Long-term stability of cortical ensembles

Area of Science:

• Neuroscience
• Systems Neuroscience
• Cognitive Neuroscience

Background:

• Neuronal ensembles are crucial for memory and perception.
• The temporal stability and flexibility of neuronal ensembles remain poorly understood.

Purpose of the Study:

• To investigate the long-term stability and dynamics of neuronal ensembles in the visual cortex.
• To determine if neuronal ensembles can serve as a substrate for enduring neural representations.

Main Methods:

• Utilized two-photon multiplane calcium imaging in awake mice.
• Tracked the activity of pyramidal neurons in layer 2/3 of the visual cortex over several weeks.
• Recorded both spontaneous and visually evoked neuronal responses.

Main Results:

• Less than half of individual neurons remained active across imaging sessions.
• Identified stable neuronal ensembles that persisted for weeks, with some lasting up to 46 days.
• Observed that 'core' neurons within stable ensembles exhibited stronger functional connectivity.
• Some neuronal ensembles were transient, appearing in only a single session.

Conclusions:

• Neuronal ensembles demonstrate remarkable stability over weeks, suggesting they can underpin long-lasting memories and perceptual states.
• The findings reveal a combination of stable and transient neuronal ensembles, indicating a flexible neural substrate.
• Stable ensembles are characterized by persistent 'core' neurons with enhanced functional connectivity.