The NMDA receptor participates in respiration-related mitral cell synchrony.

The N-methyl-D-aspartate (NMDA)-type glutamate receptor participates in the excitation of olfactory bulb mitral cells and is important in granule-cell-mediated feedback-inhibition. In the present study, extracellular unit recordings were made in vivo to demonstrate that the firing rates of mitral cells are not affected by peripheral administration of the non-competitive NMDA receptor antagonist MK-801. However, while over 50% of odor-driven mitral cell activity is normally correlated with the respiratory cycle, only about 10% of mitral cell activity is correlated with the respiratory cycle 30 min after MK-801 administration. Thus, the NMDA receptor is a participant in normal respiration-related mitral cell activity and may have an important role in the formation of bulb oscillations that encode olfactory information. Furthermore, the NMDA receptor is in a position to mediate activity-dependent changes in the bulb that rely on synchronous activity.