Open AccessPostsynaptic Odorant Concentration Dependent Inhibition Controls Temporal Properties of Spike Responses of Projection Neurons in the Moth Antennal Lobe
Author(s) -
Terufumi Fujiwara,
Tomoki Kazawa,
Stephan Shuichi Haupt,
Ryohei Kanzaki
Publication year - 2014
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0089132
Subject(s) - antennal lobe , calcium imaging , inhibitory postsynaptic potential , postsynaptic potential , calcium , electrophysiology , neuroscience , biology , biophysics , neuron , olfactory system , olfaction , chemistry , biochemistry , receptor , organic chemistry
Although odorant concentration-response characteristics of olfactory neurons have been widely investigated in a variety of animal species, the effect of odorant concentration on neural processing at circuit level is still poorly understood. Using calcium imaging in the silkmoth ( Bombyx mori ) pheromone processing circuit of the antennal lobe (AL), we studied the effect of odorant concentration on second-order projection neuron (PN) responses. While PN calcium responses of dendrites showed monotonic increases with odorant concentration, calcium responses of somata showed decreased responses at higher odorant concentrations due to postsynaptic inhibition. Simultaneous calcium imaging and electrophysiology revealed that calcium responses of PN somata but not dendrites reflect spiking activity. Inhibition shortened spike response duration rather than decreasing peak instantaneous spike frequency (ISF). Local interneurons (LNs) that were specifically activated at high odorant concentrations at which PN responses were suppressed are the putative source of inhibition. Our results imply the existence of an intraglomerular mechanism that preserves time resolution in olfactory processing over a wide odorant concentration range.