Effects of caloric stimuli on frog ampullar receptors.
Hear Res
; 137(1-2): 8-14, 1999 Nov.
Article
en En
| MEDLINE
| ID: mdl-10545629
ABSTRACT
The observation that caloric nystagmus can be evoked even in microgravity conditions argues against Barany's convective theory. To justify this result, gravity-independent mechanisms (mainly endolymphatic volume changes and direct action of the temperature on vestibular sensors) are believed to contribute to caloric-induced activation of vestibular receptors. To define the importance of both gravity-dependent and gravity-independent mechanisms, the posterior semicircular canal of the frog was thermally stimulated by a microthermistor positioned close to the sensory organ. The stimulus produced a gravity-dependent transcupular pressure difference that, depending on the position of the heater, could result in either excitation or inhibition of ampullar receptor sensory discharge. When the heater was positioned on the ampulla, or when the canal rested on the horizontal plane, no responses could be evoked by thermal stimuli. These results suggest that, in our experimental conditions (DeltaT up to 1.5 degrees C), neither a thermally induced expansion of the endolymph nor a direct action of the temperature on vestibular sensors play any major role.
Buscar en Google
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Rana esculenta
/
Ampolla Hepatopancreática
/
Nistagmo Fisiológico
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Hear Res
Año:
1999
Tipo del documento:
Article
País de afiliación:
Italia