part of part of in taxon contributes to morphology of Tetrapoda pretectal region olivary pretectal nucleus Small distinct nucleus in the pretectum of mammals involved in the pupillary light reflect. In rats, it is an olive shaped (anterior) nucleus lying ventral to the brachium of the superior colliculus (Paxinos, The rat nervous system, 2nd ed, 1995, pg. 862). Physiologically, it is identified by neurons sensitive to luminance changes. Wikipedia:Olivary_pretectal_nucleus BAMS:OPt BM:MB-Tec-OPT MBA:706 HBA:9086 BAMS:APT olivary nucleus of superior colliculus pretectal olivary nucleus BAMS:OP DHBA:12186 BAMS:APN BAMS:OPT DMBA:16589 UBERON:0002565 anterior pretectal nucleus BIRNLEX:1037 FMA:72405 nucleus of midbrain tectum pretectal nucleus