A. Bohmer et al., CONTRIBUTIONS OF SINGLE SEMICIRCULAR CANALS TO CALORIC NYSTAGMUS AS REVEALED BY CANAL PLUGGING IN RHESUS-MONKEYS, Acta oto-laryngologica, 116(4), 1996, pp. 513-520
We demonstrated specific responses from the anterior and the posterior
semicircular canal to irrigation of the outer ear canal with cold wat
er in the Rhesus monkey. This required i) three-dimensional analysis o
f the evoked eye movements in the planes of the semicircular canals (c
anal plane vectors, CPV); ii) assessing these CPV responses in eight d
ifferent head positions relative to gravity; iii) comparing the respon
ses in 6 normal animals (12 ears) with responses after selective plugg
ing of pairs of semicircular canals (all, both lateral, and right ante
rior+left posterior). The results showed: i) Irrigation of the outer e
ar canal with cold water induces thermoconvection also in the posterio
r and anterior semicircular canals. This can be inferred from the sinu
soidal modulation of eye movement components with changes in position
of the corresponding semicircular canal plane relative to gravity; ii)
Specific vertical canal responses occur exclusively in the direction
of the corresponding semicircular canal, though they are superimposed
with response components of other origin, one probably related to endo
lymph shift in the lateral semicircular canal; iii) before possible cl
inical application, these different response components of vertical ca
nals will need to be determined in humans.