Scientists are looking to see if they can “interfere” with how to brain consciously makes decisions after successfully pin-pointing the exact moment when its nerve cells create the signal to carry out an action, it was revealed today.
Professor Gabriel Kreiman, associate professor at the Harvard Medical School, Boston, USA, and neurosurgeon Itzhak Fried, of the University of California at Los Angeles, will tell delegates at the Festival of Neuroscience in London this week how neurons create the signal before we are even aware that we will perform the action.
They hope their work could be useful in helping to understand which neuronal circuits are in charge of “free will”.
The scientists had a rare opportunity to record the activity of more than 1,000 neurons in the frontal and temporal lobes, among epilepsy patients who had electrodes implanted to try to identify the source of their seizures.
Fried implanted their brains with microwires to capture the extracellular electrical activity of neurons and the researchers were able to “interrogate the activity of neurons and neural ensembles in the human brain at high spatial and temporal resolution”, according to Prof Kreiman.
Patients were asked to move their index finger to click a computer mouse and to report when they made that decision.
“Based on the activity of small groups of neurons, we could predict this decision several hundreds of milliseconds and, in some cases, seconds before the action. In a variant of the main experiment, the patients were allowed to choose whether to use their left hand or right hand and we showed that we could also predict this decision,” said Prof Kreiman.
He will tell delegates at the conference, which takes place at the Barbican Centre in London between April 7 and 10, that “the activity of multiple neurons in extremely simple neural circuits precedes volition – in this case the decision to make a simple movement – until a threshold is crossed and the action is taken”.
* Delegates will also hear from two UK academics who will report that one of the main ingredients of “legal high” Benzo Fury acts on brain tissue like both a stimulant and a hallucinogen.
This combination is often found in illegal drugs and which can make them dangerous to users, say Dr Jolanta Opacka-Juffry, principal lecturer in neuroscience and director of the health sciences research centre at the University of Roehampton, and Dr Colin Davidson, senior lecturer in neuropharmacology and expert in drugs of addiction at St George’s University of London.
They studied the effect of 5-APB, which is also known as 5-(2-aminopropyl) benzofuran, on samples from the brains of rats, focusing in particular at the effect it had on serotonin receptors and compared the effects of 5-APB with those caused by cocaine and amphetamine.
“We have found that 5-APB behaves a little like amphetamine – that is, like a stimulant with addictive potential – and a bit like a hallucinogen, acting via serotonin receptors. This kind of mixed properties can be found in some illegal ‘designer’ drugs,” says Dr Opacka-Juffry.
“This finding is significant because it demonstrates that some ‘legal highs’ may have addictive properties, which are unlikely to be well-known amongst the users of these drugs. In addition, its effects on the serotonin receptors – known as 5-HT2A receptors – would suggest that it may lead to high blood pressure by causing constriction of the blood vessels, which would make the drug more dangerous.
“It is possible that the reason these drugs are so popular is because they are seen as safer than their illegal counterparts. It is important to challenge these assumptions.”
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