Impaired smooth‐pursuit in Parkinson's disease: normal cue‐information memory, but dysfunction of extra‐retinal mechanisms for pursuit preparation and execution. Issue 3 (29th March 2015)

• Record Type: Journal Article
• Authors: Fukushima, Kikuro; Ito, Norie; Barnes, Graham R.; Onishi, Sachiyo; Kobayashi, Nobuyoshi; Takei, Hidetoshi; Olley, Peter M.; Chiba, Susumu; Inoue, Kiyoharu; Warabi, Tateo
• Is Part Of: Physiological reports. Volume 3:Issue 3(2015:Mar.)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2015-03-29
• Subjects: Extra‐retinal mechanisms -- memory -- Parkinson's disease -- priming effects -- smooth‐pursuit; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.12361
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: While retinal image motion is the primary input for smooth‐pursuit, its efficiency depends on cognitive processes including prediction. Reports are conflicting on impaired prediction during pursuit in Parkinson's disease. By separating two major components of prediction (image motion direction memory and movement preparation) using a memory‐based pursuit task, and by comparing tracking eye movements with those during a simple ramp‐pursuit task that did not require visual memory, we examined smooth‐pursuit in 25 patients with Parkinson's disease and compared the results with 14 age‐matched controls. In the memory‐based pursuit task, cue 1 indicated visual motion direction, whereas cue 2 instructed the subjects to prepare to pursue or not to pursue. Based on the cue‐information memory, subjects were asked to pursue the correct spot from two oppositely moving spots or not to pursue. In 24/25 patients, the cue‐information memory was normal, but movement preparation and execution were impaired. Specifically, unlike controls, most of the patients (18/24 = 75%) lacked initial pursuit during the memory task and started tracking the correct spot by saccades. Conversely, during simple ramp‐pursuit, most patients (83%) exhibited initial pursuit. Popping‐out of the correct spot motion during memory‐based pursuit was ineffective for enhancing initial pursuit. The results were similar irrespective of levodopa/dopamine agonist medication. Our results indicate that the extra‐retinal mechanisms of most patients are dysfunctional in initiating memory‐based (not simple ramp) pursuit. A dysfunctional pursuit loop between frontal eye fields (FEF) and basal ganglia may contribute to the impairment of extra‐retinal mechanisms, resulting in deficient pursuit commands from the FEF to brainstem. Abstract : Using smooth‐pursuit tasks that did or did not require cue‐information memory, most patients with Parkinson's disease exhibited normal memory, but movement preparation/execution were impaired. Especially, most of them lacked initial pursuit during the memory‐based pursuit task, suggesting specific dysfunction of extra‐retinal mechanisms for memory‐based pursuit initiation.