Inhibition in the Limulus lateral eye in situ.

Barlow, Robert B.; Fraioli, Anthony J.

doi:10.1085/jgp.71.6.699

Cited by 27 publications

(10 citation statements)

References 30 publications

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“…Light from a tungsten filament source was projected on the screen by a large fiberoptic bundle (diameter 2.5 cm). This technique provided uniform illumination of all but the most peripherally located ommatidia in the eye (Barlow and Fraioli, 1978). It was used primarily in the experiments in Figures 11 and 12 that investigated the sensitivity of the retina by measuring the intensity-response function of the ERG response.…”

Section: Methodsmentioning

confidence: 99%

Circadian rhythms in the Limulus visual system

Rb¹

1983

J. Neurosci.

153

128

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A circadian clock in the Limulus brain generates efferent optic nerve activity at night. The endogenous activity begins near dusk, continues during the night, and stops near dawn. Approximately 10 to 20 efferent fibers in each lateral optic nerve trunk fire in close synchrony with one another and with the efferent fibers in the opposite nerve trunk producing bursts of nerve impulses at night. The synchronous bursting activity indicates extensive coupling in the brain among the efferent neurons or among the circadian pacemakers that drive them.The efferent optic nerve activity mediates circadian rhythms in retinal responses. Electroretinograms (ERGS) from both the lateral eyes and median ocelli exhibit circadian rhythms of equal phase. Sectioning the optic nerves abolishes the rhythms. When the animal is kept in darkness, the phase of the rhythm can be shifted by illuminating the lateral eyes but not the median ocelli. The endogenous rhythm persists for at least 1 year in darkness without attenuation and without substantial changes in the circadian period. Across a large population of animals the duration of the circadian period ranges from 22.2 to 25.5 hr, with a mean value of 23.9 f 0.7 hr (n = 75).The nighttime increase in ERG amplitude represents a 20-to loo-fold increase in retinal sensitivity. Most of the increased sensitivity results from an increase in the number of photons absorbed by the photoreceptors at night. A small component may be due to an increase in gain. Pulses of current delivered to the lateral optic nerve during the day mimic the effects of endogenous efferent activity and transform the eye to the nighttime state.The Limulus visual system has evolved numerous mechanisms for adapting visual sensitivity to daily fluctuations in the photic environment. A key to understanding the organization of the visual system is the circadian clock and its associated neural circuitry.

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Section: Methodsmentioning

confidence: 99%

Circadian rhythms in the Limulus visual system

Rb¹

1983

J. Neurosci.

153

128

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“…Hydras may have branched from other animals about 600 million years ago (MYA), though that number is not certain [Budd, 2008]. Nervous systems that use some form of selective signal enhancement can be found in almost all other animals that have been studied including crabs,°ies, birds, and people [e.g., Barlow and Fraioli, 1978;Beck and Kastner, 2009;Mysore and Knudsen, 2013; van Swinderen, 2012]. These phyla and classes of animals are thought to have diverged from each other in the late Cambrian during the so-called Cambrian explosion, around 550À520 MYA.…”

Section: The Evolution Of Attentionmentioning

confidence: 99%

A Mechanistic Theory of Consciousness

Graziano

Webb²

2014

Int. J. Mach. Conscious.

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Recently we proposed a theory of consciousness, the attention schema theory, based on¯ndings in cognitive psychology and systems neuroscience. In that theory, consciousness is an internal model of attention or an \attention schema". Consciousness relates to attention in the same way that the internal model of the body, the \body schema", relates to the physical body. The body schema is used to model and help control the body. The attention schema is used to model and help regulate attention, a data-handling process in the brain in which some signals are enhanced at the expense of other signals. We proposed that attention and the attention schema co-evolved over the past half-billion years. Over that time span, the attention schema may have taken on additional functions such as promoting the integration of information across diverse domains and promoting social cognition. This paper summarizes some of the main points of the attention schema theory, suggests how a brain with an attention schema might conclude that it has a subjective awareness, and speculates that the same basic properties can be engineered into machines.

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“…Under uniform illumination during the day, the total amount of inhibition exerted on a receptor is about 66-75% of its excitation (i.e. A^iir, = 0.15k c Trr}) yielding a center mechanism with peak sensitivity, k c , about 100 times that of the surround (Barlow & Fraioli, 1978;Brodie et al, 1978;F.A. Dodge & E. Kaplan, unpublished results).…”

Section: Conservation Of Contrast Sensitivity Day and Nightmentioning

confidence: 94%

Limulusvision in the ocean day and night: Effects of image size and contrast

1996

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Male horseshoe crabs, Limulus polyphemus, use their eyes to locate mates day and night. We investigated their ability to detect targets of different size and contrast in a mating area of Buzzards Bay, Cape Cod, MA. We found that males can see large, high-contrast targets better than small, low-contrast ones. For targets of the same size, animals must be about 0.1 m closer to a low-contrast target to see it as well as a high-contrast one. For targets of the same contrast, animals must be approximately 0.2 m closer to a small target to see it as well as one twice as large. A decrease of 0.05 steradians in the size of the retinal image of a target can be compensated by a four-fold increase in contrast. About 60% of the animals detect black targets subtending 0.110 steradians (equivalent to an adult female viewed from about 0.56 m), while only 20% detect targets subtending 0.039 steradians. This study shows that horseshoe crabs maintain about constant contrast sensitivity under diurnal changes in light intensity in their natural environment. As a consequence of circadian and adaptive mechanisms in the retina, male horseshoe crabs can detect female-size objects about equally well day and night.

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Inhibition in the Limulus lateral eye in situ.

Cited by 27 publications

References 30 publications

Circadian rhythms in the Limulus visual system

Circadian rhythms in the Limulus visual system

A Mechanistic Theory of Consciousness

Limulusvision in the ocean day and night: Effects of image size and contrast

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