Neural network simulations of the primate oculomotor system III. An one-dimensional, one-directional model of the superior colliculus

Bozis, A.; Moschovakis, Adonis

doi:10.1007/s004220050472

Cited by 57 publications

(50 citation statements)

References 86 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous modeling studies have suggested that the effects of SC lesions on saccade metrics can also be reconciled with linear vector summation when intracollicular interactions are incorporated (Badler and Keller 2002;Bozis and Moschovakis 1998;. How SC inputs and intracollicular interactions may shape the SC movement fields, and thereby the SC population activity, is beyond the scope of this study.…”

Section: Effects Of Sc Lesionsmentioning

confidence: 96%

“…Note, however, that vector averaging is a nonlinear operation for which it is not obvious how it could be achieved through fixed connections between the SC and the brain stem (Badler and Keller 2002;Bozis and Moschovakis 1998;Groh 2001;. Moreover, the vector-averaging premise for the spatial-to-temporal transformation does not account for the "stretching" of horizontal and vertical saccade components that is needed to obtain straight oblique saccades.…”

Section: Earlier Theories and Controversiesmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic Ensemble Coding of Saccades in the Monkey Superior Colliculus

Goossens

Opstal²

2006

Journal of Neurophysiology

225

View full text Add to dashboard Cite

. The deeper layers of the midbrain superior colliculus (SC) contain a topographic motor map in which a localized population of cells is recruited for each saccade, but how the brain stem decodes the dynamic SC output is unclear. Here we analyze saccade-related responses in the monkey SC to test a new dynamic ensemble-coding model, which proposes that each spike from each saccade-related SC neuron adds a fixed, site-specific contribution to the intended eye movement command. As predicted by this simple theory, we found that the cumulative number of spikes in the cell bursts is tightly related to the displacement of the eye along the ideal straight trajectory, both for normal saccades and for strongly curved, blink-perturbed saccades toward a single visual target. This dynamic relation depends systematically on the metrics of the saccade displacement vector, and can be fully predicted from a quantitative description of the cell's classical movement field. Furthermore, we show that a linear feedback model of the brain stem, which is driven by dynamic linear vector summation of measured SC firing patterns, produces realistic two-dimensional (2D) saccade trajectories and kinematics. We conclude that the SC may act as a nonlinear, vectorial saccade generator that programs an optimal straight eye-movement trajectory. I N T R O D U C T I O NThe midbrain superior colliculus (SC) is a sensorimotor interface that is critically involved in the control of rapid gaze shifts. An important problem in understanding its role in gaze control is how the spatial distribution of movement-related activity in its motor map is ultimately transformed into the temporal code carried by motor neurons (Sparks and HartwichYoung 1989). In this study, we analyzed saccade-related responses in the monkey SC to test a new theoretical framework for the involvement of the SC in the generation of saccades in two dimensions (2D). First, we present a novel analysis of SC spike trains that provides evidence for dynamic vector summation of movement contributions provided by each spike of each cell in the active population. We then analyze the spatialtemporal distribution of SC activity. The results are used to test the predictions and emerging properties of our new ensemblecoding theory, which assumes dynamic, linear decoding of the SC population activity by the brain stem saccade generator. Finally, we propose and test a new quantitative description of dynamic SC movement fields that is implied by our theory. In what follows, we first explain why a new approach is called for by highlighting the main findings that have led to several controversies. These controversies include 1) static versus dynamic involvement of the SC, 2) vector summation versus vector averaging of the population activity, and 3) feedforward versus feedback involvement of the SC. Earlier theories and controversies

show abstract

Section: Effects Of Sc Lesionsmentioning

confidence: 96%

Section: Earlier Theories and Controversiesmentioning

confidence: 99%

Dynamic Ensemble Coding of Saccades in the Monkey Superior Colliculus

Goossens

Opstal²

2006

Journal of Neurophysiology

225

View full text Add to dashboard Cite

show abstract

“…The result is often an "averaging saccade," which lands somewhere in between the spatial locations of the two visual targets (see Chou et al 1999 for a summary of results in this area). Collicular maps with local excitation and longer-range lateral inhibition predict that the two loci of activity generated by the visual stimuli will inhibit each other, but both will excite the locus on the map between the two regions of visual activation (Van Opstal and Van Gisbergen 1989;Arai et al 1994;Das et al 1996;Bozis and Moschovakis 1998). The result will be that these two loci of SC activity will coalesce into a single active site located between the original two.…”

Section: Introductionmentioning

confidence: 92%

“…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%

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

Arai

Keller

2004

Biol Cybern

View full text Add to dashboard Cite

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.

show abstract

“…Models of the SC in saccade generation have been developed primarily using single-point visual stimulation (Lee et al, 1988;Van Opstal and Van Gisbergen, 1989;McIlwain, 1991;Arai et al, 1993aArai et al, ,b, 1994Van Opstal and Kappen, 1993;Das et al, 1996;Bozis and Moschovakis, 1998;Quaia et al, 1998Quaia et al, , 1999. Based on the well known fact that individual saccades are associated with a large population of active SC neurons (Schiller and Koerner, 1971;Wurtz and Goldberg, 1972;Sparks et al, 1976;Sparks and Mays, 1980;Munoz and Wurtz, 1995) and that there are excitatory connections linking large regions of the SC (McIlwain, 1982), the models fall into the general class of distributed coding models (Lee et al, 1988;McIlwain, 1991;Quaia et al, 1998Quaia et al, , 1999.…”

Section: Implications For Population Coding In Scmentioning

confidence: 99%

Competitive Stimulus Interactions within Single Response Fields of Superior Colliculus Neurons

Li¹,

Basso²

2005

J. Neurosci.

View full text Add to dashboard Cite

In addition to its role in saccade generation, the superior colliculus (SC) is involved in target selection, saccade selection, and shifting the focus of spatial attention. Here, we investigated the influence of saccade selection on sensory interactions within single response fields (RFs) of SC neurons. One or two differently shaped stimuli were presented within single RFs of SC neurons, and the shape of a centrally located cue indicated whether and where to make a saccade (Go-Go) or whether to make or withhold a saccade (Go/No-Go). We found that, when two stimuli appeared at different locations within a single RF, SC neuronal activity was reduced compared with when a single stimulus appeared in isolation within the center of the RF in both the Go-Go and Go/No-Go tasks. In both tasks, a subsequent cue indicating one stimulus as a saccade target reduced the influence of the second stimulus located within the RF. We found that the time course of the suppression resulting from the two stimuli was ϳ130 ms, a time close to that seen in cortex. Finally, we found that the influence of two stimuli within single RFs of SC neurons changed over time in both the Go-Go and the Go/No-Go tasks. Initially, the neurons averaged the influence of two stimuli. As the trial progressed, the SC neurons signaled only the saccade vector that was produced. We conclude that cues to shift gaze, like attention, modulate the influence of sensory interactions, providing additional support for the linkage between attention and saccade selection.

show abstract

Neural network simulations of the primate oculomotor system III. An one-dimensional, one-directional model of the superior colliculus

Cited by 57 publications

References 86 publications

Dynamic Ensemble Coding of Saccades in the Monkey Superior Colliculus

Dynamic Ensemble Coding of Saccades in the Monkey Superior Colliculus

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

Competitive Stimulus Interactions within Single Response Fields of Superior Colliculus Neurons

Contact Info

Product

Resources

About