Fig. 6.

Collicular ‘build-up’ cells This shows the population activity in collicular build-up cells during one of the saccades illustrated in Fig. 4 (left). Our simulated build-up cells are those that signal the error in the hidden cause (target fixation location). A shows this as if we had imaged the right superior colliculus, which represents the left side of space. We have made use of the known retinotopy of the colliculus (Quaia et al., 1998) to plot this activity. B shows a set of simulated recordings of single cells from the onset to end of the saccade. Each cell represents a different retinotopic location, indicated by the angles given for each plot. Note that the eccentricity increases with each row. C shows real data (adapted from Munoz and Wurtz, 1995b) from single unit recordings of build-up cells in the superior colliculus.