Optokinetic Drum Research Articles

Head movements during optokinetic stimulation in the alert rabbit.

Pigmented rabbits with their heads free to move about the vertical axis were seated inside a rotating optokinetic drum in order to evoke the optocollic reflex (OCR). At drum velocities below 5 degrees/s, head movements were inconsequential, and eye velocity generally matched drum velocity. At velocities between 5-15 degrees/s head movements were irregular and slight; head velocity was less than 20% of drum velocity, and gaze was undercompensatory by 1-3 degrees/s (retinal image motion of 1-3 degrees/s). At drum velocities above 15 degrees/s, and especially above 30 degrees/s, head movements were substantial (more than 20% of the drum velocity), but gaze was undercompensatory by 60-70% of the stimulus velocity. In the same rabbits in the same test periods and conditions, the vestibulo-collic reflex (VCR) was evoked with vision with minimal gaze undercompensation relative to a stationary surround; however, when deprived of vision the VCR gain dropped. The present results support the notion that with vision, the OCR does not contribute significantly to the improvement of the VCR response, since massive undercompensation of the gaze relative to the rotating drum was required in OCR testing to evoke head movements similar to those seen in VCR tests. Due to many differences in operating characteristics of the vestibular and optokinetic systems, and due to the nature of OCR testing, there were several unexpected results: in some cases head movements did not result in summation of vestibular and optokinetic reflexes, and with sinusoidal drum rotations of about 2 degrees/s2 peak acceleration there was overcompensation (gaze moves faster than the drum) for intervals up to 20 s. Thus, optokinetically generated active head movements could produce behavior strongly contrasting with passively induced head movements in visual-vestibular tests. It is tentatively concluded that in mammals there is a vestigial and specific optokinetic control of gaze and that the optokinetic control of the head is weak (relative to the eyes). However, other non-reflex mechanisms controlling head movements-such as stimulus entrainment and temporal asymmetries in the vestibular and optokinetic reflexes-must also be considered to explain all facets of the data.

25 AUDITORY AND VISUAL PRETERM DEVELOPMENT OF EXTREMELY OF PREMATURE INFANTS

Early auditory and visual responses were assessed in 47 premature infants with BW below 1300 gms born at Johns Hopkins Hospital in 1983. These extremely premature infants (67% were at or below 28 wks gestation) were assessed weekly, from 1 week until discharge, using a bell, light and optokinetic drum. All premature infants, from 25 wks postconceptional age (PCA) and beyond, had some response to the bell and light. The majority (>80%) habituated to the bell and light at their initial exam at one week of age. Optokinetic nystagmus (OKN) could be elicited as early as 30 wks PCA, and improved with increasing postconceptional age. Definite OKN was present in the majority of premature infants by 36 wks PCA, and was universally present by 40 wks PCA. No premature infant (even those at term) blinked in response to a visual threatening gesture. Alerting to the bell, blinking to light and habituation may be useful in assessing sensory abilities of the extremely premature infant below 30 wks PCA, whereas optokinetic nystagmus to the OKN drum is a more practical and objective measure of visual abilities of premature infants closer to term.

A light-weight, low-cost optokinetic drum

Optokinetic nystagmus (OKN), a periodic sawtooth movement of the eyes, is maximally elicited when a subject's entire visual field is moving. The most appropriate stimulus for the generation of OKN is an optokinetic drum that completely surrounds the subject. Such drums tend to be massive and can only be accelerated rapidly with a powerful motor. This report describes construction details of a drum designed especially to minimize moment of inertia and cost as well.

Interaction of substrate, gravity and visual cues in the control of compensatory eye responses in the spiny lobster,Palinurus vulgaris

1. The compensatory eyestalk movements ofPalinurus vulgaris have been measured in response to oscillations of the body, substrate and patterned visual surround about a body-parallel horizontal axis. The stimuli were delivered alone, and in fourteen different combinations (Fig. 2). 2. Responses are greatest (amplitude gain ca. 1.5) when the mechanical inputs, substrate and gravity, are combined synergistically (Fig. 3 a). The effect of the optokinetic stimulus is gain-limiting (Fig. 3b, c). 3. When analysed over a wide frequency range (0.001–0.4 Hz), substrate and optokinetic drum movements result in quite different response curves (Figs. 4a, c), combinations of these stimuli produce responses at an intermediate level when synergistic (Fig. 4b), but at a low level when antagonistic (Fig. 4d). 4. Turning the animal inside a stationary optokinetic drum, to produce synergistic action of vision and statocyst input, improves the compensatory response (Fig. 5: P8). 5. The threefold stimulus combination which simulates an external disturbance (condition 3, Fig. 2) elicits eye responses which are exactly compensatory at all frequencies tested (Fig. 6). 6. When the visual surround is devoid of pattern (but presents a gradient of light intensity, centred above) the eye response to substrate movement is attenuated (Fig. 7), whereas the gravity response is enhanced (Fig. 8). 7. Timing relationships display consistent phase advances with decreasing frequency (Fig. 9, Fig. 10). 8. These results are discussed in terms of the gain-limiting properties of the optokinetic system, and the action of a visual factor responsive to the vectorial component of the stimulating light.

Quantitative analysis of the human visual vestibulo-ocular reflex in sinusoidal rotation.

In order to investigate interaction of the vestibular and optokinetic system, a visual vestibulo-ocular reflex (V-VOR) gain in forty-five normal subjects was measured by manual and computer analysis. The test subjects sat in a newly devised, pendular rotating chair in an optokinetic drum. With this device pendular harmonic sinusoidal rotation and optokinetic stimuli could be given simultaneously. The test subjects were rotated sinusoidally at amplitudes of 120 degrees and 240 degrees and at frequencies of 0.05 Hz and 0.1 Hz (maximum velocities 18.8 degrees/s, 37.7 degrees/s, 75.4 degrees/s), and with eyes closed and open. Within these pendular stimuli, there was no response decline phenomenon nor influence of amplitude on frequency. The pure VOR gain measured in dark room with eyes open was about 0.6 and did not vary with the eyes closed as long as mental alertness was maintained. The V-VOR gain in a stationary optokinetic drum with eyes open was about 1.1. From our observations, the 0.1 Hz sinusoidal rotation with an amplitude of 240 degrees (maximum velocity, 75.4 degrees/s) is an appropriate stimulation for the V-VOR and VOR test battery in clinical practice.

Cervico-vestibular and visuo-vestibular interaction. Self-motion perception, nystagmus, and gaze shift.

In 8 healthy subjects we studied self-motion perception and nystagmus due to sinusoidal stimulation (amplitude 90 degrees peak to peak, frequency 0.05 Hz) of the horizontal semicircular canals, the cervical proprioceptors, and the retina. We used an electrically driven rotatory chair and optokinetic drum combination. For cervical stimulation the subject's head was placed in a clamp, attached to the drum. Eye movements were recorded by means of electrooculography, d.c. amplification. Subjects signalled the estimated head position by means of a 'joystick'. In the present series of experiments the vestibular and cervical informations were played off against each other in combined stimulation conditions with an interstimulus phase lag of 0 to 315 degrees, in steps of 45 degrees. Similarly, the vestibular and visual informations were played off against each other. Concerning estimated head position, our main finding is that both the visually and the cervically induced illusion of head rotation overrule the vestibular sensation of head motion. The ocular response to combined vestibular plus cervical stimulation shows that both nystagmus slow phases and saccades of the cervical and the vestibular responses add up by vectorial summation.

The variable gain element of the vestibulo-ocular reflex is common to the optokinetic system of the cat

The gain (slow-phase eye velocity/head velocity) of the vestibulo-ocular reflex (VOR) of 6 alert cats was sequentially adapted to values between 0.2 and 1.66 by the chronic wearing of visual reversing or 2 X magnifying spectacles, combined with forced rotation in the light. Gain was measured during sinusoidal oscillation in darkness at 0.05 Hz at a peak velocity of about 30 degrees/s. In each state of VOR gain adaptation, optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN) were measured in a full-field optokinetic drum at velocities of 20-80 degrees/s. Steady-state, slow-phase, optokinetic eye velocity nearly equaled low drum velocities, but saturated at higher velocities and declined when drum velocity further increased. The saturation velocity varied in relation to VOR gain, ranging from 10-20 degrees/s at a VOR gain of 0.2-0.4, to 65 degrees/s at a VOR gain of 1.66. The means that the variable gain element of the VOR is shared by the optokinetic system (OKS). OKAN, measured in darkness, had a roughly exponential decay. The time constant of OKAN (Tokan) also varied with VOR gain, ranging form about 2 s at a VOR gain of 0.2, to 10 s at a VOR gain of 1.66. This is a novel finding which suggests that the velocity-storage mechanism was also affected by gain changes. A model is proposed in which a neural, variable-gain element is located in a positive-feedback, velocity-storage loop common to both the VOR and the OKS. Computer simulation showed that this hypothesis could account for most of the observed changes in OKN saturation and Tokan with changes in VOR gain. The model also predicts that low frequency VOR phase lead in darkness should increase with decreasing VOR gain. Experimental VOR phase lead at 0.05 Hz varied from about 10 degrees for VOR gains above 1.1 to about 50 degrees for VOR gains below 0.3. Such phase-lead data agree with the trend predicted by the model.

Optokinetic nystagmus in the pigeon (Columba livia). I. Study in monocular and binocular vision.

A study of optokinetic nystagmus (OKN) as produced by monocular or binocular stimulation was carried out in the pigeon. Nystagmus was provoked by constant speed rotation (13 or 36 °/s) of an optokinetic drum lined with alternate black and white vertical stripes. With the animal's head immobilized, the electro-oculogram of each eye was recorded for both directions of rotation. I. Depending on the response to monocular stimulation, the animals were put into three categories: (1) no nystagmus was detected in either eye, (2) nystagmus was found in the stimulated eye only, (3) both eyes displayed nystagmus. Moreover, the percentage of responses was greater for temporal to nasal (T-N) stimulation than for nasal to temporal (N-T) stimulation. II. Computer analysis performed in the last group of animals showed that: (1) In monocular stimulation: (a) OKN of the stimulated eye was asymmetrical, that is, the frequency, amplitude and average slow-phase velocity (¯V) of the nystagmus beats were higher in T-N (preferential direction) stimulation. (b) OKN of the masked eye was symmetrical. (c) OKN of the two eyes was conjugate, but the amplitude and velocity (¯V) were greater in the stimulated eye, this difference being more noticeable in the T-N direction than for the N-T one. (2) In binocular stimulation the monocular effects were partially summated and OKN remained asymmetrical, with a higher amplitude for the T-N stimulated eye. III. OKN was followed by optokinetic after-nystagmus (OKAN) for short durations of stimulation, and by reverse optokinetic after-nystagmus (R-OKAN) for longer durations of stimulation. In both monocular and binocular stimulation the nystagmus response (OKN, OKAN and R-OKAN) was conjugate, but always larger in the eye moving in the T-N direction (slow phase).

前庭性動眼反射の定量的分析 第１報 振幅と周波数に関する分析

A vestibulo-ocular reflex (VOR) test was carried out on forty-five normal subjects. The subjects sat in a newly devised, pendular, rotating chair in an optokinetic drum, by which device sinusoidal rotation and optokinetic stimulation could be given simultaneously.They were rotated sinusoidally at amplitudes of 120 degrees and 240 degrees, at frequencies of 0.05Hz and 0.1Hz. With these stimulations there was no response decline phenomenon nor influence of amplitude on frequency.The VOR gain measured in the dark room with the eyes open was about 0.6, and did not vary when the eyes closed. The VOR gain in the light room in a stationary optokinetic drum was about 1.1. In relation to the pendular optokinetic nystagmus test, the 0.1Hz sinusoidal rotation with an amplitude of 240 degrees was an appropriate stimulation.

Electrophysiological correlates of the reversed postoptokinetic nystagmus in the rabbit: Activity of vestibular and floccular neurons

Unit activity changes accompanying the optokinetic nystagmus (OKN) and reversed postoptokinetic nystagmus (RPN) in the rabbit were examined in 180 vestibular and floccular neurons. After initial charging of the RPN generator by 60-min optokinetic stimulation, a sequence of 1-min optokinetic stimulation (OKN) followed by 1-min darkness (RPN) and 1-min illumination of the stationary optokinetic drum (L), was cycled while corresponding unit activity changes were recorded during 3–5 cycles and evaluated with a computer. About 50% of vestibular neurons (type A) increased their activity during OKN and/or decreased it during RPN with respect to the L period, whereas 24% (type B) reacted in a reciprocal manner. The remaining neurons were either unaffected or responded in an atypical way. Most floccular neurons (75%) were activated during ipsilateral optokinetic stimulation, but were not significantly affected by RPN. It is suggested that the neural trace of RPN develops in the vestibular complex and vestibulocerebellum as a part of the process compensating for the effect of continued optokinetic stimulation.

The effect of lesions of the dorsal cap of the inferior olive on the vestibulo-ocular and optikinetic systems of the cat

The gain (eye velocity/head velocity) of the vestibulo-ocular reflex (VOR) of cats was measured in the dark and light for sinusoidal head oscillations at 0.05 and 1.2 Hz with peak velocity of about 30 deg/sec. Animals wore visual reversing prisms chronically and were also subjected to forced oscillation in the light at 0.05 Hz for 2 h per day. Such experience produced adaptive reduction in VOR gain in the dark from 0.85 to 0.10 within about 4 days; qualitatively similar effects were observed at 1.2 Hz. In 4 cats, the dorsal cap of the inferior olive was located electrophysiologically by its responses to visual motion, and bilateral electrolytic lesions were made in or near this structure. The location of lesions was subsequently identified by histology. After lesions, 3 cats were unable to make adaptive changes in VOR gain when confronted with the same reversing prism paradigm; the fourth exhibited appreciable retardation of adaptation. These results imply that the dorsal cap is essential for plastic adaptation of the VOR. However, all cats retained the ability to use reversed vision to reduce VOR gain in the light after lesions. Optokinetic nystagmus (OKN) and optokinetic after nystagmus (OKAN) were measured in a striped optokinetic drum, before and after dorsal cap lesions, at drum velocities of 20 and 40 deg/sec. Lesions of the dorsal cap in 4 cats did not impair either OKN or OKAN. This result indicates that the climbing fiber system reaching the flocculus from the inferior olive is not essential for such optokinetic movements.

Short report: Reading difficulty as a presenting symptom in Wilson's disease

A case of Wilson's disease is reported in which the major symptom before treatment was a reading disability. This was caused by ocular dysmetria, and the abnormal eye movements were recorded by electronystagmography and optokinetic drum testing.

Ontogeny of Visual Acuity of Rainbow Trout Under Normal Conditions and Light Deprivation

Abstract The development of visual acuity (minimum separable visual angle) in rainbow trout (Salmo gairdneri) was investigated from hatching to one year old trout by eliciting optomotor reactions in an optokinetic drum. I. The first optomotor responses were found 10 days after hatching with a visual angle of 30° of arc. Then a rapid increase in the visual resolving power occurs leading to a visual angle of about 1° at the end of the larval period. Up to the age of one year the visual angle of rainbow trout improves slightly to final 14' of arc. 2. Light deprivation during rearing causes a severe impairment ot visual acuity during the first 40 days after hatching (best visual angle only 2°05' of arc). 3. The results are discussed with respect to synaptogenetical and biochemical findings in the tectum opticum of rainbow trout under the same rearing conditions.

Visual‐vestibular interaction and cerebellar atrophy

The vestibular and optokinetic ocular control systems were studied in 10 patients with cerebellar atrophy and in 10 normal subjects using (1) constant velocity optokinetic stimulation, (2) sinusoidal rotation in the dark, and (3) sinusoidal rotation in the light with a surrounding fixed optokinetic drum. The gain (maximum slow component velocity/maximum head or drum velocity) of induced nystagmus was calculated from electro-oculographic recordings. Optokinetic nystagmus was abnormal in seven patients and the average optokinetic gain in the patients was significantly (p less than 0.01) less than that of the normal group. Three patients with "clinically pure" cerebellar atrophy had increased vestibular responses, and one patient with clinical signs of peripheral neuropathy had decreased responses, probably due to associated vestibular nerve disease. The average vestibulo-ocular reflex gain in patients did not differ significantly from controls (p greater than 0.05). Three patients had normal vestibular and optokinetic responses when tested independently, but had abnormal visual-vestibular interaction. These patients probably had selective disorders of the midline cerebellar pathways that mediate visual-vestibular interaction. By studying each system, both independently and during interaction, all patients were identified as abnormal, and a more precise anatomic localization of the atrophy was obtained.

Saccadic, smooth pursuit, and optokinetic eye movements of the trained cat.

1. Cats were trained to track a small target by rewarding them for keeping their eyes on target. Eye movements were measured by the electromagnetic search coil technique. 2. Cat saccades are qualitatively similar to primate saccades, but exhibit more variability in their parameters. However, they have longer durations and lower maximum velocities than primate saccades. As in the monkey, the duration of the horizontal or vertical component of an oblique saccade is lengthened when the orthogonal component has a larger amplitude. Cat saccades can be modified in midflight like human saccades. Opening the visual feed-back loop by controlling target position with eye position causes the cat to execute a staircase of equal amplitude saccades if a retinal error is present. Increasing the amount of visual feed-back induces saccadic oscillations. 3. Horizontal smooth pursuit of a 0 . 5 deg visual target is limited to velocities of less than 1 deg/sec. However, moving an optokinetic background with the 0 . 5 deg target enables the cat to achieve higher horizontal smooth eye velocities of up to 8 . 5 deg/sec. Prolonged (10-20 sec) constant velocity rotation of an optokinetic drum evokes horizontal slow-phase velocities of up to 28 deg/sec. In response to vertical movements of the target and optokinetic background, smooth eye movements reached 6 deg/sec maximum upward velocities but only 2 . 5 deg/sec maximum downward velocities. Opening the feed back loop with no retinal error present causes the eye to exhibit a growing smooth trajectory. The response to a Rashbass step-ramp target suggests that the feline smooth response is a function of target movement rather than displacement. 4. These data suggest that cat saccadic eye movements resemble those of primates while the cat smooth pursuit and optokinetically induced eye movements are more similar to those of the rabbit.

Restoration of vision in genetically eyeless axolotls ( Ambystoma mexicanum)

Eyes grafted into genetically eyeless axolotls at embryonic stages 26 or 27 (early tailbud stage) are capable of establishing retinotectal connections and restoring near normal vision. Normal vestibulo-ocular reflexes are also present in most of the eyeless mutants having grafted eyes. The animals are capable of accurately localizing objects in visual space and demonstrate following movements in an optokinetic drum. Evoked potentials can be recorded from the surfaces of the tectal lobes of eyeless mutants having a right eye graft which do not differ significantly from those recorded from a normal animal, except that recordings can still be obtained from the ipsilateral tectal lobe in the former following section of the intertectal fibers. This indication of direct retinotectal connections to the ipsilateral tectum was confirmed by histological examination which also showed that the optic fibers entering the diencephalon high on the lateral wall are initially directed toward the normal optic tract position before proceeding to be tectum.

Visual stimulation: effects on vestibular habituation.

The influence of various forms of visual stimulation presented during the course of vestibular habituation to a caloric stimulus was studied. Eye movements which were either complementary or in opposition to the induced vestibular nystagmus were produced with an optokinetic drum. In addition, the effect of visual fixation during vestibular-response periods was studied. In all cases, the cats that received visual stimulation during the majority of the caloric trials habituated more slowly than did animals that received all the habituation trials in total darkness. These data conflict with previous reports of vestibular-visual interactions. Possible explanations for the discrepancy include species differences, distraction provided by the visual stimuli, and the transfer of learning from the dark to light conditions.

An optokinetic drum device.

A home-built optokinetic drum device is described, and sources of parts and supplies are suggested.

A study of visual orientation mechanisms in turtles and guinea pigs.

Studies of the optomotor response of Pseudemys scripta were carried out. Performance of the binocular animals was very reliable. No habituation was exhibited, nor was there any particular effect of suddenly reversing the direction of movement of the optokinetic stimulus drum. Monocular performance was deficient when movement past the open eye was in the temporal-to-nasal direction, while it was completely absent when the stripes were moved in the nasal-to-temporal direction. Each eye appears to be specialized for the detection of temporal-to-nasal movement. The guinea pig also exhibits some of these same characteristics.

Latency and gain of the rabbit's optokinetic reactions to small movements

The rabbit's optokinetic reactions to small movements of short duration were measured, using averaging techniques. Reactions to position steps (amplitude 0.5–4°) of the optokinetic drum were entirely absent. Trapezoid movement was followed well; the gain of the reactions was entirely determined by the velocity of the stimulus, in accordance with earlier findings. Velocities up to 1°/sec were followed well; at higher stimulus velocities gain decreased sharply. Reaction time of the system to sudden movement (velocity steps) was around 100 msec, with sharp increase for velocities below 0.1°/sec. This may indicate that a minimal displacement of the order of the inter-receptor distance on the retina is required for motion detection.