title: Cue-dependent memory-based smooth-pursuit in normal human subjects: importance of extra-retinal mechanisms for initial pursuit.
abstract: Using a cue-dependent memory-based smooth-pursuit task previously applied to monkeys, we examined the effects of visual motion-memory on smooth-pursuit eye movements in normal human subjects and compared the results with those of the trained monkeys. These results were also compared with those during simple ramp-pursuit that did not require visual motion-memory. During memory-based pursuit, all subjects exhibited virtually no errors in either pursuit-direction or go/no-go selection. Tracking eye movements of humans and monkeys were similar in the two tasks, but tracking eye movements were different between the two tasks; latencies of the pursuit and corrective saccades were prolonged, initial pursuit eye velocity and acceleration were lower, peak velocities were lower, and time to reach peak velocities lengthened during memory-based pursuit. These characteristics were similar to anticipatory pursuit initiated by extra-retinal components during the initial extinction task of Barnes and Collins (J Neurophysiol 100:1135-1146, 2008b). We suggest that the differences between the two tasks reflect differences between the contribution of extra-retinal and retinal components. This interpretation is supported by two further studies: (1) during popping out of the correct spot to enhance retinal image-motion inputs during memory-based pursuit, pursuit eye velocities approached those during simple ramp-pursuit, and (2) during initial blanking of spot motion during memory-based pursuit, pursuit components appeared in the correct direction. Our results showed the importance of extra-retinal mechanisms for initial pursuit during memory-based pursuit, which include priming effects and extra-retinal drive components. Comparison with monkey studies on neuronal responses and model analysis suggested possible pathways for the extra-retinal mechanisms.
authors.affiliation: Clinical Brain Research Laboratory, Department of Neurology, Toyokura Memorial Hall, Sapporo Yamanoue Hospital, Yamanote 6-9-1-1, Nishiku, Sapporo 063-0006, Japan.
authors.forename: Norie
authors.initials: N
authors.lastname: Ito
authors.forename: Graham R
authors.initials: GR
authors.lastname: Barnes
authors.forename: Junko
authors.initials: J
authors.lastname: Fukushima
authors.forename: Kikuro
authors.initials: K
authors.lastname: Fukushima
authors.forename: Tateo
authors.initials: T
authors.lastname: Warabi
mesh_terms: D000818:Animals; D003463:Cues; D005260:Female; D006801:Humans; D008251:Macaca; D008297:Male; D008568:Memory / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011597:Psychomotor Performance / Q000502:physiology*; D011698:Pursuit, Smooth / Q000502:physiology*; D012160:Retina / Q000502:physiology; D013045:Species Specificity; D055815:Young Adult