Functional Properties of Adult-born Juxtaglomerular Cells in the Mammalian Olfactory Bulb

In the OB, postnatally generated interneurons have been well characterized morphologically, but very little is known concerning their physiology and function. Obtaining recordings from neurons identified as newly generated has been primarily impeded by the difficulty in distinguishing between previously generated and newly generated neurons in living brain tissue. Combining retroviral-mediated labeling of newly generated neurons with patch-clamp electrophysiology, we demonstrated that soon after new cells enter the layers of the olfactory bulb, they display voltage-dependent currents typical of more mature neurons. We also show that these "newcomers" express functional GABA and glutamate receptor channels, respond synaptically to stimulation of the olfactory nerve, and may establish both axodendritic and dendrodendritic synaptic contacts within the olfactory bulb. These data provide a basic description of the physiology of newly generated cells in the OB and show that such new cells are functional neurons that synaptically integrate into olfactory bulb circuitry soon after their arrival.