Identifiable neurons inhibited by Earth-strength magnetic stimuli in the molluscTritonia diomedea

Abstract

SUMMARY Diverse animals use the Earth's magnetic field as an orientation cue, but little is known about the sensory, processing and motor elements of the neural circuitry underlying magnetic orientation behavior. The marine mollusc Tritonia diomedea has both a magnetic compass sense and a simple nervous system accessible to electrophysiological analysis. Previous studies have revealed that four identifiable neurons, known as LPd5, RPd5, LPd6 and RPd6, respond with enhanced electrical activity to changes in Earth-strength magnetic fields. Here we report that two additional neurons, LPd7 and RPd7,are inhibited by magnetic stimuli. Cobalt fills of the Pd7 neurons indicated that two prominent neurites emerge from the soma and project to the periphery through the ipsilateral cerebral nerves CeN6 and CeN3; in some cases, a third neurite was visible in CeN2. The nerves extend to the anterior region of the animal where they innervate the lateral body walls, oral veil and mouth region. Action potentials in the Pd7 neurons propagate from the central ganglia toward the periphery. Thus, the Pd7 cells have characteristics of efferent neurons. The precise function of these cells during magnetic orientation behavior, however, remains to be determined.

Laboratory behavioural assay of insect magnetoreception:magnetosensitivity of Periplaneta americana

“…However, vertebrate nervous systems are much more complex and sensitive to experimental treatment than the invertebrate one (Johnsen and Lohmann, 2005). Recent positive results on the mollusc Tritonia, which is a classical model for mechanisms of learning and memory studies, show a promising route for neuro-behavioural linking in magnetoreception research (Cain et al, 2005;Cain et al, 2006;Wang et al, 2004). We see our work as a contribution from the insect science side.…”

Do geomagnetic storms change the behaviour of the stingless bee guiruçu (Schwarziana quadripunctata)?

“…Despite a recent increase in physiological and behavioural studies, it is still poorly understood (Nemec et al 2005;Wang et al 2004;Becker and Gerisch 1981;Acosta-Avalos et al 2001).…”

Decreased plasma levels of nitric oxide metabolites, angiotensin II, and aldosterone in spontaneously hypertensive rats exposed to 5 mT static magnetic field

“…There is substantial and growing evidence that static magnetic fields (SMF) less than 1 tesla (T) can influence physiological processes in vivo: pain [Takeshige and Sato, 1996;Vallbona et al, 1997;Holcomb et al, 2000;Brown et al, 2002;Hinman, 2002;Weintraub et al, 2003], bone repair and formation [Bruce et al, 1987;Mevissen et al, 1994;Darendeliler et al, 1997;Yan et al, 1998;Xu et al, 2001], inflammation and wound healing [Lud and Demeckiy, 1990;Weinberger et al, 1996;Man et al, 1999;Alfano et al, 2001;Segal et al, 2001;Rogachefsky et al, 2004], anticonvulsant effects [McLean et al, 2003], enhanced chemotherapy [Gray et al, 2000], spatial discrimination learning [Levine and Bluni, 1994], melatonin reduction [Welker et al, 1983;Olcese et al, 1985;Olcese and Reuss, 1986;Stehle et al, 1988], cyclic AMP reduction [Rudolph et al, 1988], central nervous system function [Rosen and Lubowsky, 1987;Veliks et al, 2004], action potential generation [Lohmann et al, 1991;Popescu and Willows, 1999;Wang et al, 2003Wang et al, , 2004, enhanced tumor apoptosis [Tofani et al, 2001[Tofani et al, , 2002, and increased c-fos gene expression [Němec et al, 2001]. Therefore, characterizing the physiological transduction mechanism of SMF on BP in both hypertension and hypotension, remains an important area of research toward the development of better p...…”