title: Orienting of attention and Parkinson's disease: tactile inhibition of return and response inhibition.
abstract: There is growing evidence for cognitive impairments in Parkinson's disease (PD), including in the orienting of attention and inhibition of return (IOR). IOR refers to the slowing of a response to a target stimulus presented in the same location as a previous stimulus. While some researchers have reported normal levels of visual IOR in PD patients using cue-target tasks, others have reported significant reductions in IOR in this patient group. However, the inhibitory effects observed in cue-target tasks may reflect non-ocular response inhibition associated with withholding a response from the cue stimulus, rather than attentional or oculomotor processes. Many researchers working with normal participants have circumvented this confound by using a target-target task, in which a response is made to all peripheral stimuli. Here, we compared IOR measured in cue-target and target-target tasks, using tactile rather than visual stimuli. Both the PD and the control groups exhibited significant inhibitory effects in the cue-target task, but only the control group exhibited significant IOR in the target-target task. Our results demonstrate a reduction, or elimination, of IOR in PD and this change may have been underestimated in previous studies, in which methodologically flawed cue-target tasks were used. This reduction in IOR may reflect impaired inhibitory processes or hyper-reflexive orienting in parkinsonian patients.
authors.affiliation: School of Biological Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, UK. Ellen@Poliakoff.org.uk
authors.forename: Ellen
authors.initials: E
authors.lastname: Poliakoff
authors.forename: Donald J
authors.initials: DJ
authors.lastname: O'Boyle
authors.forename: A Peter
authors.initials: AP
authors.lastname: Moore
authors.forename: Francis P
authors.initials: FP
authors.lastname: McGlone
authors.forename: Frederick W J
authors.initials: FW
authors.lastname: Cody
authors.forename: Charles
authors.initials: C
authors.lastname: Spence
mesh_terms: D000368:Aged; D001288:Attention; D003463:Cues; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009949:Orientation; D010300:Parkinson Disease / Q000523:psychology*; D010775:Photic Stimulation / Q000379:methods; D010812:Physical Stimulation / Q000379:methods; D011930:Reaction Time; D014110:Touch; D014732:Vibration