Brain stimulation over dorsomedial prefrontal cortex modulates effort-based decision making.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Computational Psychiatry

Background:

• Engaging in strenuous mental activities involves balancing potential benefits against the costs of mental effort.
• The specific brain rhythms causally involved in these cost-benefit calculations remain largely unknown.

Purpose of the Study:

• To investigate the causal role of midfrontal theta oscillations in the motivation to exert mental effort.
• To determine if modulating theta activity influences willingness to engage in demanding cognitive tasks.

Main Methods:

• Utilized transcranial alternating current stimulation (tACS) targeting the dorsomedial prefrontal cortex to modulate midfrontal theta oscillations.
• Participants decided on willingness to perform a demanding working memory task for monetary rewards.
• Employed computational modeling with a hierarchical Bayesian drift diffusion model to analyze decision-making processes.

Main Results:

• Midfrontal theta tACS significantly increased participants' willingness to exert mental effort for monetary rewards.
• Working memory performance remained unaffected by the theta tACS intervention.
• Computational modeling indicated that theta tACS shifted the decision-making starting bias towards high-reward, high-effort options without altering evidence accumulation speed.

Conclusions:

• Midfrontal theta oscillations play a causal role in the motivation to engage in goal-directed mental effort.
• Non-invasive brain stimulation targeting theta rhythms can enhance the willingness to undertake demanding cognitive tasks.
• Findings provide insights into the neural mechanisms underlying effort-based decision-making and motivation.