Johannes Frasnelli

Publications (65) View all

• Article: Response times and response accuracy for odor localization and identification.

  Luc Kéïta, Johannes Frasnelli, Valérie La Buissonnière-Ariza, Franco Lepore
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  ABSTRACT: Although significant progress has been made over the last decades, the chemical senses remain less well explored than vision or audition. One method to assess participants' ability to identify or localize odors consists in the application of dichotomous stimuli (e.g. left and right sided stimulation). In this study we aimed to explore localization and identification mechanisms by investigating whether response times and response accuracy were correlated, with the aim of establishing the pertinence of response times as an additional measure for assessment of the olfactory function (1). We further examined an advantage of the right nostril which has been reported in several publications (2). We delivered two mixed olfactory/ trigeminal odors (benzaldehyde and eucalyptol) to one nostril at a time in a pseudorandomized order to 23 normosmic participants; the other nostril received an odor free airpuff. In half of the trials we asked the participants to detect the stimulated nostril; in the other half, they indicated which odor they had received. We recorded response accuracy and response times. Participants reached higher accuracy for odor identification than for localization, driven by benzaldehyde. For the stimulus eucalyptol exclusively, we observed that participants were faster to respond after stimulation of the right nostril than to the left nostril, in the localization task. Finally, response times were correlated with response accuracy for the identification task, but not for localisation. Our findings suggest that odor identification is easier than odor localization. In addition, we find further support for an advantage of the right nostril over the left nostril. Moreover, the measurement of reaction times may supplement other techniques of the assessment of odor identification.
  Neuroscience 02/2013; · 3.38 Impact Factor
• Source

  Available from: Johan N Lundström

  Article: Orbitofrontal Cortex and Olfactory Bulb Volume Predict Distinct Aspects of Olfactory Performance in Healthy Subjects.

  Janina Seubert, Jessica Freiherr, Johannes Frasnelli, Thomas Hummel, Johan N Lundström
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  ABSTRACT: While recent studies suggest an important role of higher order olfactory brain areas for basic olfactory performance, the extent to which cortical and peripheral neural markers account for separate portions of the variability in olfactory perceptual acuity is still unclear. We addressed this question by correlating voxel-based morphometry data from 90 healthy adults with olfactory performance measures. Supplementing this approach with region of interest (ROI) analyses of functionally defined olfactory cortical regions and olfactory bulb volume, we sought to disentangle the relative contribution of central and peripheral areas to behavioral variability. Whole-brain analyses revealed a significant positive correlation of gray matter volume and olfactory function scores in the right orbital sulcus. This effect was confirmed by the ROI analyses, which further indicated a significant association of the olfactory score with olfactory bulb volume. Moreover, a functional dissociation was observed, with central and peripheral mechanisms explaining different aspects of the observed behavioral variance in the olfactory subscores. In line with previous clinical studies, these data thus suggest an important role of regional gray matter volume in the right orbitofrontal cortex and olfactory bulb volume for olfactory performance in healthy individuals.
  Cerebral Cortex 08/2012; · 6.54 Impact Factor
• Article: Olfaction in athletes with concussion.

  Vanessa Charland-Verville, Maryse Lassonde, Johannes Frasnelli
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  ABSTRACT: Moderate to severe traumatic brain injuries (TBIs) commonly lead to olfactory dysfunction; it is, however, unclear whether and to what degree mild TBI such as concussions, which are common sports injuries, affect olfactory function. We therefore aimed to evaluate smell function in athletes who sustained one or more sport concussions in a cross-sectional design. Twenty-two University-level football players with one or multiple concussions and 13 control athletes without a history of concussion participated. We measured olfactory function by using the Sniffin' Sticks test to assess subjects' ability to discriminate and identify odors as well as their detection thresholds. In addition, we assessed odor intensity and pleasantness. We used number of concussions and time since the last concussion as independent variables and measure of olfactory function as dependent variables. Although we did not observe any significant effect of the number of concussions, athletes with a longer delay from time of concussion scored significantly weaker than more recently concussed subjects on the odor identification test and on an aggregate olfactory score. Accordingly, we observed a significant negative linear correlation between the odor identification score and the time elapsed since the last concussion. These findings suggest a possible degenerative effect of concussions on olfactory function.
  American Journal of Rhinology and Allergy 05/2012; 26(3):222-6.
• Article: The effect of Alzheimer's disease and Parkinson's disease on olfaction: a meta-analysis.

  Shady Rahayel, Johannes Frasnelli, Sven Joubert
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  ABSTRACT: Impaired sense of smell is one of the earliest clinical features in both Alzheimer's disease (AD) and Parkinson's disease (PD). A meta-analysis was performed on articles obtained from the PubMed database in order to determine what aspects of olfaction are affected in these two diseases. By applying strict criteria, we included a total of 81 studies meeting the following criteria: (1) patients had a clinical diagnosis of AD or PD; (2) patients were compared to a healthy control group; (3) patients and controls were age-matched; (4) olfactory function was assessed by means of a psychophysical olfactory test; (5) mean and standard deviation were reported. Results indicate that AD and PD patients are more impaired on odor identification and recognition tasks than on odor detection thresholds task. In addition, PD patients are more impaired on detection thresholds than AD patients. These results suggest that PD patients are more impaired on low-level perceptual olfactory tasks whereas AD patients are more strongly impaired on higher-order olfactory tasks involving specific cognitive processes. The effect appears more pronounced for AD than PD, which seem to be affected more homogeneously. In conclusion, olfactory identification and recognition appear as the most interesting candidates to be included in a battery to detect subclinical cases in AD. In parallel, detection thresholds should be included in such a battery for subclinical PD patients.
  Behavioural brain research 03/2012; 231(1):60-74. · 3.22 Impact Factor
• Source

  Available from: Veronika Schöpf

  Article: Dual processing streams in chemosensory perception.

  Johannes Frasnelli, Johan N Lundström, Veronika Schöpf, Simona Negoias, Thomas Hummel, Franco Lepore
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  ABSTRACT: Higher order sensory processing follows a general subdivision into a ventral and a dorsal stream for visual, auditory, and tactile information. Object identification is processed in temporal structures (ventral stream), whereas object localization leads to activation of parietal structures (dorsal stream). To examine whether the chemical senses demonstrate a similar dissociation, we investigated odor identification and odor localization in 16 healthy young subjects using functional MRI. We used two odors-(1) eucalyptol; (2) a mixture of phenylethanol and carbon dioxide)-which were delivered to only one nostril. During odor identification subjects had to recognize the odor; during odor localization they had to detect the stimulated nostril. We used general linear model (GLM) as a classical method as well as independent component analysis (ICA) in order to investigate a possible neuroanatomical dissociation between both tasks. Both methods showed differences between tasks-confirming a dual processing stream in the chemical senses-but revealed complementary results. Specifically, GLM identified the left intraparietal sulcus and the right superior frontal sulcus to be more activated when subjects were localizing the odorants. For the same task, ICA identified a significant cluster in the left parietal lobe (paracentral lobule) but also in the right hippocampus. While GLM did not find significant activations for odor identification, ICA revealed two clusters (in the left central fissure and the left superior frontal gyrus) for this task. These data demonstrate that higher order chemosensory processing shares the general subdivision into a ventral and a dorsal processing stream with other sensory systems and suggest that this is a global principle, independent of sensory channels.
  Frontiers in Human Neuroscience 01/2012; 6:288. · 2.34 Impact Factor