title: Scratching Induces Overactivity in Motor-Related Regions and Reward System in Chronic Itch Patients.
abstract: Scratching evokes a rewarding and pleasurable sensation, particularly in chronic itch patients. To date, no study has investigated the cerebral activity during scratching in chronic itch patients and whether it differs from that in healthy subjects. Using arterial spin labeling functional magnetic resonance imaging, we analyzed and compared the cerebral mechanism of self-scratching and its correlation with pleasurability in 10 patients with chronic itch and in 10 healthy controls. Cowhage was applied to the right forearm to induce itch. Scratching significantly attenuated the itch sensation (P<0.001) and evoked an associated pleasurability. Scratching-induced pleasurability significantly activated the reward system in the chronic itch and healthy groups, confirming that this reward system has a crucial role in scratching-induced pleasurability. A higher activity during scratching in chronic itch patients, versus healthy controls, was noted in brain regions related to motor control and motivation to act, including the supplementary motor area, premotor cortex, primary motor cortex, and midcingulate cortex, as well as the caudate nucleus involved in the reward system. This overactivity may be associated with the addictive scratching and/or neural hypersensitization.
authors.affiliation: Department of Dermatology and Temple Itch Center, Temple University School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Hideki
authors.initials: H
authors.lastname: Mochizuki
authors.affiliation: Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: Alexandru D P
authors.initials: ADP
authors.lastname: Papoiu
authors.affiliation: Department of Dermatology and Temple Itch Center, Temple University School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Leigh A
authors.initials: LA
authors.lastname: Nattkemper
authors.affiliation: Department of Dermatology and Temple Itch Center, Temple University School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Lin
authors.affiliation: Virginia Tech-Wake Forest University, School of Biomedical Engineering and Sciences, Winston-Salem, North Carolina, USA; Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kraft
authors.affiliation: Department of Neurobiology & Anatomy, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Coghill
authors.affiliation: Department of Dermatology and Temple Itch Center, Temple University School of Medicine, Philadelphia, Pennsylvania, USA. Electronic address: gil.yosipovitch@tuhs.temple.edu.
authors.forename: Gil
authors.initials: G
authors.lastname: Yosipovitch
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping / Q000379:methods*; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000502:physiology*; D002560:Cerebrovascular Circulation; D002908:Chronic Disease; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011537:Pruritus / Q000503:physiopathology* / Q000523:psychology; D012016:Reference Values; D012201:Reward; D055815:Young Adult