Figure 14.

Circuit diagram of connections between zona incerta (ZI) and the midbrain tectum. The collicular layers that provide gaze-related signals to the brainstem and spinal cord are targeted by a largely inhibitory (red) incertotectal projection from the ventral ZI (vZI). These same SC layers provide input to ZI that is denser in the dorsal layer (dZI) than vZI. The projection to vZI terminates on incertotectal neurons. The dZI supplies a largely excitatory (green) input to the nuclei of the pretectum. This same layer is the predominant target of inputs from the pretectal nuclei. The two layers have different targets in the dorsal thalamus and receive different inputs, a few of which are indicated.