Interflash Interval Research Articles

Evidence for Extended Charging Periods Prior to Terrestrial Gamma Ray Flashes

AbstractWe present an analysis of lightning interflash intervals in 219 terrestrial gamma ray flash (TGF) producing thunderstorms. Clustering was used to identify groups of lightning sferics, interpreted as individual thunderstorms, in combined World Wide Lightning Location Network and Earth Networks Total Lightning Network data. In these individual groups of sferics, analysis was done on the lightning flash frequency within ±10 min of the Fermi recorded TGF. We find that typical interflash intervals immediately prior to TGFs are 24% longer than mean interflash intervals in their individual producing storms, while the interflash intervals immediately following the TGFs are typically 8% shorter than normal. The significance of these results, tested using a numerical bootstrap method, was found to be highly significant for the pre‐TGF interval. These results could imply that a stronger electric field is necessary for the production of TGFs and may help to explain why some lightning strikes produce TGFs while others do not.

Real-Time Imaging Reveals Properties of Glutamate-Induced Arc/Arg 3.1 Translation in Neuronal Dendrites

The immediate early gene Arc (also Arg3.1) produces rapid changes in synaptic properties that are linked to de novo translation. Here we develop a novel translation reporter that exploits the rapid maturation and "flash" kinetics of Gaussia luciferase (Gluc) to visualize Arc translation. Following glutamate stimulation, discrete Arc-Gluc bioluminescent flashes representing sites of de novo translation are detected within 15s at distributed sites in dendrites, but not spines. Flashes are episodic, lasting ∼20 s, and may be unitary or repeated at ∼minute intervals at the same sites. Analysis of flash amplitudes suggests they represent the quantal product of one or more polyribosomes, while inter-flash intervals appear random, suggesting they arise from a stochastic process. Surprisingly, glutamate-induced translation is dependent on Arc open reading frame. Combined observations support a model in which stalled ribosomes are reactivated to rapidly generate Arc protein.

Spatiotemporal averaging of perceived brightness along an apparent motion trajectory

Objects are critical functional units for many aspects of visual perception and recognition. Many psychophysical experiments support the concept of an "object file" consisting of characteristics attributed to a single object on the basis of successive views of it, but there has been little evidence that object identity influences apparent brightness and color. In this study, we investigated whether the perceptual identification of successive flashed stimuli as views of a single moving object could affect brightness perception. Our target stimulus was composed of eight wedge-shaped sectors. The sectors were presented successively at different inter-flash intervals along an annular trajectory. At inter-flash intervals of around 100 ms, the impression was of a single moving object undergoing long-range apparent motion. By modulating the luminance between successive views, we measured the perception of luminance modulation along the trajectory of this long-range apparent motion. At the inter-flash intervals where the motion perception was strongest, the luminance difference was perceptually underestimated, and forced-choice luminance discrimination thresholds were elevated. Moreover, under such conditions, it became difficult for the observer to correctly associate or "bind" spatial positions and wedge luminances. These results indicate that the different luminances of wedges that were perceived as a single object were averaged along its apparent motion trajectory. The large spatial step size of our stimulus makes it unlikely that the results could be explained by averaging in a low-level mechanism that has a compact spatiotemporal receptive field (such as V1 and V2 neurons); higher level global motion or object mechanisms must be invoked to account for the averaging effect. The luminance averaging and the ambiguity of position-luminance "binding" suggest that the visual system may evade some of the costs of rapidly computing apparent brightness by adopting the assumption that the characteristics of an object are invariant over successive views.

Audiovisual relative timings determine sound-induced flash fission versus flash fusion effects

When observers are required to make judgments of the number of rapidly presented flashes of light, there is a tendency to either overestimate the count (‘flash fission’) or underestimate the count (‘flash fusion’), depending on the duration of the inter-flash interval (Bowen, 1989). Similarly, pairing the flashes with more or less loud, rapid beeps also results in fission and fusion effects (the sound-induced flash illusion, Andersen, Tiippana, & Sams, 2004; Shams, Kamitani, & Shimojo, 2000, 2002). Our aims were to determine how much these sound induced effects are dependent upon timings between clicks and flashes, and how these critical timings relate to the audiovisual ‘window of integration’ of around 100msec. A high contrast, 2° disc was flashed (11.7 ms, 7° periphery) in the presence of 0, 1, 2, or 3 beeps (7 ms, ∼ 75dbA, 3.5 kHz) with various audiovisual relative timings between 12 and 300 msec. Results from naive observers demonstrate flash fusion when >100 ms separated all stimuli, whereas flash fission was reported for separation <50 ms, with the transition from fission to fusion occurring rapidly. These results were replicated in stepped-on, ramped-off or ramped-on, stepped off discs. Large and consistent fission effects occurred when the sounds were presented: 1. during the ramp and 2. within 100 ms of the transient. A control experiment showed that no consistent illusory rapid change was induced by the beeps in a disc smoothly ramping on and off. We propose that the fission effects are occurring as the result of an intersensory process, whilst the fusion effect are occurring as the result of response bias.

Flash visibility degradation compresses apparentbrief inter-flash intervals as does saccadic eye movement

Flash visibility degradation compresses apparentbrief inter-flash intervals as does saccadic eye movement

Temperature-dependent geographic variation in the flashes of the firefly Luciola cruciata (Coleoptera: Lampyridae)

This study examined the regression of male interflash intervals of Luciola cruciata on ambient air temperatures at five sites in central Japan. The result indicated a significant negative correlation between these two variables at any of the sites. The regression lines varied from site to site and, therefore, the five local populations were classified into three types; the fast-flash, slow-flash, and intermediate types. This classification was supported by molecular biological studies, but contradicted the results of previous ecological studies based on interflash intervals only. My result suggests that first the slow-flash type and then the intermediate type evolved from an ancestral fast-flash type. The geographic variation in flashes of this firefly may have arisen from shifts in the response of male flashes to ambient temperature.

Time compression increases with eccentricity: a magnocellular property

Accurate time perception is crucial in peripheral vision especially for the spatial perception during actions. To investigate the dynamics of time perception in peripheral vision, parvocellular-biased and magnocellular-biased flashes were presented at different eccentricities (0-48 degrees ) in an interflash interval discrimination task. Results showed an increase in time compression with eccentricity for both stimuli (magnocellular-biased and parvocellular-biased flashes). Nevertheless, when stimulus visibility was 'equalized' across the visual field, the increase in time compression was only found for magnocellular-biased stimuli. Thus, we suggest that the magnocellular pathway accounts for time underestimation. Moreover, its increase with eccentricity could be an inherent property of the magnocellular system more than a result of a decrease in stimulus visibility.

Direction of Visual Apparent Motion Driven Solely by Timing of a Static Sound

In temporal ventriloquism, auditory events can illusorily attract perceived timing of a visual onset [1-3]. We investigated whether timing of a static sound can also influence spatio-temporal processing of visual apparent motion, induced here by visual bars alternating between opposite hemifields. Perceived direction typically depends on the relative interval in timing between visual left-right and right-left flashes (e.g., rightwards motion dominating when left-to-right interflash intervals are shortest [4]). In our new multisensory condition, interflash intervals were equal, but auditory beeps could slightly lag the right flash, yet slightly lead the left flash, or vice versa. This auditory timing strongly influenced perceived visual motion direction, despite providing no spatial auditory motion signal whatsoever. Moreover, prolonged adaptation to such auditorily driven apparent motion produced a robust visual motion aftereffect in the opposite direction, when measured in subsequent silence. Control experiments argued against accounts in terms of possible auditory grouping, or possible attention capture. We suggest that the motion arises because the sounds change perceived visual timing, as we separately confirmed. Our results provide a new demonstration of multisensory influences on sensory-specific perception [5], with timing of a static sound influencing spatio-temporal processing of visual motion direction.

Reduction of stimulus visibility compresses apparent time intervals

The neural mechanisms underlying visual estimation of subsecond durations remain unknown, but perisaccadic underestimation of interflash intervals may provide a clue as to the nature of these mechanisms. Here we found that simply reducing the flash visibility, particularly the visibility of transient signals, induced similar time underestimation by human observers. Our results suggest that weak transient responses fail to trigger the proper detection of temporal asynchrony, leading to increased perception of simultaneity and apparent time compression.

Intrasession variability of the full-field ERG

(1) To document variability of the full-field ERG within single recording sessions under ISCEV standards. (2) To identify clinical factors contributing to the observed variability. Nine volunteer subjects were studied, aged 19-32 with no history of retinal disease. ISCEV standard ERGs were recorded. Dark-adapted "standard combined" and light-adapted "cone" b-wave amplitudes and implicit times were measured. Multiple flashes were presented at different interflash intervals and after different periods of dark and light adaptation. The stability of the stimulus flash was measured with a photometer. The statistical coefficient of variability was roughly 2.5% for the standard combined b-wave amplitude and 4.5% for the cone b-wave. B-wave implicit times showed a coefficient of variability of 2% for standard combined responses and 1.25% for cone responses. Variation in interflash interval, dark and light adaptation times, and sporadic unusual waveforms influenced measured b-wave amplitudes. Intrasession variability is much lower than previously reported values for intersession variability. Nonetheless, it represents a baseline of variability that will affect results and that may be minimized by recognition and control of contributing factors.

Absence of Normal Photic Integration in the Circadian Visual System: Response to Millisecond Light Flashes

Light is the most prominent synchronizing stimulus for circadian rhythms. The circadian visual system responds in accordance with the energy content of photic stimuli longer than a few seconds. Here, as few as three flashes (2 ms each delivered to hamsters over 5 or 60 min at circadian time 19) elicited large phase advances. Ten or more flashes were required to induce FOS protein in the suprachiasmatic nucleus (SCN), and such induction occurred throughout the entire SCN, as well as outside the nucleus. High-density flash stimulation (0.5 s interflash interval) was ineffective, but response increased as the interval increased up to 4 s. In an irradiance response test, phase shifts appeared to be all-or-none with threshold irradiance between 140 and 1070 microW/cm2, implying lack of stimulus energy summation. Nevertheless, an irradiance ineffective when delivered as 10 flashes induced phase shifts when given as 100 flashes, but the response was substantially smaller than elicited by 10 flashes, each with approximately 1 log unit more irradiance. The results also show reduced sensitivity of flash-induced FOS response in the intergeniculate leaflet compared with the SCN, contrary to studies using longer light stimuli. Masking was robust and prolonged in response to 10 flashes. The data demonstrate that the circadian visual system responds markedly to brief, intense light stimuli without normal photic integration. This may involve a second input pathway different from that mediating the effects of longer, dimmer photic stimuli.

Life cycle and behaviour of the aquatic firefly Luciola leii (Coleoptera: Lampyridae) from Mainland China

AbstractThe aquatic larvae of the firefly Luciola leii Fu and Ballantyne occur on the substrate of rice fields and ditches in Hubei Province of central China. The behaviour and ecology of L. leii are described. We recorded L. leii larvae attacking four species of aquatic snails: Lymnaea stagnalis (L.) (Basommatophora: Lymnaeidae), Gyraulus convexiusculus (Hutton) (Basommatophora: Planorbidae), Radix auricularia (L.) (Lymnaeidae), and Bellamya purificata Heude (Mesogastropoda: Viviparidae). At dusk, flying males produced two types of advertising flashes. One type consisted of a train of 8 rapid, green flashes followed by 2–3 slow, prolonged flashes produced by patrolling males as a long-distance signal. The duration of flashes in the patrolling pattern was 530 ms and the interflash interval was 80 ms. The other type was a short-range signal consisting of a green glow, which was emitted by flying males that had located a female. Once a female had been located, the male landed and switched to a courting pattern. The male courtship pattern consisted of single flashes of about 400 ms duration, delivered every 1.8 s. Females produced single answering flashes of 910 ms duration, with a latency of approximately 630 ms after the male flash. Luciola leii was univoltine. Females oviposited 1 to 7 times (mean = 4.78). Females laid, on average, 187.19 eggs. The eggs hatched at 21.52 days. Eggs became luminescent 4 or 5 days before hatching. The larval stage had six instars. Mature larvae climbed onto land to construct pupal cells at the end of April of the next year. The pupal stage lasted, on average, 4.88 days. The imago lasted 10.13 days. No predators of larvae were observed. The spider Tetragnatha praedonia Koch (Araneae: Tetragnathidae) was frequently observed to capture adult male fireflies in its web.

Flash Activity in Two Synchronic Firefly Species (Coleoptera: Lampyridae)

Synchronic flashing in fireflies is a precisely timed behavior. This is a potentially useful tool to study sensory processing, the location and circuitry of the flash oscillator, and neuroeffector processing and coupling. Synchronic flashing, once thought to occur only in Southeast Asian fireflies, has recently been shown to be a prominent part of the behavior of a North American Photinus and Photuris species. To gain insights into the mechanisms of synchronic timing in fireflies, we compared spontaneous flashing and entrainment flashing in Photuris frontalis LeConte, a synchronic firefly found in Georgia's Coastal Plain, to analogous flashing in Pteroptyx malaccae Olivier, a synchronic firefly found in Malaysia. The timing of spontaneously produced flashes and entrainment flashes was recorded by photometry. Artificially produced, rhythmic stimulus flashes were used to induce a counterfeit synchrony (between subject fireflies and an LED), i.e., flash entrainment. We found that the spontaneously produced interflash intervals were repeated with a high degree of precision in P. frontalis and P. malaccae. However, the pattern of flashing was different during spontaneous flashing and flash entrainment. An isolated P. frontalis flashed intermittently during spontaneously flashing and entrainment flashing. Flash entrainment in P. frontalis started with an initial inhibition and then steady-state entrainment occurred with a fixed delay. In contrast, an isolated P. malaccae flashed continuously during spontaneous flashing and entrainment flashing. No initial inhibition occurred at the start of entrainment, and there was a gradual change in interflash interval until steady-state entrainment occurred at a fixed delay. We think that in-depth studies of the flash activities of different synchronic firefly species, including the locally available P. frontalis, could help our understanding of rhythmic temporal coordination of behavior by the nervous system.

Gene Diversity and Geographic Differentiation in Mitochondrial DNA of the Genji Firefly, Luciola cruciata (Coleoptera: Lampyridae)

The Genji firefly, Luciola cruciata, is divided into two ecological types, the fast-flash and slow-flash types, on the basis of the interflash interval of mate-seeking males. To evaluate the evolutionary origin of the two types, 62 populations were examined by restriction fragment length polymorphism analysis of the mitochondrial cytochrome oxidase (CO) II gene. As a result, 19 haplotypes were detected, and their distributions were indigenous to local areas. Phylogenetic trees constructed from sequence comparison of the haplotypes revealed three major clades (I, II, and III). The boundary of haplotypes between clades I and II is approximately concordant with the geological structure of the Japanese Islands, which is a great rupture zone called the Fossa Magna, and the distribution of haplotypes in clades III and I–II corresponds to the Kyushu and Honshu-Shikoku Islands, respectively. The results suggest a vicariant scenario in which current L. cruciata diversity would have arisen from phylogenetic separations subsequent to the formation process of the Japanese Islands based on the molecular clock. The CO II gene trees also suggested that the fast-flash type should be considered an ancestral form, while the slow-flash type would be a derived one. The divergence time between the slow- and the fast-flash types is estimated to be about 4.6 to 2.0 mya (the Pliocene epoch).

Dissociating sensory and cognitive contributions to visual persistence II. Photoreceptor integration of flash pairs as a function of interflash interval, intensity, integration site, and candidate code.

Perceived duration can be assessed behaviorally by adjusting the interval between two flashes so that an observer just perceives a certain relation between them. In such studies, the cognitive characteristics of the required relation necessarily interact with the sensory characteristics of the responses evoked by the two flashes. To dissociate the contributions of these two factors, we executed a physiological study which yielded more complete information on the role of each factor in two paradigms which have been used to characterize perceived duration behaviorally, namely the persistence-of-form design and the successive field design. The effect of sensory manipulations have yielded particularly problematic results in these two paradigms because opposite trends were found when intensity was varied. Intracellular recordings were therefore taken from photoreceptor cells exposed to procedural manipulations which match the sensory and cognitive variations employed in behavioral paradigms. The sensory variables of flash intensity, state of adaptation, and flash interval were explored with some completeness. Cognitive factors were assessed in two ways. First, the contribution of the neural site of sensory integration was determined by making a clear distinction between data collected when all stimuli affect the same receptors versus data collected when different stimuli affect different receptors. Second, the consequences of arbitrary choices of candidate code and dependent variable were also explored. When so organized, the physiological data provide a coherent basis for harmonizing apparently contradictory behavioral results because they qualitatively paralleled the behavioral data's complex dependence on intensity and interval. In particular, both direct and inverse dependencies of response duration on intensity exist in both physiology and behavior with the exact nature of the trend depending as much on the cognitive analysis of the neural responses as on their dynamics and energetics. Further, large quantitative differences were found which also were an expression of the different ways in which the two behavioral paradigms affect receptor potentials.

The a-wave of the dark adapted electroretinogram in glaucomas: are photoreceptors affected?

AIMSTo evaluate whether the a-wave of the dark adapted flash electroretinogram (ERG) is affected by glaucomatous damage.METHODSERGs were recorded in 20 patients (age 33–65 years) with advanced glaucomas (primary and...

13] Electroretinographic determination of human Rod flash response in vivo

This chapter describes a “paired-flash” electroretinogram (ERG) method that circumvents the constraint just noted, and in human subjects yields approximate determination of the full time course of the massed rod response to a test flash of arbitrary intensity. Studies to date investigating the paired-flash technique in human subjects indicate that this method yields, to good approximation, the full time course of the massed rod photoreceptor response to a test flash. Support for this conclusion comes primarily from the correspondence of kinetic, sensitivity, and light adaptation properties of the paired-flash-derived response with photocurrent response properties of human and other mammalian rods in vitro . Results obtained with the paired-flash method motivate further work in both human subjects and experimental animals to refine this in vivo approach for studying rod phototransduction. The chapter also identifies a number of considerations likely to be important for future development of the technique, including the refinement of procedures to subtract the cone contribution at short interflash intervals, and to better correct for postreceptor contributions and desensitization of the probe flash response.

A model of the perceived relative positions of moving objects based upon a slow averaging process

We extend the local energy model of position detection to cope with temporally varying position signals and the perception of relative position. The extension entails two main components. First, a form of persistence for the position signal based on the temporal impulse response function of the visual system. Secondly, we hypothesise that the perceived relative position of two objects is determined by a slow average of the difference of the objects’ position signals. The model explains why briefly flashed static dots are perceived to lag behind continuously visible moving dots, without the need for a motion extrapolation process [Nijhawan, R. (1994). Nature, 370, 256–257]. The dependence of this illusion on parameters such as the velocity, duration, frequency and number of flashes of the motion trajectories is accurately captured by the model. Furthermore, the model makes two predictions. First, briefly flashed dots on a staircase trajectory should lead dots with a long duration. Secondly, it should be possible to abolish the lag-effect between continuously visible and stroboscopically moving objects by halting the continuously visible dots during the interflash interval of the stroboscopic dots. Both predictions are corroborated in experiments.

Multi-flash ERG in cone dystrophies and cone-rod dystrophies

Scotopic electroretinograms elicited with a multiple flash procedure were reported to be helpful in diagnosis of macular diseases. To evaluate the contribution of rods and cones to the recovery of light responses as recorded with this technique we performed a triple flash ERG procedure in patients with cone dystrophies and cone-rod dystrophies. In 8 patients with cone dystrophy and 8 patients with cone-rod dystrophy and also in 18 healthy controls we recorded a standard ERG and the scotopic triple flash ERG with intensities between 0.01 and 0.2 cds/m2. Interflash intervals were adjusted at 140, 280, and 560 ms. Responses of the standard ERG were analysed as well as b-wave amplitudes at the short dark interval (140 ms) and the longer dark interval (280 ms). These responses were compared to responses after a long interflash interval (560 ms). Using a theoretical model parameters of b-wave recovery were determined and compared between the groups. In cone dystrophies responses of the scotopic triple flash ERG and the b-wave recovery parameters were normal whereas in combined dystrophies the triple flash responses were abnormal and the recovery data were pathologic. Cones did neither contribute to responses obtained with the multiple flash technique nor did they affect b-wave recovery as tested with this technique. Pathologic responses as described earlier with this technique in macular diseases could only be attributed to pathomechanisms globally affecting the rod system, e.g. dysfunction of retinal energy metabolism.

A behavioral study of temporal processing and visual persistence in young and aged rats.

Young rats were presented with light flash prepulses varying in duration from 1 to 128 ms, with light offset or light onset fixed at 70 ms prior to an acoustic startle stimulus (Experiment 1A), and, with single or paired 1-ms flashes, the 2nd (or only) flash given 100 to 500 ms before the startle, and 1 ms to 400 ms interflash intervals (Experiment 1B). Older rats (10 and 20 months old) received the same single and double flashes but with the maximum interflash interval extended to 1,500 ms (Experiment 2). Reflex inhibition increased with increased duration from 1 to 8 ms and decreased as light onset progressively exceeded 100 ms. Inhibition for both single and double flashes also declined for onset lead times beyond 100 ms, then increased for a double flash once the interflash interval exceeded 100 ms in young and middle-aged rats and 1,500 ms in the oldest rats. Peak inhibition was much reduced in the oldest rats at short lead times but was greater than that of younger rats at long lead times. These data suggest that aged rats process visual stimuli more slowly than younger rats and show poorer temporal acuity coupled with greater visual persistence.