The torque-angle transfer function of the human eye

Thomas, Jan Peter

doi:10.1007/bf00288556

Cited by 29 publications

(4 citation statements)

References 12 publications

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“…The difference in the time course of horizontal and vertical saccades, which may be seen in Fig. 3, is attributed to the stiffer elasticity of the horizontal recti muscles compared with the composite stiffness of the four muscles which are involved in vertical eye rotations (Thomas, 1967).…”

Section: Discussionmentioning

confidence: 99%

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The dynamics of small saccadic eye movements

Thomas¹

1969

The Journal of Physiology

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SUMMARY1. The mechanical characteristics of the system comprising the eyeball and its attachments have been determined, by applying rotational forces to the eyeball, and using an accelerometer on a contact lens to measure the resulting movement.2. The angular acceleration-versus-time curves of small saccades have been recorded. Some of these saccades are made whilst the eye is being vibrated by external forces.3. A mechanical model of the orbital system has been formulated. This is considered to bear a relationship to the structures in the orbit. 4. The model has been used to deduce the force pattern of the active component in the extraocular muscles during the execution of a saccade. It is concluded that a saccade is initiated by a rapid rise of tension. After a short time, the tension falls to a lower level, which is the new steady-state level. The present findings are therefore basically different from those of previous workers, in that we deduce a change in the force pattern during the course of the movement.5. In the execution of saccades of various sizes, both the strength and duration of the brief heightened tension are found to vary. For a 4 degree saccade, the transient tension is approximately 36 g, lasting for approxi-

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Section: Discussionmentioning

confidence: 99%

“…In the first experiment, the results of which have been reported elsewhere (Thomas, 1967), the mechanical characteristics of the system comprising the eyeball and its attachments have been measured. The subject lies supine, and his head is fixed by means of a dental impression bite-bar.…”

Section: Methodsmentioning

confidence: 99%

The dynamics of small saccadic eye movements

Thomas¹

1969

The Journal of Physiology

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“…This step response indicates that the system appears to be largely overdamped. The small fast motion has been investigated by applying sinusoidal forces to a contact lens on the eye (17) and demonstrating that the inertia J resonates with a stiff spring (thought to be the series elastic component) at 35 hertz with a damping factor of 0.5. Theoretical studies (18) suggest that the principal source of viscosity, which constitutes the greatest mechanical impedance to rapid movements, resides in the force-velocity relationship of muscle itself.…”

Section: The Final Common Pathmentioning

confidence: 99%

Eye Movement Control in Primates

Robinson

1968

Science

222

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“…It has been demonstrated by Robinson (1973) that eqn (2) which describes motoneurone behaviour reflects the relationship between muscle force and eye position, and that the ratio r/lk corresponds to a dominant time constant of mechanical characteristics in the orbit, although the peripheral mechanics is more correctly described by higher-order equation with nonlinearities (Robinson, 1964; Thomas, 1967;Cook & Stark, 1968). In the monkey, firing rate of motoneurones during saccades tends to saturate and the relationship with instantaneous eye velocity is less linear than that in the cat.…”

Section: Abducens Motoneuronesmentioning

confidence: 99%

Neural correlates of horizontal vestibulo‐ocular reflex cancellation during rapid eye movements in the cat.

Berthoz¹,

Droulez²,

Vidal³

et al. 1989

The Journal of Physiology

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SUMMARY1. The aim of the present study is to describe the behaviour of identified secondorder vestibular neurones in the alert cat during eye saccades. A selection of neurones which are involved in horizontal eye movements has been made. The activity has been compared with a selected sample of abducens motoneurones recorded in the same animals.2. Alert head-fixed cats were used for this study. Eye movements were recorded by the scleral search coil technique. Abducens motoneurones were identified by antidromic stimulation from the VIth nerve with chronically implanted electrodes.They were recorded extracellularly. 3. Second-order vestibular neurones were identified by orthodromic stimulation from the vestibular organs. They were recorded intra-axonally and injected with horseradish peroxidase after recording of their physiological characteristics. Their morphology was reconstructed from frozen sections.4. All the recorded vestibular neurones showed various amounts of eye position sensitivity. The firing rate (F) -horizontal eye position (H) characteristics are compared for abducens and vestibular neurones. The population average values are F = 33 + 4 H for motoneurones and F = 51 + 2-4 H for vestibular neurones.5. All recorded vestibular neurones showed an increase of discharge rate during contralateral horizontal saccades and a strong decrease or pause during ipsilateral saccades. Firing rate -horizontal eye velocity sensitivity has been calculated.6. Results suggest a strong inhibitory input on vestibular neurones from the saccadic generator. This mechanism underlies the suppression of the vestibulo-ocular reflex during saccades. Our results suggest that in the cat, for saccades of amplitude smaller than 20 deg, there is a variable degree of suppression which is provided by a projection of excitatory bursters (EBNs) on second-order vestibular neurones through inhibitory type II neurones.7. We also conclude from this study that the eye position sensitivity of vestibular second-order neurones is in fact a motor signal indicating a motor error, i.e. the amount of head or eye movement which remains to be done in order to align gaze on target with the eyes centred in the orbit.

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The torque-angle transfer function of the human eye

Cited by 29 publications

References 12 publications

The dynamics of small saccadic eye movements

The dynamics of small saccadic eye movements

Eye Movement Control in Primates

Neural correlates of horizontal vestibulo‐ocular reflex cancellation during rapid eye movements in the cat.

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