Contextual interaction between novelty and reward processing within the mesolimbic system.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• Long-term memory for novel events relies on medial temporal lobe (MTL) circuitry.
• This circuitry overlaps with reward-processing areas like the ventral striatum, dopaminergic midbrain, and medial orbitofrontal cortex (mOFC).
• A functional link, termed the novelty 'exploration bonus,' may connect novelty and reward to motivate exploration.

Purpose of the Study:

• To investigate the interaction between novelty and reward in memory formation.
• To identify neural signals associated with the novelty 'exploration bonus' using fMRI.
• To understand how the brain integrates novelty and reward information for long-term memory.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed during a scene encoding task.
• Participants encoded novel scenes with varying reward values.
• Neural activity was analyzed for correlations with memory performance and task conditions.

Main Results:

• Reward-related long-term memory correlated with activity in the MTL, ventral striatum, and substantia nigra/ventral tegmental area (SN/VTA).
• The hippocampus showed a main effect of novelty, while the striatum showed a main effect of reward.
• An interaction between novelty and reward, indicative of an exploration bonus, was observed in the hippocampus.

Conclusions:

• MTL novelty signals are processed for reward-predicting value in the mOFC, influencing striatal reward responses.
• The striatum and SN/VTA modulate MTL-dependent long-term memory formation.
• The hippocampus integrates novelty and reward to generate contextual exploration bonus signals.