N. Dieringer et H. Straka, STEPS TOWARD RECOVERY OF FUNCTION AFTER HEMILABYRINTHECTOMY IN FROGS, Otolaryngology and head and neck surgery, 119(1), 1998, pp. 27-33
Removal of the labyrinthine organs on one side results in a number of
severe postural and dynamic reflex deficits, Over time some of these b
ehavioral deficits normalize again, At a chronic stage the brain of fr
ogs exhibits a number of changes in vestibular and propriospinal circu
its on the operated side that were studied in vitro, The onset of chan
ges in the vestibular nuclear complex was delayed, became evident only
after head posture had recovered by more than 50%, and was independen
t of the presence or absence of a degeneration of vestibular nerve aff
erent fibers, The time course of changes measured in the isolated spin
al cord paralleled the time course of normalization of head and body p
osture. Results obtained after selective lesions of individual labyrin
thine nerve branches show that unilateral inactivation of utricular af
ferent inputs is a necessary and sufficient condition to provoke postu
ral deficits and propriospinal changes similar to those after the remo
val of all labyrinthine organs, The presence of multiple synaptic chan
ges at distributed anatomic sites over different periods of time sugge
sts that different parts of the central nervous system are involved in
the normalization of different manifestations of the vestibular lesio
n syndrome.