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Several lines of research on converge for the conclusion that high and low hostile men differ with respect to autonomic regulation of stress. The functional cerebral systems approach has provided a theoretical framework to account for this finding across the individual sensory, motor, and premotor modalities. The current experiment extends and elaborates upon a functional cerebral systems based model that posits a role for the right frontal region in regulation of sympathetic tone after stress. The experiment builds upon prior work illustrating the utility of this model to stress by positing mild dizziness as a potential frontal lobe stressor demonstrating hostility group differences in sympathetic arousal. Dizziness was induced by brief clockwise angular rotation about the vertical neuroaxis. Consistent with vestibular research indicating clockwise rotation impacts the right hemisphere (relative to counterclockwise rotation), it was expected that hostile individuals would exhibit higher skin conductance levels after rotation compared with low hostile individuals. The experiment also included a dichotic listening task both before and after rotation to examine the effects of rotary stress on dichotic phoneme identification. The experiment was conducted in three blocks: A dichotic listening task comprised the first block, followed by application of rotary stress as the second block, and a follow-up dichotic listening task post- rotary stress. It was predicted that rotation would induce an auditory perceptual shift towards the left ear. Results confirmed expected group differences in sympathetic response to rotary stress. High hostiles had greater overall skin conductance immediately following rotation. High hostiles failed to habituate skin conductance levels to mild rotation 7 minutes post-rotary stress. Lateralized effects of skin conductance remain unconfirmed at this time. No group differences were found for either block of the dichotic listening task. Overall, results are interpreted to support a model of frontal region capacity limitation for regulation of stress, including vestibular dysfunction. / Master of Science

It is well established that exposure to virtual motion environments (VME) can elicit postural instability (PI) in addition to motion sickness (MS). While research has found sex differences in motion sickness, the results of experimental studies are equivocal regarding these differences, and previous studies utilizing VME have failed to address the factor of sex differences in terms of hormonal fluctuations, which may also be instrumental in behavioral responses to VME, such as PI. The intent of this investigation was to determine whether exposure to VME, during various phases of the menstrual cycle (premenstrual, permenstrual, ovulation) would reveal sex differences in MS and PI during some phases, but not others. The first experiment involved men and women completing Daily Living Logs for a period of 40 days to provide a baseline for any sex differences (and for women, menstrual phase differences) in motion related activity and symptomatology. The second experiment involved 24 participants (6 men) viewing a rotating Archimedes spiral for a period of twenty minutes. Exposures were timed to place each woman in three phases of her menstrual cycle; men were exposed by yoking their exposure time to a female counterpart. Multiple measures of PI and MS were recorded before, after and during exposure. Results of the first experiment found no significant effects of sex or phase upon symptomatology, revealing no support for the theory of a reporting bias as influencing sex differences in MS or PI elicited in the laboratory. The second experiment found no significant effect of sex of phase upon any of the PI measures, but found significant interaction effects of sequence and phase, as well as sequence and sex, upon reported magnitude ratings of illusory self-motion perception. There were also significant effects of sex found upon measures of MS, with women reporting more discomfort to exposure to motion stimulation, as compared to men. There were no significant effects of phase upon any of the MS measures. While these findings show no support for a reporting bias influencing the sex differences found experimentally induced MS, it yields no evidence to support a hormonal influence on these differences.

名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成4年12月22日 市川真澄氏の博士論文として提出された

Lorsqu’ils explorent leur environnement, les humains comme les autres animaux ont la capacité d’utiliser de nombreuses sources d’information afin d’estimer la distance qu’ils parcourent. Le flux optique est un indice important dans la perception de la distance parcourue. De plus, il a été montré que l’ajout d’un point de vue oscillant à une simulation visuelle de mouvement propre vers l’avant modulait cette perception. A travers ce travail, nous nous sommes intéressés à tester si la perception de la distance parcourue était également affectée par un point de vue oscillant, mimant de manière plus ou moins fidèle les mouvements de la tête lors de la marche. Dans six premières expériences, il était demandé aux participants stationnaires, confrontés à un flux optique simulant leur propre mouvement vers l’avant, d’indiquer quand ils pensaient avoir atteint la position d’une cible distante initialement perçue. Une expérience subséquentes s'est intéressée à déterminer si l’absence de ces oscillations jouait un rôle important dans l’estimation de la distance parcourue lorsqu’ils marchaient sur un tapis roulant. Enfin, dans une dernière expérience nous avons développé une mesure dynamique de la distance parcourue à travers l’utilisation d’une tâche demandant aux participants de pointer continuellement la position d’une cible distante initialement perçue. Dans l’ensemble, nos résultats montrent qu’un point de vue oscillant joue un rôle important dans la perception visuelle du mouvement propre et que de nombreux paramètres semblent être impliqués dans ce processus, incluant les informations visuelles et proprioceptives mais également l’aspect écologique de la marche naturelle. / When exploring their environment, humans and other animals have the ability to use many sources of information to estimate the distance they travel. Several studies have shown that optic flow is a significant cue to perceive distance travelled. Furthermore, it was found that adding various viewpoint oscillations to a purely translational optic flow, simulating forward self-motion, modulated this perception. In a series of experiments, we tested whether the perception of distance travelled was also affected by viewpoint oscillation, similar to head motion during natural walking. A first series of experiments, participants were exposed to an immersive optic flow simulating forward self-motion and they were asked to indicate when they thought they had reached the remembered position of a previously seen target. Two further experiments aimed to test whether the idiosyncrasy of viewpoint oscillations affects the perception of distance travelled in stationary observers and whether the absence of their own viewpoint oscillation played an important role in subjects’ estimates, while they were walking on a treadmill. And finally, in a last experiment we tried to develop a dynamic measure of distance travelled to a previously seen target, with a continuous pointing task method. Overall, our results show that viewpoint oscillations play an important role in visual self-motion perception and that several parameters (including visual information, proprioceptive information and ecological aspects of natural walking) seem to be involved in this process.

La Flavescence dorée est une maladie à phytoplasme incurable qui affecte la vigne. Cette pathologie est uniquement transmise de plante à plante par la cicadelle vectrice Scaphoideus titanus. Malgré l'importance de cette maladie, peu d'études ont été menées sur le vecteur. Ce travail de thèse vise à apporter des connaissances sur la biologie et l'écologie de S. titanus mais aussi de manière plus générale sur l'écologie des insectes phytophages. Trois grands thèmes ont été abordés dans ce mémoire : i) les relations entre l'insecte et son environnement à travers l'influence des températures hivernales sur les œufs en diapause, ii) les relations de l'insecte avec sa plante hôte en examinant l'attractivité de cette dernière et le comportement alimentaire du vecteur, iii) les interactions entre congénères par l'étude du comportement d'agrégation des larves. Les résultats obtenus indiquent que 1) des températures froides ne sont pas indispensables à la levée de diapause mais affectent la protandrie en régulant le sex-ratio opérationnel, 2) l'attractivité de la plante hôte est en grande partie liée à sa couleur et il existe des différences de comportement en fonction du stade de développement, 3) les mâles et les femelles n'ont pas le même comportement alimentaire, ce qui pourrait expliquer leur différentes capacités de vection, 4) l'agrégation des larves ne semble pas due à un recrutement actif de leur part et pourrait contribuer à un transfert horizontal de phytoplasme d'insecte à insecte via la plante. A terme, ces connaissances pourront contribuer à l'élaboration de pistes alternatives à la lutte chimique actuelle contre cette cicadelle dans le cadre d'une réduction des intrants. / The Flavescence dorée is an incurable phytoplasma disease of grapevine. This pathology is exclusively transmitted from plant to plant by the leafhopper vector Scaphoideus titanus. Despite the importance of this disease, few studies have been conducted on the vector. This thesis aims to provide knowledge on the biology and ecology of S. titanus but also more broadly on the ecology of phytophagous insects. Three major themes were addressed in this thesis: i) the relationships between the insect and its environment through the influence of winter temperatures on diapausing eggs, ii) the relationships of the insect with its host plant by examining the attractiveness of the plant and the feeding behaviour of the vector, iii) interactions between congeners in the study of the aggregative behaviour of larvae. Our results indicate that 1) cold temperatures are not essential to break the diapause but contribute to protandry through operational sex ratio regulation, 2) the attractiveness of the host plant is largely due to its colour and different instars exhibit differences in behavioural choices, 3) males and females have different feeding behaviour which may explain their different efficiencies at vection, 4) the aggregation of larvae did not seem to result from active recruitment and could contribute to horizontal insect to insect transfer of phytoplasma through the plant. Such knowledge can contribute to the development of alternative S. titanus pest management techniques.