DELETION of a single gene switches the sexual orientation of female mice, causing them to engage in sexual behaviour that is typical of males. Korean researchers found that deleting the appropriately named FucM gene, which encodes an enzyme called fucose mutarotase, causes masculinization of the mouse brain, so that female mice lacking the gene avoid the advances of males and try to mate with other females instead. The findings probably have little relavence to human sexual orientation, however. FucM is one of a family of enzymes involved in rearranging the atoms in small sugar molecules…
MAGNETIC nanoparticles targeted to nerve cell membranes can be used to remotely control cellular activity and even the simple reflex behaviours of nematode worms, according to research by a team of biophysicists at the University of Buffalo. The new method, which is described in the journal Nature Nanotechnology, could be very useful for investigating how cells interact in neuronal networks, and may eventually lead to new therapies for cancer and diabetes. Heng Huang and her colleagues synthesized manganese-iron nanoparticles, each just 6 millionths of a millimeter in diameter, and coated…
WHO could have guessed that a protein isolated from pond scum would transform the way researchers investigate the brain? The protein, called channelrhodopsin (ChR), is found in algae and other microbes, and is related to the molecule in human photoreceptors that captures light particles. Both versions control the electrical currents that constantly flow in and out of cells; one regulates the algae's movements in response to light, the other generates the nervous impulses sent along the optic nerve to the brain. Unlike its human equivalent, the algal ChR controls the currents directly because…
FOR most of us, the ability to navigate our environment is largely dependent on the sense of vision. We use visual information to note the location of landmarks, and to identify and negotiate obstacles. These visual cues also enable us to keep track of our movements, by monitoring how our position changes relative to landmarks and, when possible, our starting point and final destination. All of this information is combined to generate a cognitive map of the surroundings, on which successful navigation of that environment later on depends. Despite the importance of vision for navigation,…
APPLYING for a job? The weight of the clipboard to which your CV is attached may influence your chances of getting it. Negotiating a deal? Sitting in a hard chair may lead you to drive a harder bargain. Those are two of the surprising conclusions of a study published in today's issue of Science, which shows that the physical properties of objects we touch can unconsciously influence our first impressions of other people and the decisions we make about them. Josh Ackerman of the Sloan School of Management at MIT, and psychologists Chris Nocera and John Bargh of Harvard and Yale Universities,…
BRAIN implants containing microelectrodes are used widely in the laboratory and clinic, both to stimulate nerve cells and to record their activity. Researchers routinely implant electrode arrays into the brains of rodents to investigate the neuronal activity associated with spatial navigation, or into monkeys' brains to gain a better understanding of the mechanisms of motor control. As a result, we now have brain-computer interfaces that can help paralysed patients to communicate or control a prosthetic limb. Electrode arrays can also be used to assess vegetative patients, and to treat…
THE dangers of obesity are very well known. Being overweight is associated with an increased risk of coronary heart disease and stroke, the two leading causes of death in the Western world. Gout is more common in overweight people, with the risk of developing the condition increasing in parallel with body weight. Obese people are twice as likely to develop type 2 diabetes as those who are not overweight, and being overweight is also associated with several types of cancer. The list goes on... Less well known is the effect of obesity on the brain. In the past few years, however, it has…
TRICHOTILLOMANIA (or hair pulling) is a condition characterised by excessive grooming and strong, repeated urges pull out one's own hair. It is classified as an obsessive-compulsive disorder (OCD), and is relatively common, affecting about 2 in 100 people. Sufferers normally feel an increasing sense of tension before pulling out their scalp hair, facial hair, and even pubic hair, eyelashes or eyebrows. This provides gratification, but only briefly. Hair pulling is usually thought of as being psychological in origin, but an intruiging new study now suggests that it occurs as a result of…
DAYDREAMING is a critical component of conscious experience. The mind can perform mental time travel - it occasionally strays from the present moment, to recollect an experience from the near or distant past, or to imagine an event that has not yet taken place. We know that thinking about the future is dependant on memory, because patients with amnesia cannot imagine new experiences. It involves piecing together fragments of past experiences to generate a plausible simulation of what might happen. This may have been an important development in human evolution, as it enables us anticipate a…
OF all the techniques used by neuroscientists, none has captured the imagination of the general public more than functional magnetic resonance imaging (fMRI). The technique, which is also referred to as functional neuroimaging and, more commonly, "brain scanning", enables us to peer into the human brain non-invasively, to observe its workings and correlate specific thought processes or stimuli to activity in particular regions. fMRI data affect the way in which people perceive scientific results: colourful images of the brain have persuasive power, making the accompanying data seem more…
GAMBLING is extremely popular, with lottery tickets, casinos, slot machines, bingo halls and other forms of the activity generating revenues of more than £80 billion each year in the UK alone. For most people, gambling is nothing more than an entertaining way to pass the time. But for some, it becomes a compulsive and pathological habit - they spend increasing amounts of time gambling, because tolerance builds up quickly, and experience withdrawal symptoms when they aren't gambling. The terms "tolerance" and "withdrawal" are normally associated with drug addiction, and indeed pathological…
SUBJECTIVE experience poses a major problem for neuroscientists and philosophers alike, and the relationship between them and brain function is particularly puzzling. How can I know that my perception of the colour red is the same as yours, when my experience of the colour occupies a private mental world to which nobody else has access? How is the sensory information from an object transformed into an experience that enters conscious awareness? The neural mechanisms involved are like a black box, whose inner workings are a complete mystery.  In synaesthesia, the information entering one…
MIRROR movements are involuntary movements that mimic, and occur simultaneously with, voluntary movements on the opposite side of the body. The movements are known to occur because of a failure in communication between the two sides of the nervous system. They are thought to be normal during infancy and early childhood, but usually diminish with age and disappear altogether by the age of 10, following maturation of the corpus callosum, the massive bundle of nerve fibres connecting the left and right hemispheres of the brain. A large genetic study published online in the journal Science now…
WHEN talking about our feelings, we often use expressions that link emotions with movements or positions in space. If, for example, one receives good news, they might say that their "spirit soared", or that they are feeling "on top of the world". Conversely, negative emotions are associated with downward movements and positions - somebody who is sad is often said to be "down in the dumps", or feeling "low". According to a new study published in this month's issue of the journal Cognition, expressions such as these are not merely metaphorical. The research provides evidence of a causal link…
DO you smile because you're happy, or are you happy because you are smiling? Darwin believed that facial expressions are indeed important for experiencing emotions. In The Expression of the Emotions in Man and Animals, he wrote that "the free expression by outward signs of an emotion intensifies it...[whereas]...the repression...of all outward signs softens our emotions." This idea was subsequently elaborated by the great psychologist William James, who suggested that "every representation of a movement awakens in some degree the actual movement which is its object."  Botox, which is used by…
WILLIAMS Syndrome (WS) is a rare neurodevelopmental disorder caused by the deletion of about 28 genes from the long arm of chromosome 7. It is characterized by mild to moderate mental retardation and "elfin" facial features. Most strikingly, individuals with WS exhibit highly gregarious social behaviour: they approach strangers readily and indiscriminately, behaving as if everybody were their friend. And, according to a study published today in the journal Current Biology, they are the only known group of individuals who do not form racial stereotypes. Most of us stereotype others implicitly…
WHEN making moral judgements, we rely on our ability to make inferences about the beliefs and intentions of others. With this so-called "theory of mind", we can meaningfully interpret their behaviour, and decide whether it is right or wrong. The legal system also places great emphasis on one's intentions: a "guilty act" only produces criminal liability when it is proven to have been performed in combination with a "guilty mind", and this, too, depends on the ability to make reasoned moral judgements. MIT researchers now show that this moral compass can be very easily skewed. In a new study…
Click to enlarge images ARTISTS employ a number of different techniques to represent implied motion in two-dimensional works. One of these, commonly used in posters, comics and animation, is the affine shear effect, whereby a moving object is depicted as leaning into the direction of movement. Cartoonists also use action lines to depict movement and speed, with straight lines conveying fast movements and wavy lines conveying slower ones. Motion can also be conveyed by superimposing several images showing the successive positions of a movement, or by a blurred image showing the different…
THIS is the left cerebral hemisphere of an 18-month-old infant who lived some 800 years ago. Such finds are extremely rare, because nervous tissue is soft and normally begins to decompose soon after death, so this specimen is unique in that it has been far better preserved than any other. Although reduced by about 80% of its original weight, many of its anatomical features have remained intact. The frontal, temporal and occipital lobes have retained their original shape; the gyri and sulci (the grooves and furrows on the surface, respectively labelled G and S, above) are easily recognizable;…
SNAKES have a unique sensory system for detecting infrared radiation, with which they can visualize temperature changes within their immediate environment. Using this special sense, they can image the body heat radiating from warm-blooded animals nearby. This enables them to track their prey quickly and with great accuracy, even in the dark, and to target the most vulnerable parts of the prey's body when they strike. It also warns them of the presence of predators, and may be used to find appropriate locations for building dens. Infrared detection is known to be mediated by a specialized…