Schematic view of stimulation and recording sites. The box in the reconstructed section from the right midbrain in the left panel indicates the position of the PNC shown at higher magnification in the right panel (dorsal is up, medial is to the left). Neurons were recorded from the most dorsal and caudal nuclei of the PNC, the nucleus of the optic tract (NOT) and the posterior pretectal nucleus (PPN). No topographical segregation between spontaneously active cells (indicated by asterisks) and neurons without spontaneous activity (filled circles) was observed within the PNC. The stimulation electrode (black bar) was placed in the optic tract at the dorso-lateral border of the PNC medial to the lateral posterior thalamic nucleus (LP). Other abbreviations used, APN, anterior pretectal nucleus, OPN, olivary pretectal nucleus, LGN, lateral geniculate nucleus, MGB, medial geniculate body, SN, substantia nigra.