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Where we choose to look is fundamental to our interactions with other human beings. Although on some occasions we might wish to look someone straight in the eye, at other times we decide to avert gaze and look away. Sometimes the choice isn't straightforward, and we have to select between conflicting actions. Even if we do make a choice, we might subsequently change our mind and select an alternative response before it's too late.
In a study that casts light on the process of choosing between alternative eye movements, researchers at Imperial College London have demonstrated that the medial frontal cortex, an area of the brain previously implicated in controlling actions and making choices, responds differently to choosing freely between actions and changing from one choice to select another one.
The new work utilizes functional magnetic resonance imaging, or fMRI, to assess areas of neuronal activity in precise areas of the brain during different tasks related to choice. The researchers asked healthy volunteers in a magnetic resonance scanner to freely choose where to look or, alternatively, told them where to shift their eyes. On some occasions, the volunteers were asked to change their plan, regardless of whether they had made it themselves or had been instructed where to look.
Using this new technique, Dr. Husain and his colleagues found that distinct areas within the medial frontal cortex were involved in these functions. One part of medial frontal cortex was active when people freely made a choice, whereas a different part responded to situations of conflict, i.e., when one plan had to be quickly discarded in favor of an alternative one.
These findings indicate that free choice and conflict are represented separately - but in neighboring areas - within the brain. They may help to explain why people who have damage to this part of the brain often encounter difficulty in both initiating actions and in making difficult choices.
Parashkev Nachev, Geraint Rees, Andrew Parton, Christopher Kennard, and Masud Husain: "Volition and Conflict in Human Medial Frontal Cortex"
The other members of the research team include Parashkev Nachev and Christopher Kennard of Imperial College London; Geraint Rees of University College London; and Andrew Parton and Masud Husain of Imperial College London and University College London. This work was funded by the Wellcome Trust.
Publishing in Current Biology, Volume 15, Number 2, January 26, 2005, pages 122–128. http://www.current-biology.com.
Journal
Current Biology