title: Impaired visual discrimination learning in anorexia nervosa.
abstract: The primate dopamine system is involved in appetitively motivated behaviours, including certain forms of learning, for example, visual discrimination learning. Furthermore, food restriction in animals and anorexia in humans is associated with impaired dopamine signaling. Based on this, we hypothesized that patients with anorexia nervosa (AN) would show a deficit in visual discrimination learning. In a dynamic categorization task involving the learning of a series of two-alternative forced-choice visual discriminations, conceptually identical to one shown to activate dopamine neurons in primates, and sensitive to dopaminergic manipulations in humans, patients with AN showed a deficit in learning that was most pronounced in the early stages of acquisition. In contrast, AN showed spared performance on a pattern recognition memory test sensitive to medial temporal lobe lesions, but insensitive to dopaminergic manipulations. We conclude that impaired appetitive function in patients with AN extends to include deficits in visual discrimination learning, and that this deficit represents indirect evidence for altered dopaminergic neurotransmission in AN.
authors.affiliation: MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 2EF, UK. andrew.lawrence@mrc-cbu.cam.ac.uk
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Lawrence
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dowson
authors.forename: Gillian L
authors.initials: GL
authors.lastname: Foxall
authors.forename: Ruth
authors.initials: R
authors.lastname: Summerfield
authors.forename: Trevor W
authors.initials: TW
authors.lastname: Robbins
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Sahakian
mesh_terms: D000328:Adult; D000856:Anorexia Nervosa / Q000503:physiopathology*; D001066:Appetite / Q000502:physiology*; D004193:Discrimination Learning / Q000502:physiology*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology*; D018709:Statistics, Nonparametric; D013702:Temporal Lobe
chemical_list: D004298:Dopamine