title: A microstructural analysis of schedule-induced polydipsia reveals incentive-induced hyperactivity in an animal model of ADHD.
abstract: Recent research has suggested that frequent short bursts of activity characterize hyperactivity associated with attention deficit hyperactivity disorder (ADHD). This study determined whether such pattern is also visible in schedule-induced polydipsia (SIP) in the spontaneously hypertensive rat (SHR), an animal model of ADHD. Male SHR, Wistar Kyoto (WKY) and Wistar rats were exposed to 40 sessions of SIP using a multiple fixed-time (FT) schedule of food delivery with FT 30-s and FT 90-s components. Stable performance was analyzed to determine the extent to which SIP-associated drinking is organized in bouts. The Bi-Exponential Refractory Model (BERM) of free-operant performance was applied to schedule-induced licks. A model comparison analysis supported BERM as a description of SIP episodes: licks were not produced at a constant rate but organized into bouts within drinking episodes. FT 30-s induced similar overall licking rates, latencies to first licks and episode durations across strains; FT 90-s induced longer episode durations in SHRs and reduced licking rate in WKY and Wistar rats to nearly baseline levels. Across schedules, SHRs made more and shorter bouts when compared to the other strains. These results suggest an incentive-induced hyperactivity in SHR that has been observed in operant behaviour and in children with ADHD.
authors.affiliation: Laboratorios de Conducta Animal, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), C/ Juan del Rosal 10, Ciudad Universitaria, 28040 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Íbias
authors.affiliation: Laboratorios de Conducta Animal, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), C/ Juan del Rosal 10, Ciudad Universitaria, 28040 Madrid, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pellón
authors.affiliation: Department of Psychology, Arizona State University, P.O. Box 871104, Tempe, AZ 85287-1104, USA. Electronic address: federico.sanabria@asu.edu.
authors.forename: Federico
authors.initials: F
authors.lastname: Sanabria
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology* / Q000235:genetics; D004195:Disease Models, Animal; D008297:Male; D009042:Motivation / Q000502:physiology*; D059606:Polydipsia / Q000209:etiology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017208:Rats, Wistar; D012055:Reinforcement Schedule; D013045:Species Specificity
keywords: BERM; Hyperactivity; Licking Bouts; Schedule-induced polydipsia; Spontaneously hypertensive rat