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Local motion detectors are required for the computation of expansion flow-fields.

Schilling T, Borst A - Biol Open (2015)

Bottom Line: Tethered flying fruit flies, when confronted with an expansion flow-field, reliably turn away from the pole of expansion when presented laterally, or perform a landing response when presented frontally.Here, we show that the response to an expansion flow-field is independent of the overall luminance change and edge acceleration.As we demonstrate by blocking local motion-sensing neurons T4 and T5, the response depends crucially on the neural computation of appropriately aligned local motion vectors, using the same hardware that also controls the optomotor response to rotational flow-fields.

View Article: PubMed Central - PubMed

Affiliation: Department of Circuits-Computation-Models, Max-Planck-Institute of Neurobiology, Martinsried D-82152, Germany.

No MeSH data available.


Related in: MedlinePlus

Characterization of the avoidance behavior elicited by different stimuli. Average turning responses of Canton-S wild-type flies, elicited by expanding stimuli. (A) Illustration of the flight setup. (B) Avoidance response to a vertical bar expanding horizontally presented at ±50°. The bar expands from 0° to 180° in 1 s, n=13. (C) Velocity tuning of the avoidance response to an expanding bar with expansion velocities from 40 to 5400 deg/s. The flies reacted with comparable strong turning to a broad range of expansion velocities from 180° to 2700° with a maximum at 360 deg/s, n=10. (D-I) Turning responses to different expansion/looming stimuli, n=10. (D-F) Avoidance responses to a dark looming square (D), a bright looming square (E) and a looming square with a checkerboard pattern (F). (G) Response to a dimming 120°×120° square. (H) Avoidance response to a horizontal bar expanding vertically at a velocity of 360 deg/s, width=60°, presented at ±60°. (I) Avoidance of two 10° broad vertical stripes moving away from each other for 0.25 s at a velocity of 360 deg/s. (J,K) Reactions to a looming bar where either the anterior or the posterior edge is moving, n=10. (L) The sum of the single edge responses (upper line) and the response to the sum of both edges moving (lower line), n=10. FtB, front to back; BtF, back to front. All data represent mean±s.e.m.
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BIO012690F1: Characterization of the avoidance behavior elicited by different stimuli. Average turning responses of Canton-S wild-type flies, elicited by expanding stimuli. (A) Illustration of the flight setup. (B) Avoidance response to a vertical bar expanding horizontally presented at ±50°. The bar expands from 0° to 180° in 1 s, n=13. (C) Velocity tuning of the avoidance response to an expanding bar with expansion velocities from 40 to 5400 deg/s. The flies reacted with comparable strong turning to a broad range of expansion velocities from 180° to 2700° with a maximum at 360 deg/s, n=10. (D-I) Turning responses to different expansion/looming stimuli, n=10. (D-F) Avoidance responses to a dark looming square (D), a bright looming square (E) and a looming square with a checkerboard pattern (F). (G) Response to a dimming 120°×120° square. (H) Avoidance response to a horizontal bar expanding vertically at a velocity of 360 deg/s, width=60°, presented at ±60°. (I) Avoidance of two 10° broad vertical stripes moving away from each other for 0.25 s at a velocity of 360 deg/s. (J,K) Reactions to a looming bar where either the anterior or the posterior edge is moving, n=10. (L) The sum of the single edge responses (upper line) and the response to the sum of both edges moving (lower line), n=10. FtB, front to back; BtF, back to front. All data represent mean±s.e.m.

Mentions: In order to characterize visual features which elicit avoidance responses, we confronted tethered flying flies (Fig. 1A) with various visual stimuli presented laterally at an angle of ±50° to the flight course. The first stimulus consisted of a vertical dark bar expanding with different angular velocities to 180° width. A typical collision avoidance response to a bar expanding at a constant velocity of 180 deg/s is shown in Fig. 1B: After a brief latency the animals attempted to turn away as long as the stimulus was presented. The strength of the avoidance response was strongly dependent on the angular expansion velocity of the stimulus with a maximal response at a velocity of 340 deg/s (Fig. 1C). Objects moving towards a fly with a constant velocity induce not a constantly but exponentially increasing expansion pattern on the retina. To mimic a physically realistic approach dynamic, we used looming squares and presented them with different patterns inducing either a decrease, an increase or no overall luminance change. A looming dark square (Fig. 1D), a bright square on a dark background (Fig. 1E) and a square with a checkerboard pattern (Fig. 1F) elicited similar avoidance responses independent of the global luminance change. In addition, dimming of a laterally presented square with 120° width induced even a slight turning towards the square (Fig. 1G). A looming horizontal bar expanding only vertically elicited an avoidance yaw turn (Fig. 1H) comparable in amplitude and time-course to the reaction away from a horizontally expanding bar. Finally, we replaced the expanding bar by two vertical bars moving away from each other for 0.25 s at a velocity of 360 deg/s. This elicited an avoidance behavior away from the stimulus (Fig. 1I). In summary, we found no or little influence of the overall luminance change on the reaction of the fly.Fig. 1.


Local motion detectors are required for the computation of expansion flow-fields.

Schilling T, Borst A - Biol Open (2015)

Characterization of the avoidance behavior elicited by different stimuli. Average turning responses of Canton-S wild-type flies, elicited by expanding stimuli. (A) Illustration of the flight setup. (B) Avoidance response to a vertical bar expanding horizontally presented at ±50°. The bar expands from 0° to 180° in 1 s, n=13. (C) Velocity tuning of the avoidance response to an expanding bar with expansion velocities from 40 to 5400 deg/s. The flies reacted with comparable strong turning to a broad range of expansion velocities from 180° to 2700° with a maximum at 360 deg/s, n=10. (D-I) Turning responses to different expansion/looming stimuli, n=10. (D-F) Avoidance responses to a dark looming square (D), a bright looming square (E) and a looming square with a checkerboard pattern (F). (G) Response to a dimming 120°×120° square. (H) Avoidance response to a horizontal bar expanding vertically at a velocity of 360 deg/s, width=60°, presented at ±60°. (I) Avoidance of two 10° broad vertical stripes moving away from each other for 0.25 s at a velocity of 360 deg/s. (J,K) Reactions to a looming bar where either the anterior or the posterior edge is moving, n=10. (L) The sum of the single edge responses (upper line) and the response to the sum of both edges moving (lower line), n=10. FtB, front to back; BtF, back to front. All data represent mean±s.e.m.
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BIO012690F1: Characterization of the avoidance behavior elicited by different stimuli. Average turning responses of Canton-S wild-type flies, elicited by expanding stimuli. (A) Illustration of the flight setup. (B) Avoidance response to a vertical bar expanding horizontally presented at ±50°. The bar expands from 0° to 180° in 1 s, n=13. (C) Velocity tuning of the avoidance response to an expanding bar with expansion velocities from 40 to 5400 deg/s. The flies reacted with comparable strong turning to a broad range of expansion velocities from 180° to 2700° with a maximum at 360 deg/s, n=10. (D-I) Turning responses to different expansion/looming stimuli, n=10. (D-F) Avoidance responses to a dark looming square (D), a bright looming square (E) and a looming square with a checkerboard pattern (F). (G) Response to a dimming 120°×120° square. (H) Avoidance response to a horizontal bar expanding vertically at a velocity of 360 deg/s, width=60°, presented at ±60°. (I) Avoidance of two 10° broad vertical stripes moving away from each other for 0.25 s at a velocity of 360 deg/s. (J,K) Reactions to a looming bar where either the anterior or the posterior edge is moving, n=10. (L) The sum of the single edge responses (upper line) and the response to the sum of both edges moving (lower line), n=10. FtB, front to back; BtF, back to front. All data represent mean±s.e.m.
Mentions: In order to characterize visual features which elicit avoidance responses, we confronted tethered flying flies (Fig. 1A) with various visual stimuli presented laterally at an angle of ±50° to the flight course. The first stimulus consisted of a vertical dark bar expanding with different angular velocities to 180° width. A typical collision avoidance response to a bar expanding at a constant velocity of 180 deg/s is shown in Fig. 1B: After a brief latency the animals attempted to turn away as long as the stimulus was presented. The strength of the avoidance response was strongly dependent on the angular expansion velocity of the stimulus with a maximal response at a velocity of 340 deg/s (Fig. 1C). Objects moving towards a fly with a constant velocity induce not a constantly but exponentially increasing expansion pattern on the retina. To mimic a physically realistic approach dynamic, we used looming squares and presented them with different patterns inducing either a decrease, an increase or no overall luminance change. A looming dark square (Fig. 1D), a bright square on a dark background (Fig. 1E) and a square with a checkerboard pattern (Fig. 1F) elicited similar avoidance responses independent of the global luminance change. In addition, dimming of a laterally presented square with 120° width induced even a slight turning towards the square (Fig. 1G). A looming horizontal bar expanding only vertically elicited an avoidance yaw turn (Fig. 1H) comparable in amplitude and time-course to the reaction away from a horizontally expanding bar. Finally, we replaced the expanding bar by two vertical bars moving away from each other for 0.25 s at a velocity of 360 deg/s. This elicited an avoidance behavior away from the stimulus (Fig. 1I). In summary, we found no or little influence of the overall luminance change on the reaction of the fly.Fig. 1.

Bottom Line: Tethered flying fruit flies, when confronted with an expansion flow-field, reliably turn away from the pole of expansion when presented laterally, or perform a landing response when presented frontally.Here, we show that the response to an expansion flow-field is independent of the overall luminance change and edge acceleration.As we demonstrate by blocking local motion-sensing neurons T4 and T5, the response depends crucially on the neural computation of appropriately aligned local motion vectors, using the same hardware that also controls the optomotor response to rotational flow-fields.

View Article: PubMed Central - PubMed

Affiliation: Department of Circuits-Computation-Models, Max-Planck-Institute of Neurobiology, Martinsried D-82152, Germany.

No MeSH data available.


Related in: MedlinePlus