offenders with ASPD. Approximately half of male prisoners in England and Wales will meet diagnostic criteria for ASPD. The majority of such men are not true psychopaths (ASPD-P). They are characterised by emotional instability, impulsivity and high levels of mood and anxiety disorders. They typically use aggression in a reactive way in response to a perceived threat or sense of frustration.

However, about one third of such men will meet additional diagnostic criteria for psychopathy (ASPD+P). They are characterised by a lack of empathy and remorse, and use aggression in a planned way to secure what they want (status, money etc.). Previous research has shown that psychopaths’ brains differ structurally from healthy brains, but until now, none have examined these differences within a population of violent offenders with ASPD.

Dr Nigel Blackwood from the Institute of Psychiatry at King’s and lead author of the study says: ‘Using MRI scans we found that psychopaths had structural brain abnormalities in key areas of their ‘social brains’ compared to those who just had ASPD. This adds to behavioural and developmental evidence that psychopathy is an important subgroup of ASPD with a different neurobiological basis and different treatment needs.

‘There is a clear behavioural difference amongst those diagnosed with ASPD depending on whether or not they also have psychopathy. We describe those without psychopathy as ‘hot-headed’ and those with psychopathy as ‘cold-hearted’. The ‘cold-hearted’ psychopathic group begin offending earlier, engage in a broader range and greater density of offending behaviours, and respond less well to treatment programmes in adulthood, compared to the ‘hot-headed’ group. We now know that this behavioural difference corresponds to very specific structural brain abnormalities which underpin psychopathic behaviour, such as profound deficits in empathising with the distress of others.’

The researchers used Magnetic Resonance Imaging (MRI) to scan the brains of 44 violent adult male offenders diagnosed with Anti-Social Personality Disorder (ASPD). Crimes committed included murder, rape, attempted murder and grievous bodily harm. Of these, 17 met the diagnosis for psychopathy (ASPD+P) and 27 did not (ASPD-P). They also scanned the brains of 22 healthy non-offenders.

The study found that ASPD+P offenders displayed significantly reduced grey matter volumes in the anterior rostral prefrontal cortex and temporal poles compared to ASPD-P offenders and healthy non-offenders. These areas are important in understanding other people’s emotions and intentions and are activated when people think about moral behaviour. Damage to these areas is associated with impaired empathising with other people, poor response to fear and distress and a lack of ‘self-conscious’ emotions such as guilt or embarrassment.

Dr Blackwood explains: ‘Identifying and diagnosing this sub-group of violent offenders with brain scans has important implications for treatment. Those without the syndrome of psychopathy, and the associated structural brain damage, will benefit from cognitive and behavioural treatments. Optimal treatment for the group of psychopaths is much less clear at this stage.’

Source: Neuroscience News

ScienceDaily (May 7, 2012) — Greater purpose in life may help stave off the harmful effects of plaques and tangles associated with Alzheimer’s disease, according to a new study by researchers at Rush University Medical Center.

Greater purpose in life may help stave off the harmful effects of plaques and tangles associated with Alzheimer’s disease, according to a new study. (Credit: © Nejron Photo / Fotolia)

The study is published in the May issue of the Archives of General Psychiatry.

"Our study showed that people who reported greater purpose in life exhibited better cognition than those with less purpose in life even as plaques and tangles accumulated in their brains," said Patricia A. Boyle, PhD.

"These findings suggest that purpose in life protects against the harmful effects of plaques and tangles on memory and other thinking abilities. This is encouraging and suggests that engaging in meaningful and purposeful activities promotes cognitive health in old age."

Boyle and her colleagues from the Rush Alzheimer’s Disease Center studied 246 participants from the Rush Memory and Aging Project who did not have dementia and who subsequently died and underwent brain autopsy. Participants received an annual clinical evaluation for up to approximately 10 years, which included detailed cognitive testing and neurological exams.

Participants also answered questions about purpose in life, the degree to which one derives meaning from life’s experiences and is focused and intentional. Brain plaques and tangles were quantified after death. The authors then examined whether purpose in life slowed the rate of cognitive decline even as older persons accumulated plaques and tangles.

While plaques and tangles are very common among persons who develop Alzheimer’s dementia (characterized by prominent memory loss and changes in other thinking abilities), recent data suggest that plaques and tangles accumulate in most older persons, even those without dementia. Plaques and tangles disrupt memory and other cognitive functions.

Boyle and colleagues note that much of the Alzheimer’s research that is ongoing seeks to identify ways to prevent or limit the accumulation of plaques and tangles in the brain, a task that has proven quite difficult. Studies such as the current one are needed because, until effective preventive therapies are discovered, strategies that minimize the impact of plaques and tangles on cognition are urgently needed.

"These studies are challenging because many factors influence cognition and research studies often lack the brain specimen data needed to quantify Alzheimer’s changes in the brain," Boyle said. "Identifying factors that promote cognitive health even as plaques and tangles accumulate will help combat the already large and rapidly increasing public health challenge posed by Alzheimer’s disease."

The Rush Memory and Aging Project, which began in 1997, is a longitudinal clinical-pathological study of common chronic conditions of aging. Participants are older persons recruited from about 40 continuous care retirement communities and senior subsidized housing facilities in and around the Chicago Metropolitan area. More than 1,500 older persons are currently enrolled in the study.

Source: Science Daily

ScienceDaily (May 7, 2012) — Depressive symptoms that are present in midlife or in late life are associated with an increased risk of developing dementia, according to a report in the May issue of Archives of General Psychiatry, a JAMA Network publication.

Nearly 5.3 million individuals in the United States have Alzheimer disease (AD) and the resulting health care costs in 2010 were roughly $172 billion, the authors write as background information in the study. “Prevalence and costs of AD and other dementias are projected to rise dramatically during the next 40 years unless a prevention or a cure can be found. Therefore, it is critical to gain a greater understanding of the key risk factors and etiologic underpinnings of dementia from a population-based perspective,” the authors write.

Deborah E. Barnes, Ph.D., M.P.H., of the University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, and colleagues evaluated data from 13,535 long-term Kaiser Permanente members and examined depressive symptoms assessed in midlife (1964-1973) and in late life (1994-2000) and risks of developing dementia, Alzheimer disease (AD) and vascular dementia (VaD; dementia resulting from brain damage from impaired blood flow to the brain).

Depressive symptoms were present in 14.1 percent of study participants in midlife only, 9.2 percent in late life only and 4.2 percent in both. During six years of follow-up, 22.5 percent of patients were diagnosed with dementia; 5.5 percent with Alzheimer disease and 2.3 percent with VaD.

When examining AD and VaD separately, patients with late-life depressive symptoms had a two-fold increase in AD risk, and patients with midlife and late-life symptoms had more than a three-fold increase in VaD risk.

"Our findings suggest that chronic depression during the life course may be etiologically associated with an increased risk of dementia, particularly VaD, whereas depression that occurs for the first time in late life is likely to reflect a prodromal stage of dementia, in particular AD," the authors conclude.

Source: Science Daily

ScienceDaily (May 7, 2012) — The deletion of part of a gene that plays a role in the synthesis of carnitine — an amino acid derivative that helps the body use fat for energy — may play a role in milder forms of autism, said a group of researchers led by those at Baylor College of Medicine and Texas Children’s Hospital.

"This is a novel inborn error of metabolism," said Dr. Arthur Beaudet, chair of molecular and human genetics at BCM and a physician at Texas Children’s Hospital, and the senior author of the report that appears online in the Proceedings of the National Academy of Sciences. "How it is associated with the causes of autism is as yet unclear. However, it could point to a means of treatment or even prevention in some patients."

Deletion leads to imbalance

Beaudet and his international group of collaborators believe the gene deletion leads to an imbalance in carnitine in the body. Meat eaters receive about 75 percent of their carnitine from their diet. However, dietary carnitine levels are low in vegetarians and particularly in vegans. In most people, levels of carnitine are balanced by the body’s ability to manufacture its own carnitine in the liver, kidney and brain, starting with a modified form of the amino acid lysine.

Carnitine deficiency has been identified when not enough is absorbed through the diet or because of medical treatments such as kidney dialysis. Genetic forms of carnitine deficiency also exist, which are caused when too much carnitine is excreted through the kidneys.

In this new inborn error, there is a deletion in the second exon — the protein-coding portion of a gene — of the TMLHE gene, which includes the genetic code for the first enzyme in the synthesis of carnitine (TMLHE stands for trimethyllysine epsilon which encodes the enzyme trimethyllysine dioxygenase).

Studies in the laboratory that identified the deletion were led by Dr. Patricia B.S. Celestino-Soper, as a graduate student in Beaudet’s laboratory at BCM, and by Dr. Sara Violante, a graduate student in the laboratory of Dr. Frédéric M. Vaz of the Academic Medical Center in Amsterdam.

Frequency of deletion

To determine the frequency of the gene deletion, Beaudet and his colleagues tested male autism patients who were the only people with the disorder in their families (simplex families) from the Simons Simplex Collection, the South Carolina Early Autism Project and Houston families. In collaboration with laboratories and researchers in Nashville, Los Angeles, Paris, New York, Toronto and Cambridge (United Kingdom), they tested affected male siblings in families with more than one male case of autism (multiplex families).

When they looked at the TMLHE genes in males affected by autism and compared them to normal controls, they found that the gene alteration is a fairly common one, occurring in as many as one in 366 males unaffected by autism. It was not significantly more common in males within families in which there is only one person with autism. However, it is nearly three times more common in families with two or more boys with autism.

No syndromic form

Beaudet said most of the affected males with the deletion did not have syndromic autism that is frequently associated with other serious diseases. In many instances, syndromic autism affects physical development as well as cognitive, which is reflected in their facial features as well as other parts of their bodies. None of the six boys affected with autism (where information was available) had the syndromic form of disease. Their intelligence quotients and cognitive scores varied, with some being far below normal and others normal.

"Most of the males we identified with the TMLHE deficiency were apparently normal as adults," said Beaudet, although detailed information on learning and behavior was not available on these "control" males. "The gene deletion is neither necessary nor sufficient in itself to cause autism."

"TMLHE deficiency itself is likely to be a weak risk factor for autism, but we need to do more studies to replicate our results," Beaudet said. He estimated that at the rates found in his study, the deficiency might be a factor in about 170 males born with autism per year in the United States. This would equate to about one-half of one percent of autism cases.

The authors from Amsterdam found major increases in some carnitine-related chemicals and absence of others in both urine and plasma. These metabolic alterations were found to be predictive of the dysfunction of the TMLHE gene and therefore can be used to identify males with this disorder.

It remains uncertain whether TMLHE deficiency is benign or causes autism by affecting the function of neurons through toxic accumulation or deficiency of a variety of chemical metabolites.

"We believe that the most attractive hypothesis at this time is that the increased risk of autism is modified by dietary intake of carnitine from birth through the first few years of life," said Beaudet.

He and his colleagues are undertaking three studies to further their understanding of the TMLHE deficiency. In one, they will attempt to replicate the findings in multiplex families. In a second, they will study carnitine levels in the cerebrospinal fluid of infants with autism — both those who have the gene deficiency and those who do not. In a third study, they plan to begin giving boys under age 5 with autism carnitine or a related supplement and determine whether this improves the behavior of those with the TMLHE deficiency and those without.

Source: Science Daily

ScienceDaily (May 7, 2012) — One of the world’s most important fossils has a story to tell about the brain evolution of modern humans and their ancestors, according to Florida State University evolutionary anthropologist Dean Falk.

Taung surrounded by a juvenile chimp skull and human skull, the latter having a fontanelle and metopic suture. The metopic suture is visible on the frontal lobe of Taung’s endocast. (Credit: CT-based images by M. Ponce de León and Ch. Zollikofer, University of Zurich)

The Taung fossil — the first australopithecine ever discovered — has two significant features that were analyzed by Falk and a group of anthropological researchers. Their findings, which suggest brain evolution was a result of a complex set of interrelated dynamics in childbirth among new bipeds, were published May 7 in the Proceedings of the National Academy of Sciences.

"These findings are significant because they provide a highly plausible explanation as to why the hominin brain might grow larger and more complex," Falk said.

The first feature is a “persistent metopic suture,” or unfused seam, in the frontal bone, which allows a baby’s skull to be pliable during childbirth as it squeezes through the birth canal. In great apes — gorillas, orangutans and chimpanzees — the metopic suture closes shortly after birth. In humans, it does not fuse until around 2 years of age to accommodate rapid brain growth.

The second feature is the fossil’s endocast, or imprint of the outside surface of the brain transferred to the inside of the skull. The endocast allows researchers to examine the brain’s form and structure.

After examining the Taung fossil, as well as huge numbers of skulls belonging to apes and humans, as well as corresponding 3-D CT (three-dimensional computed tomographic) scans, and taking into account the fossil record for the past 3 million years, Falk and her colleagues noted three important findings: The persistent metopic suture is an adaptation for giving birth to babies with larger brains; is related to the shift to a rapidly growing brain after birth; and may be related to expansion in the frontal lobes.

"The persistent metopic suture, an advanced trait, probably occurred in conjunction with refining the ability to walk on two legs," Falk said. "The ability to walk upright caused an obstretric dilemma. Childbirth became more difficult because the shape of the birth canal became constricted while the size of the brain increased. The persistent metopic suture contributes to an evolutionary solution to this dilemma."

The later fusion of the metopic suture is most likely an adaptation of hominins who walked upright to be able to more easily give birth to babies with relatively large brains. The unfused seam is also related to the shift to rapidly growing brains after birth, an advanced human-like feature as compared to apes.

"The later fusion was also associated with evolutionary expansion of the frontal lobes, which is evident from the endocasts of australopithecines such as Taung," Falk said.

The Taung fossil, which is estimated to be around 2½ million years old, was discovered in 1924 in Taung, South Africa. It became the “type specimen,” or main model, of the genus Australopithecus africanus when it was announced in 1925.

An australopithecine is any species of the extinct generaAustralopithecus or Paranthropus that lived in Africa, walked on two legs and had relatively small brains.

Source: Science Daily