Figure 2. Receptive field properties of collicular neurones encountered in the present study.

A, receptive field (RF) area of collicular neurones vs. their eccentricity from area centralis. Note that consistent with numerous previous reports (cf. Waleszczyk et al. 1999) there is a clear positive correlation between eccentricity of the RF position and size of the RF area. B, percentage histogram of eye dominance classes of collicular neurones. Class 1 cells are monocular cells which respond only to photic stimuli presented via the contralateral eye; class 2 cells are binocular cells which respond more strongly to photic stimuli presented via the contralateral eye; class 3 cells are binocular neurones which responds equally well to stimuli presented through either eye; class 4 cells are also binocular but respond more vigorously to stimuli presented through the ipsilateral eye; class 5 cells are monocular and respond only to stimuli presented via the ipsilateral eye. C, velocity profiles of collicular cells encountered. The cells were classified according to criteria established by Waleszczyk et al. (1999). LVE (low velocity excitatory) cells respond optimally to stimuli moving at velocities not exceeding 40 deg s⁻¹; LVE/HVE (low-velocity excitatory/high-velocity excitatory) cells give clear-cut excitatory responses over a very wide range of velocities (1-1000 deg s⁻¹), while the HVE (high-velocity excitatory) cells give clear-cut responses at velocities 20-1000 deg s⁻¹; Not det, not determined.