The lyon clinical olfactory test: validation and measurement of hyposmia and anosmia in healthy and diseased populations.

The LCOT is a self-administered test designed to assess olfactory deficits. Altogether, 525 subjects contributed to the validation. Elderly participants were well represented in this sample. In a validation study (study 1), 407 healthy and 17 anosmic volunteers between 15 and 91 years of age underwent threshold, supraliminal detection, and identification testing. Cutoff values for normosmia and hyposmia were calculated and applied in a second study in a group of patients with smell complaints and in a group of Alzheimer patients with age-matched controls. Incidence of smell deficit was estimated at 5.6% in the healthy population of study 1, and at 16% in the elderly control group of study 2. Assessment of the ability of each subtest to discriminate between groups showed that LCOT is relevant to differentiating between perception and identification deficits and between Alzheimer's and hyposmic patients.

Respiratory cycle as time basis: an improved method for averaging olfactory neural events.

In the mammalian olfactory system, neural activity appears largely modulated by respiration. Accurate analysis of respiratory synchronized activity is precluded by the variability of the respiratory frequency from trial to trial. Thus, the use of respiratory cycle as the time basis for measuring cell responses was developed about 20 years ago. Nevertheless, averaging oscillatory component of the activity remains a challenge due to their rhythmic features. In this paper, we present a new respiratory monitoring setup based on the measurement of micropressure changes induced by nasal airflow in front of the nostril. Improvements provided by this new monitoring setup allows automatic processing of respiratory signals in order to extract each respiratory period (expiration and inspiration). The time component of these periods, which can differ from trial to trial, is converted into a phase component defined as [-pi, 0] and [0, pi] for inspiration and expiration, respectively. As opposed to time representation, the phase representation is common to all trials. Thus, this phase representation of the respiratory cycle is used as a normalized time basis permitting to collect results in a standardized data format across different animals and providing new tools to average oscillatory components of the activity.

Development of the ETOC: a European test of olfactory capabilities.

A number of smell tests designed to evaluate human olfactory capabilities have been published, but none have been validated cross-culturally. The aim of this study was therefore to develop a reliable and quick olfactory test that could be used to evaluate efficiently the olfactory abilities of a European population. This test, named ETOC and based on a combination of a supra-threshold detection task and an identification task, was designed to be a cross-cultural tool that would measure the decline in olfactory performance with ageing. Two versions of the ETOC, one easy and one less easy, were used to test the olfactory performance of European citizens in three countries (France, Sweden and the Netherlands). The results indicated that neither version of the ETOC is culture-dependent, and that both give scores that well reflect the decrease in olfactory abilities with increasing age. A retest session showed that the less easy (and final) version of the ETOC is also highly reliable.

Perceptual, affective, and cognitive judgments of odors: pleasantness and handedness effects.

The present study sought to examine the differential processing of pleasant, neutral, and unpleasant odors. The effects of the nostril stimulated (left or right) and the type of judgment (perceptual, affective, or cognitive) performed on the olfactory stimuli were also studied. To this end, 64 subjects were asked to smell pleasant, neutral, and unpleasant odors under four conditions (detection, intensity, pleasantness, and familiarity tasks). The participants were to perform these tasks as quickly as possible, while response times were recorded. The results showed that (i) unpleasant odors were assessed more rapidly than neutral or pleasant odors, and that this was specifically true (ii) during right nostril stimulation, and (iii) during pleasantness assessment, suggesting possible differential cerebral hemisphere involvement, with a right-side advantage for processing of unpleasant affect in olfaction. A handedness effect on familiarity judgment is also discussed.