scholarly journals Efferent control of temporal response properties of the Limulus lateral eye.

1990 ◽  
Vol 95 (2) ◽  
pp. 229-244 ◽  
Author(s):  
R Batra ◽  
R B Barlow
Keyword(s):  
Optic Nerve ◽  
Low Frequency ◽  
Transfer Characteristic ◽  
Nerve Fibers ◽  
Visual Sensitivity ◽  
Temporal Response ◽  
Lateral Eye ◽  
Rapid Changes ◽  
Modulated Light ◽  
The Brain

The sensitivity of the Limulus lateral eye exhibits a pronounced circadian rhythm. At night a circadian oscillator in the brain activates efferent fibers in the optic nerve, inducing multiple changes in the physiological and anatomical characteristics of retinal cells. These changes increase the sensitivity of the retina by about five orders of magnitude. We investigated whether this increase in retinal sensitivity is accompanied by changes in the ability of the retina to process temporal information. We measured the frequency transfer characteristic (FTC) of single receptors (ommatidia) by recording the response of their optic nerve fibers to sinusoidally modulated light. We first measured the FTC in the less sensitive daytime state and then after converting the retina to the more sensitive nighttime state by electrical stimulation of the efferent fibers. The activation of these fibers shifted the peak of the FTC to lower frequencies and reduced the slope of the low-frequency limb. These changes reduce the eye's ability to detect rapid changes in light intensity but enhance its ability to detect dim flashes of light. Apparently Limulus sacrifices temporal resolution for increased visual sensitivity at night.

Histochemical localization of acetylcholinesterase in the lateral eye and brain of Limulus polyphemus: Might acetylcholine be a neurotransmitter for lateral inhibition in the lateral eye?

1994 ◽  
Vol 11 (5) ◽  
pp. 989-1001 ◽  
Author(s):  
Eric P. Hornstein ◽  
Daniel L. Sambursky ◽  
Steven C. Chamberlain
Keyword(s):  
Optic Nerve ◽  
Lateral Inhibition ◽  
Horseshoe Crab ◽  
Compound Eye ◽  
Nerve Fibers ◽  
Intense Staining ◽  
Histaminergic Neurons ◽  
Lateral Eye ◽  
Weak Staining ◽  
The Brain

AbstractThe distribution of acetylcholinesterase (AChE) in the lateral eye and brain of the horseshoe crab was investigated with histochemical means using standard controls to eliminate butyrylcholinesterase and nonspecific staining. Intense staining was observed in the neural plexus of the lateral compound eye, in the lateral optic nerve, and in various neuropils of the brain. Nerve fibers with moderate to weak staining were widespread in the brain. No sornata were stained in either the lateral eye or the brain. The distribution of acetylcholinesterase in the supraesophageal ganglia and nerves of the giant barnacle was also investigated for comparison. Although both the median optic nerve of the barnacle and the lateral optic nerve of the horseshoe crab appear to contain the fibers of histaminergic neurons, only the lateral optic nerve of the horseshoe crab shows AChE staining. Other parts of the barnacle nervous system, however, showed intense AChE staining. These results along with the histochemical controls eliminate the possibility that some molecule found in histaminergic neurons accounted for the AChE staining but support the possibility that acetylcholine might be involved as a neurotransmitter in lateral inhibition in the horseshoe crab retina. Two reasonable neurotransmitter candidates for lateral inhibition, histamine and acetylcholine, must now be investigated.

Cell-Based Model of the Limulus Lateral Eye

1998 ◽  
Vol 80 (4) ◽  
pp. 1800-1815 ◽  
Author(s):  
Christopher L. Passaglia ◽  
Frederick A. Dodge ◽  
Robert B. Barlow
Keyword(s):  
Optic Nerve ◽  
Natural Habitat ◽  
Correlation Coefficients ◽  
Visual Space ◽  
Cellular Level ◽  
Nerve Fibers ◽  
Lateral Eye ◽  
Horseshoe Crabs ◽  
Parametric Analyses ◽  
Nerve Recordings

Passaglia, Christopher L., Frederick A. Dodge, and Robert B. Barlow. Cell-based model of the Limulus lateral eye. J. Neurophysiol. 80: 1800–1815, 1998. We present a cell-based model of the Limulus lateral eye that computes the eye's input to the brain in response to any specified scene. Based on the results of extensive physiological studies, the model simulates the optical sampling of visual space by the array of retinal receptors (ommatidia), the transduction of light into receptor potentials, the integration of excitatory and inhibitory signals into generator potentials, and the conversion of generator potentials into trains of optic nerve impulses. By simulating these processes at the cellular level, model ommatidia can reproduce response variability resulting from noise inherent in the stimulus and the eye itself, and they can adapt to changes in light intensity over a wide operating range. Programmed with these realistic properties, the model eye computes the simultaneous activity of its ensemble of optic nerve fibers, allowing us to explore the retinal code that mediates the visually guided behavior of the animal in its natural habitat. We assess the accuracy of model predictions by comparing the response recorded from a single optic nerve fiber to that computed by the model for the corresponding receptor. Correlation coefficients between recorded and computed responses were typically >95% under laboratory conditions. Parametric analyses of the model together with optic nerve recordings show that animal-to-animal variation in the optical and neural properties of the eye do not alter significantly its response to objects having the size and speed of horseshoe crabs. The eye appears robustly designed for encoding behaviorally important visual stimuli. Simulations with the cell-based model provide insights about the design of the Limulus eye and its encoding of the animal's visual world.

Axonal injury in the optic nerve: a model simulating diffuse axonal injury in the brain

1989 ◽  
Vol 71 (2) ◽  
pp. 244-253 ◽  
Author(s):  
T. A. Gennarelli ◽  
L. E. Thibault ◽  
R. Tipperman ◽  
G. Tomei ◽  
R. Sergot ◽  
...  
Keyword(s):  
Brain Injury ◽  
Optic Nerve ◽  
Axonal Injury ◽  
Diffuse Axonal Injury ◽  
Nerve Fibers ◽  
Axonal Damage ◽  
Electron Microscopic ◽  
Axonal Swelling ◽  
Content Type ◽  
The Brain

✓ A new model of traumatic axonal injury has been developed by causing a single, rapid, controlled elongation (tensile strain) in the optic nerve of the albino guinea pig. Electron microscopy demonstrates axonal swelling, axolemmal blebs, and accumulation of organelles identical to those seen in human and experimental brain injury. Quantitative morphometric studies confirm that 17% of the optic nerve axons are injured without vascular disruption, and horseradish peroxidase (HRP) studies confirm alterations in rapid axoplasmic transport at the sites of injury. Since 95% to 98% of the optic nerve fibers are crossed, studies of the cell bodies and terminal fields of injured axons can be performed in this model. Glucose utilization was increased in the retina following injury, confirming electron microscopic changes of central chromatolysis in the ganglion cells and increased metabolic activity in reaction to axonal injury. Decreased activity at the superior colliculus was demonstrated by delayed HRP arrival after injury. The model is unique because it produces axonal damage that is morphologically identical to that seen in human brain injury and does so by delivering tissue strains of the same type and magnitude that cause axonal damage in the human. The model offers the possibility of improving the understanding of traumatic damage of central nervous system (CNS) axons because it creates reproducible axonal injury in a well-defined anatomical system that obviates many of the difficulties associated with studying the complex morphology of the brain.

Retinotopic organization of lateral eye input to Limulus brain

1982 ◽  
Vol 48 (2) ◽  
pp. 505-520 ◽  
Author(s):  
S. C. Chamberlain ◽  
R. B. Barlow
Keyword(s):  
Optic Nerve ◽  
Subunit Structure ◽  
Combined Effects ◽  
Microelectrode Recordings ◽  
Basic Subunit ◽  
Lateral Eye ◽  
Retinotopic Organization ◽  
The Brain ◽  
Simple Rotation ◽  
Anterior Posterior

1. The retinotopic organization of retinal inputs from the lateral eye of Limulus to the optic ganglia of the brain was determined from microelectrode recordings of nerve impulses. 2. The central connections of the natural subunits of the lateral optic nerve were determined using cobalt impregnation of cut axons. 3. Complete retinal maps exist in both the lamina and medulla. The laminar map is a simple rotation and folding of the retinal array. The medullar map is more complex as a result of the combined effects of the chiasma and the basic subunit structure of the optic nerve, which is preserved in the lamina and medulla. 4. The chiasma between the lamina and medulla reverses the anterior-posterior axis of the retinal map. There is no corresponding reversal in the dorsal-ventral axis.

scholarly journals Inhibition in the Limulus lateral eye in situ.

1978 ◽  
Vol 71 (6) ◽  
pp. 699-720 ◽  
Author(s):  
R B Barlow ◽  
A J Fraioli
Keyword(s):  
Optic Nerve ◽  
Nerve Fibers ◽  
Linear Functions ◽  
Inhibitory Effects ◽  
Cellular Processes ◽  
Sustained Oscillations ◽  
Lateral Eye ◽  
Retinal Pathways ◽  
Low Levels

Inhibition in the Limulus lateral eye in situ is qualitatively similar to that in the excised eye. In both preparations ommatidia mutually inhibit one another, and the magnitude of the inhibitory effects are linear functions of the response rate of individual ommatidia. The strength of inhibition exerted between single ommatidia is also about the same for both preparations; however, stronger effects can converge on a single ommatidium in situ. At high levels of illumination of the retina in situ the inhibitory effects are often strong enough to produce sustained oscillations in the discharge of optic nerve fibers. The weaker inhibitory influences at low levels of illumination do not produce oscillations but decrease the variance of the optic nerve discharge. Thresholds for the inhibitory effects appear to be determined by both presynaptic and postsynaptic cellular processes. Our results are consistent with the idea that a single ommatidium can be inhibited by more of its neighbors in an eye in situ than in an excised eye. Leaving intact the blood supply to the eye appears to preserve the functional integrity of the retinal pathways which mediate inhibition.

scholarly journals Contrast adaptation in the Limulus lateral eye

2015 ◽  
Vol 114 (6) ◽  
pp. 3234-3241
Author(s):  
Tchoudomira M. Valtcheva ◽  
Christopher L. Passaglia
Keyword(s):  
Optic Nerve ◽  
White Noise ◽  
Horseshoe Crab ◽  
Noise Analysis ◽  
Nerve Fibers ◽  
Contrast Adaptation ◽  
Lateral Eye ◽  
Neuronal Mechanisms ◽  
Adaptive Processes ◽  
Mean Luminance

Luminance and contrast adaptation are neuronal mechanisms employed by the visual system to adjust our sensitivity to light. They are mediated by an assortment of cellular and network processes distributed across the retina and visual cortex. Both have been demonstrated in the eyes of many vertebrates, but only luminance adaptation has been shown in invertebrate eyes to date. Since the computational benefits of contrast adaptation should apply to all visual systems, we investigated whether this mechanism operates in horseshoe crab eyes, one of the best-understood neural networks in the animal kingdom. The spike trains of optic nerve fibers were recorded in response to light stimuli modulated randomly in time and delivered to single ommatidia or the whole eye. We found that the retina adapts to both the mean luminance and contrast of a white-noise stimulus, that luminance- and contrast-adaptive processes are largely independent, and that they originate within an ommatidium. Network interactions are not involved. A published computer model that simulates existing knowledge of the horseshoe crab eye did not show contrast adaptation, suggesting that a heretofore unknown mechanism may underlie the phenomenon. This mechanism does not appear to reside in photoreceptors because white-noise analysis of electroretinogram recordings did not show contrast adaptation. The likely site of origin is therefore the spike discharge mechanism of optic nerve fibers. The finding of contrast adaption in a retinal network as simple as the horseshoe crab eye underscores the broader importance of this image processing strategy to vision.

scholarly journals INHIBITORY INTERACTION OF RECEPTOR UNITS IN THE EYE OF LIMULUS

1957 ◽  
Vol 40 (3) ◽  
pp. 357-376 ◽  
Author(s):  
H. K. Hartline ◽  
Floyd Ratliff
Keyword(s):  
Optic Nerve ◽  
Light Stimulus ◽  
Linear Equations ◽  
Nerve Fibers ◽  
The Other ◽  
Optical Systems ◽  
Inhibitory Interaction ◽  
Lateral Eye ◽  
Rate Of Increase ◽  
Maintained Discharge

The inhibition that is exerted mutually among the receptor units (ommatidia) in the lateral eye of Limulus has been analyzed by recording oscillographically the discharge of nerve impulses in single optic nerve fibers. The discharges from two ommatidia were recorded simultaneously by connecting the bundles containing their optic nerve fibers to separate amplifiers and recording systems. Ommatidia were chosen that were separated by no more than a few millimeters in the eye; they were illuminated independently by separate optical systems. The frequency of the maintained discharge of impulses from each of two ommatidia illuminated steadily is lower when both are illuminated together than when each is illuminated by itself. When only two ommatidia are illuminated, the magnitude of the inhibition of each one depends only on the degree of activity of the other; the activity of each, in turn, is the resultant of the excitation from its respective light stimulus and the inhibition exerted on it by the other. When additional receptors are illuminated in the vicinity of an interacting pair too far from one ommatidium to affect it directly, but near enough to the second to inhibit it, the frequency of discharge of the first increases as it is partially released from the inhibition exerted on it by the second (disinhibition). Disinhibition simulates facilitation; it is an example of indirect effects of interaction taking place over greater distances in the eye than are covered by direct inhibitory interconnections. When only two interacting ommatidia are illuminated, the inhibition exerted on each (decrease of its frequency of discharge) is a linear function of the degree of activity (frequency of discharge) of the other. Below a certain frequency (often different for different receptors) no inhibition is exerted by a receptor. Above this threshold, the rate of increase of inhibition of one receptor with increasing frequency of discharge of the other is constant, and may be at least as high as 0.2 impulse inhibited in one receptor per impulse discharged by the other. For a given pair of interacting receptors, the inhibitory coefficients are not always the same in the two directions of action. The responses to steady illumination of two receptor units that inhibit each other mutually are described quantitatively by two simultaneous linear equations that express concisely all the features discussed above. These equations may be extended and their number supplemented to describe the responses of more than two interacting elements.

scholarly journals Mach bands in the lateral eye of Limulus.

1975 ◽  
Vol 65 (6) ◽  
pp. 709-730 ◽  
Author(s):  
R B Barlow ◽  
D A Quarles
Keyword(s):  
Optic Nerve ◽  
Piecewise Linear ◽  
Theoretical Models ◽  
Nerve Fibers ◽  
Uniqueness Condition ◽  
Response Patterns ◽  
Lateral Eye ◽  
Mach Bands ◽  
Different Dimensions ◽  
Mach Band

Patterns of optic nerve activity were computed for stationary step patterns of illumination from theoretical models of lateral inhibiton based on revised Hartlin-Ratliff equations. The computed response patterns contain well-defined Mach bands which match closely in amplitude and shape those recorded from single optic nerve fibers of the Limulus lateral eye. Theory and experiment show that the amplitude of the Mach bands is reduced by in inhibitory nonlinearity, the width of the Mach bands is approximately equal to the lateral dimension of the inhibitory field, but the shapes of the Mach bands are poor indices of the precise configuration of the inhibitory field. Theorems are proved establishing the equivalence of Mach-band patterns for models of different dimensions and a uniqueness condition for solutions of the piecewise linear model.

Changes in the Total Power of Beta and Theta Bands When Using EEG Biofeedback in Primary School-Age Children Having Difficulties with Voluntary Regulation

2020 ◽  
pp. 331-340
Author(s):  
Yuliya S. Dzhos ◽  
◽  
Irina A. Men’shikova ◽  
Keyword(s):  
Left Hemisphere ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
School Age Children ◽  
Total Power ◽  
Eeg Biofeedback ◽  
Beta Band ◽  
Bioelectric Activity ◽  
Voluntary Regulation ◽  
The Brain

This article presents the results of the study on spectral electroencephalogram (EEG) characteristics in 7–10-year-old children (8 girls and 22 boys) having difficulties with voluntary regulation of activity after 10 and 20 neurofeedback sessions using beta-activating training. Brain bioelectric activity was recorded in 16 standard leads using the Neuron-Spectrum-4/VPM complex. The dynamics was assessed by EEG beta and theta bands during neurofeedback. An increase in the total power of beta band oscillations was established both after 10 and after 20 sessions of EEG biofeedback in the frontal (p ≤ 0.001), left parietal (p ≤ 0.036), and temporal (p ≤ 0.003) areas of the brain. A decrease in the spectral characteristics of theta band oscillations was detected: after 10 neurofeedback sessions in the frontal (p ≤ 0.008) and temporal (p ≤ 0.006) areas of both hemispheres, as well as in the parietal area of the left hemisphere (p ≤ 0.005); after 20 sessions, in the central (p ≤ 0.004), frontal (p ≤ 0.001) and temporal (p ≤ 0.001) areas of both hemispheres, as well as in the occipital (p ≤ 0.047) and parietal (p ≤ 0.001) areas of the left hemisphere. The study into the dynamics of bioelectric activity during biofeedback using EEG parameters in 7–10-year-old children with impaired voluntary regulation of higher mental functions allowed us to prove the advisability of 20 sessions, as the increase in high-frequency activity and decrease in low-frequency activity do not stop with the 10th session. Changes in these parameters after 10 EEG biofeedback sessions are expressed mainly in the frontotemporal areas of both hemispheres, while after a course of 20 sessions, in both the frontotemporal and central parietal areas of the brain.

Melatonin As a Modulator of Degenerative and Regenerative Signaling Pathways in Injured Retinal Ganglion Cells

2019 ◽  
Vol 25 (28) ◽  
pp. 3057-3073 ◽  
Author(s):  
Kobra B. Juybari ◽  
Azam Hosseinzadeh ◽  
Habib Ghaznavi ◽  
Mahboobeh Kamali ◽  
Ahad Sedaghat ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Mitochondrial Dysfunction ◽  
Signaling Pathways ◽  
Retinal Ganglion Cells ◽  
Molecular Mechanisms ◽  
Nitrosative Stress ◽  
Ganglion Cells ◽  
Axon Growth ◽  
Nerve Fibers ◽  
Retinal Ganglion

Optic neuropathies refer to the dysfunction or degeneration of optic nerve fibers caused by any reasons including ischemia, inflammation, trauma, tumor, mitochondrial dysfunction, toxins, nutritional deficiency, inheritance, etc. Post-mitotic CNS neurons, including retinal ganglion cells (RGCs) intrinsically have a limited capacity for axon growth after either trauma or disease, leading to irreversible vision loss. In recent years, an increasing number of laboratory evidence has evaluated optic nerve injuries, focusing on molecular signaling pathways involved in RGC death. Trophic factor deprivation (TFD), inflammation, oxidative stress, mitochondrial dysfunction, glutamate-induced excitotoxicity, ischemia, hypoxia, etc. have been recognized as important molecular mechanisms leading to RGC apoptosis. Understanding these obstacles provides a better view to find out new strategies against retinal cell damage. Melatonin, as a wide-spectrum antioxidant and powerful freeradical scavenger, has the ability to protect RGCs or other cells against a variety of deleterious conditions such as oxidative/nitrosative stress, hypoxia/ischemia, inflammatory processes, and apoptosis. In this review, we primarily highlight the molecular regenerative and degenerative mechanisms involved in RGC survival/death and then summarize the possible protective effects of melatonin in the process of RGC death in some ocular diseases including optic neuropathies. Based on the information provided in this review, melatonin may act as a promising agent to reduce RGC death in various retinal pathologic conditions.

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