Frontiers in Human Neuroscience
Drinking water can boost cognitive performance
There is evidence that mild dehydration has a negative effect on the brain's performance. Caroline Edmonds and colleagues from the University of East London and the University of Westminster here report that drinking water can improve performance on tasks that require a rapid response, particularly when thirsty. They tested 34 adults, who had not eaten or drunk anything overnight, for memory, attention, learning, and reaction time. Subjects were tested on two mornings: once after they had consumed a cereal bar and water, and once after eaten a cereal bar only. Reaction times were up to 14% shorter after drinking water, especially for those who felt thirsty. Unexpectedly, performance on a complex-rule-learning task became slightly worse after drinking. Future research will have to determine why drinking water can be beneficial for some cognitive tasks, but not for others, say the authors.
Dr Caroline Edmonds
School of Psychology
University of East London, UK
Frontiers in Psychiatry
Differences in brain circuitry make it more difficult for impulsive persons to control their craving for cigarettes
Impulsiveness plays an important role in addiction to drugs. For example, impulsiveness is strongly associated with smoking, in particular with an early onset of smoking and frequent relapses of smokers who try to quit. Furthermore, impulsiveness is known to promote drug craving, a key feature of addiction and one of the best predictors of relapse. In the first study on the neural pathways that underlie the relationship between impulsivity and cigarette craving, Josiane Bourque and colleagues from the University of Montreal, Canada, found that impulsive people (who experienced the most intense cravings in response to images of cigarettes) showed diminished activity in the posterior cingulate cortex of the brain. Bourque and colleagues conclude that a lower activity in this region makes it more difficult for impulsive people to control their cravings for cigarettes and other drugs.
Dr Stéphane Potvin
Centre de recherche de l'Institut Universitaire de Santé Mentale de Montréal &
Department of Psychiatry, Faculty of Medicine, University of Montreal, Canada
Frontiers in Neural Circuits
A mutant strain of zebrafish is an alternative model for Rett syndrome in humans
An important challenge for neuroscientists is to find cures for diseases that affect the central nervous system, such as autism, Alzheimer's, or Parkinson's disease. For this purpose, researchers use several vertebrate species as model organisms. The zebrafish has recently received much attention because it has many advantages over other vertebrate models. For example, development of its nervous system can be followed from its earliest stages in naturally behaving individuals.
Thomas Pietri and colleagues from six institutes in France, Spain, and the USA developed a strain of zebrafish with a nonfunctional mecp2 gene ("methyl CpG binding protein 2", which controls many other genes). In humans, defects in mecp2 cause Rett syndrome, a disease within the family of autism spectrum disorders. Patients with Rett syndrome (mostly girls and women, since mecp2 lies on the X chromosome) often show mental retardation, stereotyped hand movements, seizures, and an increased response to sensory stimuli.
Surprisingly, zebrafish without mecp2 survive and reproduce normally, unlike mice with defective mecp2. But Pietri and colleagues found that the mutation modifies the behavior of zebrafish: mutant embryos respond more to tactile stimulation, while mutant larvae swim less and appear to have a reduced preference for the walls of their tank. Understanding why zebrafish without mecp2 develop only mild symptoms could lead to new directions in the search for treatments of Rett sydrome in humans.
Dr Thomas Pietri
Ecole Normale Supérieure
IBENS Section Neuroscience, France
Frontiers in Cellular and Infection Microbiology
How do tick-borne diseases evade the tick's immune system?
Ticks, blood-sucking arthropods that occur across the world, can transmit viruses, bacteria, and protozoa that threaten the health of their vertebrate hosts. Dangerous diseases transmitted by ticks include Lyme disease, which attacks humans in Europe and the USA and is caused by Borrellia bacteria; babesiosis, caused by the protozoan Babesia (a relative of the malaria parasite) that infects pets, cattle, and sometimes humans; and anaplasmosis, caused by the Anaplasma bacterium, which can have serious effects on cattle. Before such diseases can be transmitted to uninfected hosts, they need to circumvent the tick's immune system and persist in the hostile environment of the tick's body.
Ondrej Hajdusek and colleagues from the Czech Republic and Spain here summarize recent knowledge about the major components of tick immune system and focus on their interaction with the relevant tick-transmitted pathogens. Availability of the tick genomic database and feasibility of functional genomics based on RNA interference greatly contribute to the understanding of molecular and cellular interplay at the tick-pathogen interface and may provide new targets for blocking the transmission of tick pathogens, say the authors.
Dr Petr Kopáček
Institute of Parasitology
Biology Centre, Academy of Science of the Czech Republic
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