EEG features in patients with Parkinson's disease during directional perception of olfactory stimuli

Introduction. Olfactory dysfunction is considered to be an early and relatively important marker of Parkinson's disease (PD). Olfactory studies using objective neurophysiological methods may become one of the diagnostic tests to identify individuals with a high risk of developing PD. The aim of the study was to assess the spectral and topographic characteristics of bioelectrical brain activity in patients with PD during directional perception of olfactory stimuli. Materials and methods. This study included 30 patients with PD (mean age was 66.5 6.5 years). The control group consisted of 20 people without PD (mean age was 65.3 8.5 years). Lavender oil, clove oil, camphor oil and -mercaptoethanol solution (an aversive stimulus) were used for olfactory stimulation, while distilled water was used as a control test. The test subject sat with their eyes closed and inhaled the presented smell for 30 seconds, while an EEG recording was made during this time. Study results. Olfactory stimulation in patients with PD showed increased synchronicity of the 3 rhythm in the right hemisphere, as well as the rhythm in the parieto-occipital regions of both hemispheres. These changes indicate significant activation of internal (endogenous) attention, increased overall, non-specific readiness potential, as well as the involvement of the limbic-reticular complex in olfactory perception. Olfactory perception in the control group was accompanied by reduction in the 1 rhythm amplitude in the parieto-occipital regions bilaterally, which may indicate moderate activation of external (exogenous) attention and the posterior attention system responsible for simple perception processes. Conclusion. Increased 3 rhythm amplitude in the right hemisphere and increased rhythm amplitude, observed during directional olfactory perception, may indicate olfactory dysfunction and should be viewed as an additional indicator when establishing a diagnosis of Parkinsons disease.

The Complexity of Olfactory Art The Use of Scent as Concept and Context in the Work of Art

The sense of smell is a powerful sense that offers many possibilities. To speak of olfactory art, there must be the intention to use odour or olfaction as both context and concept of the work of art. For this, we speak about the terms Olfactory Context and Olfactory Concept. The Olfactory Context can be divided into the Intrinsic and Intentional Odour Values. The intrinsic odour value brings with it their significance, while the intentional odour value gives an extra meaning to a smell. In addition, the Olfactory Perception is part of the Olfactory Concept of the artwork. To perceive this, the smell must be transferred to the spectator. The way in which an odour is transferred in a work largely determines how the smell is interpreted in relation to the work. The odour transfer and odour situation determine how an odour gets to the viewer. We call these methods of odour transfer Olfactory Transfers and divide them into five categories: Flowers, Smell Devices, Scent Spaces, Time and Translations. In most cases, Olfactory Transfers are used in crossovers. Together with the various possibilities of using the Olfactory Context, they also demonstrate the Complexity of Olfactory Art. The 1st Olfactory Art Manifest explains the differences in olfactory art, while the 2nd Olfactory Art Manifest demonstrates the Complexity of Olfactory Art.

RADT-34. OLFACTORY PERCEPTION DURING PROTON RADIATION AND DIFFERENCES IN FREQUENCY OF OLFACTORY PERCEPTIONS BASED ON PROTON CRANIOSPINAL IRRADIATION TECHNIQUE FOR PEDIATRIC BRAIN TUMOR PATIENTS

BACKGROUND Unusual olfactory perception has been reported during brain radiation treatments but is infrequent and does not typically interfere with the ability to deliver treatment or cause notable distress. METHODS We performed a retrospective review of 127 pediatric patients treated with proton radiation therapy (PRT) for primary brain tumors in a single institution between 2016-2021. Patients received PRT to the brain as part of craniospinal irradiation (CSI) followed by a boost to the brain. Proton CSI was delivered with 3D-CRT protons (n=53) or pencil beam scanning technique (PBS) (n=74). Within the PBS group, treatment delivery to the CSI utilized a single PA field (n=24) or two posterior oblique fields (n=50). We collected data on abnormal olfactory sensations, nausea/vomiting, and the use of medical intervention for those symptoms. RESULTS Our cohort included 80 males and 47 females. The median age of patients was 10 years old (range, 3 – 21). Seventy-one patients received concurrent chemotherapy. Prior to PRT, 31 patients were nauseous. During the radiation course, 104 patients developed worsening nausea while 63 patients reported episodes of emesis. Four patients vomited while receiving radiation. Seventeen patients reported olfactory perceptions during CSI. We found a higher rate of olfactory perception in patients treated with PBS (n=16, 22%) than 3D-CRT (n=1, 2%) (p=0.001) and, within the PBS group, patients treated with a single PA field (n=11, 46%) than two oblique fields (n=5, 10%) (p=0.002). Seventy-eight patients required intervention including addition of anti-emetic or anti-anxiety medication. Two patients required sedation due to the malodorous smell during CSI. We did not find any significant difference in nausea/vomiting based on treatment technique. CONCLUSIONS PBS and PBS technique influence olfactory perceptions but not the occurrence of the rate of nausea/vomiting. Further studies should be performed to validate these findings and determine techniques to minimize unpleasant olfactory perceptions.

Odours count: human olfactory ecology appears to be helpful in the improvement of the sense of smell

Odours modify human behaviour. Research in this field develops rapidly, providing more and more exciting discoveries. In this context, our daily odorous environment has been surprisingly poorly explored. The aim of our study was to quantify olfactory perception and preliminarily identify factors affecting the frequency of odorous experiences. We were also interested in knowing whether human olfactory ecology relates with olfactory performance. In this study, patients with olfactory deficits (n = 62) and healthy controls (n = 97) had their olfactory threshold and odour identification abilities measured before and after a two-week intervention comprising counting of conscious perception of odours naturally occurring in the environment. In both groups, we observed enhanced olfactory performance after the intervention suggesting that (1) the conscious focus on odours may change its perception, and that (2) social and physical environment can effectively stimulate the human olfactory system, presumably supporting the improvement of olfactory sensitivity.

The Effect of an Active Plant-Based System on Perceived Air Pollution

Active plant-based systems are emerging technologies that aim to improve indoor air quality (IAQ). A person’s olfactory system is able to recognize the perceived odor intensity of various materials relatively well, and in many cases, the nose seems to be a better perceiver of pollutants than some equipment is. The aim of this study was to assess the odor coming out of two different test chambers in the SenseLab, where the participants were asked to evaluate blindly the level of acceptability, intensity, odor recognition, and preference at individual level with their noses. Two chambers were furnished with the same amount of new flooring material, and one of the chambers, Chamber A, also included an active plant-based system. The results showed that in general, the level of odor intensity was lower in Chamber B than in Chamber A, the level of acceptability was lower in Chamber A than in Chamber B, and the participants identified similar sources in both chambers. Finally, the preference was slightly higher for Chamber B over Chamber A. When people do not see the interior details of a room and have to rely on olfactory perception, they prefer a room without plants.

Contextual variation and objectivity in olfactory perception

According to Smell Objectivism, the smells we perceive in olfactory experience are objective and independent of perceivers, their experiences, and their perceptual systems. Variations in how things smell to different perceivers or in different contexts raise a challenge to this view. In this paper, I offer an objectivist account of non-illusory contextual variation: cases where the same thing smells different in different contexts of perception and there is no good reason to appeal to misperception. My central example is that of dihydromyrcenol, a substance that can smell both woody and citrusy depending on what other odourants one has recently been exposed to. I first argue that the subjects’ apparently conflicting reports about the way dihydromyrcenol smells are best understood as comparative characterisations of a smell. Given this understanding, different reports can be correctly made in response to perceiving the very same smell. I then argue that the phenomenal difference between the experiences subjects have across contexts can be explained compatibly with Smell Objectivism. On the account proposed, subjects perceive the very same smell but different qualities, notes, or aspects of it are salient to them, depending on the context of perception. I then consider how the proposed defence of Smell Objectivism can be adapted to other cases where the same thing is reported as smelling different in different contexts.

Predicting the colour associated with odours using an electronic nose

Predicting olfactory perception with an electronic nose can aid in the design and evaluation of olfactory-based experiences. We investigate whether the human perception of odours can be predicted outside the bounds of perceived pleasantness and semantic descriptors. We tuned an electronic nose to predict an odour's colour in the CIELAB colour space using human judgements. This revealed that the crossmodal associations people have towards colours could be predicted. Our electronic nose system can predict an odour's colour with a 70 – 81% machine-human similarity rating. These findings suggest a systematic and predictable link exists between the chemical features of odours and the colour associated to them. These findings highlight the possibilities of predicting human olfactory perception using an electronic nose.