title: Matching of feedback inhibition with excitation ensures fidelity of information flow in the anterior piriform cortex.
abstract: Odor-evoked responses in mitral cells of the olfactory bulb are characterized by prolonged patterns of action potential (spike) activity. If downstream neurons are to respond to each spike in these patterns, the duration of the excitatory response to one spike should be limited, enabling cells to respond to subsequent spikes. To test for such mechanisms, we performed patch-clamp recordings in slices of the mouse anterior piriform cortex. Mitral cell axons in the lateral olfactory tract (LOT) were stimulated electrically at different intensities and with various frequency patterns to mimic changing input conditions that the piriform cortex likely encounters in vivo. We found with cell-attached measurements that superficial pyramidal (SP) cells in layer 2 consistently responded to LOT stimulation across conditions with a limited number (1-2) of spikes per stimulus pulse. The key synaptic feature accounting for the limited spike number appeared to be somatic inhibition derived from layer 3 fast-spiking cells. This inhibition tracked the timing of the first spike in SP cells across conditions, which naturally limited the spike number to 1-2. These response features to LOT stimulation were, moreover, not unique to SP cells, also occurring in a population of fluorescently labeled interneurons in glutamic acid decarboxylase 65-eGFP mice. That these different cortical cells respond to incoming inputs with 1-2 spikes per stimulus may be especially critical for relaying bulbar information contained in synchronized oscillations at beta (15-30Hz) or gamma (30-80Hz) frequencies.
authors: University of Colorado Anschutz Medical Campus, Department of Physiology & Biophysics, 12800 East 19th Avenue, Aurora, CO 80045, United States. Electronic address: dsheridan@regis.edu.
authors: D C
authors: DC
authors: Sheridan
authors: Department of Biomedical Sciences, Colorado State University, 1680 Campus Delivery, Fort Collins, CO 80523, United States.
authors: A R
authors: AR
authors: Hughes
authors: Institute of Experimental Medicine, Division of Medical Gene Technology, Budapest, Hungary.
authors: F
authors: F
authors: Erdélyi
authors: Institute of Experimental Medicine, Division of Medical Gene Technology, Budapest, Hungary. Electronic address: szabo.gabor@koki.mta.hu.
authors: G
authors: G
authors: Szabó
authors: Department of Biomedical Sciences, Colorado State University, 1680 Campus Delivery, Fort Collins, CO 80523, United States. Electronic address: Shane.Hentges@colostate.edu.
authors: S T
authors: ST
authors: Hentges
authors: University of Colorado Anschutz Medical Campus, Department of Physiology & Biophysics, 12800 East 19th Avenue, Aurora, CO 80045, United States. Electronic address: Nathan.Schoppa@ucdenver.edu.
authors: N E
authors: NE
authors: Schoppa
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D005260:Female; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009433:Neural Inhibition / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D066195:Piriform Cortex / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
keywords: gamma oscillations; inhibition; mitral cell; olfactory; piriform cortex