title: Too much to count on: impaired very small numbers in corticobasal degeneration.
abstract: Patients with corticobasal degeneration (CBD) have calculation impairments. This study examined whether impaired number knowledge depends on verbal mediation. We focused particularly on knowledge of very small numbers, where there is a precise relationship between a cardinality and its number concept, but little hypothesized role for verbal mediation. We evaluated accuracy and reaction time (RT) for matching dot arrays and Arabic numerals involving smaller (2-4) and larger (5-9) cardinalities in non-aphasic patients with CBD (n=16), frontotemporal dementia (FTD; n=23), and healthy controls (n=15). CBD were less accurate and slowed at judging smaller Arabic numeral-dot array stimuli compared to FTD patients and controls. Moreover, only CBD showed longer RTs judging successively larger number-dot array pairs among the smaller cardinalities. Difficulty judging very small numbers is impaired in CBD, suggesting degraded representation of precise number knowledge that does not depend on language functioning.
authors.affiliation: Department of Neurology, University of Pennsylvania Medical Center, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA.
authors.forename: Casey
authors.initials: C
authors.lastname: Halpern
authors.forename: Robin
authors.initials: R
authors.lastname: Clark
authors.forename: Peachie
authors.initials: P
authors.lastname: Moore
authors.forename: Katy
authors.initials: K
authors.lastname: Cross
authors.forename: Murray
authors.initials: M
authors.lastname: Grossman
mesh_terms: D000368:Aged; D001284:Atrophy; D001479:Basal Ganglia / Q000473:pathology / Q000502:physiology / Q000503:physiopathology; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000473:pathology / Q000502:physiology / Q000503:physiopathology; D003072:Cognition Disorders / Q000209:etiology* / Q000503:physiopathology; D003704:Dementia / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D016555:Matched-Pair Analysis; D008433:Mathematics; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D012660:Semantics