The olfactory sulcus is a groove that runs anterior-posteriorly (from front to back) in the inferior surface of the frontal lobe, separating the straight gyrus (gyrus rectus) from the medial orbital gyrus.
Depth of Olfactory Sulcus and Schizophrenia
Abnormal forebrain development during the embryonic stage is often characterized by a shallow olfactory sulcus. The adjacent orbital sulcus does not develop until the third trimester and so is immune to early intrauterine insults. Olfactory and orbital sulcal depths have been measured by scientists from the School of Medicine of the University of Pennsilvania in 36 patients and 28 control subjects. Patients had shallower olfactory sulci, but normal orbital sulci. Olfactory and orbital sulcal depths were correlated in controls, but not in patients. Olfactory sulcal depth may therefore be a biomarker denoting an early embryonic disruption in individuals at risk for schizophrenia.