PMC

Flow diagrams of three possible forms of interaction between the chasing system and the optomotor following system. The input to the chasing system is θ_e, i.e. the error angle of the target relative to the frontal midline of the fly's visual field. g_c and g_o are the internal gains of the chasing system and the optomotor system, respectively. The input to the optomotor system is provided by φ_bg, i.e. the angular velocity of the environment (i.e. background). φ_out is the final turning response of the animal which is the sum of the turning responses mediated by the optomotor system and the chasing system. (A) Additive scheme: The signals mediating the turning responses of the chasing and the optomotor system are just added. There are no other interactions within the nervous system between the two system. (B) Efference copy scheme: As the additive scheme; however a copy of the turning command (‘efference copy’) is added to the input signal of the optomotor system to cancel during chasing behavior the visual feedback resulting from turns evoked by the optomotor system. (C) Suppressive scheme: A copy of the chasing control signal does not interact with the optomotor input signal in a linear way, as does the efference copy scheme, but reduces the internal optomotor gain or even suppresses the optomotor signal completely. Gain control has the advantage that the copy of the chasing signal does not need to be exactly adjusted to the visual feedback which cannot easily be predicted under natural flight conditions (A,B modified from Collett, ).

Optomotor Response in wildtype and dopamine receptor Dop1R1 (DopR) mutant flies. (A) Optomotor response as defined by % time spent in the correct quadrant. In the first minute, Quadrant 4 is the terminal optomotor target for flies, in the second minute Quadrant 1 is the target (optomotor response direction symbolized by black arrows). (B) Optomotor response in DopR^f02676/DopR^f02676 homozygous mutant flies. (C) Comparison of optomotor response in wildtype and DopR^f02676/DopR^f02676 homozygous mutant flies. (D) Velocity of wildtype and DopR^f02676/DopR^f02676 mutant flies during the standard stampede assay condition. (E) Comparison of velocity for wildtype and DopR mutant flies in response to different assay conditions (no stimuli visual motion stimuli alone startle alone startle + visual motion). SEM represented for all conditions (A–C) n = 12 for all conditions. One-Way analysis of variance (ANOVA) with Bonferroni Correction. (D,E) n = 20 for all conditions. Paired T-tests (A–E) ****p < 0.0001 ***p < 0.001, **p < 0.01, *p < 0.05.

A) Schematic of the optomotor arenas and behavioral box. B) Diagram of a single arena and optomotor stimulus. Trials begin with a pinwheel stimulus, centered on the fly. For each trial, the rotational direction (red arrow) of the stimulus is randomized. As the animal moves, the pinwheel position is updated to stay centered on the fly. Trials end when the stimulus is removed after 2s. C) Four sample raw individual angular velocity time series. Flies typically respond to optomotor stimuli by turning in the direction of the rotation of the stimulus. Shaded rectangles indicate the direction of pinwheel rotation, line color angular acceleration. D) Trial-triggered average optomotor response across all individuals. Change in body angle (left) is relative to body angle at stimulus onset. Sign indicates turns with (positive) or against (negative) the direction of stimulus rotation. E) Comparison of the observed distribution of individual average optomotor indices (n = 1,860) to the distribution expected under a null model in which all flies turn with identical statistics, generated by bootstrap resampling. F) Population average optomotor index as a function of stimulus contrast (0-1). Pinwheel contrast was randomly varied on a trial-by-trial basis. G) Average optomotor index as a function of stimulus spatial frequency and stimulus angular velocity.

a, Schematic of preparation for evoking optomotor responses using wide-field motion (top), and the turning responses of animals presented with alternating-direction wide-field motion. b, Example of a male’s turning during an optomotor trial. Each row consists of three stimulus cycles. Purple bars indicate when the grating is rotating. c, Example of the functional response (ΔF/F₀) of P1 neurons during an optomotor trial, before and during the grating oscillates, as well as the angular velocity and linear speed of the animal. d, Histogram of angular velocities observed during courtship trials (gray) and during optomotor trials (purple). e, Histogram of linear speeds observed during courtship trials (gray) and during optomotor trials (purple). f-i, Scatter plots of P1 activity versus the tracking index (f), the stimulus position (g), the linear speed (h) and the angular velocity (i) of all animals during courtship trials. j, Correlation between P1 activity and the parameters explored in k-n during courtship trials. Individual data points are animals. k-n, Scatter plots of P1 activity versus the optomotor tracking index (k), the velocity of the grating (l), the linear speed (m) and the angular velocity (n) of all animals during optomotor trials. o, Correlation between P1 activity and the parameters explored in p-s during optomotor trials. Individual data points are animals. All shaded line plots are mean±s.e.m.; *indicates p < 0.05, **indicates p < 0.01, *** indicates p < 0.001, and **** indicates p < 0.0001. Details of statistical analyses and group sizes are given in .