Laser stimulation of the skin for quantitative study of decision-making and motivation

Abstract

Summary: Neuroeconomics studies how decision-making is guided by the value of rewards and punishments. But to date, little is known about how noxious experiences impact decisions. A challenge is the lack of an aversive stimulus that is dynamically adjustable in intensity and location, readily usable over many trials in a single experimental session, and compatible with multiple ways to measure neuronal activity. We show that skin laser stimulation used in human studies of aversion can be used for this purpose in several key animal models. We then use laser stimulation to study how neurons in the orbitofrontal cortex (OFC), an area whose many roles include guiding decisions among different rewards, encode the value of rewards and punishments. We show that some OFC neurons integrated the positive value of rewards with the negative value of aversive laser stimulation, suggesting that the OFC can play a role in more complex choices than previously appreciated. Motivation: Understanding how the brain processes aversive events across species to guide decisions has been limited by the lack of an aversive stimulus that is temporally precise, easily titratable, usable over many trials, and compatible with multiple measures of neuronal activity. We show that skin laser stimulation fulfills all these requirements and can be used to deliver aversive stimuli across multiple model organisms. We then use laser stimulation to show that some neurons in the prefrontal cortex integrate the positive value of rewards with the negative value of laser-stimulation.

Keywords

• neuroeconomics
• aversion
• decision
• orbitofrontal
• value
• motivation