title: Motor-response generation as a source of aging-related behavioural slowing in choice-reaction tasks.
abstract: OBJECTIVE
  To analyze the effects of stimulus-response (SR) processing modes on different central stages of sensorimotor processing in order to evaluate their contribution to aging-related behavioural slowing.
  
  
  METHODS
  Components of stimulus- and response-related potentials (ERPs/RRPs) and lateralized readiness potentials (LRPs) were analyzed in two groups of young (mean 22.5 years) and older adults (mean 58.3 years) during an auditory and a visual four-choice-reaction task.
  
  
  RESULTS
  (1) Reaction time (RT) depended on the SR type, indicating SR-specific differences in processing, which did not vary with age. (2) For each SR type, the RT increased with age. RT slowing was not accompanied by significant delays in early stimulus processing (as reflected by P1 and N1 latencies) nor in response selection (as reflected by the onset of stimulus-locked LRP), but resulted from a prolongation of contralateral motor activity during motor response execution indexed by earlier, longer durated and larger motor-related potentials in older adults. These aging effects were observed for each SR type.
  
  
  CONCLUSIONS
  In a four-choice-reaction task, (1) task complexity rather than differences in cognitive strategy or activation patterns subserving SR-specific processing leads to response slowing with aging and (2) the most plausible contributor to this slowing is the cortical response generation system.
authors.affiliation: Leibniz Research Institute for Working Environment and Human Factors, Ardeystr. 67, D-44139 Dortmund, Germany.
authors.forename: Vasil
authors.initials: V
authors.lastname: Kolev
authors.forename: Michael
authors.initials: M
authors.lastname: Falkenstein
authors.forename: Juliana
authors.initials: J
authors.lastname: Yordanova
mesh_terms: D000328:Adult; D000375:Aging / Q000523:psychology*; D002755:Choice Behavior / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials; D007839:Functional Laterality; D006801:Humans; D008875:Middle Aged; D011597:Psychomotor Performance; D011930:Reaction Time