Vagal afferent projections to lobule VIIa of the rabbit cerebellar vermis related to cardiovascular control.
In decerebrate rabbits we recorded simultaneously field potentials in lobule VIIa of the vermal cerebellar cortex and the vagal compound action potentials (vCAPs) proximally in the vagus nerve following electrical stimulation distally in the same nerve at different intensities. Four principal components of the vCAP were distinguished based on their peak conduction velocities. Their velocities were component I, 67-100 m/s; II, 28-50 m/s; III, 6-28 m/s, IV, 0.4-1.3 m/s. A collision test based on stimulating the recurrent laryngeal nerve identified component I and sub-component IIa of the vCAP as being due to the motor fibres of the descending limb of the nerve. The field potentials evoked in lobule VIIa by electrical stimulation of the cervical vagus nerve were climbing fibre responses as judged by the characteristics of their lamina profile and their response to high frequency stimulation. These field potentials in lobule VIIa correlated most closely with the component III of the vCAP; particularly with a sub-component IIIa of the vagus. Based on the investigations by Evans and Murray (1954) (Histological and functional studies on the fibre composition of the vagus nerve of the rabbit. J. Anat. (Lond.) 88, 320-337) in the rabbit, and by Paintal (1963) (Vagal afferent fibres. Ergeb. Physiol. 52, 74-156) and Mei (1970) (Cardiovascular and respiratory vagal mechanoreceptors in the cat. Exp. Brain Res. 11, 480-501) in the cat, component III is most likely to be due to receptors from the heart and a part of the pulmonary stretch receptors.
Kondo
M
M
Department of Physiology, Oita Medical University, Japan. kondo@oita-med.ac.jp
Sears
T A
TA
Sadakane
K
K
Nisimaru
N
N
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001933:Brain Stem / Q000502:physiology; D002319:Cardiovascular System / Q000294:innervation*; D002415:Cats; D002525:Cerebellar Cortex / Q000033:anatomy & histology / Q000502:physiology*; D002531:Cerebellum / Q000502:physiology; D003655:Decerebrate State; D004558:Electric Stimulation; D005071:Evoked Potentials; D009046:Motor Neurons / Q000502:physiology; D009412:Nerve Fibers / Q000502:physiology; D011817:Rabbits; D014630:Vagus Nerve / Q000502:physiology*