title: Sub-processes of working memory in the N-back task: an investigation using ERPs.
abstract: OBJECTIVE
  The N-back task is frequently used in working memory studies. N-parameters allow experimental psychologists to analyze the sub-processes of N-back tasks in addition to general processing. However, previous imaging studies have not closely scrutinized these sub-processes. In the current study, three sub-processes in the N-back task were proposed using a logical task analysis: matching, replacement and shift. Domain-specific lateralization in spatial and verbal working memory was investigated in terms of this model.
  
  
  METHODS
  This model was tested with two ERP experiments during N-back tasks, one conceptual (top-down) and one data-driven (bottom-up).
  
  
  RESULTS
  Domain-specific lateralization was observed as predicted in the shift sub-process of the conceptual task and in the replacement sub-process of the data-driven task. Match-specific lateralization was also found.
  
  
  CONCLUSIONS
  The results support our three-sub-process model of the N-back task and our hypothesis that replacement is a data-driven process with a posterior locus whereas shift is a more conceptual process with a more frontal locus.
  
  
  CONCLUSIONS
  The proposed model correctly predicted ERP patterns in conceptual and data-driven N-back tasks and is potentially useful in understanding the neurophysiologic basis of N-back task performance. The similarity between match- and domain-specific lateralization in N-back tasks raised several issues for further investigation.
authors.affiliation: Department of Neurology, Chang Gung Memorial Hospital - Kaohsiung Medical Center, Chang Gung University College of Medicine, 123, Ta-Pei Road, Niao-Song, Kaohsiung County, Taiwan. ynchen@cgmh.org.tw
authors.forename: Yung-Nien
authors.initials: YN
authors.lastname: Chen
authors.forename: Suvobrata
authors.initials: S
authors.lastname: Mitra
authors.forename: Friederike
authors.initials: F
authors.lastname: Schlaghecken
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013060:Speech