A distributed model of the saccade system: simulations of temporally perturbed saccades using position and velocity feedback

Arai, Kuniharu; Das, Sanjoy; Keller, Edward L.; Aiyoshi, Eitaro

doi:10.1016/s0893-6080(99)00077-5

Cited by 42 publications

(47 citation statements)

References 35 publications

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“…The details of the colliculus-only network have been published (Arai et al 1999), so we provide only a brief explanation of its connectivity and operation here. The SC network shown in Fig.…”

Section: Two-dimensional Distributed Saccade Modelmentioning

confidence: 99%

“…As described in the introduction, the previously optimized intracollicular connection matrix (W), which included local excitatory weights and extensive long-range inhibitory weights, was modified to include only shortrange lateral inhibitory interconnections. The pattern of the local excitatory connections used was the same as previously reported (Arai et al 1999). Values of the modified intracollicular connections as a function of space (distance between two units) on the SC map were set to [0.48, 0.29, 0.30, 0.05, −0.30, 0, 0, 0, 0, 0, 0] for distances between two units [0,1,2,3,4,5,6,7,8,9,10].…”

Section: Figmentioning

confidence: 99%

“…In a previous paper (Arai et al 1999) we modeled the known inhibitory input to the SC from the SNr as a global signal that was turned off just before saccade onset, leaving distributed activity in the model SC to be governed entirely by intracollicular connections and inhibitory feedback from the SBGs. In the present paper we use a more realistic representation of the perisaccadic signal input to the SC from the SNr.…”

Section: Figmentioning

confidence: 99%

“…Previous distributed models of the saccadic system have used lateral inhibitory connections within the superior colliculus (SC) to insure that only a single locus of activity is present on the collicular motor map by the time of saccade onset (Van Opstal and Van Gisbergen 1989;Arai et al 1994;Optican 1994;Massone and Khoshaba 1995;Grossberg et al 1997;Bozis and Moschovakis 1998;Arai et al 1999;Badler and Keller 2002). This type of behavior on a neural map is called winner-take-all.…”

Section: Introductionmentioning

confidence: 99%

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A model of the saccade-generating system that accounts for trajectory variations produced by competing visual stimuli

Arai

Keller

2004

Biol Cybern

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Variable saccade trajectories are produced in visual search paradigms in which multiple potential target stimuli are present. These variable trajectories provide a rich source of information that may lead to a deeper understanding of the basic control mechanisms of the saccadic system. We have used published behavioral observations and neural recordings in the superior colliculus (SC), gathered in monkeys performing visual search paradigms, to guide the construction of a new distributed model of the saccadic system. The new model can account for many of the variations in saccade trajectory produced by the appearance of multiple visual stimuli in a search paradigm. The model uses distributed feedback about current eye motion from the brainstem to the SC to reduce activity there at physiologically realistic rates during saccades. The long-range lateral inhibitory connections between SC cells used in previous models have been eliminated to match recent physiological evidence. The model features interactions between visually activated multiple populations of cells in the SC and distributed and topologically organized inhibitory input to the SC from the SNr to produce some of the types of variable saccadic trajectories, including slightly curved and averaging saccades, observed in visual search tasks. The distributed perisaccadic disinhibition of SC from the substantia nigra (SNr) is assumed to have broad spatial tuning. In order to produce the strongly curved saccades occasionally recorded in visual search, the existence of a parallel input to the saccadic burst generators in addition to that provided by the distributed input from the SC is required. The spatiotemporal form of this additional parallel input is computed based on the assumption that the input from the model SC is realistic. In accordance with other recent models, it is assumed that the parallel input comes from the cerebellum, but our model predicts that the parallel input is delayed during highly curved saccadic trajectories.

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Section: Two-dimensional Distributed Saccade Modelmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A model of the saccade-generating system that accounts for trajectory variations produced by competing visual stimuli

Arai

Keller

2004

Biol Cybern

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“…The SRBN resumed its burst ϳ6 ms after the stimulation ceased and before the saccade resumed. One possible explanation of these data is that the SC receives both negative velocity and position feedback from downstream EBNs to help restart its activity because the saccade has not been completed (Arai et al 1999). However, this experiment does not rule out the possibility that the saccade is restarted by more central structures (e.g., the frontal eye fields) or by networks internal to the SC.…”

Section: Introductionmentioning

confidence: 99%

Evidence That the Superior Colliculus Participates in the Feedback Control of Saccadic Eye Movements

Soetedjo

Kaneko

Fuchs

2002

Journal of Neurophysiology

129

102

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There is general agreement that saccades are guided to their targets by means of a motor error signal, which is produced by a local feedback circuit that calculates the difference between desired saccadic amplitude and an internal copy of actual saccadic amplitude. Although the superior colliculus (SC) is thought to provide the desired saccadic amplitude signal, it is unclear whether the SC resides in the feedback loop. To test this possibility, we injected muscimol into the brain stem region containing omnipause neurons (OPNs) to slow saccades and then determined whether the firing of neurons at different sites in the SC was altered. In 14 experiments, we produced saccadic slowing while simultaneously recording the activity of a single SC neuron. Eleven of the 14 neurons were saccade-related burst neurons (SRBNs), which discharged their most vigorous burst for saccades with an optimal amplitude and direction (optimal vector). The optimal directions for the 11 SRBNs ranged from nearly horizontal to nearly vertical, with optimal amplitudes between 4 and 17°. Although muscimol injections into the OPN region produced little change in the optimal vector, they did increase mean saccade duration by 25 to 192.8% and decrease mean saccade peak velocity by 20.5 to 69.8%. For optimal vector saccades, both the acceleration and deceleration phases increased in duration. However, during 10 of 14 experiments, the duration of deceleration increased as fast as or faster than that of acceleration as saccade duration increased, indicating that most of the increase in duration occurred during the deceleration phase. SRBNs in the SC changed their burst duration and firing rate concomitantly with changes in saccadic duration and velocity, respectively. All SRBNs showed a robust increase in burst duration as saccadic duration increased. Five of 11 SRBNs also exhibited a decrease in burst peak firing rate as saccadic velocity decreased. On average across the neurons, the number of spikes in the burst was constant. There was no consistent change in the discharge of the three SC neurons that did not exhibit bursts with saccades. Our data show that the SC receives feedback from downstream saccade-related neurons about the ongoing saccades. However, the changes in SC firing produced in our study do not suggest that the feedback is involved with producing motor error. Instead, the feedback seems to be involved with regulating the duration of the discharge of SRBNs so that the desired saccadic amplitude signal remains present throughout the saccade.

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Abundance of Degrees of Freedom

Scudder

Mays

Tobin

et al. 2008

Encyclopedia of Neuroscience

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A distributed model of the saccade system: simulations of temporally perturbed saccades using position and velocity feedback

Cited by 42 publications

References 35 publications

A model of the saccade-generating system that accounts for trajectory variations produced by competing visual stimuli

A model of the saccade-generating system that accounts for trajectory variations produced by competing visual stimuli

Evidence That the Superior Colliculus Participates in the Feedback Control of Saccadic Eye Movements

Abundance of Degrees of Freedom

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