Figure 3.

Average normalized temporal impulse responses across all of the cells. (A) Mean temporal profiles of the strongly biphasic (open symbols) and the weakly biphasic (closed symbols) nondirectional cells. Vertical lines represent ±1 SEM. A considerable latency difference can be seen between these two classes of cells, the weakly biphasic cells on average reaching their peak response at precisely the point at which the responses of the strongly biphasic cell population is at zero, as it is reversing phase. Thus these two types of cells are in quadrature temporal relation to each other. (B) Mean temporal profiles of the first and second SVD components of the directional cells’ RFs. Note that the time courses of the early (open symbols) and late (close symbols) components correspond to the time courses of the strongly biphasic and the weakly biphasic nondirectional cells, respectively. Note also that although directional cells are more biphasic overall, the early principal component is strongly biphasic, whereas the later component is much less biphasic. (C) Mean profiles of rotated SVD components of the directional cells. Here each pair is rotated so that one of the components is as monophasic as possible. Note that the time courses of the early (open symbols) and late (closed symbols) components of the directional cells are almost indistinguishable from those of the strongly biphasic and weakly biphasic nondirectional cells, respectively.