Phase locking across odor concentrations.

(A) Circular phase graphs; length of the red arrow indicates the strength of phase locking; direction of the arrow indicated mean spike phase with respect to the field potential (peak of average activity in PNs, defined as zero phase). (Left) Feedback motif, PNs (top), KCs (middle), and LHNs (bottom), across low (left) and high (right) odor concentration. (Right) Feed-forward motif. (B) Schematic diagram comparing preferred firing phase of different cell types in FB model (left), FF model (right) and recordings made in vivo from locust (middle). (C) Phase locking across odor concentrations. (Left) KCs show stable phase locking (minimal phase change across concentrations) with more stability in the FB condition (red) than the FF condition (blue). (Middle) The phase of LHNs firing advances as odor concentration increases. The FB model (red) generated an almost linear shift with increasing odor concentration. The FF model (blue) produced a drastic phase shift between low and medium concentration, which levels out to no change at high odor concentrations. (Right) GGN responds much later in the FB model than in the FB model. Results from the FB model match observations made in vivo.