The New York Times has an interesting account of the syndrome once known as 'hysteria'. Many problems once given this label have of course been shunted off to some other label now that more is known about them (once upon a time, hysteria was said to be the second most common disease in Europe -- beaten only by that other catch-all: fever). But there is still a kernel that stubbornly fails to be explained. Nowadays, it's been re-labelled as "conversion disorder" -- a nice label that doesn't mean anything to anybody. The heart of this disorder is that (a) the patient is not faking, and (b) there's nothing medically wrong with them. But now that we can see the brain at work, we have a better idea of what's going on. A study published some years ago provides an example. The patient was a woman who was paralyzed on the left side of her body; she had no identifiable organic lesion that would account for this. A brain scan revealed that when she tried to move her “paralyzed leg,” her primary motor cortex wasn't activated, but other areas -- ones associated with action and emotion -- were activated instead, apparently suppressing movement in her leg. The next big question of course is how this happens.

A study that has found auditory mirror neurons in people (mirror neurons activate when an activity is observed, rather than performed by the person himself) has also found that how empathetic we are is linked to the activity of these mirror neurons -- those whose mirror neurons are more strongly activated are more empathic.

Some people are extreme 'larks' -- they go to bed at 6 or 7pm and get up at 4am. Their circadian rhythm runs fast. A German study has now found that this sort of behavior is linked to the mutation of a particular gene.