A specific role for serotonin in overcoming effort cost

Area of Science:

• Neuroscience
• Behavioral Economics
• Psychopharmacology

Background:

• Serotonin is crucial for behavioral regulation, influencing decisions involving costs like delay or punishment.
• Previous theories suggested serotonin modulates the impact of these costs on action selection.

Purpose of the Study:

• To investigate serotonin's role in regulating effort-based decision-making.
• To determine if selective serotonin reuptake inhibitors (SSRIs) affect the willingness to exert effort.

Main Methods:

• A double-blind, placebo-controlled study involving 58 healthy participants.
• Participants received either escitalopram (an SSRI) or placebo for 8 weeks.
• Behavioral task measuring the trade-off between physical effort (handgrip force) and monetary reward.

Main Results:

• Escitalopram treatment led to increased effort production and higher monetary payoffs compared to placebo.
• Computational analysis revealed a specific reduction in the subjective cost of effort.
• No significant change was observed in the valuation of monetary incentives.

Conclusions:

• Serotonin specifically modulates the cost of effort in action selection, extending its known regulatory roles.
• Findings provide a computational mechanism for the clinical effects of SSRIs in depression, potentially related to motivation.
• This research offers new insights into the neurobiological underpinnings of effort-based decision-making.