Stochasticity in Ca2+ Increase in Spines Enables Robust and Sensitive Information Coding
A–C, Distributions of the Ca2+ response along the PF-CF interval (left) in 0.1 µm3 (a spine volume) (A), in 5,000 µm3 (a cell volume) (B), and in 10 µm3 (C). The probability components (middle) and the amplitude components (right) are also shown. The colors in the left and right panels code the probability of the Ca2+ response at the indicated PF-CF interval. Arrowheads in the left panels indicate the thresholds between two peaks of the bimodal marginal distributions. The probability components denote the frequencies of the Ca2+ response above/below the thresholds (solid/dashed lines, respectively), and the amplitude components denote the Ca2+ response above/below the thresholds (indicated by solid/dashed braces, respectively). The PF-CF interval was defined by the time difference between the first PF and CF inputs. D, Volume-dependency of the input timing information coded by the total distribution of the Ca2+ response (black), by the probability component (red), and by the amplitude component (blue). E, Volume-dependency of the input timing information per volume. F, Relative contribution of the probability (red) and amplitude (blue) component to the input timing information.