You see a pedestrian about to step out in front of an oncoming car. Is it better to calmly call out a warning, or to scream?
Of course, it’s better to scream — but not just because a scream is loud. Car alarms, police sirens and smoke alarms are all loud, too. But, like screams, they also feature fast but perceptible fluctuations in loudness, usually at frequencies of between 40 and 80 Hz, making them acoustically “rough”. Quite why such sounds should be so attention-grabbing, and even unbearable, hasn’t been clear. Now a team led by Luc Arnal at the University of Geneva has found that this type of sound triggers activity in brain areas related not just to hearing but also to aversion and to pain. This makes them impossible to ignore.
In an era of TED talks, podcasts, and audiobooks, it’s easy to choose to listen to factual information or fiction, rather than to read it. But is that a good thing? Are there any differences in the way the brain processes the meaning of words that are heard rather than read? According to the researchers behind a thorough new study, published in the Journal of Neuroscience, the answer to this last question is “no”. But it may still be too soon to conclude that listening to an audiobook is effectively the same as reading it.
In a world made for right-handed people, life can sometimes be frustrating if you are among the 10% or so who are “adextral” — that is, left-handed or ambidextrous. Now a new grievance can be added to the list. Brain imaging researchers are systematically excluding adextrals from participating in their studies, according to an analysis of recent research papers published in top neuroimaging journals. Yet there’s no good reason to exclude this population, say the authors — and in fact, the practice could be detrimental to research.
Hearing voices that don’t exist in the outside world is the most common form of hallucination experienced by people with a diagnosis of schizophrenia or related conditions and it can be very distressing. However, there is a growing recognition that hearing voices is not always pathological. Many mentally well people hear voices (or “auditory verbal hallucinations”) – in fact, around 6-7 per cent of adults in the general population report having had such experiences at some point in their lives.
This has led some experts to propose a “continuum model” in which the same fundamental underlying mechanism leads to hearing voices in healthy people and in patients with a clinical diagnosis, but that for various reasons, such as a traumatic past, the experience is more troublesome and distressing for the patients. However, a new open-access paper in Schizophrenia Bulletin challenges the continuum model, finding an important brain difference between patients who hear voices and voice-hearing healthy controls.
If you have healthy vision, there will be a specific region of your brain (in the visual cortex) that responds most strongly whenever you look at faces, and similar regions that are especially responsive to the sight of words or natural scenes. What’s more, in any two people, these face, word and scene regions are located in pretty much the same spot in the brain. However, there is not a specific region for every possible category of visible stimulus – there are no “car” or “shoe” regions, for example (at least, not that have been identified to date). Is that because childhood experience is critical for training the visual cortex – we spend a lot of time looking at faces, say, but not cars? And, if so, in theory, could a lot of childhood time spent looking at a different type of object generate its own dedicated, individual category region?
The answer is “yes”, at least according to an ingenious study, published in Nature Human Behaviour, of people who played a Pokémon game for years of their childhood.
Picture in your mind a futuristic, technologically enhanced human. Perhaps you imagined them with a subcutaneous device in their arm for phone calls and browsing the internet. Maybe they are wearing smart glasses for augmented reality. What I’d wager you didn’t think of is the presence of an artificial sixth digit attached to each hand. However, a breakthrough open-access study in Nature Communications – the first to study the physiology and sensorimotor mechanics of polydactyly volunteers (people born with extra fingers) – shows the feasibility and practical advantages that would be gained from such an extra appendage. The results also have implications for the medical treatment of polydactyl people, who often have their extra finger removed at birth on the presumption that it will be of no benefit to them.
You spend about 10 per cent of your waking hours with your eyes shut, simply because of blinking. Every few seconds, each time you blink, your retinas are deprived of visual input for a period lasting anywhere between tens to hundreds of milliseconds (500 milliseconds is equivalent to half a second). You don’t usually notice this because your brain suppresses the dark spells and stitches together the bursts of visual information seamlessly. But these dips in visual processing in the brain do have an impact: a new study in Psychological Science finds that, in an important way, they cause your sense of the passing of time to stop temporarily.
Now a new study sheds some light into what’s going in the brain when people smoke cannabis – and it turns out that the effects can be quite different depending on the specific strain of the drug. The research, published recently in the Journal of Psychopharmacology, suggests that cannabis disrupts particular brain networks – but some strains can buffer against this disruption.
In case you hadn’t noticed, there is an ongoing debate about the existence of differences between women’s and men’s brains, and the extent to which these might be linked to biological or to cultural factors. In this debate, a real game-changer of a study would involve the identification of clear-cut sex differences in foetal brains: that is, in brains that have not yet been exposed to all the different expectations and experiences that the world might offer. A recent open-access study published in Developmental Cognitive Neuroscience by Muriah Wheelock at the University of Washington and her colleagues, including senior researcher Moriah Thomason at New York University School of Medicine, claims to have done just that, hailed by the researchers themselves as “confirmation that sexual dimorphism in functional brain systems emerges during human gestation” and in various ways by the popular press as, for example, The Times of London’s headline: “Proof at last: women and men are born to be different”.
Does this study live up to the claims made by its authors and, more excitedly, those passing the message on? I think not.
Think about the concepts of “red” and “justice” and you’ll notice a key difference. If you’re sighted, you’ll associate “red” most strongly with the sensory experience, which relates to signals from cone cells in your eyes. “Justice”, in contrast, doesn’t have any associated sensory qualities – as an abstract concept, you’ll think about its meaning, which you learnt via language, understanding it to be related to other abstract concepts like “fairness” or “accountability”, perhaps. But what about blind people – how do they think about “red”?
A brain-imaging study of 12 people who had been blind from birth, and 14 sighted people, published recently in Nature Communications, shows that while for sighted people, sensory and abstract concepts like “red” and “justice” are represented in different brain regions, for blind people, they’re represented in the same “abstract concept” region.