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Updated: Aug 8, 2026
Imaging Odor-Evoked Activities in the Mouse Olfactory Bulb using Optical Reflectance and Autofluorescence Signals
Published on: October 31, 2011
Reciprocal intraglomerular excitation and intra- and interglomerular lateral inhibition between mouse olfactory bulb
Nathaniel N Urban1, Bert Sakmann
1Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Heidelberg 69120, Germany. nurban@cmu.edu
Insights
Olfactory bulb mitral cells exhibit both inhibitory and excitatory coupling. Excitatory connections occur when mitral cell dendrites share the same glomerulus, suggesting a novel synaptic transmission mechanism.
Area of Science:
- Neuroscience
- Olfactory System Research
- Cellular Electrophysiology
Background:
- Understanding olfactory bulb function requires elucidating how sensory inputs are processed.
- Mitral cells are key output neurons in the olfactory bulb, transforming glomerular activity into neural signals.
Purpose of the Study:
- To investigate the functional connectivity between mitral cells in the olfactory bulb.
- To correlate observed functional connectivity with the known anatomical network of mitral cells.
Main Methods:
- Paired whole-cell voltage recordings were performed on olfactory bulb slices.
- Analysis focused on identifying inhibitory and excitatory coupling between mitral cell pairs.
Main Results:
- Both inhibitory and excitatory functional connections were identified between mitral cells.
- Excitatory coupling, mediated by NMDA and AMPA receptors, occurred specifically between mitral cells with apical dendrites in the same glomerulus.
- Inhibitory coupling manifested as GABAergic inhibitory postsynaptic potentials (IPSPs).
Conclusions:
- Functional connectivity, including direct excitation, shapes mitral cell action potential patterns.
- Excitatory coupling between mitral cells appears to be glomerulus-specific.
- This glomerulus-dependent excitatory coupling suggests a non-anatomically defined synaptic mechanism for fast synaptic transmission.
Abstract:
How patterns of odour-evoked glomerular activity are transformed into patterns of mitral cell action potentials (APs) in the olfactory bulb is determined by the functional connectivity of the cell populations in the bulb. We have used paired whole-cell voltage recordings from olfactory bulb slices to compare the functional connectivity of mitral cells to the known anatomy of the mitral cell network. Both inhibitory and excitatory coupling were observed between pairs of mitral cells. Inhibitory coupling was seen as an increased frequency of small, asynchronous GABAergic IPSPs following APs in the presynaptic cell. Excitatory coupling was short in latency, beginning about 1.3 ms after the presynaptic AP and was mediated by both NMDA and AMPA receptors. Mitral cell pairs were coupled by excitation if and only if their apical dendrites terminated in the same glomerulus. The excitatory coupling between mitral cells resembles conventional fast synaptic transmission in its time course, amplitude and latency, despite the absence of evidence for anatomically defined synapses between mitral cells.
