In monkeys making value-based decisions, amygdala neurons are sensitive to cue value as distinct from cue salience

Area of Science:

• Neuroscience
• Decision Neuroscience
• Primate Neurophysiology

Background:

• Neurons in the lateral intraparietal (LIP) area respond to cues predicting rewards/penalties based on motivational salience, not value.
• This suggests LIP's role in attention capture, leaving open the question of value encoding elsewhere in the brain.
• Understanding how different brain regions represent value is crucial for deciphering value-based decision-making processes.

Purpose of the Study:

• To investigate whether amygdala neurons encode cue value in a task where LIP neurons show motivational salience sensitivity.
• To differentiate between motivational salience and value encoding in distinct brain areas during decision-making.
• To establish a functional distinction between the amygdala and LIP in representing outcome information.

Main Methods:

• Recorded neuronal activity in the amygdala of macaque monkeys performing a task with cues predicting variable rewards and penalties.
• Compared amygdala neuronal responses to reward-predicting and penalty-predicting cues with previously published LIP data.
• Analyzed firing rates in relation to predicted reward and penalty sizes to distinguish salience from value encoding.

Main Results:

• Amygdala neurons showed responses to reward-predicting cues similar to LIP, with stronger firing for large rewards.
• Unlike LIP, few amygdala neurons were sensitive to penalty size, and sensitivity to negative value was weaker than positive value.
• Amygdala neurons encoded cue value, whereas LIP neurons encoded motivational salience, establishing a functional separation.

Conclusions:

• Amygdala neurons encode the value of predicted outcomes, distinguishing between positive (reward) and negative (penalty) values.
• LIP neurons primarily encode motivational salience, capturing attention towards significant events regardless of their specific value.
• The findings reveal a functional specialization between the amygdala and LIP in processing information relevant to value-based choices.