title: Spontaneous and light-evoked discharge of the isolated abdominal nerve cord of crayfish in vitro reveals circadian oscillations.
abstract: We examined the well-known spontaneous discharge (SD) and light-evoked (PD) discharge of the crayfish caudal photoreceptor for the possible existence of a daily rhythm in spike frequency. To do this, we isolated the abdominal nerve cord in vitro and studied its discharge frequency in constant darkness. Single cosinor analysis revealed significant SD and PD circadian rhythms (P < .05) with periods tau = 24.4h and 24.2h, respectively. These oscillations correspond to an endogenous circadian discharge of the caudal photoreceptor that is enhanced by light. The importance of this rhythm in the adaptive behavior of crayfish is discussed.
authors.affiliation: Laboratorio de Neurofisiología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, México.
authors.forename: J
authors.initials: J
authors.lastname: Prieto-Sagredo
authors.forename: M L
authors.initials: ML
authors.lastname: Fanjul-Moles
mesh_terms: D000200:Action Potentials; D000818:Animals; D003400:Astacoidea / Q000502:physiology* / Q000528:radiation effects; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects*; D005071:Evoked Potentials / Q000528:radiation effects; D005260:Female; D066298:In Vitro Techniques; D008027:Light; D008297:Male; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology* / Q000528:radiation effects*