Figure 2.
Examples of local field potential signal recorded before and during odor sampling. A, Raw signal (0.1-300 Hz) during spontaneous activity. In the absence of odor, γ bursts (60-90 Hz) are present at each respiratory cycle. B, Raw signal (0.1-300 Hz) before, during, and after odor sampling (horizontal bar). Single trial to the S+ odor (geraniol) is shown from the same posteroventral recording site in the beginner condition (top) and in the expert condition (bottom). Note that an increase in the β oscillatory response can be observed in the expert condition even in the raw signal. C, Time-frequency analysis representation (from wavelet transform) of the same signal shown in B in the beginner condition. Left, In the γ band. Right, In the β band. Odor sampling duration is indicated with white vertical bars. x-Axis, Time (in sec); y-axis, frequency from 60 to 90 Hz (left), and 15-40 Hz (right) from top to bottom. The color scale represents signal power (μV2). The same time scale is used for all representations. D, Example of individual and filtered signals in the β band (15-40 Hz) recorded simultaneously in four recording sites; expert condition in response to sampling the S+ odor (geraniol, white vertical bar). One can see the obvious difference, at least in amplitude, in odor-induced β response. E, Time-frequency analysis representation corresponding to the local field potential signals in D. Odor sampling duration is indicated with white vertical bars. x-Axis, Time (in sec); y-axis, frequency from 15 to 40 Hz, from top to bottom. The color scale expresses signal power (μV2). The same time and color scale is used for all representations.