title: Visual-discrimination learning ability and beta-amyloid accumulation in the dog.
abstract: Young, middle-aged, and old beagle dogs were tested on several visual-discrimination tasks: reward- and object-approach learning, object discrimination and reversal, long-term retention of a reversal problem, and a size-discrimination task. Beta-amyloid accumulation in the entorhinal, prefrontal, parietal, and occipital cortices was quantified using immunohistochemical and imaging techniques at the conclusion of cognitive testing. Middle-aged and old dogs were impaired in size-discrimination learning. In each task, a subset of aged dogs was impaired relative to age-matched peers. Beta-amyloid accumulation was age-dependent. However, not all middle-aged and old dogs showed beta-amyloid accumulation in the entorhinal cortex. The error scores from dogs tested with a nonpreferred object during visual discrimination learning and from reversal learning were correlated with beta-amyloid in the prefrontal but not entorhinal cortex. Size-discrimination and reward and object-approach learning error scores were correlated with beta-amyloid accumulation in the entorhinal but not prefrontal cortex. The results of these studies support an association between cognitive test and the location and extent of beta-amyloid pathology.
authors.affiliation: Institute for Brain Aging and Dementia, University of California, Irvine, 92697-4540, USA. ehead@uci.edu
authors.forename: E
authors.initials: E
authors.lastname: Head
authors.forename: H
authors.initials: H
authors.lastname: Callahan
authors.forename: B A
authors.initials: BA
authors.lastname: Muggenburg
authors.forename: C W
authors.initials: CW
authors.lastname: Cotman
authors.forename: N W
authors.initials: NW
authors.lastname: Milgram
mesh_terms: D016229:Amyloid beta-Peptides / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology*; D004285:Dogs; D018728:Entorhinal Cortex / Q000737:chemistry / Q000378:metabolism; D005260:Female; D005556:Form Perception / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology; D009778:Occipital Lobe / Q000737:chemistry / Q000378:metabolism; D010296:Parietal Lobe / Q000737:chemistry / Q000378:metabolism; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000737:chemistry / Q000378:metabolism; D012193:Reversal Learning / Q000502:physiology; D012201:Reward
chemical_list: D016229:Amyloid beta-Peptides