Cognitive-Motor Neuroscience Group
Lab Head: Professor Marjan Jahanshahi
We have used random number generation (RNG) as an example of a task that involves response selection under competition. To select responses in a strategic and random fashion, participants have to suppress habitual counting which is a prepotent response in this task. With imaging we have shown that the dorsolateral prefrontal cortex is engaged in RNG and makes an essential contribution to the inhibition of habitual counting as disruption of this area with rTMS significantly increases habitual counting during RNG. DBS of the STN also increases habitual counting during fast-paced RNG, which with imaging we have shown to be associated with decreased activation of the prefrontal cortex and anterior cingulate and increased activation of the GPi, and altered pallidal-prefrontal and cingulate coupling with STN stimulation relative to when the stimulators are off. Thus, DBS of the STN impairs inhibition of prepotent responses in PD.
Examples of relevant publications
Brown RG Jahanshahi M, Marsden CD (1993) Response choice in Parkinson's disease. Brain, 116, 869-885.
Jahanshahi M Dirnberger G Fuller R Frith CD (2000) The role of the dorsolateral prefrontal cortex in random number generation: A study with positron emission tomography. Neuroimage, 12, 713-725.
Jahanshahi M Profice P Brown RG Ridding MC Dirnberger G Rothwell JC (1998) The effects of transcranial magnetic stimulation over the dorsolateral prefrontal cortex on suppression of habitual counting during random number generation. Brain, 121, 1533-1544.
Thobois S Hotton G Pinto S Wilkinson L Limousin-Dowsey P Brooks D Jahanshahi M (2007) Deep brain stimulation of the subthalamic nucleus alters pallidal coupling with prefrontal cortex during response selection under competition. J Cerebral Blood Flow & Metabolism, Jun;27(6):1173-84.
Thobois et al (2007) J Cerebral Blood Flow & Metabolism, 27(6):1173-84.