Figure 8: Summary of components underlying the rat PII response to a light step. (a) The interactions between the various components derived from our modeling are shown for the brightest luminance. Hence, there appear to be a minimum of three components underlying the scotopic ERG PII elicited using a light step. ((1) and (3): unfilled diamonds, (2): black circles, (4): unfilled circles, (5): grey diamonds, and (6): black diamonds). (b)–(d) show individual components plotted on a contour plot, as a function of time and luminance, with larger amplitudes indicated by warmer colors. (b) (1) has fast rise and decay characteristics with a low sensitivity to light. With longer times (1) transitions to m(3). After stimulus offset, m(3) continues as m(5) and relaxes back to baseline. (c) m(2) has slow rise and decay characteristics and is more sensitive to light. After stimulus offset, m(2) continues as (4) and relaxes back to baseline. (d) A long latency small amplitude sustained positive component m(6) occurs after stimulus offset at higher luminances.