Stimulation of the subthalamic nucleus and impulsivity: release your horses.
OBJECTIVE
In Parkinson disease (PD) patients, deep brain stimulation (DBS) of the subthalamic nucleus (STN) may contribute to certain impulsive behavior during high-conflict decisions. A neurocomputational model of the basal ganglia has recently been proposed that suggests this behavioral aspect may be related to the role played by the STN in relaying a "hold your horses" signal intended to allow more time to settle on the best option. The aim of the present study was 2-fold: 1) to extend these observations by providing evidence that the STN may influence and prevent the execution of any response even during low-conflict decisions; and 2) to identify the neural correlates of this effect.


METHODS
We measured regional cerebral blood flow during a Go/NoGo and a control (Go) task to study the motor improvement and response inhibition deficits associated with STN-DBS in patients with PD.


RESULTS
Although it improved Unified Parkinson Disease Rating Scale motor ratings and induced a global decrease in reaction time during task performance, STN-DBS impaired response inhibition, as revealed by an increase in commission errors in NoGo trials. These behavioral effects were accompanied by changes in synaptic activity consisting of a reduced activation in the cortical networks responsible for reactive and proactive response inhibition.


CONCLUSIONS
The present results suggest that although it improves motor functions in PD patients, modulation of STN hyperactivity with DBS may tend at the same time to favor the appearance of impulsive behavior by acting on the gating mechanism involved in response initiation.
Ballanger
Benedicte
B
Division of Brain, Imaging and Behaviour-Systems Neuroscience, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.
van Eimeren
Thilo
T
Moro
Elena
E
Lozano
Andres M
AM
Hamani
Clement
C
Boulinguez
Philippe
P
Pellecchia
Giovanna
G
Houle
Sylvain
S
Poon
Yu Yan
YY
Lang
Anthony E
AE
Strafella
Antonio P
AP
D000368:Aged; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D002755:Choice Behavior / Q000502:physiology*; D046690:Deep Brain Stimulation / Q000379:methods*; D005260:Female; D006801:Humans; D007175:Impulsive Behavior / Q000000981:diagnostic imaging / Q000209:etiology / Q000628:therapy*; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy; D049268:Positron-Emission Tomography / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D012720:Severity of Illness Index; D013223:Statistics as Topic; D020531:Subthalamic Nucleus / Q000502:physiology*