Figure 2

Time-delay embedding of intracellular recordings reveals varied dynamical trajectories and equations are fitted to them. (a) Excitatory (red) and inhibitory (blue) transmembrane current, and potential (green). Gold bars: stimulus on/off times. Outlined boxes: periods defining on response (early box) and off response (late box). Stimulus on time through the end of the off response defines the full response. Gray: periods defining deflection as the difference between early and late period means. (b) Left column: Time-delay embeddings illustrated with every 20th one-millisecond delay of recordings from panel a. Right column: Neural trajectories visualized after singular value decomposition of 100 one-millisecond delays. (c) Two trajectories coinciding with the most (gold) and least (aqua) preferred stimuli (largest/smallest mean deflection respectively) for one cell from eight recording categories. Fig. S10b succinctly characterizes all trajectories. Central axes (gold/aqua bars) are parallel. Trajectory characteristics include: axial displacement of densest regions (see ^R,SV, ^I,SI, ^I,OI), opposed directions of divergence (^R,SV), and nesting (^I,OI, ^E,OI, ^I,CI, ^E,CI, ^I,SI). Most cell’s trajectories occupy conic regions (see Fig. S10), but some (^R,CV, ^E,SI, ^R,SV) are cylindrical or spheroid when plotted together.