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Microsaccades inhibition triggered by a repetitive visual distractor is not subject to habituation: Implications for the programming of reflexive saccades.
Cortex ( IF 3.2 ) Pub Date : 2020-08-14 , DOI: 10.1016/j.cortex.2020.07.013
Francesca Bonetti 1 , Matteo Valsecchi 2 , Massimo Turatto 1
Affiliation  

The oculomotor capture triggered by a peripheral onset is subject to habituation, a basic form of learning consisting in a response decrement toward a repeatedly presented stimulus. However, it is unclear whether habituation of reflexive saccades takes place at the saccadic programming or execution stage (or both). To address this issue, we exploited the fact that during fixation the programming of a reflexive saccade exerts a robust but short-lasting phasic inhibition in the absolute microsaccadic frequency. Hence, if habituation of reflexive saccades occurs at the programming stage, then this should also affect the microsaccadic frequency, with a progressive reduction of the inhibitory phase. Conversely, if habituation occurs only at the later stage of saccade execution, the no change in the microsaccadic pattern is expected. Participants were repeatedly exposed to a peripheral onset distractor, and when eye movements were allowed, we replicated the oculomotor capture habituation. Crucially, however, when fixation was maintained the microsaccadic response did not change as exposure to the onset progressed, suggesting that habituation of reflexive saccades does not take place at the programming stage in the superior colliculus (SC), but at the later stage of saccade execution in the brainstem, where the competition between different saccades might be resolved. This scenario challenges one of the main assumptions of the competitive integration model for oculomotor control, which assumes that competition between exogenous and endogenous saccade programs occurs in the (SC). Our results and interpretation are instead in agreement with neurophysiological studies in non-human primates showing that saccadic adaption, another form of oculomotor plasticity, takes place downstream from the SC.



中文翻译:

由重复性视力干扰器触发的微扫视抑制不受习惯影响:对自反扫视的编程具有影响。

由周围发作触发的动眼神经捕获易习惯,这是一种基本的学习形式,包括对重复出现的刺激的反应递减。但是,尚不清楚反射性扫视的习惯化是否发生在扫视程序设计或执行阶段(或两者兼而有之)。为了解决这个问题,我们利用了这样一个事实,即在固定过程中,反射性扫视的程序会在绝对微跳频中发挥强大而持久的相位抑制作用。因此,如果反射性扫视的习惯发生在编程阶段,则这也应影响微跳动频率,并逐渐减少抑制相。相反,如果习惯化仅发生在扫视执行的后期,则预期微s模式不会改变。参与者反复暴露于周围性发作牵引器上,并且当允许眼球运动时,我们复制了动眼肌捕获习惯。然而,至关重要的是,当保持固定时,微acc的反应不会随着发作的进展而改变,这表明自反射性扫视的适应性不是在上丘(SC)的程序设计阶段发生,而是在扫视的后期进行。在脑干中执行,可以解决不同扫视之间的竞争。这种情况挑战了以下主要假设之一:当维持固定时,微眼跳反应不会随着发作的进展而改变,这表明自反射性扫视的适应性不是在上丘(SC)的编程阶段发生,而是在脑干扫视执行的后期。 ,可以解决不同扫视之间的竞争。这种情况挑战了以下主要假设之一:当维持固定时,微眼跳反应不会随着发作的进展而改变,这表明自反射性扫视的适应性不是在上丘(SC)的编程阶段发生,而是在脑干扫视执行的后期。 ,可以解决不同扫视之间的竞争。这种情况挑战了以下主要假设之一:动眼控制的竞争性集成模型,该模型假定(SC)中发生了外源扫视程序与内源扫视程序之间的竞争。相反,我们的结果和解释与在非人类灵长类动物中进行的神经生理学研究一致,表明眼睑适应性运动是动眼可塑性的另一种形式,发生在SC下游。

更新日期:2020-08-14
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