Tectal influence of nucleus isthmi Model for tectal influence of right nucleus isthmi.
Neurons are simple gating devices.
In turn, right nucleus isthmi projects topographically to left tectal lobe. T is temporal part of frontocontralateral visual field. N is nasal part of frontocontralateral visual field. Right nucleus isthmi receives topographic input from right tectal lobe. We show the part of right nucleus isthmi that projects to the region of the right tectal lobe which receives retinal input from area C, the monocular ipsilateral region of the left eye.