[Reaction of single cercal mechanoreceptors of the cricket, Gryllus bimaculatus, to mechanical stimulation].

Naked tungsten microelectrodes were introduced through the chitinous wall close to the cell body of the receptor cells of trichoid hair sensillae, and responses to airpuffs, and rectangular, and trapezoidal displacements of the hair were recorded. Receptors of dorsal zone are activated during lateral deflection, those of ventral zone--during medial deflection and receptors of medial and lateral zones--during deflection to the cercal base. Sensitivity of receptors to the air-puffs is a function of hair length, the largest hairs being most sensitive. During trapezoidal displacement of the hair with different velocities of the slope, discharge frequency of the dynamic response is a function of velocity and angle in the range of angles up to 3-5 degrees (fig. 1). Discharge frequency of the stationary phase (corresponding to the plateau of the stimulus) is mainly a function of velocity in the range up to 6 degrees (fig. 2). The presence of sensillae with different hair length, and hence sensitivity, and definite directionality of receptors in different hair length, and hence sensitivity, and definite directionality of receptors in different zones may provide a basis for amplitude, velocity and direction discrimination of air-puffs or low-frequency mechanical stimulation by the cercal system of crickets.