Figure 2.

Phase resetting of FLPs. The free-running neural oscillator was perturbed at different phases and, as a result, its phase was reset due to a transient change in the length of the current cycle during which the perturbation was active (A). The intrinsic firing period P_i (see black bar on top of the third cycle that contains the perturbation) was shortened by a perturbation applied at phase ϕ = 0.5 (see dashed red trace and the corresponding red bar on top of the third cycle). The same perturbation applied at phase ϕ = 0.3 (measured from the peak of the action potential—see vertical dotted lines) lengthened the current cycle (see continuous blue trace and the corresponding blue bar on top of the third cycle). (B) The average membrane potential of 100 noisy traces (thick black line) perturbed at 100 equally spaced phases during the third cycle is less noisy and retains some low frequency oscillations present in all individual traces. All traces were aligned at stimulus onset and only two of them are shown (red dashed and blue dashed-dotted). (C) LFP recordings also aligned at laser stimulus onset show an average LFP trace (black thick trace) that is almost noise free and retains some spectral characteristics of its components. At the same time, the shape of the average LFP trace is significantly different from any individual traces.