Author: vaughanbell

An article from The Psychologist has just been made available on the ‘anarchic hand syndrome’ – the brain injury-related condition where the hand performs actions against a person’s will.

One evening we took our patient, Mrs GP, to dinner with her family. We were discussing the implication of her medical condition for her and her relatives, when, out of the blue and much to her dismay, her left hand took some leftover fish-bones and put them into her mouth (Della Sala et al., 1994). A little later, while she was begging it not to embarrass her any more, her mischievous hand grabbed the ice-cream that her brother was licking. Her right hand immediately intervened to put things in place and as a result of the fighting the dessert dropped on the floor. She apologised profusely for this behaviour that she attributed to her hand’s disobedience. Indeed she claimed that her hand had a mind of its own and often did whatever ‘pleased it’. This condition is known as anarchic hand: people experience a conflict between their declared will and the action of one of their hands.

The article is by neurologist Sergio Della Sala who has been researching anarchic hand syndrome for many years.

It discusses the possible causes of the condition, and what these disruptions to human ‘free will’ tell us about how the brain generates the conscious control of actions.

Link to article.

There’s a piece in The Guardian discussing recent investigations into treating severe depression using deep brain stimulation – a technique that uses a permanently implanted electrode to stimulate a specific brain area.

This technique has been used to successfully treat some of the movement symptoms in Parkinson’s disease and is now being researched to see if it can be applied more widely.

Preliminary research by neuroscientists in Canada and the Netherlands has already suggested that the treatment could prove effective. Last year, Helen Mayberg, a neurologist at Emory University’s school of medicine in Atlanta, published the results of a decade of research which pinpointed a 2.5cm-wide part of the brain called the subgenual cingulate region (SCR) as playing a major role in dealing with affective information. The SCR is the lowest part of a deep band of tissue running along the central part of the brain. Dr Mayberg had noticed that this region was overactive in depressed people and that its activity correlated with their changing symptoms. When they were treated with antidepressant drugs, the activity went down.

Link to article from The Guardian
Link to Wikipedia article on DBS.
Link to previous post on Mind Hacks on ‘Modern-day psychosurgery’.

I’ve just noticed that Christian has written up a great summary of recent research which suggests that people with Tourette Syndrome, a neurological condition that causes involuntary movements or vocal outbursts, have better ‘cognitive control’ than people without the syndrome.

This is quite surprising, as at first site, you might think that people with Tourette’s have poor control because of their involuntary movements.

In the study, the experimenters assessed cognitive control by asking participants to make quick eye movements to on-screen targets. The participants with Tourette’s could do this far more effectively than the control participants.

The fact that people with Tourette’s can do these tasks better than others may be due to the fact that they have a lot of practice trying to control their tics. In fact, it is a myth that they have no control, as some people can ‘hold in’ tics and ‘release’ them at a more appropriate time.

Fast eye movements (or saccades) are researched quite extensively as they seem to give an indication of brain function, and can be affected by genetic abnormalities, mental illness and certain drugs (as this review reported, and as Christian’s own research has indicated).

Link to summary of research from BPS Research Digest

A report in today’s Nature describes an association between IQ score and changes in the thickness of the brain’s grey matter through childhood and adolesence.

The researchers, led by neuroscientist Philip Shaw, used structural MRI scans to measure changes in the brain, and scanned the same children as they grew up.

Crucially, the findings do not indicate that more intelligent children have a generally thicker cortex, but that the thickness of the cortex changes at different rates for children with different IQ scores:

When the researchers split the children into three groups according to their initial IQ scores, they noticed a characteristic pattern of changes in the brains of the group with the highest scores. The thickness of the cortex — the outer layer of the brain that controls high-level functions such as memory — started off thinner than that of the other groups, but rapidly gained depth until it was thicker than normal during the early teens. All three groups converged, with the children having cortexes of roughly equal thickness by age 19. The strongest effect was seen in the prefrontal cortex, which controls planning and reasoning.

Anything to do with IQ tends to be controversial, as the concept has been used in political arguments (particularly to do with race), and there is much debate about how well IQ tests actually relate to the more general (and more vague) concept of intelligence.

Link to Nature news report on study.
Link to abstract of scientific paper.

The Wikipedia article on the action potential is just beautiful – clearly written and wonderfully illustrated.

The action potential is the electrical impulse that travels along nerve cells, facilitating communication throughout the brain and peripheral nervous system.

The action potential was researched by Alan Hodgkin and Andrew Huxley, who managed to generate equations which explained the process. Unsurprisingly, they won the Nobel prize for their efforts.

Link to Wikipedia article on the action potential.