Symbol | Interpretation | Notes |
---|---|---|
T | Duration of epoch | Chosen by experimenter |
N(T) | Number of spikes from the output neuron in epoch, T | Measured experimentally |
〈N(T)〉 | Mean spike count from the output neuron; also read as the expectation of the spike count | Measured experimentally using repetitions of identical stimuli |
Var[N(T)] | Variance of spike count from the output neuron | Measured experimentally using repetitions of identical stimuli |
n_{i}(T) | Number of spikes from the i^{th} input neuron in epoch, T | Unknown; we assume that input and output spike counts are the same, on average: 〈N(T)〉 = 〈n_{i}(T)〉 |
λ | Intended spike rate of the output neuron; result of the neural computation | Theoretical quantity; assumed to be constant over the epoch, so 〈N(T)〉 = 〈λT〉; this assumption can be relaxed, however; then, |
C_{VISI} | Coefficient of variation of ISI distribution, which characterizes a renewal process: ς_{ISI}/μ_{ISI} | Theoretical quantity; can only be measured when λ is constant; for the renewal processes considered here C_{VISI} is the same for all possible values of λ |
Average correlation coefficient between pairs of input neurons | Estimated experimentally from pairwise recording, using repetitions of identical stimuli |
Note the distinction between experimentally measurable and theoretical quantities.