Properties of elementary movement detectors in the flyCalliphora erythrocephala

Schuling, F. H.; Mastebroek, H. A. K.; Bult, R.; Lenting, B. P. M.

doi:10.1007/bf00619192

Cited by 41 publications

(33 citation statements)

References 23 publications

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“…Because evidence for an inhibitory interaction between the movement-detector input channels was partly derived from apparent motion experiments, we applied these stimuli to the fly visual system, too. In contrast to previous studies (32)(33)(34)(35), we tested this question under virtually the same stimulus conditions used to establish the multiplicative interaction of the movement-detector input channels (12). The stimuli consisted of two stationary, vertical stripes, the brightness of which could be varied independently.…”

Section: Resultsmentioning

confidence: 99%

Direction selectivity of blowfly motion-sensitive neurons is computed in a two-stage process.

Borst

Egelhaaf

1990

Proc. Natl. Acad. Sci. U.S.A.

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Direction selectivity of motion-sensitive neurons is generally thought to result from the nonlinear interaction between the signals derived from adjacent image points. Modeling of motion-sensitive networks, however, reveals that such elements may still respond to motion in a rather poor directionally selective way. Direction selectivity can be significantly enhanced if the nonlinear interaction is followed by another processing stage in which the signals of elements with opposite preferred directions are subtracted from each other. Our electrophysiological experiments in the fly visual system suggest that here direction selectivity is acquired in such a two-stage process.Neurons with directionally selective responses to motion are found at different levels of the nervous system in animals as phylogenetically distant as insects and primates. It is an essential requirement for any mechanism underlying direction selectivity that it has at least two input channels subserving neighboring points in visual space, which, after being processed in an asymmetric way, interact nonlinearly (1-3) (Fig. 1 A). Various formal operations have been proposed for this nonlinear interaction, such as a logical gate (4), a multiplication (5-7), and a summation followed by a squaring (8) or a threshold operation (9, 10). However, such a singlestage mechanism may also respond to nonmotion stimuli as, for instance, changes in the mean light intensity (11,12). Because these direction-independent response components are identical in two single-stage mechanisms with the same receptive field but opposite polarity, they can be eliminated by subtracting the output of two such units (Fig. 1B). If such a two-stage process is perfectly mirror-symmetrical, it responds with the same amplitude but an opposite sign to motion in opposite directions (5,6,12). However, even if the symmetry is not exact, direction selectivity is enhanced by a subtraction stage as compared with the corresponding singlestage model (12).The first model of motion detection worked out in formal terms (5), the so-called correlation-type movement detector, makes use of this simple computational principle. This mechanism was initially proposed on the basis of experimental studies on insects (3, 5, 6), where it can account for motion detection surprisingly well under both steady-state and transient stimulus conditions (2, 6, 13-16). Although much effort has been made to characterize the nonlinear interaction, which could be shown to be well approximated by a multiplication (12, 17), there is so far not much direct evidence for the second processing step of direction selectivity, the subtraction stage.In contrast to insects, the responses of directionally selective cells in vertebrates are usually interpreted without taking the possibility of this second processing stage into account (see, however, ref. 18). Instead, most studies are based on a particular single-stage mechanism that goes back to the seminal study of Barlow and Levick (4) on directionally selective retinal g...

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Section: Resultsmentioning

confidence: 99%

Direction selectivity of blowfly motion-sensitive neurons is computed in a two-stage process.

Borst

Egelhaaf

1990

Proc. Natl. Acad. Sci. U.S.A.

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“…This property has been previously exploited to provide confirmation of the validity of the correlator model in application to fly optomotor responses (Buchner, 1976;Buchner, 1984;van Hateren, 1990) and to directly compare the sampling distance of fly LPTCs with the spacing of ommatidia (Schuling et al, 1989;Srinivasan and Dvorak, 1980). We used this property combined with the known angular spacing of Eristalis ommatidia (Fig.·1A,C) to estimate the relative contributions of the EMD types 1 and 2 (with inputs from neighboring ommatidia and next-but-one neighboring ommatidia, respectively).…”

Section: Estimating Contributions From Type 1 and Type 2 Emdsmentioning

confidence: 97%

A `bright zone' in male hoverfly (Eristalis tenax) eyes and associated faster motion detection and increased contrast sensitivity

Straw

Warrant

O’Carroll

2006

Journal of Experimental Biology

119

124

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contrast sensitivity exists in portions of the receptive field served by large diameter facet lenses of males and is not observed in females. Finally, temporal frequency tuning is also significantly faster in this frontal portion of the world, particularly in males, where it overcompensates for the higher spatial-frequency tuning and shifts the predicted local velocity optimum to higher speeds. These results indicate that increased retinal illuminance due to the bright zone of males is used to enhance contrast sensitivity and speed motion detector responses. Additionally, local neural properties vary across the visual world in a way not expected if HS cells serve purely as matched filters to measure yaw-induced visual motion.

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“…A speed of 3000°/s implies an image shift per frame of 3000/370 ϭ 8.1°, which is several times the interommatidial angle ⌬ ϭ 1.5°of Calliphora. The interommatidial angle is the angle between neighboring sampling directions and is considered the main sampling base of the inputs of the elementary movement detectors (Buchner, 1976;Schuling et al, 1989). Thus, a shift larger than the interommatidial angle will not effectively stimulate the movement sensitive-neurons, because it artificially jumps past ommatidia; this would never happen during a real physical movement.…”

Section: Methodsmentioning

confidence: 99%

Function and Coding in the Blowfly H1 Neuron during Naturalistic Optic Flow

Hateren¹,

Kern²,

Schwerdtfeger³

et al. 2005

J. Neurosci.

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Naturalistic stimuli, reconstructed from measured eye movements of flying blowflies, were replayed on a panoramic stimulus device. The directional movement-sensitive H1 neuron was recorded from blowflies watching these stimuli. The response of the H1 neuron is dominated by the response to fast saccadic turns into one direction. The response between saccades is mostly inhibited by the front-toback optic flow caused by the forward translation during flight. To unravel the functional significance of the H1 neuron, we replayed, in addition to the original behaviorally generated stimulus, two targeted stimulus modifications: (1) a stimulus in which flow resulting from translation was removed (this stimulus produced strong intersaccadic responses); and (2) a stimulus in which the saccades were removed by assuming that the head follows the smooth flight trajectory (this stimulus produced alternating zero or nearly saturating spike rates). The responses to the two modified stimuli are strongly different from the response to the original stimulus, showing the importance of translation and saccades for the H1 response to natural optic flow. The response to the original stimulus thus suggests a double function for the H1 neuron, assisting two major classes of movement-sensitive output neurons targeted by H1. First, its strong response to saccades may function as a saccadic suppressor (via one of its target neurons) for cells involved in figure-ground discrimination. Second, its intersaccadic response may increase the signal-to-noise ratio (SNR) of wide-field neurons involved in detecting translational optic flow between saccades, in particular when flying speeds are low or when object distances are large.

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Properties of elementary movement detectors in the flyCalliphora erythrocephala

Cited by 41 publications

References 23 publications

Direction selectivity of blowfly motion-sensitive neurons is computed in a two-stage process.

Direction selectivity of blowfly motion-sensitive neurons is computed in a two-stage process.

A `bright zone' in male hoverfly (Eristalis tenax) eyes and associated faster motion detection and increased contrast sensitivity

Function and Coding in the Blowfly H1 Neuron during Naturalistic Optic Flow

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