Worms exhibit various behaviors in NGM, particularly in response to chemotactic drugs and certain toxicants, affecting worm pirouettes (Pierce-Shimomura et al., 1999).
To illustrate these differences, let’s observe two worms with distinct behaviors:
Worm #68: Shows more pirouettes, resulting in a meandering trajectory.
Worm #73: Displays a relatively straight trajectory.
To quantify these behavioral variances, we calculate the changes in trajectory angle for each worm. Starting from the XY position of each particle (file worm_trails.csv), the software computes the instantaneous angle between positions, followed by the calculation and accumulation of the deviation in this angle.
The result is a cumulative angle change, normalized to the number of millimeters traveled by the specific particle.
In the example, the calculations table reveals that Particle #68 has a Trajectory Turning Rate of 35.75 DeltaDegrees/mm, compared to Particle #73 with a Trajectory Turning Rate of 7.37 DeltaDegrees/mm.
Enabling the Beta-test option allows the inclusion of these calculations in the report.
Additionally, a file named “particle_angle.csv” is generated in the acquisition folder, containing all intermediate calculations for the reported value. Note that the information in the file is expressed in radians. To convert radians to degrees: degree_angle = rad_angle * 180 / 3.14.
Some “calculation” asumptions to keep in mind:
– Trajectory Turning Rate is not reported for particles traveling less than 2mm because they cause a significant distortion of average results.
– The trajectory angle is calculated every 0.5mm of movement based on the centroid of the worm. The function to calculate this angle is the inverse tangent function [arctan (x/y)]. Additionally, the track is smoothed using a moving average window of 5 frames to eliminate the angle effect caused by body bends