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Titolo:
Strategic control over saccadic eye movements: Studies of the fixation offset effect
Autore:
Machado, L; Rafal, RD;
Indirizzi:
Univ Coll N Wales, Dept Psychol, Bangor LL57 2DG, Gwynedd, Wales Univ CollN Wales Bangor Gwynedd Wales LL57 2DG LL57 2DG, Gwynedd, Wales
Titolo Testata:
PERCEPTION & PSYCHOPHYSICS
fascicolo: 6, volume: 62, anno: 2000,
pagine: 1236 - 1242
SICI:
0031-5117(200008)62:6<1236:SCOSEM>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
HUMAN EXPRESS SACCADES; TRANSCRANIAL MAGNETIC STIMULATION; MONKEY SUPERIOR COLLICULUS; ELECTRICAL-STIMULATION; WARNING SIGNALS; REACTION-TIMES; FIELDS; LATENCY; POINT; DISENGAGEMENT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Social & Behavioral Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Machado, L Univ Coll N Wales, Dept Psychol, Bangor LL57 2DG, Gwynedd, Wales Univ Coll N Wales Bangor Gwynedd Wales LL57 2DG Gwynedd, Wales
Citazione:
L. Machado e R.D. Rafal, "Strategic control over saccadic eye movements: Studies of the fixation offset effect", PERC PSYCH, 62(6), 2000, pp. 1236-1242

Abstract

dWe studied the strategic (presumably cortical) control of ocular fixationin experiments that measured the fixation offset effect (FOE) while manipulating readiness to make reflexive or voluntary eye movements. The visual grasp reflex, which generates reflexive saccades to peripheral visual signals, reflects an opponent process in the superior colliculus (SC) between fixation cells at the rostral pale, whose activity helps maintain ocular position and increases when a stimulus is present at fixation, and movement cells, which generate saccades and are inhibited by rostral fixation neurons. Voluntary eye movements are controlled by movement and fixation cells in thefrontal eye field (FEF). The FOE-a decrease in saccade latency when the fixation stimulus is extinguished-has been shown to reflect activity in the collicular eye movement circuitry and also to have an activity correlate in the FEF. Our manipulation of preparatory set to make reflexive or voluntaryeye movements showed that when reflexive saccades were frequent and voluntary saccades were infrequent, the FOE was attenuated only for reflexive saccades. When voluntary saccades were frequent and reflexive saccades were infrequent, the FOE was attenuated only for voluntary saccades. We conclude that cortical processes related to task strategy are able to decrease fixation neuron activity even in the presence of a fixation stimulus, resulting in a smaller FOE. The dissociation in the effects of a fixation stimulus on reflexive and voluntary saccade latencies under the same strategic set suggests that the FOEs for these two types of eye movements may reflect a change in cellular activity in different neural structures, perhaps in the SC for reflexive saccades and in the FEF for voluntary saccades.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/08/20 alle ore 13:41:02