Sensory Deviancy Detection Measured Directly Within the Human Nucleus Accumbens

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Environmental changes necessitate comparing expectations with actual outcomes to guide behavior.
• The nucleus accumbens (NAcc) is a crucial brain region for integrating information from the hippocampus and neocortex.
• The NAcc is hypothesized to play a role in mediating expectancy-outcome comparisons.

Purpose of the Study:

• To investigate the role of the nucleus accumbens (NAcc) in processing auditory stimulus deviancy.
• To record and analyze event-related potentials directly from the human NAcc.
• To determine if NAcc activity reflects the statistical properties of sensory environments.

Main Methods:

• Direct intracranial recordings of event-related potentials from the NAcc in 5 human participants.
• Participants listened to trains of auditory stimuli with varying degrees of deviation from background stimuli.
• Analysis of NAcc activity in response to deviant stimuli and its relationship to scalp potentials.

Main Results:

• An early mismatch signal (50-220 ms) was observed in the NAcc in response to all deviant auditory stimuli.
• NAcc signal amplitude correlated with the level of stimulus deviancy, reflecting sensitivity to statistical regularities.
• The NAcc mismatch signal predicted later scalp potentials (300-400 ms).

Conclusions:

• The human nucleus accumbens (NAcc) generates an early neural signal indicative of stimulus deviancy.
• NAcc activity encodes the statistical statistics of the sensory environment.
• These findings provide direct evidence for the NAcc's role in a network for processing environmental statistics and informing behavior.