| Autor: |
Zak, Joseph D., Schoppa, Nathan E. |
| Předmět: |
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| Zdroj: |
Journal of Physiology; 1/15/2022, Vol. 600 Issue 2, p393-417, 25p |
| Abstrakt: |
GABAergic periglomerular (PG) cells in the olfactory bulb are proposed to mediate an intraglomerular 'high-pass' filter through inhibition targeted onto a glomerulus. With this mechanism, weak stimuli (e.g. an odour with a low affinity for an odourant receptor)mainly produce PG cell-driven inhibition but strong stimuli generate enough excitation to overcome inhibition. PG cells may be particularly susceptible to being activated by weak stimuli due to their intrinsically small size and high input resistance. Here, we used dual-cell patch-clamp recordings and imaging methods in bulb slices obtained from wild-type and transgenic rats with labelled GABAergic cells to test a number of predictions of the high-pass filtering model. We first directly compared the responsiveness of PG cells with that of external tufted cells (eTCs), which are a class of excitatory cells that reside in a parallel but opposing position in the glomerular circuitry. PG cells were in fact found to be no more responsive than eTCs at low levels of sensory neuron activity. While PG cells required smaller currents to be excited, this advantage was offset by the fact that a given level of sensory neuron activity produced much smaller synaptic currents. We did, however, identify other factors that shaped the excitation/inhibition balance in a manner that would support a high-pass filter, including glial glutamate transporters and presynaptic metabotropic glutamate receptors. We conclude that a single glomerulus may act as a high-pass filter to enhance the contrast between different olfactory stimuli throughmechanisms that are largely independent cell-intrinsic properties. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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