title: The benefits of magnetic resonance imaging methods to extend the knowledge of the anatomical organisation of the periaqueductal gray in mammals.
abstract: The periaqueductal gray (PAG) is a mesencephalic brain structure involved in the expression of numerous behaviours such as maternal, sexual and emotional. Histological approaches showed the PAG is composed by subdivisions with specific cell organisation, neurochemical composition and connections with the rest of the brain. The comparison of studies performed in rodents and cats as the most often examined species, suggests that PAG organisation differs between mammals. However, we should also consider the plurality of the methods used in these studies that makes difficult the comparison of the PAG organisation between species. Therefore, to study the PAG in all mammals including human, the most relevant in vivo imaging method seems to be the magnetic resonance imaging (MRI). The purpose of this review was to summarize the knowledge of the anatomical organisation of the PAG in mammals and highlights the benefits of MRI methods to extend this knowledge. Results obtained by MRI so far support the conclusions of ex vivo studies, especially to describe the subdivisions and the connections of the PAG. In these latter, diffusion-weighted MRI and functional connectivity seem the most appropriate methods. In conclusion firstly, the MRI seems to be the best judicious method to compare species and improve the comprehension of the role of the PAG. Secondly, MRI is an in vivo method aimed to manage repeated measures in the same cohort of subjects allowing to study the impact of aging and the development on the anatomical organisation of the PAG.
authors.affiliation: PRC, INRA, CNRS, IFCE, Université de Tours, 37380 Nouzilly, France.
authors.forename: Ophélie
authors.initials: O
authors.lastname: Menant
authors.affiliation: Université François-Rabelais de Tours, Inserm, Imagerie et Cerveau UMR U930, Tours, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Andersson
authors.affiliation: Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Dóra
authors.initials: D
authors.lastname: Zelena
authors.affiliation: PRC, INRA, CNRS, IFCE, Université de Tours, 37380 Nouzilly, France. Electronic address: elodie.chaillou@tours.inra.fr.
authors.forename: Elodie
authors.initials: E
authors.lastname: Chaillou
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008322:Mammals / Q000033:anatomy & histology*; D010487:Periaqueductal Gray / Q000033:anatomy & histology* / Q000166:cytology / Q000378:metabolism
keywords: Acetylcholine (esterase) (PubChem CID:187); Beta endorphin (PubChem CID: (1-9) 3081525 (2-9) 133304 (6-31) 16142384 (13-31) 44149515); Colchicine (PubChem CID:6167); Connections; Immunohistochemistry; Magnetic resonance imaging; Met-enkephalin (PubChem CID: 443363); Neuroanatomy; Nicotinamide adenine dinucleotide phosphate (diaphorase) (PubChem CID: 42609791); Nissl staining; PAG; Serotonin (PubChem CID: 5202); Tyrosine (hydroxylase) (PubChem CID: 6057)