Month: September 2005

Today’s featured article on Wikipedia is a fantastic piece on one of the most mysterious areas of the brain – the cerebellum.

There are more connections in the cerebellum than in the whole of the rest of the brain put together, yet it is still not clear what sort of contribution it makes to thought and behaviour.

It is known that it is essential for movement, as damage to this area can produce tremor and other movement disorders – such as a condition called cerebellar ataxia.

Curiously, it also seems to be involved in almost every other form of mental activity.

If you want a reliable way of annoying anyone presenting results from a brain scanning study, put your hand up and ask what the activity in the cerebellum signifies. It almost always occurs, but is very difficult to explain with our current understanding.

The Wikipedia article is a great summary of current knowledge though, and gives an insight into an area where neuroscience is increasingly going to focus its sights as time goes on.

Link to Wikipedia article on the cerebellum.

Neuroscientist Christof Koch manages to write an odd article on consciousness and gets an obscure word into the title of a piece published in The Scientist.

Apparently ‘inchoate’ (I had to look it up) means “partially but not fully in existence”, which pretty much sums up the article.

It starts with a brief overview of the history of consciousness and then gives a few snapshots of recent research projects, all of which seems fine until there’s a strange paragraph on a study of mice who have had their nicotine receptors altered…

While the β2 knockout animals move rapidly through a novel terrain with little exploration, animals in which nicotinic transmission has been restored in the VTA [ventral tegmental area] show more adaptive behavior that, if observed in humans, would be associated with planning and consciousness.

Quite how exploratory behaviour in laboratory mice is ‘associated’ with human consciousness eludes me right now.

As one of the few talking mice in existence, perhaps we should ask Mickey about his conscious experience and extrapolate to his smaller cousins?

Link to article ‘The Inchoate Science of Consciousness’.

Science News has an article on studies suggesting increasing links in the brain process involved in drug addiction and obesity, also suggesting that some of the treatments for drug abuse may also be of use in overeating.

When Volkow and her colleagues looked at the brains of 10 obese people, the team found a dopamine-receptor deficiency identical to that in drug addicts. Volkow stresses that obesity seems to be a significantly more complex disorder than drug abuse because many unrelated factors, such as glandular problems, lack of exercise, or a genetic predisposition to storing fat, can lead to weight gain. However, the brains of several of the obese volunteers in Volkow’s study seemed to be telling another story: “These people were compulsively driven to eat as if food were their stimulus of choice,” she says.

More information on the neuroscience of obesity is available in an issue of Nature Neuroscience made available online as an open-access publication.

Link to article ‘Food Fix’.
Link to Nature Neuroscience on ‘Feeding regulation and obesity’.

American Family Physician has an article on the curious phenomena of ‘psychogenic nonepileptic seizures’. These can look like tonic-clonic epileptic seizures; that commonly involve falling to the floor, limb shaking and unconsciousness, but are not accompanied by a disturbance in brain activity, and are thought to be related to underlying emotional issues or psychological distress.

Epilepsy is usually diagnosed with the assistance of an EEG assessment, where unusual brain activity is suggestive of the condition. A short burst of disruption (a ‘slow wave’) is show on the left, from my own epilepsy EEG.

Psychogenic nonepileptic seizures can be diagnosed when the person’s behaviour suggests a seizure, but no brain disturbance is detected.

The idea that symptoms can appear, but are produced by an underlying emotional conflict rather than the normal process of organic disorder has a long history, most associated with 19th century French neurologist Jean-Martin Charcot.

The condition was originally labelled ‘hysteria’, although is now given the less pejorative names of conversion disorder or ‘medically unexplained symptoms’.

The condition is often linked to emotional disturbance and a history of physical or sexual abuse and the presence of other psychiatric disorders. It is often considered that they are an unconcious attempt to express distress or resolve internal conflict.

Importantly, however, the symptoms are not ‘faked’, as is sometimes unkindly suggested. The person concerned typically has little or no conscious control over their symptoms or their effect, which suggests the mind and brain has a capacity for impenetrable self-deception in some cases.

Researchers are now attempting to understand how this happens, with books being published on the psychology and neuroscience of conversion disorder. Nevertheless, despite this recent work, the condition is still largely mysterious.

Link to article on ‘Psychogenic nonepileptic seizures’ (via BrainBlog).
Link to review of Conversion Hysteria: Towards a Cognitive Neuropsychological Account.