title: Compromised approximate number system acuity in extremely preterm school-aged children.
abstract: OBJECTIVE
  The aim of this study was to compare the approximate number system acuity in children born extremely preterm aged 6 years 6 months and typically developing, age-matched peers.
  
  
  METHODS
  This population-based follow-up study included 65 children born before 27 gestational weeks (35 males, 30 females; mean gestational age 25.4 wks [SD 1.1 wk]; mean birthweight 789 g [SD 158 g]) and 47 typically developing children (24 females, 23 males) at the age of 6 years 6 months. A battery of cognitive tests was administered, including a computerized test for measuring approximate number system acuity and tests for general cognition, working memory, processing speed, and visual attention. Approximate number system outcome measures were means of Weber fraction (w) values and response time in milliseconds.
  
  
  RESULTS
  The 43 extremely preterm children in whom usable data were obtained performed significantly worse than the typically developing children on the approximate number system task (w=0.30 [SD 0.23] vs. 0.17 [SD 0.13]; p=0.003) and were significantly slower (response time=2934 ms [SD 1102 ms] vs 2376 ms [SD 310 ms]; p=0.002). The differences remained when adjusting for differences in other cognitive functions (p=0.03).
  
  
  CONCLUSIONS
  Preterm birth has a negative impact on an individual's ability to rapidly approximate and compare numbers of visually presented items. This deficiency is thought to be a consequence of dorsal stream dysfunction. Future studies will investigate whether this deficiency is correlated with lower mathematical proficiency in this group of children.
authors.affiliation: Department of Clinical Neuroscience, The Karolinska Institute, Stockholm, Sweden; Center of Neurodevelopmental Disorders, The Karolinska Institute, Stockholm, Sweden.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Hellgren
authors.forename: Justin
authors.initials: J
authors.lastname: Halberda
authors.forename: Lea
authors.initials: L
authors.lastname: Forsman
authors.forename: Ulrika
authors.initials: U
authors.lastname: Adén
authors.forename: Melissa
authors.initials: M
authors.lastname: Libertus
mesh_terms: D000367:Age Factors; D002648:Child; D002657:Child Development; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D003118:Color Perception; D018672:Community Health Planning; D002658:Developmental Disabilities / Q000150:complications*; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D047928:Premature Birth / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology