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Bazhenov, Maxim Network Model for the Odor-Specific Slow Temporal Patterns in Locust OlfactoryInterneurons Locust antennal lobe projection neurons (PNs) display slow temporal patterns of activity in response to olfactory stimuli. These patterns are composed of 100-200ms epochs of depolarizing and hyperpolarizing activity, which are stimulus specific and reproducible. We investigated the possibility that long lasting inhibition between local neurons (LNs) and PNs might be responsible for these temporal patterns. This hypothesis was investigated with computer models of interacting PNs and LNs which included voltage and calcium-dependent currents described by the Hodgkin-Huxley type of kinetics. Odor stimulation was modeled by postsynaptic activation of odor-specific subsets of PNs and LNs. We found that slow inhibition produced a slow hyperpolarization in some of the PNs and controlled spike activity in ways similar to those observed experimentally. Depending on the stimulus-specific temporal patterns of activity in the presynaptic LNs, the hyperpolarization in the PNs lasted from 100 to 400 ms. After the termination of the olfactory stimulation, a depolarization appeared in many of the the PNs, which outlasted the stimulus, as often observed experimentally. The slow temporal patterns of activity in PNs were stimulus specific and showed relatively small changes when the fast inhibitory connections between LNs and from LNs to PNs were blocked. The model predicts that slow inhibition may play an important role in the temporal encoding of olfactory information in this system.
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