Snakes and spiders: Revealing the wiring that allows us to adapt to the unexpected

ScienceDaily (Jan. 31, 2011) — Wouldn't life be easy if everything happened as we anticipated? In reality, our brains are able to adapt to the unexpected using an inbuilt network that makes predictions about the world and monitors how those predictions turn out. An area at the front of the brain, called the orbitofrontal cortex, plays a central role and studies have shown that patients with damage to this area confuse memories with reality and continue to anticipate events that are no longer likely to happen.

See Also:Mind & BrainNeuroscienceIntelligenceBrain InjuryPerceptionPsychologyLanguage AcquisitionLiving WellReferenceFunctional neuroimagingOccipital lobeNeocortex (brain)Limbic system

The brain's ability to react adaptively, becomes crucial for survival, when faced with potential dangers, such as snakes and spiders, so to what extent does the harmfulness of an anticipated outcome affect our brain's event monitoring system? Not at all, reveals a new study published in the February 2011 issue of Elsevier's Cortex: the processes are the same, regardless how scary the anticipated event.

The team of researchers, supervised by Prof. Armin Schnider of the University Hospitals of Geneva in Switzerland, recorded functional magnetic resonance images (fMRI) while healthy volunteers performed a task in which they repeatedly saw a pair of faces and had to predict on which face a target was about to appear. The target could be a simple black disk (neutral stimulus) or a spider (potentially harmful stimulus). The researchers found a strong activation of the brain's visual areas whenever the spider appeared. However, irrespective of whether the disk or the spider was the target, its unexpected absence activated a cerebral network including the orbitofrontal cortex.

The findings show that, while the potential harmfulness of an event strongly affects brain responses, it does not influence the way the brain reacts when the expected event does not occur. The study supports the notion that the orbitofrontal cortex is "at the centre of a specific cerebral network which functions as a generic outcome monitoring system," says Louis Nahum, the first author of the study. "This capacity is probably as old in evolution as the instinctive reaction to threatening stimuli; its failure deprives the brain of the ability to remain in phase with reality," notes Armin Schnider.

Email or share this story:

The changing roles of two hemispheres in stroke recovery

ScienceDaily (Jan. 31, 2011) — Most people who survive a stroke recover some degree of their motor, sensory and cognitive functions over the following months and years. This recovery is commonly believed to reflect a reorganisation of the central nervous system that occurs after brain damage. Now a new study, published in the February 2011 issue of Elsevier's Cortex, sheds further light on the recovery process through its effect on language skills.

See Also:Health & MedicinePsychology ResearchNervous SystemBrain TumorMind & BrainBrain InjuryIntelligenceLanguage AcquisitionReferenceBrain damageThalamusAmnesiaFunctional neuroimaging

For almost all right-handed people and for about 60% of left-handers, damage to the left side of the brain causes a condition known as aphasia, an acute or chronic impairment of language skills. The syndrome is strongly associated with damage to the left hemisphere of the brain; however, there is a long-standing controversy regarding the involvement of parts of the right hemisphere in language functions and their contribution to recovery from aphasia. The majority of experts stress the role of the dominant left side in language recovery, while others argue for a complementary (or compensatory) function of the right hemisphere.

Odelia Elkana, from the Hebrew University, Jerusalem, and colleagues investigated the systematic patterns of reorganisation in the brain's language functions, and their relation to linguistic performance, in patients recovering from childhood brain damage to the left hemisphere. They used functional MRI to detect patterns of brain activity while patients performed various linguistic tasks inside the scanner. The new study focused on a rare group of children whose brain damage had occurred after they had already developed language skills but while the brain was still developing, and therefore most able to reorganise its language functions.

According to the authors, the findings suggest that "recovery is a dynamic, ongoing process, may last for years after onset and is reflected in an increasing proficiency of inter-hemispheric coordination, rather than just in an increase of activation in one side or the other. Therefore, the role of each hemisphere in the recovery process is not only dependent on the stage of recovery (acute, sub-acute or chronic stage), but also within each of these stages it may continuously change over time."

Email or share this story:

Rural underage binge drinkers put their health at risk, German study finds

ScienceDaily (Feb. 6, 2011) — Binge drinking is often considered to be a problem of towns and cities but new research published in BioMed Central's open access journal BMC Public Health shows that binge drinking in rural areas is more of a problem than previously thought.

See Also:Mind & BrainAlcoholismBehaviorNutrition ResearchScience & SocietyWorld DevelopmentPublic HealthUrbanizationReferenceDrunkennessFetal alcohol spectrum disorderBulimia nervosaAlcoholism

Dr Carolin Donath, from the Psychiatric University Clinic Erlangen, looked at the drinking patterns of over 44,000 15 and 16 year olds in Germany and found that more than 93% of the young people from the countryside and over 86% of those from urban areas had tried alcohol. Of the adolescents who had drunk alcohol in the last month, 78% from rural areas and 74% from cities admitted to binge drinking (5 or more drinks at one time).

Dr Carolin Donath says that, "Whilst there is awareness of the problems of binge drinking in towns and cities, this study demonstrates that both drinking and binge drinking are as much of a problem for rural teenagers."

Binge drinking in school children has social ramifications as well as increasing health risks. Not only does alcohol abuse affect school work, and hence job prospects, but being drunk increases the likelihood of accidents among traffic and of unsafe sexual behaviour. This pattern of drinking also causes long term damage to the brain resulting in permanent brain damage, including memory problems and cognitive defects, and increasing risk of heart disease and cancer.

Email or share this story:

Hope for stroke victims

ScienceDaily (Feb. 8, 2011) — Much of the devastation of stroke and head trauma is due to damage caused the overproduction of a substance in the brain called glutamate. Preventing this damage has been impossible, until now, as many drugs don't cross the so-called blood-brain barrier, and those that do often don't work as intended. But a method originally devised at the Weizmann Institute of Science may, in the future, offer a way to avert such glutamate-induced harm.

See Also:Health & MedicineBrain TumorStroke PreventionPsychology ResearchMind & BrainBrain InjuryDisorders and SyndromesMultiple SclerosisReferenceAstrocyteExcitotoxicity and cell damageDopamine hypothesis of schizophreniaGlutamic acid

Prof. Vivian I. Teichberg of the Institute's Neurobiology Department first demonstrated a possible way around these problems in 2003. Glutamate -- a short-lived neurotransmitter -- is normally all but absent in brain fluids. After a stroke or injury, however, the glutamate levels in brain fluid become a flood that over-excites the cells in its path and kills them. Instead of attempting to get drugs into the brain, Teichberg had the idea that one might be able to transport glutamate from the brain to the blood using the tiny "pumps," or transporters, on the capillaries that work on differences in glutamate concentration between the two sides. Decreasing glutamate levels in blood would create a stronger impetus to pump the substance out of the brain. He thought that a naturally-occurring enzyme called glutamate-oxaloacetate transaminase (GOT, for short) could "scavenge" blood glutamate, significantly lowering its levels. By 2007, Teichberg and his colleagues had provided clear evidence of the very strong brain neuroprotection that oxolacetate (a chemical similar to GOT) afforded rats exposed to a head trauma.

Two new studies -- conducted by Francisco Campos and others from the lab of Prof. Jose Castillo in the University of Santiago de Compostela, Spain -- now provide a definitive demonstration of Teichberg's results. In the first, the scientists conclusively showed that oxoloacetate injected into rats with stroke-like brain injuries reduces glutamate levels both in the blood and in the affected brain region, while significantly lessening both cell death and the swelling that can accompany stroke. In the second, a team of neurologists in two different hospitals checked the levels of glutamate and GOT in several hundred stroke victims who were admitted to their hospitals. They found that the most significant predictor of the prognosis -- how well they would recover at three months and how much brain damage they would suffer -- was the levels of these two substances. High glutamate levels correlated with a poor outcome, high GOT levels with a better one.

The overall implication of these two papers is that administering GOT might improve a patient's chances of recovering, as well as speeding up the process. In addition to stroke and head trauma, a number of diseases are characterized by an accumulation of glutamate in the brain, including Alzheimer's disease, Parkinson, multiple sclerosis, epilepsy, glaucoma, certain brain tumors and amyotrophic lateral sclerosis, and there is hope that, in the future, treatments to scavenge glutamate could relieve the symptoms and improve the outcomes for a number of neurological problems. Yeda, the technology transfer arm of the Weizmann Institute, holds a patent for this method.

Prof. Vivian I. Teichberg's research is supported by the Nella and Leon Benoziyo Center for Neurosciences; the Carl and Micaela Einhorn-Dominic Brain Research Institute; and the Legacy Heritage Fund Program of the Israel Science Foundation. Prof. Teichberg is the incumbent of the Louis and Florence Katz-Cohen Professorial Chair of Neuropharmacology.

Email or share this story:

Neuroimaging shows how the brain learns mental skills

ScienceDaily (Feb. 9, 2011) — Movements become skilled and automatic with practise, so tasks like riding a bicycle can be performed without much attention or mental effort. New research by scientists at Royal Holloway, University of London provides evidence that the cerebellum, a part of the brain used to store memories for skilled movements, could also store memories important for mental skills -- such as the rules used to interpret traffic light signals.

See Also:Mind & BrainNeuroscienceIntelligenceBrain InjuryMemoryPerceptionPsychologyReferenceMemoryProcrastinationLimbic systemAttention

The prefrontal cortex, in the frontal lobe, uses problem-solving to establish the correct rules using attention, and the new research raises the possibility that the cerebellum then learns to implement them skilfully with little conscious attention, freeing the prefrontal cortex to direct attention to new problems.

The study, published in the Journal of Neuroscience, reports that brain imaging was used to scan volunteers during learning, and that in a part of the cerebellum known to be connected with the prefrontal cortex, activity changed from one practice trial to the next. The rate of change was faster for rules that became automatic more quickly. After practice, volunteers used simple rules quickly and accurately even when attention drawn away by a 'distractor' task performed at the same time.

Dr Ramnani, from the Department of Psychology at Royal Holloway said: "The study adds to the groundwork for understanding cognitive deficits in patients with cerebellar damage and improving strategies for their rehabilitation. It also raises the possibility that the cerebellum might be used for the skillful, automatic and unconscious use of mathematical and grammatical rules."

Email or share this story:

Advanced macular degeneration is associated with an increased risk of bleeding stroke, study finds

ScienceDaily (Feb. 10, 2011) — Older people with late-stage, age-related macular degeneration (AMD) appear to be at increased risk of brain hemorrhage (bleeding stroke), but not stroke caused by brain infarction (blood clot), according to research presented at the American Stroke Association's International Stroke Conference 2011.

See Also:Health & MedicineStroke PreventionElder CareBrain TumorMind & BrainBrain InjuryStrokeDisorders and SyndromesReferencePeripheral visionMulti-infarct dementiaCerebral contusionBrain damage

"Other studies have found there are more strokes in older individuals with late AMD, but ours is the first to look at the specific types of strokes," said Renske G. Wieberdink, M.D., study researcher and epidemiologist at Erasmus Medical Center in Rotterdam, the Netherlands. "We found the association is with brain hemorrhage, but not brain infarction."

AMD is degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in AMD, central vision loss may occur. Age-related macular degeneration usually produces a slow, painless loss of vision. Early signs of vision loss from AMD include shadowy areas in your central vision or unusually fuzzy or distorted vision.

Because the number of brain hemorrhages observed in the study was small, the findings will need to be corroborated in a larger group, Wieberdink said.

"These findings should be considered preliminary," she said. "Patients and physicians must be very careful not to over-interpret them. We don't know why there are more brain hemorrhages in these patients or what the relationship with AMD might be. This does not mean that all patients with late-stage AMD will develop brain hemorrhage."

Beginning in 1990, the Rotterdam Study is a prospective, population-based cohort investigation into factors that determine the occurrence of cardiovascular, neurological, ophthalmological, endocrinological and psychiatric diseases in older people.

The researchers tallied stroke incidence among 6,207 participants 55 years and older. All of the participants were stroke-free at the study's outset. AMD was assessed during scheduled eye examinations, and participants with the condition were divided into five different stages of AMD, and whether their condition was wet AMD or dry AMD. Participants were tracked for an average of 13 years. Of the 726 persons who suffered a stroke in that time, 397 were brain infarctions, 59 were brain hemorrhages and the stroke type was not available for 270.

Late AMD (stage 4) was associated with a 56 percent increased risk of any type of stroke. Late AMD, both the dry and the wet form, was strongly associated with more than six times the risk of brain hemorrhage, but not with brain infarction. Early AMD (stages 1-3) did not increase the risk of any stroke. Associations were adjusted for possible confounders, such as diabetes, blood pressure, anti-hypertensive medications, smoking status, body mass index, alcohol use and C-reactive protein levels.

"We cannot yet say if there is a common causal pathway or mechanism of action yet -- this association needs to be further investigated," Wieberdink said. "But I don't think it is a causal relationship. It seems more likely that late AMD and brain hemorrhage both result from some as yet unknown common mechanism."

If the findings are replicated, it may be possible to develop some stratification of risk among such patients, Wieberdink said.

Co-authors are: Lintje Ho, M.D.; Kamran Ikram, M.D., Ph.D.; Peter Koudstaal, M.D., Ph.D.; Albert Hofman, M.D., Ph.D.; Hans Vingerling, M.D., Ph.D.; and Monique Breteler, M.D., Ph.D. Author disclosers and funding information are on the abstract.

Email or share this story:

Ischemic stroke hospitalizations decline in middle-aged, elderly, increases in young

ScienceDaily (Feb. 9, 2011) — The number of acute ischemic stroke hospitalizations among middle-aged and older men and women fell between 1994 and 2007, but sharply increased among those under age 35 -- including teens and children -- according to research presented at the American Stroke Association's International Stroke Conference 2011.

See Also:Health & MedicineStroke PreventionHeart DiseaseElder CareMind & BrainStrokeCaregivingBrain InjuryReferenceMulti-infarct dementiaStrokePeripheral visionCoronary heart disease

Analysts at the U.S. Centers for Disease Control and Prevention (CDC), reviewing hospitalization data by age and gender, identified declining rates of 51 percent in girls 0-4 years and 25 percent in men and 29 percent in women over 45.

However, the number of ischemic stroke hospitalizations increased 51 percent in males between ages 15 and 34 during the period studied. The rate increased 17 percent in females between 15 and 34.

Among children and teens, they found a 31 percent increase in boys between 5 to 14 years and a 36 percent increase among girls 5 to 14 years.

Among the younger middle-aged set, they found a 47 percent increase among men 35-44 and a 36 percent increase among women 35-44.

"I believe this is the first large study to report these findings, stratified by age and gender," said Xin Tong, M.P.H., a health statistician with the CDC's Division for Heart Disease and Stroke Prevention in Atlanta.

"We cannot link anything in particular to the trend in younger patients, but I believe the role of obesity and hypertension will prompt a big discussion. Unfortunately, right now we can't speculate on the causes."

The unit of analysis was hospitalization, so researchers couldn't draw any firm connections or determine what factors are driving the increase in ischemic stroke cases among the young. Ischemic stroke occurs when blood supply to the brain becomes obstructed, usually by a clot or narrowing of the arteries. The risk of long-term brain damage can be reduced significantly if patients receive the clot-busting tissue plasminogen activator (tPA) within three or four and a half hours after stroke onset.

Hospitals and physicians should be aware of the rising risk of stroke in young people, and the necessity to educate them about stroke symptoms, Tong said.

"Acute ischemic stroke is currently considered something that mostly happens to older people, but awareness of rising rates in the young is important or else tPA and other important stroke treatment may be unnecessarily delayed in younger patients," she said.

Tong said her group is pursuing additional investigation on this subject.

Co-authors are: Elena V. Kuklina, M.D., Ph.D.; Cathleen Gillespie, M.S.; and Mary G. George, M.D., M.S.P.H.

Email or share this story: