First neurophysiological approach to the retino-tectal projections inDiscoglossus pictus (Anura)

Gaillard, Françoise; García, R. Ortiz; Roussel, H.

doi:10.1007/bf00612509

Cited by 4 publications

(1 citation statement)

References 22 publications

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“…This guarantees 439 a single trigger location at the point of the strongest input in the case that several excitations unequal in strength occur. Actually, this leads to a dominance of the contralateral visual input which in the salamander brain is generally stronger than the ipsilateral one (Gaillard et al 1988;Manteuffel et al 1989). When the sensorimotor threshold element and the sensory lateral inhibition mechanism are eliminated by direct electrical stimulation of the premotor efferents applied with the same strength at different locations, this will produce an intermediate saccadic metrics in our model.…”

Section: E(x Y) = ~ ~ A= (A~ ~R (A: V) D~c D~r mentioning

confidence: 96%

A model of the saccadic sensorimotor system of salamanders

Manteuffel

Roth

1993

Biol. Cybern.

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A model of the saccadic system of salamanders on the basis of electrophysiological and anatomical results is presented. The model includes centers found to be significant for the guidance of saccades in these comparatively simple vertebrates. In particular, these are the optic tectum, the bulbar reticular formation and the motor system. The latter consists of two pairs of neck-muscles, an epaxial and a hypaxial one driven by their respective motoneurons. The model includes a visual, a sensori-motor, and a motor level. At the sensory level, the retinal coordinates are transferred to the optic tectum to establish an orthogonal map of visual angles. A secondary visual map of the ipsilateral eye with a pointsymmetrical organization exists in addition. The premotor system of the tectum was modelled according to an ensemble-coding principle. Thus, local activation of the visual map results in recruitment of an appropriate number of tectal premotor units. Simulation of the model reproduces correct metric properties of salamander saccades under varying stimulus presentations.

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Section: E(x Y) = ~ ~ A= (A~ ~R (A: V) D~c D~r mentioning

confidence: 96%

A model of the saccadic sensorimotor system of salamanders

Manteuffel

Roth

1993

Biol. Cybern.

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Topographic relationships of ipsi- and contralateral visual inputs to the rostral tectum opticum in the salamander Plethodon jordani indicate the presence of a horopter

Manteuffel

Fox

Roth

1989

Neuroscience Letters

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Quantitative stimulus-response studies on sustained ganglion cells in the frog retina

García

Gaillard

1989

Vis Neurosci

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Abstract“Sustained” visual units, i.e. nonerasable (R1) and erasable (R2) units as commonly described, were recorded in the superficial layers of the rostral optic tectum of Rana esculenta and their neuronal activity (expressed as the mean firing frequency ) was quantitatively analyzed The mean value of the exponent α of the velocity function of the erasable R1 units was found to be 0.46 and the constant k to be about 24.7. The optimal stimulus diameter was equal to 2.6 deg. For the whole population of the erasable units, the exponent α was found to be between 0.36–0.75 (mean value ≈ 0.56, i.e. largely different from the values currently reported for such units) and was independent of the stimulus diameter (D = 0.6–6 deg). However, the constant k of the velocity function (range: 8.2–37.7) varied with D. Most of the erasable units (called “mixed R1-R2” units) therefore showed an R1-type velocity function with an exponent α ≈ 0.5 and a constant k ≈ 25 but reacted to other parameters as did “typical” R2 units: (i) their neuronal response was related to the stimulus diameter by a logarithmic function with a maximum obtained for D = 2.4 deg; and (ii) a variation of about 4–17% on either side of the average value of was observed, independent either of the stimulus velocity or of the diameter of the stimulus. Results are compared to known quantitative data, and the use of stimulus-response relationships as a tool for classification is discussed.

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First neurophysiological approach to the retino-tectal projections inDiscoglossus pictus (Anura)

Cited by 4 publications

References 22 publications

A model of the saccadic sensorimotor system of salamanders

A model of the saccadic sensorimotor system of salamanders

Topographic relationships of ipsi- and contralateral visual inputs to the rostral tectum opticum in the salamander Plethodon jordani indicate the presence of a horopter

Quantitative stimulus-response studies on sustained ganglion cells in the frog retina

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