title: Neuroimaging of the periaqueductal gray: state of the field.
abstract: This review and meta-analysis aims at summarizing and integrating the human neuroimaging studies that report periaqueductal gray (PAG) involvement; 250 original manuscripts on human neuroimaging of the PAG were identified. A narrative review and meta-analysis using activation likelihood estimates is included. Behaviors covered include pain and pain modulation, anxiety, bladder and bowel function and autonomic regulation. Methods include structural and functional magnetic resonance imaging, functional connectivity measures, diffusion weighted imaging and positron emission tomography. Human neuroimaging studies in healthy and clinical populations largely confirm the animal literature indicating that the PAG is involved in homeostatic regulation of salient functions such as pain, anxiety and autonomic function. Methodological concerns in the current literature, including resolution constraints, imaging artifacts and imprecise neuroanatomical labeling are discussed, and future directions are proposed. A general conclusion is that PAG neuroimaging is a field with enormous potential to translate animal data onto human behaviors, but with some growing pains that can and need to be addressed in order to add to our understanding of the neurobiology of this key region.
authors.affiliation: Pain and Analgesia Imaging Neuroscience group, McLean Hospital/Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA. linnman@nmr.mgh.harvard.edu
authors.forename: Clas
authors.initials: C
authors.lastname: Linnman
authors.forename: Eric A
authors.initials: EA
authors.lastname: Moulton
authors.forename: Gabi
authors.initials: G
authors.lastname: Barmettler
authors.forename: Lino
authors.initials: L
authors.lastname: Becerra
authors.forename: David
authors.initials: D
authors.lastname: Borsook
mesh_terms: D000818:Animals; D006801:Humans; D059906:Neuroimaging; D010487:Periaqueductal Gray / Q000502:physiology / Q000503:physiopathology*