NMDA receptors are the basis for persistent network activity in neocortex slices

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• The neocortex exhibits spontaneous slow oscillations during behavioral quiescence, characterized by Up and Down states.
• Up states represent brief periods of sustained neural activity, but their origins remain incompletely understood.

Purpose of the Study:

• To investigate the cellular and network mechanisms underlying the generation of neocortical Up states.
• To identify key factors contributing to the transition from non-Up state to Up state activity in the neocortex.

Main Methods:

• Experiments were conducted on adult mouse neocortex slices.
• Cellular and network variables were monitored during transitions between different buffer solutions.
• Manipulations included altering buffer composition and blocking NMDA receptors.

Main Results:

• No significant changes were observed in resting membrane potential or input resistance of cortical cells during Up state generation.
• A slight reduction in non-NMDA receptor-mediated excitatory postsynaptic potentials was noted.
• Enhanced intrinsic firing excitability and augmented NMDA receptor-mediated responses were associated with Up state generation.

Conclusions:

• NMDA receptor activity is critical for the generation of neocortical Up states.
• Enhanced intrinsic firing excitability alone is insufficient to induce Up states; NMDA receptor potentiation is essential.