Physiological properties of lateral line receptors of the lamprey.

Single unit recording from the lateral line nerve of the lamprey revealed the existence of two types of afferents. One type reacts to electric fields (threshold 10-30 microV/cm) and is insensitive to weak mechanical stimuli. The other type is very sensitive to water displacement and does not respond to weak electric fields. The properties of the electroreceptors of the lamprey are discussed and compared with other types of electroreceptors.

[Frequency characteristics of central neurons of the electroreceptor system of the skate in response to exposure to electric and magnetic fields]. / Issledovanie chastotnykh kharakteristik tsentral'nykh neironov élektroretseptornoi sistema skata pri deistvii élektricheskikh i magnitnykh polei.

Responses of single units to sinusoidal homogenous electrical and magnetic field stimulation were studied in the lateral-line lobes of the skate Raja radiata. The voltage gradient thresholds were in the range of 0.03-10 microV/cm. Optimal frequency ranges for electrical and magnetic stimuli were 0.05-0.5 and 2-3 Hz, respectively. Possible mechanisms and functional significance of frequency characteristics of the neurons are discussed.

[Functional properties of electroreceptors in the lamprey]. / Funktsional'nye svoistva élektroretseptorov minogi.

The impulse activity of nerve fibres in response to electric pulses and sinusoidal electric current stimulation of the electroreceptors was recorded in Lampetra fluviatilis. The electroreceptors of lamprey were excited by cathodal stimuli. Thresholds for electric stimulation were in the range of 10-60 microV/cm. Optimum frequency range in uniform electric field was 0.05-0.5 Hz. Properties of electroreceptors in lampreys and elasmobranches are discussed.

[Electrophysiologic study of the central projections of the ampullae of Lorenzini in the skate]. / Elektrofiziologicheskoe issledovanie tsentral'nykh proektsii ampul Lorentsini u skata.

A large portion of the central nervous system of the skate Raja radiata was examined for responses related to single electroreceptor organs (ampullae of Lorenzini) or their groups. It was shown that electroreceptors project to the anterior lateral lobes of the medulla, caudal portion of the auricles and the mesencephalon. A topographic segregation of electroreceptors (to the anterior lateral lobes) and mechanical lateral afferents (to the posterior lateral lobes) was found. Unit receptive fields in the anterior lateral lobe showed no absolute somatotopic organization of electroreceptive input. Three main types of mesencephalic responses were found: ipsilateral, contralateral and both ipsi- and contralateral.

[Functional characteristics of the electroreceptors of the Turkestan catfish]. / Funktsional'nye kharakteristiki élektroretseptorov turkestanskogo somika.

Experiments with recording of single fibre impulse activity from lateral-line nerve in Turkestan catfish (Glyptosternum reticulatum) show that the fish has a high-sensitive electroreceptor apparatus (threshold value in a uniform electric field was 1 muV/cm). The effective stimulus for the electroreceptors is the voltage drop across the fish skin. Impulse reactions to magnetic stimulation as well as thermal and mechanical sensitivity of the electroreceptors were observed. Biological significance of electroreceptors in Turkestan catfish is discussed.