Representational drift in primary olfactory cortex

Area of Science:

• Neuroscience
• Olfactory System Research
• Sensory Perception

Background:

• Perceptual constancy relies on stable brain representations of sensory input.
• The piriform cortex (olfactory cortex) is believed to encode odor identity.

Purpose of the Study:

• To investigate the stability of odor-evoked neural responses in the mouse piriform cortex over extended periods.
• To determine if fear conditioning or repeated odor exposure can stabilize these responses.

Main Methods:

• Electrophysiological recordings of single units in the mouse piriform cortex over several weeks.
• Utilizing a linear classifier to assess odor discrimination performance over time.
• Implementing fear conditioning and daily odor exposure paradigms.

Main Results:

• Odor-evoked responses in the piriform cortex exhibited significant drift over days to weeks.
• A classifier trained on initial responses lost accuracy, nearing chance levels after 32 days.
• Neither fear conditioning nor daily odor exposure prevented response drift.

Conclusions:

• The piriform cortex shows continuous drift in odor-evoked responses, questioning its role in stable odor perception.
• This neural instability may be a characteristic of the piriform cortex's unstructured connectivity.
• Such instability could be a property shared by other unstructured cortical areas.