Caloric stimulation of ampullar receptors: a new method to produce mechanically-evoked responses in frog semicircular canals

• Published in: Journal of neuroscience methods Vol. 88; no. 2; pp. 141 - 151
• Main Authors: Zucca, G., Botta, L., Valli, S., Giannoni, B., Mira, E., Perin, P., Valli, P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.1999; Elsevier Science
• Subjects: Animals; Biological and medical sciences; Caloric stimulation; Caloric Tests - instrumentation; Caloric Tests - methods; Evoked Potentials - physiology; Frog; Fundamental and applied biological sciences. Psychology; General aspects. Models. Methods; Ranidae; Semicircular canal; Semicircular Canals - physiology; Software; Space life sciences; Thermoconvective currents; Vertebrates: nervous system and sense organs; Vestibular receptors; Frog; Thermoconvective currents; Semicircular canal; Vestibular receptors; Caloric stimulation; Vertebrata; Methodology; Investigation method; Amphibia; Thermal stimulus; Salientia; Vestibular system; Inner ear; Isolated organ; Biological receptor
• ISSN: 0165-0270; 1872-678X
• DOI: 10.1016/S0165-0270(99)00021-7

A microthermistor positioned close to the exposed posterior semicircular canal in isolated labyrinth preparations of the frog was used to stimulate the sensory organ. Our results indicated that, depending on the position of the heater, the induced endolymphatic convection currents may result in either excitatory or inhibitory cupular deflections and thus in a modulation of ampullar receptor resting activity. Other possible thermal-dependent mechanisms, such as a direct action of the stimulus on vestibular sensors or endolymphatic volume changes, had, in the present experimental conditions, a minor role. Caloric stimulation could therefore represent a novel method to stimulate the semicircular canals ‘in situ’.