Olfactory dysfunction in multiple sclerosis: evidence of a decrease in different aspects of olfactory function.

BACKGROUND/AIMS: Numerous authors have described olfactory dysfunction in multiple sclerosis (MS) in recent years. The aim of this study was to specify the aspects of olfactory perception that are most affected and to identify any correlations with clinical, anatomical and functional data. METHODS: 50 patients with remitting or secondary progressive MS were included. Personal data were collected (medical history, characteristics of their disease, depression and disability scores and number of lesions on cerebral imaging). An olfactory test (Sniffin Sticks®) was used to evaluate subjects' olfactory function. RESULTS: The odor detection threshold is the most sensitive marker, with 40% of patients presenting hyposmia. The ability to identify odors is affected later on, and is inversely correlated with the level of disability. CONCLUSION: Our results confirm that several aspects of olfactory function are altered in MS, particularly those aspects requiring greater cognitive involvement, such as discrimination and identification of odors.

Complexity of olfactory lateralization processes revealed by functional imaging: a review.

Currently available techniques used in neurosciences and particularly cerebral imaging are contributing to a better understanding of human perception and the treatment of sensorial information. In this field, the chemical senses (taste and smell) have received little attention when compared with the auditory, visual and tactile senses. Nevertheless, recent research has been trying to overcome this. Brain regions involved in the processing of olfactory information have been investigated in several studies including a large number dealing with the question of lateralization. However, functional asymmetry in olfaction has still not been resolved and the resulting data have not been homogeneous. In this field, the contribution of cerebral imaging studies is very important insofar as it shows that the processes of functional lateralization in olfaction depend on many factors (nature of stimulus, nature of task, characteristics of subjects ...) that future research will have to consider.

Lateralization in human nasal chemoreception: differences in bilateral electrodermal responses related to olfactory and trigeminal stimuli.

The study of olfactory lateralization in humans has given rise to many publications, but the findings have often been contradictory. There is growing evidence to suggest that the nature of the olfactory stimulus influences the processes of lateralization. An important factor could be the trigeminal component. Indeed, most odorants simultaneously stimulate both olfactory (CN I) and trigeminal (CN V) systems which differ in terms of their central projections, ipsilaterally for CN I and contralaterally for CN V. The aim of this study was to investigate variations in psychophysiological measurements between a nasal input with low (phenyl ethyl alcohol (PEA)) and high (allyl isothiocyanate (AIC)) intranal trigeminal stimulation. In a first experiment (20 subjects), the intensity, hedonicity and irritation levels of stimulus were tested with a psychophysical evaluation to study the possible influences of perceptual characteristics. A second experiment (37 subjects) used bilateral electrodermal recordings and compared the skin conductance responses (SCRs) for both nasal inputs on either monorhinal and birhinal stimulations. Firstly, the electrodermal activity (EDA) results showed no differences between the two nostrils for PEA as well as AIC, but differences in relation to the type of stimulus, e.g. higher amplitude in response to AIC versus PEA. Secondly, the results indicated bilateral differences in EDA recordings related to the nature of the stimulus and are discussed in terms of hemispheric asymmetric activation.

Maternal tactile behaviour correlated with mother and newborn infant characteristics.

Filmed observations of spontaneous interactions between mothers and their newborn infants (N = 50) were used to quantify the occurrences, duration and frequency of maternal tactile behaviours (stroking, kissing, touching the clothes, etc.). The analysis of the data shows that these maternal behaviours vary from one mother to another according to the activities of the newborn infant (sleeping, arousal but not feeding, feeding) and to different biological (sex of the infant, birthweight) and social (socio-economic status of the mother) variables. These results would suggest discussion topics concerning the differences between the mother-infant interaction systems.

Olfactory and visual cues in the interaction systems between dogs and children.

Various studies have established the importance of olfactory cues in the relational systems between conspecifics by the canids and humans. The study of the behaviour of dogs towards children with clothes impregnated with body odours has led to the definition of different functions of olfaction in interspecific relational systems. An experimental situation in kennels details the behaviour of dogs in response to different combinations of visual and olfactory stimulations reproduced with a realistic child dummy. The discussion of the results deals with the contingent socio-cognitive abilities of pet dogs and their relational strategies based on the integration of different sensory modalities present in the 'social' stimulations.

[Not Available]. / Relations intraspecifiques et interspecifiques chez le chien familier: aspects analogiques et differentiels des comportements d'exploration.

Recent ethological studies on the interactions between man and his pet dog, have shown different analogies bétween the behavioural mechanisms developed during intraspecific and interspecific proximal relationships. This study characterizes new analogies between sniffing, licking and rubbing behaviours of familiar dogs, directed towards the urban environment, their conspecific and their master. The results emphasize the importance of the synergic relation between the exploratory sniffing and tasting behaviours. Different hypothesis are put forward concerning the functions of these behaviours developped by dogs during their social interactions and their importance in relations between humans and animals.

New data on communication behaviour between the young child and his pet dog.

A systematic investigation of communication behaviour between 2-to-5 year old children and their pet dogs (N=18), from video films shot in the home, shows that children take the initiative in communication more often, and that they seek more body contact with their dog. Different characteristics of the children such as age, family size and different characteristics of the dog such as size and sex are significantly correlated (p<.01 or p<.05) with the quantity of communications and with the different types of child behaviour in relation to the dog (stroking, hitting, etcz.sfnc;). This preliminary report leads to suggestions for further investigations of the data.

Children and their pet dogs : How they communicate.

The research of ethologists has provided a better understanding of the mechanisms, role and development of communication behaviour between young children and their peers. However, little is known about the communication systems between children and their pets. A study of these relational systems would be needed to understand how the child interacts with his whole environment. The present study is based on the analysis of video tapes filmed during spontaneous interactions between children from 2 to 5 years of age with their pet dog (N = 45) in their home environment. Inventories were made of the child and dog behaviours during these interactions. The results have shown the different dog behaviours induced by the child and the different child behaviours induced by the dog. The links between these behaviours and the variables which characterize both partners (age, sex, etc.) were treated by factor analysis of correspondences. These data are discussed in relation to the behavioural inventories of children and dogs with their peers and conspecifics.

[Body contact between mother and her newborn infant. Possible effect of a prenatal variable]. / Les contacts corporels entre la mère et son nouveau-né. Influence possible d'une variable prénatale.

We have found by looking at films of the spontaneous interactions between 50 mothers and their newborn babies that mothers behave in regard to touching their infants with negative correlation between the number of days that separate the estimated date of delivery from the actual date of delivery. All the same, if one takes into account the activity of the newborn (feeding, being awake without feeding and being asleep) it is only when the newborn is asleep that this correlation is to be avoided. There are different psychological and bio-psychological factors that can explain this phenomenon.

Behavioral lateralization during spontaneous smelling tasks.

The smelling behavior of 52 right-handed subjects was videotaped during tasks involving identification and recognition of different odors. Analysis showed that men more often used the right nostril than the left whatever the odor. There was no significant difference for the women. These results support a more marked cerebral asymmetry in men than in women and a main involvement of the right cerebral hemisphere in the olfactory processes at least by right-handed men.

Is there a relationship between odors and motion sickness?

The aim of this study was to evaluate the relationship between olfaction and motion sickness. A sample of 18 participants was recruited and submitted to three sessions of nauseogenic stimulations: off vertical axis rotation (OVAR), performed under conditions of olfactory stimulation with limonene (pleasant odor), petrol (unpleasant odor) or distilled water (as a control). Motion sickness was assessed before, during and after each OVAR session. In addition, participants were asked to evaluate the intensity and hedonic valence of four odors (geraniol, limonene, butanol, petrol) as well as distilled water (as a control) before and after each OVAR session. Our analysis showed that OVAR has consistently increased the induced-motion sickness. However the addition of an odor that is pleasant or unpleasant during the rotation did not affect the occurrence of motion sickness symptoms compared to the control condition. Our results also showed that intensity of odors was significantly increased after OVAR and the intensity was significantly higher for unpleasant odors than for pleasant one. For the hedonicity, OVAR made unpleasant odors more unpleasant (p<0.0001) while it made limonene odor slightly more pleasant (p<0.05). The present study highlighted the lack of influence of odors in motion-induced sickness but an impact of a nauseogenic test on olfactory perception.

Time course of odorant- and trigeminal-induced activation in the human brain: an event-related functional magnetic resonance imaging study.

It is well known that most odorants stimulate the trigeminal system but the time course of the brain regions activated by these chemical stimulations remains poorly documented, especially regarding the trigeminal system. This functional magnetic resonance imaging (fMRI) study compares brain activations resulting from the contrast between two odorant conditions (one bimodal odor and one relatively pure olfactory stimulant) according to the duration of the stimulation (i.e. one inhalation, or three or six successive inhalations). The results show striking differences in the main brain regions activated according to these durations. The caudate nucleus and the orbitofrontal cortex are only involved in short-duration stimulations, and the posterior insular cortex and post-central gyrus (SI) are only activated by long duration stimulations. Different regions of the frontal, temporal and occipital lobe are activated depending on the duration but mainly during medium-duration stimulations. These results expand on the findings of previous studies and contribute to the description of temporal networks in trigeminal perception.

Sex differences in human olfaction: between evidence and enigma.

The sex of individuals plays an important part in determining their olfactory abilities, with females generally being superior to males. The present review examines the way in which sex differences influence sensitivity, identification, familiarity, and recognition of odours. It also examines whether sex differences are more pronounced with some odours than others, and how sex differences are affected by the manner of testing. Two different explanations for the superiority of females over males in olfaction are evaluated.

Comparison between monorhinal and birhinal olfactory stimulations in bilateral electrodermal recordings.

The study of olfactory lateralization in human subjects has given rise to many publications, but the findings have often been contradictory. Most research used either birhinal or monorhinal stimulations, but rarely a comparison between these two types of olfactory input. The aim of this study was to investigate variations in psychophysiological measurements and test each side of the nose and binasal performances. This work used bilateral electrodermal recordings and compared the skin conductance responses (SCRs) for a pleasant odorant (isoamyl acetate) and an unpleasant odorant (triethylamine) in a suprathreshold concentration on 30 dextral subjects (16 females and 14 males). First, the results reported no differences between the two nostrils but differences in electrodermal activity (EDA) in relation to the odorant: 1) higher amplitude in response to unpleasant versus pleasant odorant; 2) no differences between monorhinal and birhinal stimulations for the unpleasant odour but higher amplitude in response to birhinal versus monorhinal for the pleasant odour. Second, the results showed constant bilateral differences in EDA recordings and are discussed in terms of hemispheric asymmetry activation.

[Auditory competence of the newborn infant with regard to specific and non-specific rhythms]. / Les compétences auditives du nouveau-né à l'égard de rythmes spécifiques et non spécifiques.

This study is based on the analysis of modifications in the heart-rate of newborn infants (n = 12) hearing heartbeats at 72 and 120 bpm and metronome beats at 45, 72 and 120 bpm. The results show a selective discrimination of these acoustic stimulations by the infant.

[Mother's touching behavior with regard to the newborn infant: preliminary cases]. / Les comportements de toucher de la mère à l'égard du nouveau-né: observations préliminaires.

Filmed observations of spontaneous interactions between mothers and their newborn infants were used to quantify the maternal tactile behaviours. These behaviours were analysed in relation to the activity of the newborn infant and the different characteristics of the mother and the newborn infant.

[Experimental study of olfactory and visual modalities in the communication system between child and pet dog]. / Etude expérimentale des modalités olfactives et visuelles dans les systèmes de communication entre l'enfant et le chien familier.

Different experimental methods are set up to specify the importance of the olfactory cues in the interaction systems between the young child and his pet dog. A realistic child dummy, with an affiliative or an agonistic posture, is wearing clothes of a child who is known or unknown from the animals. The study is dealt in kennels (N(o) of dogs observed: 68) and allows to define and quantify the behaviours of the dogs in response to different combinations of visual and olfactory informations. These behaviours allow to discuss the socio-cognitive abilities of the dogs and their relational strategies determined by the integration of several functional cues.

Reduced efficiency of influenza vaccine in prevention of influenza-like illness in working adults: a 7 month prospective survey in EDF Gaz de France employees, in Rhône-Alpes, 1996-1997.

The efficiency of influenza vaccine was evaluated in the working population by comparing the percentage of people presenting with an influenza-like illness (ILI) according to their influenza immunization status, drug expenses and workdays lost. A self-completed questionnaire about the vaccination was sent to 5785 people randomly chosen among 18 249 workers. When any sick leave was incurred amongst the respondents (63.3%), of whom 301 were vaccinated and 3362 unvaccinated, a clinical form was completed by the private physician and the medical adviser of the firm (Electricité de France and Gaz de France). A final self-completed questionnaire was sent to people whose sick leave was not documented by a physician's reported diagnosis. In total, we obtained complete data for 90.9% of the sampling. The vaccine coverage rate of 8.2% [95% confidence interval (95% CI) = 7.4-9.0%] was higher in men than in women, increasing with age and professional category. Among the 775 subjects with a medical diagnosis, the vaccine effectiveness was not significant: 27.3% (95% CI = -13.8 to 53.5%). In the unvaccinated group, 9.6% had days absent from work, versus 7.0% in the vaccinated group; the two populations were comparable in terms of clinical symptoms, smoking habits, exposure to respiratory risk factors and chronic pathology. The average duration of sick leave for ILI was not significantly different between vaccinated (0.5 days) and unvaccinated workers (0.6 days). Despite the large size of the population and the occurrence of an epidemic due to a virus closely related to the vaccine strain (A/Wuhan/359/95), the vaccine did not effectively protect the small vaccine group nor result in an economic benefit, whatever the professional group.

Intercorrelations among tests of lateralisation in the BALB/c mouse.

In order to examine the reliability of lateralised behaviours, BALB/c mice were tested in three different situations: the Collins paw preference test (PPT), the rotatory swimming test (RST), and the T maze test (TMT). The results showed a significant correlation between the scores of lateralisation in the PPT and the RST, but a lack of lateralisation in the TMT. Considering the tasks involved in these tests, these results appear to support the hypothesis of close links between lateralised behaviours, emotional processes, and neural pathways.