Fig. 1

Analysis of swim kinematics revealed altered exploratory behavior for hungry zebrafish. Total distance travelled (in mm) per fish over a 6 min period, b. Freezing time (in seconds) defined as periods of immobility lasting > 4 s, c. Frequency of zone transition, d. mean speed (in mm/s), e. slow time (≤ 10 mm/s) in seconds, f. fast time (≥ 150 mm/s) in seconds, g. Schematic illustration of Parallel Index. The diagram shows three consecutive points (p1, p2, and p3) in the fish’s movement trajectory. The angle α represents the change in direction between the previous movement vector (p1 to p2) and the current movement vector (p2 to p3), h. Cumulative probability distribution of Parallel Index (PI) values for zebrafish under hungry (black) and control (green) condition, i. Schematic representation of turning index. The movement path is divided into sequential points (p1, p2, p3). The turning angle is determined by comparing the current direction vector (p2 to p3) relative to the previous direction vector (p1 to p2), j. Turning index over 20 sample indexes for control (top panel in green) and hungry (bottom panel in black) condition. Each data point represents the rotational behavior at a given sample index. Dashed lines indicate the general trend and overall directional bias of turning behavior over time, k. Spatial occupancy heat map of control and l. hungry zebrafish for the exploratory behavior. For calculating turning tendency and PI, samples with a displacement of less than 50 mm were excluded from the analysis. If the angle is < 20°, the value of the cosine of this angle is considered for the parallel index calculation. Box and whisker plots are shown with arithmetic median (middle line), and boxes represent the 1 st and 3rd quartiles. Data shown as mean ± s.e.m. P values are based on non-parametric t test comparing response differences. All asterisks indicate significance (*P < 0.05, **P < 0.01, ***P < 0.001 or ****P < 0.0001), ns: not significant; Mann–Whitney U test.