Last minute rethink

22 August 2007

Neuroscientists at UCL (University College London) and Ghent University have found the brain circuit involved in thinking twice and checking impulsive behaviour. The duo discovered that an area in the fronto-median cortex of the brain is activated when you begin to think ‘I’m not going to go through with this’ and stop yourself doing what you were about to do.

According to the study, published in the ‘Journal of Neuroscience’ today, this specific brain network is involved in self-control and checks and limits our desired actions.

Professor Patrick Haggard, UCL Institute of Neuroscience, said: “Many people recognise the ‘little voice inside the head’ that stops you from doing something, like pressing the send button on an angry email. We all have choices in our daily life, and we may decide not to go ahead with something we’ve planned. Quite often we have an immediate desire to perform an action, but reflecting on the wider consequences could, and sometimes should, make us cancel the action. Our study identifies the brain processes involved in that last-minute rethink about what we’re doing. These brain functions are important for human society in general: the ability to withhold an action prevents us all from being egoists, driven by our immediate desires.”

The decision you make on whether to act or not in a given situation is crucial to everyday life. Past studies have focussed on people’s ability to cancel a prepared action in response to an external signal, like a stop sign. In this study, for the first time, the participants always prepared the action, but then decided for themselves whether to go through with the action, or whether to withhold it at the last minute. This allowed the scientists to identify the brain basis of self-initiated inhibition of action.

Brain activity in the fronto-median cortex was monitored using fMRI brain-imaging while volunteers made up their minds when to push a button. Prior to the test participants were asked to change their minds occasionally by deciding against pushing the button at the last minute.

Participants were asked to indicate when they began to prepare the action by reporting the position of a clock hand. This indicated to the scientists when the inhibitory brain activity was likely to occur, on those occasions when the participants withheld the action. A small area in the anterior fronto-median cortex of the brain was active only when people inhibited an action they had previously prepared. When people prepared and actually went through with the action, this area was considerably less active.

“We wanted to identify the brain areas that show more activity when people prepare an action and then inhibit it, than when they prepare the same action and then actually make it” said Dr Marcel Brass, Ghent University.

The researchers were even able to predict to some degree how often individual volunteers inhibited actions from the brain activity in the fronto-median cortex. Those with strong activity in this area withheld actions frequently, while those with weak activity pressed the button more frequently, despite the instruction to sometimes withhold action.

Professor Haggard said: “This could be a factor in why some individuals are impulsive, while others are reluctant to act. Developments in brain imaging are bringing us ever closer to a scientific understanding of why a particular individual is the way they are. The ability to check, reconsider and withhold an action is essential given the complex social settings in which we live.”

Notes for Editors

1. For further information please contact Alex Brew in the UCL Media Relations Office on tel: +44 (0)20 7679 9726, mobile: +44 (0)7747 565 056, out of hours +44 (0)7917 271 364, e-mail: a.brew@ucl.ac.uk

2. ‘To do or not to do: the neural signature of self control’ is published in the Journal of Neuroscience on 22 August 2007. This press release is embargoed to 22.00 BST (21.00 GMT and 17.00 Eastern time) on 21 August. Journalists can obtain copies of the paper by contacting the UCL press office.

3. The study was funded by the German Research Foundation.

4. The study was carried out by Professor Patrick Haggard at the UCL Institute of Cognitive Neuroscience and Dr Marcel Brass of Ghent University and the Max Plank Institute in Germany.

About UCL

Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender, and the first to provide systematic teaching of law, architecture and medicine. In the government’s most recent Research Assessment Exercise, 59 UCL departments achieved top ratings of 5* and 5, indicating research quality of international excellence.

UCL is the fourth-ranked UK university in the 2006 league table of the top 500 world universities produced by the Shanghai Jiao Tong University. UCL alumni include Mahatma Gandhi, Jonathan Dimbleby, Lord Woolf, Alexander Graham Bell, and members of the band Coldplay.