Paths of Carabid Beetles Walking in the Absence of Orienting Stimuli and the Time Structure of their Motor Output

Abstract

The locomotor activity of carabid beetles walking in the absence of orienting stimuli is analysed. Under such conditions the animals walk with no preferred direction and typically show a circular walking pattern which results from a motor asymmetry. Three parameters (speed, direction and angular velocity) characterising the paths are evaluated. Changes of speed and of walking direction are mutually independent. The performed autocorrelation analysis reveals a complex directional autocorrelation function with a monotone decay and a discontinuity at the origin, the curve starts with a non-zero slope. Two endogeneous processes of directional changes could be responsible for this shape of the autocorrelation function: either a broad band ‘noisy’ course of angular velocity or an uncorrelated jump process of directional changes.