Orbitofrontal neurons signal reward predictions, not reward prediction errors

Area of Science:

• Neuroscience
• Behavioral Neuroscience

Background:

• Neurons in the orbitofrontal cortex (OFC) exhibit activity during reward anticipation and consumption.
• This activity has been hypothesized to encode reward predictions, influencing adaptive behaviors and learning.
• Conversely, some research suggests OFC neural activity may reflect reward prediction errors, potentially driving learning directly.

Purpose of the Study:

• To investigate whether orbitofrontal cortex (OFC) neurons signal reward prediction errors or reflect reward predictions.
• To analyze OFC neuronal firing patterns in response to expected and unexpected changes in reward characteristics.

Main Methods:

• Neuronal recordings were conducted in rats performing an odor discrimination task.
• Neural activity was analyzed across blocks where reward number or flavor was unexpectedly altered.
• Firing patterns were examined in anticipation of and immediately following reward delivery.

Main Results:

• Orbitofrontal cortex (OFC) neurons did not exhibit reward prediction error signals, unlike dopamine neurons in the same experimental setting.
• OFC neuronal activity consistently reflected the predicted value of the reward.
• No phasic error-like responses were observed in OFC neurons following surprising changes in reward number or flavor.

Conclusions:

• Orbitofrontal cortex (OFC) neurons encode reward predictions rather than reward prediction errors.
• This finding clarifies the role of the OFC in adaptive behavior and learning by emphasizing its predictive function.
• The results differentiate OFC function from that of dopamine neurons in reward processing.