Learning improves decoding of odor identity with phase-referenced oscillations in the olfactory bulb

Area of Science:

• Neuroscience
• Computational Neuroscience
• Sensory Processing

Background:

• Local field potential oscillations coordinate neuronal activity across brain regions.
• Phase amplitude coupling (PAC) describes the interaction between different frequency bands of neural oscillations.
• Understanding neural coding in sensory systems, like olfaction, is crucial for deciphering brain function.

Purpose of the Study:

• To characterize phase amplitude coupling (PAC) and theta phase-referenced power (PRP) in the mouse olfactory bulb during odor discrimination learning.
• To investigate how PAC and PRP change as animals learn to associate odors with rewards.
• To determine if neural activity patterns related to odor identity and reward can be decoded from PAC and PRP.

Main Methods:

• Electrophysiological recordings in the mouse olfactory bulb.
• Analysis of local field potential oscillations, including phase amplitude coupling (PAC).
• Calculation of theta phase-referenced high gamma and beta power (PRP).
• Machine learning-based decoding of odorant identity and reward association from neural data.

Main Results:

• Phase amplitude coupling (PAC) dynamics changed throughout the learning process.
• Odorant-elicited changes in theta phase-referenced power (PRP) increased for rewarded odors and decreased for unrewarded odors.
• The contextual identity of an odorant (rewarded vs. unrewarded) could be decoded from peak PRP in proficient learners, but not in naive mice.
• The dimensionality of PRP decreased as animals learned to discriminate odors.

Conclusions:

• Modulation of phase-referenced information chunking during learning is integral to early olfactory processing.
• Neural plasticity in the olfactory bulb supports the acquisition of odor-reward associations.
• Theta phase-referenced power (PRP) serves as a neural correlate for learning and memory in the olfactory system.