Linked Life Data

12428142

Source:http://linkedlifedata.com/resource/pubmed/id/12428142

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2002-11-12
pubmed:abstractText
The aim of the present study was to find out whether smooth eye movements (SEMs) evoked by superior colliculus (SC) stimulation are, as suggested by Breznen et al. (1996), artefactual eye movements resulting from a non-physiological response of the saccadic generator. This question was reinvestigated in head-restrained cats. Long-lasting SC stimulation was found to evoke, in a comparable proportion, either a single saccade followed by an uninterrupted SEM or a staircase of two or three saccades interleaved with SEMs. These two different patterns of eye movements could be elicited at a near-threshold current and at low stimulation frequencies. In most cases, SEM direction clearly differed from that of the preceding saccade. This difference between SEM and saccade directions varied in a systematic way as a function of the initial saccade direction. As demonstrated by computer simulation, this observation can be explained if the neural circuit controlling SEMs reaches a saturation level earlier than the saccadic burst-generator. Our results in cats were reminiscent of those reported by Breznen et al. (1996) in the monkey only in some instances, when high frequency stimulation (400-600 Hz) was applied. Indeed, in the case of near-threshold stimulation-elicited staircase saccades, increasing the stimulation frequency led to a progressive disappearance of the smaller subsequent saccades that were substituted by uninterrupted SEM-like movements. Altogether, the present results confirm the view that SEMs are genuine eye movements. These results rule out the hypothesis that SEMs result from a saturation of the saccadic generator and strengthen the hypothesis that SEMs and saccades are distinct movements. We suggest that the same collicular efferent cells carry out the motor command to saccadic and SEM circuits and that the position error originating from the SC may be distributed amongst separate downstream motor systems.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0014-4819
pubmed:author
pubmed:issnType
Print
pubmed:volume
147
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
344-52
pubmed:dateRevised
2009-11-11
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Further evidence that a shared efferent collicular pathway drives separate circuits for smooth eye movements and saccades.
pubmed:affiliation
Laboratory of Neurophysiology, School of Medicine, Université Catholique de Louvain, 5449 Ave Hippocrate, 1200 Brussels, Brussels, Belgium. Marcus.Missal@nefy.ucl.ac.be
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't