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Hossu G, Fantin L, Charroud C, Felblinger J, Jacquot M, Ceyte H. Neural mechanisms of odour imagery induced by non-figurative visual cues. Neuropsychologia 2024; 196:108836. [PMID: 38373518 DOI: 10.1016/j.neuropsychologia.2024.108836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 02/16/2024] [Accepted: 02/16/2024] [Indexed: 02/21/2024]
Abstract
Odour imagery, the ability to experience smell when an appropriate stimulus is absent, has widely been documented as being particularly difficult. However, previous studies have shown the beneficial effect of visual cues (e.g., pictures or words) to facilitate performance in numerous tasks of olfactory nature. Therefore, the use of visual cues to evoke odours seems relevant. In this study, our interest is directed towards non-figurative coloured arrangements, which result from a patented technology and aim at chromatically representing any smell from its chemical composition and sensory description. The aim of this study was to characterise the neural mechanisms of odour imagery facilitated by these non-figurative coloured arrangements. Using functional magnetic resonance imaging, we recorded and compared hemodynamic responses during odour imagery facilitated by non-figurative coloured arrangements and pictures. Our findings reveal that the use of non-figurative coloured arrangements during odour imagery solicits olfactory and non-olfactory brain regions (orbitofrontal cortex, insula, hippocampus, thalamus, dorsolateral prefrontal cortex and supplementary motor area), which are mainly involved in olfactory processing and multimodal integration. Moreover, very similar cortical activity was found between the use of non-figurative coloured arrangements and pictures during odour imagery, with increased activity in the supplementary motor area during the use of coloured arrangements only. Overall, non-figurative coloured arrangements could become a robust tool to visually evoke odours without requiring prior familiarity with the depicted odour. Future studies should use psychometric measures to determine the relationships between brain activation, odour imagery ability and vividness of the generated odour images.
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Affiliation(s)
- Gabriela Hossu
- CHRU-Nancy, Inserm, Université de Lorraine, CIC, Innovation Technologique, F-54000, Nancy, France; Université de Lorraine, Inserm, IADI, F-54000, Nancy, France.
| | - Luca Fantin
- Université de Lorraine, Inserm, IADI, F-54000, Nancy, France; Aix Marseille Université, CNRS, ISM, Marseille, France
| | - Céline Charroud
- Unité de recherche sur les comportements et mouvements anormaux (URCMA, IGF, INSERM U661 UMR 5203), Department of Neurosurgery, Montpellier University Hospital Center, Gui de Chauliac Hospital, University of Montpellier, F-34000, Montpellier, France; Unité de pathologie cérébrale résistante, Department of Neurosurgery, Montpellier University Hospital Center, F-34000, Montpellier, France
| | - Jacques Felblinger
- CHRU-Nancy, Inserm, Université de Lorraine, CIC, Innovation Technologique, F-54000, Nancy, France; Université de Lorraine, Inserm, IADI, F-54000, Nancy, France
| | - Muriel Jacquot
- Givaudan France SAS, 43 voie des bans, 95100, Argenteuil Cedex, France
| | - Hadrien Ceyte
- Aix Marseille Université, CNRS, ISM, Marseille, France
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Boot E, Levy A, Gaeta G, Gunasekara N, Parkkinen E, Kontaris E, Jacquot M, Tachtsidis I. fNIRS a novel neuroimaging tool to investigate olfaction, olfactory imagery, and crossmodal interactions: a systematic review. Front Neurosci 2024; 18:1266664. [PMID: 38356646 PMCID: PMC10864673 DOI: 10.3389/fnins.2024.1266664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/02/2024] [Indexed: 02/16/2024] Open
Abstract
Olfaction is understudied in neuroimaging research compared to other senses, but there is growing evidence of its therapeutic benefits on mood and well-being. Olfactory imagery can provide similar health benefits as olfactory interventions. Harnessing crossmodal visual-olfactory interactions can facilitate olfactory imagery. Understanding and employing these cross-modal interactions between visual and olfactory stimuli could aid in the research and applications of olfaction and olfactory imagery interventions for health and wellbeing. This review examines current knowledge, debates, and research on olfaction, olfactive imagery, and crossmodal visual-olfactory integration. A total of 56 papers, identified using the PRISMA method, were evaluated to identify key brain regions, research themes and methods used to determine the suitability of fNIRS as a tool for studying these topics. The review identified fNIRS-compatible protocols and brain regions within the fNIRS recording depth of approximately 1.5 cm associated with olfactory imagery and crossmodal visual-olfactory integration. Commonly cited regions include the orbitofrontal cortex, inferior frontal gyrus and dorsolateral prefrontal cortex. The findings of this review indicate that fNIRS would be a suitable tool for research into these processes. Additionally, fNIRS suitability for use in naturalistic settings may lead to the development of new research approaches with greater ecological validity compared to existing neuroimaging techniques.
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Affiliation(s)
| | - Andrew Levy
- Metabolight Ltd., London, United Kingdom
- Wellcome Centre for Human Neuroimaging, University College, London, United Kingdom
| | - Giuliano Gaeta
- Health and Well-being Centre of Excellence, Givaudan UK Limited, Ashford, United Kingdom
| | - Natalie Gunasekara
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Emilia Parkkinen
- Health and Well-being Centre of Excellence, Givaudan UK Limited, Ashford, United Kingdom
| | - Emily Kontaris
- Health and Well-being Centre of Excellence, Givaudan UK Limited, Ashford, United Kingdom
| | - Muriel Jacquot
- Health and Well-being Centre of Excellence, Givaudan UK Limited, Ashford, United Kingdom
| | - Ilias Tachtsidis
- Metabolight Ltd., London, United Kingdom
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
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Zhou L, Qin M, Han P. Olfactory metacognition and memory in individuals with different subjective odor imagery abilities. Conscious Cogn 2022; 105:103416. [PMID: 36194996 DOI: 10.1016/j.concog.2022.103416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 09/23/2022] [Accepted: 09/23/2022] [Indexed: 01/27/2023]
Abstract
Imagery vividness is one of the key indicators to evaluate the ability to generate mental images. There is large inter-individual variability in olfactory imagery (OI) abilities, however, little is known about the underlying factors for individual OI abilities. Using a word cueing imagery paradigm and the trial-by-trial imagery vividness rating method, participants with high or low OI abilities (differentiated by the Vividness of Olfactory Imagery Questionnaire) completed two OI tasks with either shorter (2 s) or longer (8 s) image generation time. Participants' olfactory function, olfactory-related working memory and episodic recognition memory were measured using validated methods. Moreover, olfactory metacognition was assessed using the Odor Awareness Scale (OAS) and the Importance of Olfaction Questionnaire (IOQ). Compared to participants with high OI abilities, those with low OI abilities reported less vivid odor images during OI tasks. For participants with low OI abilities, the imagery vividness significantly improved as the image generation time increased. There was no difference regarding olfactory perception or olfactory-related memory performances between the high and the low OI ability groups. However, participants with higher OI abilities had significant higher scores on the OAS and the IOQ, indicating a superior olfactory-related metacognition. These results provide evidences supporting the underlying factors that related to variances of subjective ability of generating vivid odor mental images.
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Affiliation(s)
- Luyi Zhou
- Faculty of Psychology, Southwest University, Chongqing, China
| | - Min Qin
- Faculty of Psychology, Southwest University, Chongqing, China
| | - Pengfei Han
- Faculty of Psychology, Southwest University, Chongqing, China; MOE Key Laboratory of Cognition and Personality, Southwest University, Chongqing, China.
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Zhong Y, Jiang R, Zou L. Do you remember if you have olfactory dreams? A content analysis of LOFTER and a questionnaire survey conducted in China. Physiol Behav 2022; 252:113849. [PMID: 35597309 DOI: 10.1016/j.physbeh.2022.113849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/07/2022] [Accepted: 05/17/2022] [Indexed: 10/18/2022]
Abstract
OBJECTIVES Dreams often involve visual and auditory sensations, but olfactory experiences have not received the same amount of attention. This study explores the prevalence and content of olfactory dreams in China and investigates the relationship between olfactory imagery, olfactory significance, and olfactory dreamers. METHODS In the first part of the study, 4302 dream records from LOFTER were screened and classified to preliminarily identify the prevalence and content of olfactory dreams. In the second part, 718 participants completed an online questionnaire about olfactory dreams, imagery, and significance. RESULTS The prevalence of olfactory dreams in the diary dream entries and questionnaire survey participants were 3.95% and 18.70%, respectively. Instances in which odors appeared in dreams were more positive than negative and were mainly related to food, burning and smoke, body odor, nature, and certain environments and objects. Moreover, individuals with olfactory dreams showed better olfactory imagery, and stronger olfactory significance. CONCLUSIONS Olfactory sensations occurred in the dreams of Chinese individuals, but their prevalence was very low. Most of the odors that emerged in these dreams were ones that the dreamers were familiar with in their daily lives.
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Affiliation(s)
- Yu Zhong
- Chemical Senses and Mental Health Laboratory, Department of Psychology, School of Public Health, Southern Medical University, No. 1023 Shatainan Road, Guangzhou, Guangdong 510515, China
| | - Rui Jiang
- Chemical Senses and Mental Health Laboratory, Department of Psychology, School of Public Health, Southern Medical University, No. 1023 Shatainan Road, Guangzhou, Guangdong 510515, China; Penitentiary for Juvenile Delinquents of Guangdong Province, Guangzhou, Guangdong, China
| | - Laiquan Zou
- Chemical Senses and Mental Health Laboratory, Department of Psychology, School of Public Health, Southern Medical University, No. 1023 Shatainan Road, Guangzhou, Guangdong 510515, China.
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