[Thermoreceptor function of the stretch receptors of the river crayfish]

Cooling of the crayfish stretch receptor leads to increase and then decrease the spike frequency of slowly adapting (SA) neuron (maximum frequency at 15 degrees). Impulse activity of quickly adapting (QA) neuron arises about 12 degrees and is recoding for a long time (sometimes during 30 min.). Raising the temperature from 20 degrees to 30 degrees results in a gradual increase of the SA neuron spike frequency. Characteristic for cold thermoreceptors dynamic discharge is observed. Infra-red (IR) radiation (lambda=1--3 mum) causes a decrease of SA neuron spike frequency. QA neuron generates a brief discharge after cuting IR radiation. IR radiation acts on somato-dendro-muscle (sensory) region only. Analysis with polarizing microscope shows that the IR radiation effect on the structural organization of neurons is contrary the effect of warming and colding. It is proposed that the IR radiation effect is defined by the rise of temperature gradient in solution (dT/dx). Obtained results indicate that the crayfish stretch receptor belongs to the type of mechanocoldreceptors.