Brain State-Dependent Neocortico-Hippocampal Network Dynamics Are Modulated by Postnatal Stimuli

Area of Science:

• Neuroscience
• Systems Neuroscience
• Cognitive Neuroscience

Background:

• Neuronal communication between the cerebral cortex and hippocampus is crucial for information transfer.
• Previous research established temporal coordination but lacked insight into the spatial extent of neocortical involvement during hippocampal activity.
• Understanding the relationship between neocortical spatial activity and hippocampal events is vital for deciphering brain function.

Purpose of the Study:

• To investigate the spatial dynamics of neocortical activity in relation to hippocampal sharp wave ripples (SWRs) and theta oscillations.
• To explore how different brain states (anesthetized, natural sleep, awake) and environmental conditions affect neocortico-hippocampal interactions.
• To determine the role of postnatal experience in modulating these neural dynamics.

Main Methods:

• Mesoscopic imaging of neocortical activity in GCaMP-expressing mice.
• Simultaneous recording of hippocampal local field potentials.
• Comparison of neural activity across different behavioral states and environmental rearing conditions (isolated vs. enriched).

Main Results:

• Neocortical activity, particularly in visual and related areas, elevates around hippocampal SWRs.
• Pre-SWR activity is common in awake and sleeping states, but post-SWR activity diminishes during natural sleep.
• Urethane anesthesia induced SWR-correlated activity on a longer timescale; theta oscillations showed widespread, phase-locked neocortical activity.
• Mice reared in isolation displayed more distinct brain state-dependent neocortico-hippocampal dynamics compared to those in enriched environments.

Conclusions:

• The neocortex and hippocampus exhibit distinct, brain state-specific activity patterns.
• Postnatal environmental experience significantly modulates the dynamics of neocortico-hippocampal communication.
• These findings highlight the complex interplay between neural circuits, brain states, and environmental influences on brain function.