Figure 4. Responses of MT neurones with S-cone inputs to luminance-modulated stimuli vs. their responses to S-cone-isolating stimuli before and during inactivation of V1.

The abscissa represents the ratio of the magnitude of achromatic response during V1 inactivation to the magnitude of control response. The ordinate represents the ratio of the magnitude of the response to S-cone modulation during V1 inactivation to the magnitude of control response. These measures are the same as the inactivation ratio, as defined in the legend to Fig. 3. The key on the right explains the symbols with reference to the significance (**) of the change in the magnitude of the response during V1 inactivation in the two stimulus conditions, viz. achromatic modulation (Ach) and S-cone modulation (S).