Figure 1. Scheme illustrating the parameters describing spindle afferent discharge during ramp stretch, as formalised by Taylor et al. (1992b).

The muscle stretch signal is represented by the fine line on top, while the heavy line below reproduces a theoretical averaged instantaneous frequency curve. The descriptive parameters are: initial frequency (IF), dynamic difference (DD), dynamic index (DI), static difference (SD), static index (SI) and peak frequency (PF). Note that both IF and SI are based on average firing rates within 0.5 s intervals (see text).