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Chemosensory Disorders and Nutrition
Published in Alan R. Hirsch, Nutrition and Sensation, 2023
Carl M. Wahlstrom, Alan R. Hirsch, Bradley W. Whitman
Olfactory test results divide according to whether tests measure the ability to identify odors or ability to detect them at threshold levels. The Chicago Smell Test (see Table 2.3) and the UPSIT (see Table 2.4) which measure ability to identify odors, did not change significantly for the three subjects who completed the test. Amoore’s threshold test for thiophane, however, showed generally worsened odor detection threshold as the experiment progressed (see Table 2.5) Scores for thiophane threshold (unilateral, taking the best nostril) prior to imbibing averaged 3.75 decismels (ds) and, at point of maximum BAC, 13.75 ds, a difference of 10 ds (see Table 2.6). A difference of 10 ds indicates that subjects’ olfactory senses were 3.16 times less sensitive at their highest BAC. This impairment directly correlates with BAC (df=16, p=0.001).
Psychological representation of visual impairment
Published in John Ravenscroft, The Routledge Handbook of Visual Impairment, 2019
Jennifer C. Fielder, Michael J. Proulx
The sense of smell is important for almost all species, from finding the right food to choosing a mate (Kupers et al., 2011), and can evoke strong emotions and vivid memories (Gottfried, 2006). While it is believed that humans have a less refined sense of smell than animals, they are nonetheless able to distinguish between thousands of different odours. Like in auditory and tactile processing, it has been proposed that blind individuals, given their loss of vision, have enhanced olfactory performance. For example, Cuevas et al. (2009) found that blind individuals were better than sighted controls in the free identification of odours and odour discrimination. Furthermore, Beaulieu-Lefebvre et al. (2011) found that blind subjects have a lower odour detection threshold and report being more aware of their olfactory environment. Like with enhanced auditory and tactile perception, this is proposed to be due to cross-modal plasticity, since the olfactory bulb in the forebrain is very plastic (Li et al., 2006). Indeed, Rombaux et al. (2010) found that superior olfactory performance in blind subjects was related to increased volume of the olfactory bulb. Moreover, Kupers et al. (2011) found that congenitally blind subjects activated higher-order olfactory bulb areas more strongly than blindfolded sighted subjects.
Incapacitating Agents and Technologies: A Review *
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Malodorants can deter individuals based on a variety of physiological and psychological responses, including the following. (1) Offensive odors are often perceived as being associated with health risks (e.g., rotting food, feces) and as such, result in an avoidance reaction (Dalton, 1996, 1999). (2) Odors perceived as particularly offensive can induce feelings of ill-health, such as nausea, headache, and dizziness, and cause gagging or vomiting, all associated with a desire to vacate the area of exposure (Bickford et al., 2000). The choice of malodorant agents should take the following into account: they should (1) have appropriate physical properties, such as a liquid of high vapor pressure at ambient temperature; (2) not produce adverse local skin or eye effects; (3) not cause acute or repeated exposure systemic toxicity; (4) not be detrimental to the environment; and (5) be capable of ready decontamination. A variety of chemicals have been considered for use as malodorants or in malodorant mixtures (Pinney, 2001): these are organic sulfur compounds (Table 15.7), carbonyl compounds (see Table 15.8), and organic nitrogen or phosphorus compounds (see Table 15.9). Examples of malodorant formulations are given in Table 15.10. For descriptive and definitional purposes, the following terms are used: the odor detection threshold is the concentration of gas or vapor that can be discriminated from fresh air; the recognition threshold is the concentration at which the identity of the odor can be specified; and the odor intolerance threshold is the concentration at which the physiological and psychological effects are produced in an exposed individual, causing a desire for avoidance.
Olfactory perception in patients with a mild traumatic brain injury: a longitudinal study
Published in Brain Injury, 2022
Coline Zigrand, Benoit Jobin, Fanny Lecuyer Giguère, Jean-François Giguère, Benjamin Boller, Johannes Frasnelli
First, we found that patients with mTBI had weaker performance on the odor detection task than controls during the acute phase. This result is in line with previous studies showing that patients with mTBI had a poorer odor detection threshold than controls (13,14) in the acute phase (14). Interestingly, this cohort did not exhibit an increased odor detection threshold [see 8] despite having a more difficult time to distinguish odorous stimuli from blanks. This suggests that assessing odor detection using a go/ no go task as the one we used in this study may reveal a more subtle impairment that may go undetected when using clinical threshold tests. In fact, using an olfactometer allowed us to control the stimulation period at 500 ms. Therefore, participants were not able to adapt sniffing patterns, which is known to influence odor perception (34). In other words, we were able to measure odor detection without interference from a feedback loop via sniffing adaptation. In fact, higher error rate in go/ no go tasks have been reported for individuals suffering from a concussion in other sensory domains (e.g., vision (35)), and they may extend to the olfactory domain. Future studies should investigate to what extent this phenomenon explains altered odor detection in individuals with TBI.
Smell tests to distinguish Parkinson’s disease from other neurological disorders: a systematic review and meta-analysis
Published in Expert Review of Neurotherapeutics, 2021
Cintia C. G. Alonso, Fernanda G. Silva, Leonardo O. P. Costa, Sandra M. S. F. Freitas
We included cross-sectional studies published in full text that a) used any test to assess the olfactory function in individuals with PD and b) compared them with individuals with other neurological disorders (e.g. essential tremor, dementia with Lewy bodies, or Alzheimer’s Disease). There were no restrictions regarding the year and language of publication [11]. Any clinical tests used to assess olfactory capacity (e.g. odor detection threshold, or recognition) or odor discrimination (e.g. odor identification, memory, or intensity) in individuals with PD were considered for inclusion. Articles were excluded if they: a) were not published in a peer-reviewed journal and (b) were published as editorials, letters, comments to previously published articles, review articles, or single-case studies.
Comparison of olfactory function between neuromyelitis optica and multiple sclerosis
Published in International Journal of Neuroscience, 2018
Li-Min Li, Hui-Yue Guo, Ning Zhao, Lin-Jie Zhang, Ningnannan Zhang, Jingchun Liu, Li Yang
A T&T olfactometer test kit (Takasago Industry, Tokyo, Japan) was used to evaluate olfactory function. The test consists of five odorants, and can accurately determine odor detection threshold and recognition threshold. The test–retest reliability of this kit is equivalent to the University of Pennsylvania Smell Identification Test mostly used in Western populations [10,20]. Olfaction ability was based on the average recognition threshold for each of the five odors. A mean recognition threshold range of −2.0 to 1.0 was defined as normal olfaction, a range of 1.1–5.5 was defined as hyposmia and a range of 5.6–5.8 was defined as anosmia [22].