title: Allocentric but not egocentric orientation is impaired during normal aging: an ERP study.
abstract: OBJECTIVE
  Behavioral studies of spatial navigation in aging indicate that orientation using an allocentric reference frame (object-centered orientation) is impaired, whereas orientation using egocentric processes (self-centered orientation) is not. It has been proposed that navigational deficits may result from more general alterations of perception and attention or executive functions. The purpose of this study is to assess allocentric and egocentric representation in elderly individuals, and to determine if age-related deficits in spatial navigation are related to an attentional decline.
  
  
  METHODS
  We assessed encoding of the position of geometrical shapes, depending specifically on an allocentric or egocentric reference frame, during ERP recording in young and old subjects.
  
  
  RESULTS
  Aging was associated with a performance decline in allocentric, but not egocentric, encoding. Both allocentric and egocentric conditions elicited parietal early components P1 and N1, reflecting top-down modulation, and components P2 and N2, reflecting selective attention and stimulus categorization. We observed age-associated effects on N1 and N2 amplitudes and on N2 latency in both spatial conditions. Moreover, impaired allocentric performance in older subjects was associated with a greater P2 amplitude and delayed P2 latency compared with younger subjects.
  
  
  CONCLUSIONS
  These results suggest that elderly individuals present with deficits when spatial orientation relies on allocentric representation, and are associated with age-related deficits in spatial attention.
authors.affiliation: Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg.
authors.forename: Ségolène
authors.initials: S
authors.lastname: Lithfous
authors.affiliation: Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg.
authors.forename: André
authors.initials: A
authors.lastname: Dufour
authors.affiliation: Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg.
authors.forename: Frédéric
authors.identifier: 0000-0002-6714-3247
authors.initials: F
authors.lastname: Blanc
authors.affiliation: Laboratoire de Neurosciences Cognitives et Adaptatives, Université de Strasbourg.
authors.forename: Olivier
authors.initials: O
authors.lastname: Després
mesh_terms: D000368:Aged; D000375:Aging; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009949:Orientation / Q000502:physiology*; D065854:Spatial Navigation / Q000502:physiology*; D055815:Young Adult