Figure 7.

Local-Field Potentials Phase Lock to High-Frequency AM Envelopes

(A) Stimulus-triggered average (StimTA; black traces) related to tracking units, in response to a modulation frequency of 157.59 Hz (StimTAs over 500 repetitions). The StimTA preserves LFP components that are phase coherent to the stimulus (see Transparent Methods) and is obtained by averaging LFP windows (n = 300, randomly chosen a total of m = 500 times) associated to a particular time point (here, the 100-ms mark after stimulus onset). Randomized StimTAs are shown in red traces.

(B) Power of the StimTAs shown in A (black traces). Note that the StimTA spectrum peaks at frequencies related to the modulation rate of the stimulus, whereas the spectrum of surrogate StimTAs does not.

(C) Stimulus-triggered power (StimTP) of the LFP segments used to calculate StimTAs in (A). There is power in the LFP at frequencies around the modulation rate of the presented sounds, also when considering surrogate LFP segments (red trace).

(D) Stimulus-field coherence (StimFC; black) of recorded LFPs in response to a modulation frequency of 157.69 Hz. Calculated StimFC values were z-normalized to a baseline StimFC and are shown in the inset (light blue trace).

(E) z-normalized StimFC values across modulation rates (indicated in each sub-panel) for the subpopulations of tracking (blue) and non-tracking (red) units. Data in the figure are shown as median (solid lines) and quartiles (shaded areas).