Month: January 2007

We have the impression that our free will is supreme, but modern neuroscience is starting to challenge the idea that we are the masters of our fate and captains of our soul.

A recent article in The New York Times looked at some of the philosophical aspects of free will from the perspective of physics and neuroscience.

Newtonian physics suggests that interactions in the physical world are deterministic, that is, the outcome is predictable.

As physical objects, a crucial question is how can we have free will in a universe where every outcome is determined by what went before.

Some people have suggested that the ‘fuzzy’ nature of quantum physics might provide an answer to this, but there have been no convincing accounts of how this might work.

In neuroscience, free will is more to do with whether we have conscious control over our actions.

Two main threads of research have suggested that our experience of having complete conscious control over our actions may be an illusion.

The first is from experiments like those originally completed by Benjamin Libet. He asked people simply to move their hand whenever they felt like it and note the time when they first felt the urge to move.

While they performed this voluntary action, he recorded electrical activity from areas in the brain known to be involved in generating actions.

His experiments, and many subsequent replications, suggest that the brain’s movement areas are active about 200 milliseconds before we feel the urge to move.

In other words, we only become conscious of the intention to move after the brain has initiated the action.

The second source of doubts about our sense of free will is from patients who have suffered brain injury and discover that they have lost conscious control over their actions.

One of the most striking examples is anarchic hand syndrome, linked to frontal lobe damage, where patients find their hand has a ‘mind of its own’ and often have to prevent it from carrying out actions they don’t consciously intend.

An article in The Economist questions whether such findings are eroding the concept of legal responsibility.

This is particularly in light of court cases where evidence of neurological disturbance has been used in an attempt to persuade the jury that the person wasn’t responsible for their actions, and, therefore, not guilty of the crime in question.

Link to NYT article “Free Will: Now You Have It, Now You Don’t”.
Link to Economist article ‘Free to choose?’ (both via 3Q).

There’s a great piece in The New York Times on Prof Daniel Levitin and the rapidly developing research field tackling the cognitive neuroscience of music.

We’ve covered material related to Levitin’s recently-released book This is Your Brain on Music (ISBN 0525949690) before, but the NYT article goes into a little more detail into some of the scientific findings than previous articles.

Letivin is an ex-rock producer who eventually became disillusioned with the music industry but maintained his love of music through his work as a neuropsychologist.

For his first experiment he came up with an elegant concept: He stopped people on the street and asked them to sing, entirely from memory, one of their favorite hit songs. The results were astonishingly accurate. Most people could hit the tempo of the original song within a four-percent margin of error, and two-thirds sang within a semitone of the original pitch, a level of accuracy that wouldn’t embarrass a pro.

“When you played the recording of them singing alongside the actual recording of the original song, it sounded like they were singing along,” Dr. Levitin said.

It was a remarkable feat. Most memories degrade and distort with time; why would pop music memories be so sharply encoded? Perhaps because music triggers the reward centers in our brains. In a study published last year [pdf] Dr. Levitin and group of neuroscientists mapped out precisely how.

Observing 13 subjects who listened to classical music while in an M.R.I. machine, the scientists found a cascade of brain-chemical activity. First the music triggered the forebrain, as it analyzed the structure and meaning of the tune. Then the nucleus accumbens and ventral tegmental area activated to release dopamine, a chemical that triggers the brain’s sense of reward.

His book got a glowing review from Salon, although I’ve yet to find any reviews in the academic literature.

However, Levitin’s website has a huge amount of information on it, including the audio of interviews he’s done and the full text of all his papers, so is well worth a visit if you’re interested in checking out the area.

UPDATE: Dr Levitin emailed to say the book has indeed been reviewed in the academic literature. A review that appeared in the journal Cerebrum is available online as a pdf. Enjoy!

Link to NYT article ‘Music of the Hemispheres’ (via BrainWaves).
Link to Salon review of ‘This is Your Brain on Music’.
Link to Levitin’s website.

The always excellent ABC Radio All in the Mind has just had a particularly compelling edition where they covered a neurosurgery operation to fix a particularly dangerous type of problem – an arteriovenous malformation or AVM – in a young woman named Kia.

An AVM is a tangle of veins and arteries meaning that the usually separate arterial (oxygen rich) and venous (oxygen depleted) blood can become mixed or doesn’t flow properly.

The problem is usually present from birth owing to a problem in development, and when intact, might not cause any noticeable symptoms.

However, AVMs are known to be fragile and there is a high risk that the AVM might bleed or cause an aneurysm – potentially causing death or serious brain injury.

Therefore, if treatable (and some are so big, complex or fragile that they can’t be treated) surgeons will often opt to risk an operation to remove the AVM to prevent any catastrophes in the future.

You’d think that radio wouldn’t be a good medium to cover a surgical procedure but the programme makes for compelling listening as the neurosurgeon, Professor Jeffrey Rosenfeld, narrates each stage as the operation progresses.

The patient and other staff also describe their hopes and fears, as well as their role in the treatment.

One of the most striking things is the sound of the drill as it cuts into the skull.

Link to AITM on ‘Brain Surgery – Live on the Wireless!’