Science Times: How Do We Decide? Macaque Orbitofrontal Cortex Neurons Encode Available Options Independently in Subjective Decisions

Several recent hypotheses argue that subjective decision making is a distributed, systems-level process mediated by different regions of the brain, and is subserved by various sensory and internal aspects feeding into the decision at hand—aspects such as emotion, personality, and knowledge of outcomes. Within this framework, the orbitofrontal cortex (OFC) of the frontal lobe has been specifically implicated in making value-based decisions both in humans and nonhuman primates; however, the actual mechanisms by which the OFC weighs available options and finalizes a decision remain unclear. For example, are choices A and B encoded independently in a simple decision task? Do single neurons have a mechanism for assigning and comparing the value of each available choice or is the process distributed throughout a larger network? Furthermore, studies offering high temporal resolution are required to map crucial points in the deliberation process—design flaws often found in existing fMRI studies. Keeping these concerns in mind, this study1 sets out to measure single neuron activity and local field potentials in macaque OFCs on a single-trial basis using a reward association paradigm. To acquire a good picture of how the macaques weighed the subjective values of 2 picture items, researchers recorded from electrode implantation sites along 16 cortical locations, including OFC areas 11 and 13.

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