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John Duncan's research programme
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In this programme, experimental psychology is linked through functional brain imaging to single cell physiology. One research theme is selective attention, and its neural basis in biased competition (for a review see Duncan, 2006). A second is adaptive neural function in the frontal and parietal cortex, and its role in human intelligence (for a review see Duncan, 2001). |
Research
A multiple demand system in the human brain
Functional brain imaging shows many specializations in the human brain. At the same time, it reveals something unexpected – a specific set of regions in the frontal and parietal cortex, active for many different kinds of cognitive demand. We call this multiple-demand or MD cortex.
In MD regions, neurons show adaptive function. As tasks change, neurons adapt to code just that information that a current task requires. We ask how these adaptations occur, and how the resulting neural code controls the program of current mental activity.
Key papers:
MD activity in human intelligence 
Work in basic experimental psychology, in patients with focal brain lesions, and in fMRI links MD function to human intelligence. Standard tests of general intelligence or Spearman's g produce strong MD activity.
Though g is related to working memory, some kinds of working memory are more important than others. We have focused on working memory for tasks – for the full body of facts, rules and requirements that shapes current behaviour. Our research links g to goal neglect, or a striking loss of task rules in frontal lobe patients and other groups.
Key papers:
Duncan et al, 2000
MD representation
Single neuron data show strong selective attention in MD cortex. While task-relevant information is strongly coded, irrelevant input is discarded. In current work, we seek similar attentional modulations in fMRI.
One approach uses adaptation. When relevant information is changed or updated, fMRI activity increases through much of MD cortex. In contrast, new but irrelevant input leaves MD activity unchanged.
A second approach uses multivoxel pattern analysis (MVPA). With this method, detailed patterns of brain activity show current mental contents. As the task changes, we use MVPA to track evolving MD activity.
Key paper:
Hon et al, 2006
Clinical translation: The assessment of frontal lobe function
In many clinical conditions there is impaired frontal lobe function. Frontal lobe functions are important across the lifespan, from early development to cognitive decline in the elderly. Effective testing of these functions is important in many areas of clinical practice.
Many different frontal lobe tests have been designed, including tests of set shifting, inhibition, attentional control, and social perception. But do these tests really measure different things, and can they be linked to different areas of frontal damage? In a large clinical sample, we are assessing different kinds of "frontal lobe" test, and their independence from one another and from standard tests of general intelligence or g. Through improved understanding of frontal lobe functions we aim to rationalize clinical testing.
Key paper:
Duncan, 2005
The neurophysiology of visual and auditory attention
Attentional limits are shown by our inability to do several things at once. Deep in thought, for example, we may fail to notice a friend passing in the street. These limits reflect processing competition in many different brain systems. Correspondingly, there are many different kinds of "attention".
In current work using MEG, we consider the basis for divided attention within and between sensory modalities. Two stimuli in the same modality compete strongly to be processed; often, in contrast, we can pay attention simultaneously to a sight and a sound. We ask how these behavioural results translate into brain physiology.
Key paper:
Hein et al, 2006
People
John Duncan (programme leader) - Apoorva Bhandari (graduate student) - Ben Crittenden (graduate student) - Francesca Biondo (research staff) - Daniel Mitchell (research staff) - Marieke Mur (research staff) - Mikiko Kadohisa (research staff) - Makoto Kusunoki (research staff) - Polly Peers (research staff)