title: Executive n-back tasks for the neuropsychological assessment of working memory.
abstract: Working memory (WM) has been defined as a cerebral function which allows us to maintain and manipulate information "online". One of the most widely used paradigms to assess WM is the n-back test. Despite its extensive application, some authors have questioned its capacity to assess the manipulation of WM load. The present study introduces a new version of the n-back test to carry out this assessment. We use functional near-infrared spectroscopy (fNIRS) to evaluate prefrontal cortex (PFC) activation. The modified n-back requires monitoring of sequentially presented stimuli (in this case the days of the week). The target response relates to a stimulus which appears previously, from 0 to 2 items back, on the computer screen. Our data reveals that while modified and unmodified n-back activate the same regions of the left PFC, our modified 2-back version shows significantly higher activation in the left dorsolateral PFC (DLPFC) and the left frontal opercula. These results suggest that increased complexity in verbal WM tasks entail greater executive control, which would lead to an increase in cerebral blood flow to the areas associated with verbal WM. Therefore, an increase in the manipulation of WM load in verbal tasks reflects greater physiological activity in the left DLPFC and the left frontal opercula. The modified n-back test may also be incorporated into the armamentarium of valid instruments for the neuropsychological assessment of the maintenance and manipulation of verbal information in tasks requiring working memory.
authors.affiliation: Center for Brain Injury Rehabilitation (CRECER), C/Torneo 23, 41002 Seville, Spain.
authors.forename: Umberto
authors.initials: U
authors.lastname: León-Domínguez
authors.affiliation: Center for Brain Injury Rehabilitation (CRECER), C/Torneo 23, 41002 Seville, Spain.
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Martín-Rodríguez
authors.affiliation: Human Neuropsychology Laboratory, School of Psychology, Department of Experimental Psychology, C/Camilo José Cela s/n, Seville 41018, Spain. Electronic address: leoncarrion@us.es.
authors.forename: José
authors.initials: J
authors.lastname: León-Carrión
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D013647:Task Performance and Analysis; D014706:Verbal Learning / Q000502:physiology; D055815:Young Adult
keywords: Dorsolateral cortex; Executive memory; N-back; Near-infrared spectroscopy (fnirs); Prefrontal cortex; Working memory