title: A novel 2- and 3-choice touchscreen-based continuous trial-unique nonmatching-to-location task (cTUNL) sensitive to functional differences between dentate gyrus and CA3 subregions of the hippocampus.
abstract: BACKGROUND
  The touchscreen continuous trial-unique non-matching-to-location task (cTUNL) has been developed to optimise a battery of tasks under NEWMEDS (Novel Methods leading to New Medication in Depression and Schizophrenia, http://www.newmeds-europe.com ). It offers novel task features of both a practical and a theoretical nature compared to existing touchscreen tasks for spatial working memory.
  
  
  OBJECTIVE
  The objective of this study was to determine whether the cTUNL task is sufficiently sensitive to differentiate between dentate gyrus (DG) and CA3 hippocampal subregion contributions to performance.
  
  
  METHODS
  The effect of DG and CA3 dysfunction on memory for locations in the cTUNL task was tested. Rats were assessed on versions of the task-two-choice and three-choice-that differed in memory load. Performance was challenged using manipulations of delay and the spatial separation between target and sample locations.
  
  
  RESULTS
  Dysfunction of the DG disrupts performance across both delay and spatial separations in two-choice cTUNL when the delay is variable and unpredictable. Increasing the working memory load (three stimuli) increases sensitivity to DG dysfunction, with deficits apparent at fixed, short delays. In contrast, CA3 dysfunction did not disrupt performance.
  
  
  CONCLUSIONS
  Acquisition of cTUNL was rapid, and the task was sensitive to manipulations of delays and separations. A three-choice version of the task was found to be viable. Finally, both the two- and three-choice versions of the task were able to differentiate between limited dysfunction to different areas within the hippocampus. DG dysfunction affected performance when using unpredictable task parameters. CA3 dysfunction did not result in impairment, even at the longest delays tested.
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: C A
authors.initials: CA
authors.lastname: Oomen
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: M
authors.initials: M
authors.lastname: Hvoslef-Eide
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: D
authors.initials: D
authors.lastname: Kofink
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: F
authors.initials: F
authors.lastname: Preusser
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Mar
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: L M
authors.initials: LM
authors.lastname: Saksida
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.|MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Bussey
mesh_terms: D000818:Animals; D056654:CA3 Region, Hippocampal / Q000187:drug effects*; D002755:Choice Behavior / Q000187:drug effects; D003216:Conditioning, Operant / Q000187:drug effects*; D018891:Dentate Gyrus / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects*; D008570:Memory, Short-Term / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects*; D051381:Rats; D011930:Reaction Time / Q000187:drug effects
keywords: CA3; Dentate gyrus; Hippocampus; Memory load; Rat; Spatial working memory; Touchscreen