Two-dimensional neural network model of the primate saccadic system

Arai, Kuniharu; Keller, Edward L.; Edelman, Jay A.

doi:10.1016/s0893-6080(05)80162-5

Cited by 109 publications

(111 citation statements)

References 38 publications

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“…SGI has been proposed as a site for this competition, because it spatially encodes the loci of these multiple objects (Basso and Wurtz, 1998) and generates a spatially encoded output that commands a gaze shift toward the selected target (Sparks, 1978;Anderson et al, 1998). Some models propose that inputs to SGI encoding stimulus location combine with local recurrent excitation to increase local activity to a threshold for a command, whereas widespread inhibition originating at this locus attenuates the activity of distant cells that otherwise might command undesired movements (Van Opstal and Van Gisbergen, 1989;Arai et al, 1994;Das et al, 1996). Our objective was to test this model.…”

Section: Discussionmentioning

confidence: 99%

“…The spatial coding of saccade vectors suggests that stimuli in different parts of the visual field will simultaneously activate multiple ensembles of command cells, which compete for control of the oculomotor system (Didday, 1976;Arai et al, 1994). Some models (Van Opstal and Van Gisbergen, 1989;Arai et al, 1994;Das et al, 1996) propose that the competition is mediated by short-range excitatory connections that build up the activity of neurons in one region to the command threshold required for an orienting movement and by wide-ranging inhibitory projections that attenuate activity in other regions that might otherwise command undesired movements.…”

Section: Introductionmentioning

confidence: 99%

“…Some models (Van Opstal and Van Gisbergen, 1989;Arai et al, 1994;Das et al, 1996) propose that the competition is mediated by short-range excitatory connections that build up the activity of neurons in one region to the command threshold required for an orienting movement and by wide-ranging inhibitory projections that attenuate activity in other regions that might otherwise command undesired movements.…”

Section: Introductionmentioning

confidence: 99%

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AnIn VitroStudy of Horizontal Connections in the Intermediate Layer of the Superior Colliculus

Lee

Hall²

2006

J. Neurosci.

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Some models propose that the spatial and temporal distributions of premotor activity in the intermediate layer of the superior colliculus are shaped by neuronal ensembles that give rise to local excitatory and distant inhibitory connections. One function proposed for these connections is to mediate a "winner-take-all" network; the short-range excitatory connections build up the activity of neighboring cells that command orienting movements in one direction, whereas the wide-ranging inhibitory projections attenuate the activity of remote cells that command incompatible movements. We used in vitro photostimulation and whole-cell patch-clamp recording to test these models by measuring the spatial extent of synaptic interactions within the rat intermediate layer.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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AnIn VitroStudy of Horizontal Connections in the Intermediate Layer of the Superior Colliculus

Lee

Hall²

2006

J. Neurosci.

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“…A within-SC mechanism is supported by collicular microstimulation experiments that induce nearby excitation (McIlwain, 1982) and distant inhibition (Meredith and Ramoa, 1998;Munoz and Istvan, 1998) as recorded within the SC. Moreover, local competitive integration mechanism has been the foundation of a number of successful models of SC-mediated saccade generation (Van Opstal and Van Gisbergen, 1989;Arai et al, 1994;Trappenberg et al, 2001). An extrinsic SC mechanism is supported by in vitro rodent work combining photostimulation using caged glutamate and whole-cell patch-clamp recordings (Ozen et al, 2004;Lee and Hall, 2006).…”

Section: A Causal Role Of the Sc In Saccade Selectionmentioning

confidence: 99%

Competitive Integration of Visual and Preparatory Signals in the Superior Colliculus during Saccadic Programming

Dorris

Olivier²,

Munoz³

2007

J. Neurosci.

144

128

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Efficient behavior requires that internally specified motor plans be integrated with incoming sensory information. Motor preparation and visual signals converge in the intermediate and deep layers of the superior colliculus (SC) to influence saccade planning and execution; however, the mechanism by which these sometimes conflicting signals are combined remains unclear. We studied this issue by presenting visual distractors as monkeys prepared saccades toward an upcoming target whose timing and location were fully predictable. Monkeys made more distractor-directed errors when the spatial location of visual distractors more closely coincided with the saccadic goal. Concomitant pretarget activity of SC visuomotor neurons, whose response fields were centered on the saccadic goal, was similarly increased by the presentation of nearby distractors and inhibited by the presentation of distant distractors. Finally, subthreshold microstimulation of the SC shifted the pattern of distractor-directed errors away from the saccadic goal toward that specified by the site of stimulation. Together, our results suggest that the likelihood of saccade generation is influenced by the spatial register of internal motor preparation signals and external sensory signals across the topographically organized SC map.

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“…1A). Studies associated with averaging saccades (Arai et al 1994;Glimcher and Sparks 1993) and the SC role in spatial feedback control (Anderson et al 1998) have relied on this sequence to decode the saccade vector.The primary objective of this study was to address the order in which the two operations are implemented. It should be emphasized that our focus is not to address the specific decoding algorithm.…”

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confidence: 99%

Order of operations for decoding superior colliculus activity for saccade generation

Katnani

Gandhi²

2011

Journal of Neurophysiology

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Katnani HA, Gandhi NJ. Order of operations for decoding superior colliculus activity for saccade generation. J Neurophysiol 106: 1250-1259, 2011. First published June 15, 2011 doi:10.1152/jn.00265.2011To help understand the order of events that occurs when generating saccades, we simulated and tested two commonly stated decoding models that are believed to occur in the oculomotor system: vector averaging (VA) and center-of-mass. To generate accurate saccades, each model incorporates two required criteria: 1) a decoding mechanism that deciphers a population response of the superior colliculus (SC) and 2) an exponential transformation that converts the saccade vector into visual coordinates. The order of these two criteria is used differently within each model, yet the significance of the sequence has not been quantified. To distinguish between each decoding sequence and hence, to determine the order of events necessary to generate accurate saccades, we simulated the two models. Distinguishable predictions were obtained when two simultaneous motor commands are processed by each model. Experimental tests of the models were performed by observing the distribution of endpoints of saccades evoked by weighted, simultaneous microstimulation of two SC sites. The data were consistent with the predictions of the VA model, in which exponential transformation precedes the decoding computation.sequence of decoding; dual microstimulation; vector averaging; vector summation; center-of-mass THE SUPERIOR COLLICULUS (SC) is a critical, subcortical hub that plays a major role in converting sensory information into a motor command for saccade generation (Gandhi and Katnani 2011;Sparks 1986). Visual information in the SC is organized topographically in a logarithmic manner. A disproportionately large amount of SC tissue is allocated for (para-) foveal space and small-amplitude saccades, whereas a compressed region is attributed for the visual periphery and large-amplitude saccades (Cynader and Berman 1972;Robinson 1972). With the presentation of a stimulus, a population of neurons becomes active at a locus that represents the vector between the stimuli and line of sight (Wurtz and Goldberg 1972). Under ordinary circumstances, a comparable population discharges a highfrequency premotor burst to produce a saccade of the appropriate displacement (Sparks et al. 1976). To make certain that the saccadic eye movement lands near the desired location, two critical operations must be performed. One, the population response must be decoded using standard decoding mechanisms such as averaging or summation. Two, the SC output must undergo an exponential transformation to convert the saccade vector into visual coordinates (Ottes et al. 1986), the inverse transformation used to map visual space into SC coordinates. Studies have implemented the order of these two operations in different fashions. To the best of our knowledge, no attempt has been made to distinguish the order of these operations.In one scheme, the exponential transformation is applie...

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Two-dimensional neural network model of the primate saccadic system

Cited by 109 publications

References 38 publications

AnIn VitroStudy of Horizontal Connections in the Intermediate Layer of the Superior Colliculus

AnIn VitroStudy of Horizontal Connections in the Intermediate Layer of the Superior Colliculus

Competitive Integration of Visual and Preparatory Signals in the Superior Colliculus during Saccadic Programming

Order of operations for decoding superior colliculus activity for saccade generation

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