When during horizontal saccades in monkey does cerebellar output affect movement?

Buzunov, Elena; Mueller, Adrienne; Straube, Andreas; Robinson, Farrel R.

doi:10.1016/j.brainres.2013.02.001

Cited by 24 publications

(20 citation statements)

References 22 publications

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“…Faster saccades are evoked with higher frequencies of stimulation. This result is consistent with the reduction of horizontal peak velocity of contralateral saccades after muscimol injection in the cFN (Buzunov et al 2013;Goffart et al 2004;Robinson et al 1993). …”

Section: Effect Of Current Intensitysupporting

confidence: 79%

“…The second set combines observations made after muscimol injection in the cFN. Indeed, the reduced peak velocity that affects the horizontal component of contralateral saccades (Buzunov et al 2013;Goffart et al 2004Goffart et al , 2005 suggests that the cFN participates in the excitatory input that drives the activity of motor and internuclear neurons in the abducens nucleus. Moreover, the saccade durationdependent ipsipulsion of vertical saccades (Goffart et al 2004) indicates an excitatory drive on the abducens neurons that is unopposed by the input that ipsilateral inhibitory burst neurons (IBN) emit during vertical saccades (Scudder et al 1988).…”

Section: Neural Processes Leading To the Elicitation Of Contralateralmentioning

confidence: 99%

“…Yet, in the monkey, when they are acute, lesions in the cFN (Buzunov et al 2013;Goffart et al 2004;Quinet and Goffart 2007;Robinson et al 1993) or in the OV (Kojima et al 2010;Takagi et al 1998) severely affect the velocity of saccades in addition to making them dysmetric (not in the cat; Goffart et al 1998a). The difficulty in relating the discharge of cFN neurons to the dynamics of saccades could be due to the fact that their time course is highly stereotyped.…”

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confidence: 99%

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Cerebellar control of saccade dynamics: contribution of the fastigial oculomotor region

Quinet

Goffart

2015

Journal of Neurophysiology

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Quinet J, Goffart L. Cerebellar control of saccade dynamics: contribution of the fastigial oculomotor region. J Neurophysiol 113: 3323-3336, 2015. First published March 5, 2015 doi:10.1152/jn.01021.2014The fastigial oculomotor region is the output by which the medioposterior cerebellum influences the generation of saccades. Recent inactivation studies reported observations suggesting an involvement in their dynamics (velocity and duration). In this work, we tested this hypothesis in the head-restrained monkey with the electrical microstimulation technique. More specifically, we studied the influence of duration, frequency, and current on the saccades elicited by fastigial stimulation and starting from a central (straight ahead) position. The results show ipsilateral or contralateral saccades whose amplitude and dynamics depend on the stimulation parameters. The duration and amplitude of their horizontal component increase with the duration of stimulation up to a maximum amplitude. Varying the stimulation frequency mostly changes their latency and the peak velocity (for contralateral saccades). Current also influences the metrics and dynamics of saccades: the horizontal amplitude and peak velocity increase with the intensity, whereas the latency decreases. The changes in peak velocity and in latency observed in contralateral saccades are not correlated. Finally, we discovered that contralateral saccades can be evoked at sites eliciting ipsilateral saccades when the stimulation frequency is reduced. However, their onset is timed not with the onset but with the offset of stimulation. These results corroborate the hypothesis that the fastigial projections toward the pontomedullary reticular formation (PMRF) participate in steering the saccade, whereas the fastigiocollicular projections contribute to the bilateral control of visual fixation. We propose that the cerebellar influence on saccade generation involves recruiting neurons and controlling the size of the active population in the PMRF.

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Section: Effect Of Current Intensitysupporting

confidence: 79%

Section: Neural Processes Leading To the Elicitation Of Contralateralmentioning

confidence: 99%

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confidence: 99%

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Cerebellar control of saccade dynamics: contribution of the fastigial oculomotor region

Quinet

Goffart

2015

Journal of Neurophysiology

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“…However, by analogy with the many experiments on amplitude adaptation, we suggest that the oculomotor cerebellum could also subserve the adaptation of saccade direction. Second, inactivation of the OMV (Kojima et al, 2010a) or the caudal fastigial nucleus (cFN) to which it projects (Goffart et al, 2004; Buzunov et al, 2013), affects the deceleration phase of saccades. Moreover, inactivation of the cFN affects the falling phase of the burst of abducens motoneurons (Kojima et al, 2014), which directly determines saccade deceleration.…”

Section: Discussionmentioning

confidence: 99%

Selective reward affects the rate of saccade adaptation

Kojima

Soetedjo

2017

Neuroscience

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In this study we tested whether a selective reward could affect the adaptation of saccadic eye movements in monkeys. We induced the adaptation of saccades by displacing the target of a horizontal saccade vertically as the eye moved toward it, thereby creating an apparent vertical dysmetria. The repeated upward target displacement caused the originally horizontal saccade to gradually deviate upward over the course of several hundred trials. We induced this directional adaptation in both right- and leftward saccades in every experiment (n=20). However, in half of the experiments (n=10), we rewarded monkeys only when they made leftward saccades and in the other half only for rightward saccades. The reaction time of saccades in the rewarded direction was shorter and we, like others, interpreted this change as a sign of the reward’s preferential effect in that direction. Saccades in the rewarded direction showed more rapid adaptation of their directions than did saccades in the non-rewarded direction, indicating that the selective reward increased the speed of saccade adaptation. The differences in adaptation speed were reflected in changes in saccade metrics, which were usually more noticeable in the deceleration phases of saccades than in their acceleration phases. Because previous studies have shown that the oculomotor cerebellum is involved with saccade deceleration and also participates in saccade adaptation, it is possible that selective reward could influence cerebellar plasticity.

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confidence: 99%

Cerebellar output encodes a corrective saccadic command (Commentary on Sun et al.)

Herzfeld

Shadmehr

2016

Eur J of Neuroscience

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The integrity of the cerebellum is critical for accurate eye movements. Disruption of neurons in either the cerebellar oculomotor vermis or its projections to the most medial output nucleus of the cerebellum, the caudal fastigial nucleus (cFN), results in significant saccadic dysmetria (Ritchie, 1976;Ohtsuka et al., 1994;Goffart et al., 2004;Buzunov et al., 2013). The relationship between cFN neuron firing rates and saccade kinematic parameters is quite variable across neurons (Hepp et al., 1982;Fuchs et al., 1993), suggesting that a direct encoding of saccade parameters may not occur in the responses of individual neurons of cFN. However, previous studies have generally agreed that saccaderelated cFN neurons tend to fire earlier for horizontal saccades made in the contraversive vs. ipsiversive directions (Ohtsuka & Noda, 1991;Fuchs et al., 1993;Helmchen & B€ uttner, 1995;Kleine et al., 2003).Taken together, these results have led to the hypothesis that saccade properties are related to the timing of responses in cFN rather than response magnitude. Under this hypothesis, neurons should fire early for contraversive saccades, helping to accelerate the eye, whereas the delayed firing of ipsiversive neurons serves to decelerate and stop the eye at saccade termination. However, new data reported by Sun et al. (2016) call this view into question.Sun and colleagues recorded single-unit cFN neuron activity while primates made saccades of various magnitudes. These saccades included very small saccades, made during periods of fixation (microsaccades), as well as larger magnitude goal-directed saccades to peripheral targets. Their results suggest that cFN neuron responses exist on a continuum between these two types of saccades. That is, micro-and macrosaccades likely share common neural mechanisms of generation. Therefore, the responses of cFN neurons can be interpreted similarly across a large range of saccadic amplitudes (e.g. 0.5-15°).The duration of a typical saccade is on the order of 60 ms. Taking advantage of the temporally short nature of saccades, Sun et al. combined the responses of individual cFN neurons recorded across different sessions to yield an estimate of the firing of a population of simultaneously recorded neurons. This population response represents an estimate of the combined response of all saccade-related cFN neurons during a saccade. Strikingly, the timing of the population response did not occur earlier for contraversive compared to ipsiversive saccades, as would be anticipated by previous single-unit studies. Rather, both directions of saccades resulted in a population response that preceded the start of the saccade, and began at approximately the same time. How can these two deep nuclei be involved in saccade acceleration and deceleration when the timing of the responses to contraversive and ipsiversive saccades are not different?We recently suggested that populations of Purkinje cells (P-cells) in the oculomotor vermis (OMV) of the cerebellum encode the velocity and direction of an impending e...

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When during horizontal saccades in monkey does cerebellar output affect movement?

Cited by 24 publications

References 22 publications

Cerebellar control of saccade dynamics: contribution of the fastigial oculomotor region

Cerebellar control of saccade dynamics: contribution of the fastigial oculomotor region

Selective reward affects the rate of saccade adaptation

Cerebellar output encodes a corrective saccadic command (Commentary on Sun et al.)

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