Neurons in the Human Left Amygdala Automatically Encode Subjective Value Irrespective of Task

Area of Science:

• Neuroscience
• Decision Neuroscience
• Neuroeconomics

Background:

• The amygdala is crucial for processing internal reward signals.
• In animals, stimuli can signal reinforcer value, but human amygdala value representations are unclear.
• It is unknown if human amygdala neurons represent value signals only during explicit valuation tasks.

Purpose of the Study:

• To investigate whether human amygdala neurons represent current value signals outside of explicit valuation tasks.
• To determine if value representations are task-dependent or stimulus-driven in the human amygdala.

Main Methods:

• Recorded neural activity from 406 neurons in neurosurgical patients.
• Subjects viewed images of food items in two distinct tasks: valuation and classification.
• Simultaneously recorded from the amygdala, orbitofrontal cortex, parahippocampal cortex, entorhinal cortex, and hippocampus.

Main Results:

• Neural activity in the amygdala, orbitofrontal cortex, hippocampus, and entorhinal cortex reflected food preferences during a valuation task.
• Left amygdala neural activity consistently represented food preferences, irrespective of the task.
• This suggests that left amygdala valuation signals are stimulus-driven, not task-driven.

Conclusions:

• Human amygdala neurons, particularly in the left hemisphere, encode value signals related to food preferences.
• These value signals appear to be inherent to the stimulus rather than contingent on the specific task being performed.
• Findings advance our understanding of how the brain represents value and guides choices.