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Genes, brains and lateralisation: how solid is the evidence?

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If there were a dictionary of famous neurological quotes, “Nous parlons avec l'hémisphère gauche” by Paul Broca (1865) would be up there among the top hits. Broca’s realisation that the two sides of the brain are functionally distinct was a landmark observation. It was based on a rather small series of patients, but has since been confirmed in numerous studies. After localised brain injury, aphasia (language impairment) is far more likely after damage to the left side than the right side. And nowadays, we can visualise greater activation of the left side in neurologically intact people as they do language tasks in a brain scanner. There are many fascinating features of cerebral lateralisation, but I’m going to focus here on just one specific question: what do we know about genetic influences on brain asymmetry in humans?  There are really two questions here: (1) how do genes lead to asymmetric brain development? (2) are there genetic variants that can account for individual variat...

Psychology: Where are all the men?

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There's a lot of interest in under-representation of women in certain science subjects, but in psychology, there's more concern about a lack of men. A quick look at figures from UCAS* (Universities & Colleges Admissions Service) shows massive differences in gender ratios for different subjects. In figure 1 I’ve plotted the percentage of women accepted for subjects that had at least 6000 successful applicants to degree courses in 2011. Fig. 1. % Females accepted on popular UK degree courses 2011 Given the large sample sizes, the sex differences are statistically significant for all subjects except Media Studies, which is bang on 50%. As a psychologist, I found the most surprising thing about this plot was the huge preponderance of women in psychology. This didn’t square with my experiences: my colleagues include a good mix of men and women, so I was keen to find the explanation for the mismatch. There seemed to be several possible explanations, which aren’t mutually exclusi...

Moderate drinking in pregnancy: toxic or benign?

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There’s no doubt that getting tipsy while pregnant is a seriously bad idea. Alcohol is a toxin that can pass through the placenta to the foetus and cause damage to the developing brain.  For women who are regular heavy drinkers or binge drinkers, there is a risk that the child will develop foetal alcohol syndrome , a condition that affects physical development and is associated with learning difficulties. But what of more moderate drinking? The advice is conflicting. Many doctors take the view that alcohol is never going to be good for the developing foetus and they recommend complete abstention during pregnancy as a precautionary measure. Others have argued, though, that this advice is too extreme, and that moderate drinking does not pose any risk to the child. Last week a paper by Lewis et al was published in PLOS One providing evidence on this issue, and concluding that moderate drinking does pose a risk and should be avoided. The methodology of the paper was complex and it’s ...

Are Starbucks hiding their profits on the planet Vulcan?

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I just love the fact that the BBC have a Democracy Live channel where you can watch important government business. The Public Accounts Committee may sound incredibly dull, but I found this footage riveting. The committee grills executives from Starbucks, Amazon and Google about their tax arrangements. Quite apart from the content, it provides a wealth of material for anyone interested in how we interpret body language as a cue to a person's honesty. But for me it raised a serious issue about Starbucks. Is it run by aliens?

Flaky chocolate and the New England Journal of Medicine

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Early in October a weird story hit the media: a nation’s chocolate consumption is predictive of its number of Nobel prize-winners, after correcting for population size. This is the kind of kooky statistic that journalists  love, and the story made a splash. But was it serious? Most academics initially assumed not. The source of the story was the New England Journal of Medicine , an august publication with stringent standards, which triages a high proportion of submissions that don’t get sent out for review. (And don't try asking for an explanation of why you’ve been triaged). It seemed unlikely that a journal with such exacting standards would give space to a lightweight piece on chocolate. So the first thought was that the piece had been published to make a point about the dangers of assuming causation from correlation, or the inaccuracies that can result when a geographical region is used as the unit of analysis. But reading the article more carefully gave one pause. It did have...

Auditory processing disorder (APD): Schisms and skirmishes

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Photo credit: Ben Earwicker, Garrison Photography, Boise, ID www.garrisonphoto.org A remarkable schism is developing between audiologists in the UK and the USA on the topic of auditory processing disorder (APD) in children. In 2010, the American Academy of Audiology published clinical practice guidelines for auditory processing disorder .  In 2011, the British Society of Audiology published a position statement on the same topic, which came to rather different conclusions. This month a White Paper by the British Society of Audiology appeared reaffirming their position alongside invited commentaries. So what is all the fuss about? The argument centres on how to diagnose APD in children. Most of the tests used in the USA to identify APD involve responding to speech. One of the most widely-used assessments is the SCAN-C battery which has four subtests: Filtered words: Repeat words that have been low-pass filtered, so they sound muffled Auditory figure-ground: Repeat words that are p...