Walter B. Kulecz

Autonomic effects on R-R variations of the heart rate in the squirrel monkey: an indicator of autonomic imbalance in conflict sickness.

To assess the contribution of the autonomic nervous system (ANS) to beat-to-beat (R-R interval) variations in the squirrel monkey, heart rate was analyzed after atropine, propranolol, carbachol, or isoproterenol administration, using a computer analyzing system. Heart rate variations were expressed as coefficient of variance (CV) of mean R-R interval. CV of R-R interval clearly was reduced by atropine but not by propranolol, indicating that the effect could be mediated through the parasympathetic nerve. CV of R-R interval was measured also under vestibulo-visual conflict (VVC) situation in pitch. Although CV of R-R interval increased during VVC, this variation almost was abolished after atropine administration. Monkeys with unilateral labyrinthectomy showed smaller variations than those without operation during exposure to VVC. CV of R-R interval is a useful parameter for the objective and quantitative evaluation of ANS function and may be a good indicator to demonstrate the severity of motion sickness without invasive methods.

Vestibular-Visual Conflict Sickness in the Squirrel Monkey

When combined vestibular and visual (optokinetic) stimuli were given to squirrel monkeys in a direction and phase mismatching sinusoidal mode (in yaw plane), five of six monkeys exhibited actual emesis during three repeated exposures on separate trial days. Two animals vomited on two trial days and three animals, on one day. The incidence took place in 38.9% of the total trial days. When the identical vestibular and visual stimuli were given individually, the effect was negligible, thus confirming each stimulus magnitude was not stressful enough to produce emesis when used separately.

The role of saccular afferents in vertical optokinetic nystagmus in primates. A study in relation to optokinetic nystagmus in microgravity

SummaryAfter bilateral sacculectomies, the squirrel monkeys vertical optokinetic nystagmus showed a gain increase of slow-phase down-nystagmus and a gain decrease of the slow-phase up-nystagmus. The nystagmus beating field of the former shifted upward but that of the latter did not change clearly. These results are in general agreement with the findings in man during the recent shuttle flight and indicate the functional linkage of saccular afferents to the vertical optokinetic nystagmus.

Transection of Crossed Olivo-Cochlear Bundle and Auditory Brain Stem Responses in the Cat

The effects of transection of the crossed olivo-cochlear bundle (COCB) on auditory brain stem responses (ABR) were investigated in the cat. The threshold, the amplitude and the peak latency of waves I-1V, and interpeak latencies were compared before and after transection of the COCB. No significant change was found in these parameters of ABR after elimination of the COCB.

Asymmetry of Vertical Optokinetic After-nystagmus in Squirrel Monkeys

Asymmetry of vertical optokinetic after-nystagmus (OKAN) was studied in 6 squirrel monkeys. The slow-phase eye velocity (SPEV) of upward OKAN first-phase (OKAN-I) increased with increasing stimulus velocity, whereas the SPEV of downward OKAN-I diminished. The time constant of OKAN-I was shortened with the increase in stimulus speed in both directions. With a downward stimulus, the short stimulus duration failed to produce OKAN second-phase (OKAN-II) (upward slow-phase); however, with an increase in stimulus duration, the percentage appearance increased. There was no change in percentage appearance, regardless of the duration of upward stimulus. The asymmetry of OKAN-I and that of OKAN-II differed to a certain degree.

Change in Susceptibility to Vestibular-Visual Conflict Sickness in Monkeys by Repeated Exposure

Squirrel monkeys, susceptible to the vestibular-visual conflict sickness in pitch (with frank vomiting), were subjected to repeated exposure to pitch conflict in various modes and in a randomly mixed order (30 min daily, for 10 consecutive days). Immediately after the training, a significant decline in susceptibility was found, represented by reduced vomiting rates, reduced sickness scores, reduced salivation and improved regularity of vertical oculomotor responses. Susceptibility at the pre-training level returned when the test was repeated 10 days later. Temporary suppression of pitch conflict sickness susceptibility indicates the possibility of training crew members prior to their space flight missions to control the space motion sickness, particularly vomiting.

The Squirrel Monkey Stabil1metry

In order to characterize postural ataxia associated with peripheral vestibular lesions, we have developed a T-perch recording system suitable for squirrel monkeys (tree-living primates). This system includes strain gauges for detecting movement of the vertical shaft in the directions of anterior-posterior and left-right. Simultaneously we recorded electroencephalogram (EEG), vertical eye movement, electrocardiogram (ECG) and respiration (by pneumography). Representative Dynographic records (obtained during sleep) after unilateral and bilateral (two-staged) labyrinthectomy showed the frequent occurrence of phasic body movements: slow deviations to the lesion side and the frontward and subsequent quick rightings which occurred almost synchronously with the sleep becoming shallow (judged by EEG).