Figure 6.

A, Parameters α and β as a function of frequency. Parameter β [converted to micrometers from log(μm)] is an estimate of the mean absolute threshold of each afferent type at each frequency. Parameter α denotes the mean rate of rise of the firing rate as a function of increments in log(amplitude) of the stimulus. Parameters for a given frequency are shown only if stimuli at the two highest intensities at that frequency evoked a mean rate of at least 5 impulses/s; otherwise, parameter estimates are unreliable. B, Parameters μ and ς as a function of frequency. Parameter μ [converted to micrometers from log(μm)] is an estimate of the amplitude at which the probability that an afferent of a given type will become active is 0.5. Parameter ς denotes the slope of the sigmoid [in log(μm)⁻¹]. Sigmoid parameters for a given frequency are shown only if the stimulus at the highest intensity at that frequency activated at least 50% of the afferents; otherwise, parameter estimates are unreliable.