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Effect of macular ablation on frequency and latency of motion-induced emesis in the squirrel monkey
Abstract:
Three previously motion-emetic sensitive squirrel monkeys were rendered refractory to a standard motion-emetic regimen by a two-stage utriculosacculectomy procedure which preserved the cristae ampullares of semicircular canals. Three non-operated control squirrel monkeys tested on the same motion-emetic regimen time schedule as the operated animals remained motion-emetic sensitive with regard to incidence, frequency, and latency of motion-induced emetic responses. Following a sham surgical procedure (stapedectomy) performed on two of the latter animals and one additional new animal, the emetic incidence decreased from 100% to 89%, but the frequency and latency were not altered significantly.
Insights
Squirrel monkeys lacking vestibular function due to utriculosacculectomy surgery became resistant to motion-induced vomiting. Control and sham-operated animals remained sensitive, indicating the utricle and saccule are crucial for motion sickness.
Area of Science:
- Neuroscience
- Vestibular System Research
- Primate Models
Background:
- Motion sickness is a common neurological disorder.
- The vestibular system, particularly the otolith organs (utricle and saccule), is implicated in motion sickness.
- Previous research suggests a role for the otolith organs in mediating motion-induced emesis.
Purpose of the Study:
- To investigate the role of the utricle and saccule in motion sickness.
- To determine if removal of the utricle and saccule renders subjects refractory to motion-induced emesis.
- To assess the necessity of otolith organs for the incidence, frequency, and latency of motion sickness.
Main Methods:
- A two-stage utriculosacculectomy was performed on three motion-sickness-sensitive squirrel monkeys, preserving the semicircular canals.
- Control group: Three non-operated squirrel monkeys received the same motion-emetic regimen.
- Sham surgery (stapedectomy) was performed on two control animals and one additional animal.
Main Results:
- Utriculosacculectomized monkeys became refractory to the motion-emetic regimen.
- Control monkeys remained sensitive to motion-induced emesis.
- Sham surgery reduced emetic incidence from 100% to 89% but did not significantly alter frequency or latency.
Conclusions:
- The utricle and saccule are essential for mediating motion-induced emesis in squirrel monkeys.
- Complete or partial ablation of otolith organs significantly reduces or eliminates motion sickness.
- This study highlights the critical role of the otolith organs in the neurophysiological basis of motion sickness.