Retrograde-labeling of pretecto-vestibular pathways in cats

The projections of the nucleus of the optic tract (NOT) were studied in cats using three kinds of retrograde tracers (horseradish peroxidase wheat germ agglutinin (WGA-HRP), dextran fluorescein (DF) and dextran tetramethylrhodamine (DTR)). First, in the cases that WGA-HRP were injected into the rostral part of medial vestibular nucleus (VN), a significant number of retrograde-labeled neurons, which concentrated between 600 and 800 μm from the rostral part of the NOT, were observed in the NOT ipsilateral to the injection sites. Second, no double-labeled neurons were found following injections of DF in the medial VN and DTR in the nucleus prepositus hypoglossi (NPH) at the same time. In this experiment, it was made clear that two different kinds of neurons in the NOT projected to the medial VN and the NPH, respectively.