title: Relative processing demands influence cerebral laterality for verbal-motor integration in persons with Down syndrome.
abstract: The study of cerebral specialization in the Down syndrome (DS) population has revealed an anomalous pattern of organization. In particular, dichotic-listening studies have suggested a left-ear/right hemisphere dominance for speech perception, whereas motor control research has revealed a left hemisphere dominance for executive-motor control. In the present investigation, we employed a recent adaptation of the dichotic listening procedure to examine interhemispheric integration during the performance of a lateralized verbal-motor task. Specifically, using the selective dichotic-listening procedure, participants were required to complete a rapid left or right hand pointing movement to one of two pictorial icons corresponding to the word presented to their precued ear. We observed that persons with DS (N = 17) and age-matched controls (N = 35) exhibited a right-ear advantage (REA) for our dichotic-aiming task. While these results appear to contradict previous dichotic listening studies, we propose that the manifestation of a lateral ear advantage in the DS population may have more to do with the response requirements of the task than with the characteristics or complexity of the stimulus material.
authors.affiliation: Dept of Kinesiology and Program in Neural Science, Indiana University, Bloomington, 47408, USA. heathm@indiana.edu
authors.forename: Matthew
authors.initials: M
authors.lastname: Heath
authors.forename: Timothy N
authors.initials: TN
authors.lastname: Welsh
authors.forename: Dominic A
authors.initials: DA
authors.lastname: Simon
authors.forename: Luc
authors.initials: L
authors.lastname: Tremblay
authors.forename: Digby
authors.initials: D
authors.lastname: Elliott
authors.forename: Eric A
authors.initials: EA
authors.lastname: Roy
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D003071:Cognition / Q000502:physiology*; D004007:Dichotic Listening Tests; D004314:Down Syndrome / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D016555:Matched-Pair Analysis; D008606:Mental Processes; D000091402:Prohibitins; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology