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Showing posts from 2014

Top-down causation and the emergence of agency

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There is a paradox at the heart of modern neuroscience. As we succeed in explaining more and more cognitive operations in terms of patterns of electrical activity of specific neural circuits, it seems we move ever farther from bridging the gap between the physical and the mental. Indeed, each advance seems to further relegate mental activity to the status of epiphenomenon – something that emerges from the physical activity of the brain but that plays no part in controlling it. It seems difficult to reconcile the reductionist, reverse-engineering approach to brain function with the idea that we human beings have thoughts, desires, goals and beliefs that influence our actions. If actions are driven by the physical flow of ions through networks of neurons, then is there any room or even any need for psychological explanations of behaviour?

How vs Why To me, that depends on what level of explanation is being sought. If you want to understand how an organism behaves, it is perfectly possibl…

Autism, epidemiology, and the public perception of evidence

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“One day it's C-sections, the next it's pollution, now so many genes. Connect the dots, causation changes like the wind”

That quote is from a brief conversation I had on Twitter recently, with someone who is sceptical of the evidence that the causes of autism are overwhelmingly genetic (as described here). For me, it sums up a huge problem in how science is reported and perceived by the general public. This problem is especially stark when it comes to reportage of epidemiology studies, which seem to attract disproportionate levels of press interest.

The problem was highlighted by reports of a recent study that claims to show a statistical link between delivery by Caesarean section and risk of autism. This study was reported in several Irish newspapers, with alarming headlines like “C-sections ‘raise autism risk’” and in the UK Daily Mail, whose headline read (confusingly): “Autism '23% more likely in babies born by C-section': Women warned not to be alarmed by finding…

Autism: The Truth is (not) Out There

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Parents of a child affected by autism naturally want to know the cause. Autism can dramatically disrupt the typical childhood pattern of cognitive, behavioural and social development. At the most severe end, the child may require care for the rest of their lives. Even at the milder end, it may make mainstream education impossible and exclude many opportunities available to typically developing children. Any parent would hope that knowing the cause could lead to better treatment and management options for their child.

Unfortunately, until very recently, it has not been possible to identify causes in individual children (with rare exceptions). Science and medicine had apparently failed to solve this mystery. (I say “had”, because, as we will see below, this is no longer true). The typical experience of children and their parents in the health system has been one of frustration, often with a long diagnostic odyssey, limited options for medical intervention and a struggle to obtain access…

Exciting findings in schizophrenia genetics – but what do they mean?

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--> A paper published today represents a true landmark in psychiatric genetics. It reports results of a genome-wide association study (GWAS) of schizophrenia, involving 36,989 cases and 113,075 controls. Assembling this sample required collaboration on a massive scale, with over 300 authors involved. This huge sample gives unprecedented statistical power to detect genetic variants that predispose to disease, even if their individual effects on risk are tiny. The study reports 108 regions of the genome where genetic differences affect risk of disease. This achievement is rightly being widely celebrated and reported, but what do these results really mean?
GWAS look at sites in the genome where the particular base in the DNA sequence is variable – it might sometimes be an “A”, other times a “T”, for example. There are millions of such sites in the human genome (which comprises over 3 billion bases of sequence). Each such site represents a mutation that happened some time in the …