Information capacity of eyes

Snyder, Allan W.; Laughlin, Simon B.; Stavenga, Doekele G.

doi:10.1016/0042-6989(77)90151-1

Cited by 132 publications

(79 citation statements)

References 18 publications

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“…Spatial resolution in birds at low light levels is unknown (except for one species of owl; Fite 1973). On theoretical grounds, however, it is understood that the vertebrate eye is incapab1.e of a high degree of spatial resolution at the lowest environmental light intensities (Snyder et al 1977). Martin (1990b) concluded that birds migrating at night, even under maximum moonlight, were able to detect only the grossest details of their environment.…”

Section: Arrivals and Departures At Nightmentioning

confidence: 99%

Foraging modes of chinstrap penguins:contrasts between day and night

Jansen¹,

Boveng²,

Bengtson³

1998

Mar. Ecol. Prog. Ser.

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Penguins rely on vision to travel and hunt at sea. Vision in marine predators, particularly those hunting phototactic prey under a broad range of light intensities, must be better understood to realize how these species respond to changes in their environment. We studied the effects of daily cycles in light intensity on visual predators by examining the duration and timing of chinstrap penguins' PjrgosceUs antarctica foraging trips and the size, composition, and timing of their meals. We used radio telemetry and stomach-contents sampling to study adult penguins that were provisioning chicks during the summers of 1993 and 1994 at Seal Island, Antarctica. The penguins rarely initiated or terminated foraging trips at night, but otherwise varied the timing and duration of trips to sea. Cluster analyses using departure and arrival times revealed 5 distinct modes of foraging: 3 were strictly diurnal (early, mid-, and late) and 2 were partly nocturnal (overnight and extended). Durations of diurnal trips (4 to 11 h) were shorter than overnight (13 to 14 h) and extended trips (18 to 22 h). Early and rniddiurnal trips and extended trips were significantly shorter in 1993 than in 1994; late diurnal and overnight trip durations did not differ between years. Diurnal foraging was most common in 1993, whereas overnight foraging predominated in 1994. Shortened diurnal foraging in 1993 appears to have increased the frequency of diurnal foraging by allowing more parent birds to alternate diurnal trips within a single day and by reducing the incidence of birds extending diurnal foraging through the night. That penguins foraged more frequently by day when permitted by shorter trip durations (in 1993) suggests that they opted to forage diurnally whenever possible. Returning dlurnal and overnight foragers had greater than 99 and 74 % Antarctic krill Euphausia superba by weight in their stomachs, respectively However, overnight foragers also returned with significant amounts of highly digested remains of pelagic fish, suggesting birds were in offshore waters talung fish during the night. In contrast, only 1 out of 40 diurnal foragers from both years combined had evidence of fish. Thus, the daily light cycle affected both the timing and duration of chinstrap penguin foraging as well as the type of prey consumed during trips to sea.

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Section: Arrivals and Departures At Nightmentioning

confidence: 99%

Foraging modes of chinstrap penguins:contrasts between day and night

Jansen¹,

Boveng²,

Bengtson³

1998

Mar. Ecol. Prog. Ser.

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“…If evolution produces eyes to maximize information capacity, then the optimal resolution depends on both light level and image speed (Snyder et al, 1977a;Snyder et al, 1977b). This means animals that often view dim or fast visual scenes need lower visual acuity to collect more information.…”

Section: Predictions From Information Theorymentioning

confidence: 99%

“…Size and mass are certainly important factors for small flying insects, but acuity is equivalent to visual information. The only reason to trade resolution for sensitivity is if it improves visual performance, which is the case in really dark conditions (Snyder et al, 1977a;Snyder et al, 1977b). Without nocturnal optics, a sharp, fast visual system must become blurry and slow, or face an image swamped with photon noise.…”

Section: Introductionmentioning

confidence: 99%

Flight performance in night-flying sweat bees suffers at low light levels

Theobald

Coates

Wcislo

et al. 2007

Journal of Experimental Biology

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SUMMARY The sweat bee Megalopta (Hymenoptera: Halictidae), unlike most bees, flies in extremely dim light. And although nocturnal insects are often equipped with superposition eyes, which greatly enhance light capture, Megalopta performs visually guided flight with apposition eyes. We examined how light limits Megalopta's flight behavior by measuring flight times and corresponding light levels and comparing them with flight trajectories upon return to the nest. We found the average time to land increased in dim light, an effect due not to slow approaches, but to circuitous approaches. Some landings, however, were quite fast even in the dark. To explain this, we examined the flight trajectories and found that in dim light, landings became increasingly error prone and erratic, consistent with repeated landing attempts. These data agree well with the premise that Megalopta uses visual summation, sacrificing acuity in order to see and fly at the very dimmest light intensities that its visual system allows.

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“…This criterion gives a reliability of ϳ80% in distinguishing one signal from another, and this is commonly adopted as a good compromise between reliability and number of signal levels (Snyder et al, 1977). Although IPSP amplitudes were not strictly normally distributed, more complex statistical techniques would have been unlikely to yield improvements in estimates of signal reliability.…”

Section: Transmission At a Relatively High-gain Inhibitory Synapsementioning

confidence: 99%

The Performance of Synapses That Convey Discrete Graded Potentials in an Insect Visual Pathway

Simmons

1999

J. Neurosci.

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Synapses from nonspiking neurons transmit small graded changes in potential, but variability in their postsynaptic potential amplitudes has not been extensively studied. At synapses where the presynaptic signal is an all-or-none spike, the probabilistic manner of neurotransmitter release causes variation in the amplitudes of postsynaptic potentials. I have measured the reliability of the operation of synapses that convey small graded potentials between pairs of identified large, second-order neurons in the locust ocellar system. IPSPs are mediated by small rebound spikes, which are graded in amplitude, in the presynaptic neuron. A transfer curve plotting amplitudes of spikes against amplitudes of IPSPs has a characteristic S shape with a linear central portion where IPSP amplitude is between Ϫ0.2 and Ϫ0.6 as large as spike amplitude but shows appreciable scatter. Approximately half of the scatter is attributable to background noise, most of which originates in photoreceptors and persists in darkness. The remaining noise is intrinsic to the synapse itself and is usually 0.3-0.7 mV in amplitude. It limits the resolution with which two spike amplitudes can be distinguished from one another to ϳ2 mV and, because the linear part of the transfer curve occupies ϳ10 mV in spike amplitudes, limits the number of discrete signal levels that can be conveyed across the synapse to approximately five. The amplitude of the noise is constant throughout the synaptic operating range, which means it is unlikely that presynaptic membrane potential controls transmitter release by setting a single probability level for quantal release.

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Information capacity of eyes

Cited by 132 publications

References 18 publications

Foraging modes of chinstrap penguins:contrasts between day and night

Foraging modes of chinstrap penguins:contrasts between day and night

Flight performance in night-flying sweat bees suffers at low light levels

The Performance of Synapses That Convey Discrete Graded Potentials in an Insect Visual Pathway

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