Unilateral striatal deep brain stimulation improves cognitive control

Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VCVS) can treat obsessive-compulsive disorder (OCD) and other psychiatric conditions. Yet, optimizing its clinical efficacy is a major challenge, often hindered by incomplete knowledge of how stimulation parameters and targets affect neural activity and behavior. VCVS DBS is thought to work in part by improving cognitive control, an important decision-making component that is impaired in OCD and other illnesses. The magnitude of this cognitive control enhancement was shown to be lateralized, with right-unilateral stimulation being the most effective. Prior work developed a preclinical model of VCVS DBS by leveraging the cognitive control construct, which can be measured in humans and rodents and is modulated by analogous brain circuits. However, this work did not address laterality effects observed in humans or examine left/right stimulation differences. These effects may be critical for maximizing therapeutic benefit while avoiding aversive outcomes. This study aimed to investigate lateralization in the rodent model, where bilateral stimulation of the mid-striatum was previously shown to improve cognitive control. Right and left-unilateral stimulation reduced response times without changing accuracy, replicating the cognitive control improvement from bilateral stimulation. With computational modeling, we show that bilateral and unilateral stimulation modifies the same decision-making variables to drive this behavior change. We also establish that females have the same cognitive control improvement from stimulation as males. These findings increase our understanding of cognitive control circuits and strengthen the validity of the rodent model as a translational platform to study VCVS DBS's therapeutic mechanisms.

Here, we demonstrate that stimulating just one side of the brain (e.g. unilaterally) can be as effective as bilateral stimulation for improving cognitive control, the ability to adjust thoughts and decisions in response to environmental changes. These findings in rodents match results from prior human deep brain stimulation (DBS) studies, highlighting the validity of this preclinical model to study DBS's therapeutic mechanisms. We hypothesize that unilateral stimulation may be preferable to maximize cognitive benefits without causing off-target effects, while also reducing surgical invasiveness. Further, we demonstrate that females have the same cognitive control improvement from stimulation as males. Overall, this work answers important outstanding clinical questions regarding laterality and sex in DBS therapies for psychiatric illnesses.