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Archives of Clinical Neuropsychology :... Feb 2022Because memory decline is the hallmark of Alzheimer's disease (AD), an important endeavor for both clinicians and researchers is to improve memory performances in AD.... (Review)
Review
OBJECTIVE
Because memory decline is the hallmark of Alzheimer's disease (AD), an important endeavor for both clinicians and researchers is to improve memory performances in AD. This can be pursued by olfactory stimulation of memory in patients with AD and by studying the effects of olfactory stimulation on autobiographical memory (i.e., memory for personal information). The effects of olfactory stimulation on autobiographical memory in patients with mild AD have been reported by recent research. We thus provide the first comprehensive overview of research on odor-evoked autobiographical memory in AD. We also establish the basis for solid theoretical analysis concerning the memory improvement reported by research on odor-evoked autobiographical memory in AD.
METHOD
We examined literature on odor-evoked autobiographical memories in AD and propose the "OdAMA" (Odor-evoked Autobiographical Memory in Alzheimer's disease) model.
RESULTS AND DISCUSSION
According to OdAMA model, odor exposure activates involuntary access to specific autobiographical memories, which promotes enhanced experience subjective of retrieval in patients with AD and improves their ability to construct not only recent and remote events but also future ones. The OdAMA model could serve as a guide for researchers and clinicians interested in odor-evoked autobiographical memory in AD.
Topics: Alzheimer Disease; Humans; Memory, Episodic; Neuropsychological Tests; Odorants; Smell
PubMed: 34491308
DOI: 10.1093/arclin/acab074 -
Journal of Agricultural and Food... Nov 2023Olfaction is a multi-step process. At a peripheral level, nasal odorant metabolism contributes to olfaction via signal termination, variation, and regulation. We... (Review)
Review
Olfaction is a multi-step process. At a peripheral level, nasal odorant metabolism contributes to olfaction via signal termination, variation, and regulation. We summarize current techniques used to investigate nasal odorant metabolism and give an outlook on future approaches, such as nasal tissue models and their potential contributions in future research directions.
Topics: Odorants; Smell
PubMed: 37877768
DOI: 10.1021/acs.jafc.3c04662 -
Current Biology : CB Apr 2023New research indicates that the odor-evoked responses of human olfactory receptors can be enhanced via the non-competitive binding of an allosteric modulator. This...
New research indicates that the odor-evoked responses of human olfactory receptors can be enhanced via the non-competitive binding of an allosteric modulator. This modulatory mechanism adds an additional layer of complexity to the peripheral encoding of odors.
Topics: Humans; Olfactory Receptor Neurons; Odorants; Receptors, Odorant; Smell
PubMed: 37098335
DOI: 10.1016/j.cub.2023.03.046 -
Annual Review of Neuroscience Jul 2020Olfaction is fundamentally distinct from other sensory modalities. Natural odor stimuli are complex mixtures of volatile chemicals that interact in the nose with a...
Olfaction is fundamentally distinct from other sensory modalities. Natural odor stimuli are complex mixtures of volatile chemicals that interact in the nose with a receptor array that, in rodents, is built from more than 1,000 unique receptors. These interactions dictate a peripheral olfactory code, which in the brain is transformed and reformatted as it is broadcast across a set of highly interconnected olfactory regions. Here we discuss the problems of characterizing peripheral population codes for olfactory stimuli, of inferring the specific functions of different higher olfactory areas given their extensive recurrence, and of ultimately understanding how odor representations are linked to perception and action. We argue that, despite the differences between olfaction and other sensory modalities, addressing these specific questions will reveal general principles underlying brain function.
Topics: Animals; Brain; Humans; Nerve Net; Odorants; Olfactory Pathways; Olfactory Perception; Smell
PubMed: 32640927
DOI: 10.1146/annurev-neuro-102119-103452 -
American Journal of Rhinology & Allergy May 2021
Topics: Evidence-Based Practice; Humans; Olfaction Disorders; Smell
PubMed: 33910386
DOI: 10.1177/19458924211012799 -
American Journal of Rhinology & Allergy Mar 2023Chronic rhinosinusitis (CRS) is the leading cause of olfactory dysfunction in the general population. Olfactory dysfunction is more common in patients with CRS with... (Review)
Review
BACKGROUND
Chronic rhinosinusitis (CRS) is the leading cause of olfactory dysfunction in the general population. Olfactory dysfunction is more common in patients with CRS with nasal polyposis (CRSwNP) compared to those without polyps.
PURPOSE
The present review aims to summarize the current literature on the mechanism behind olfactory dysfunction in CRSwNP and the impact of therapy on olfactory outcomes in this patient population.
METHODS
A comprehensive review of the available literature on olfaction in CRSwNP was performed. We evaluated the most recent evidence from studies on the mechanisms behind smell loss in CRSwNP and the impact of medical and surgical therapy for CRS on olfactory outcomes.
RESULTS
The mechanism behind olfactory dysfunction in CRSwNP is not completely understood, but evidence from clinical research and animal models suggests both an obstructive component causing conductive olfactory loss and an inflammatory response in the olfactory cleft leading to sensorineural olfactory loss. Oral steroids and endoscopic sinus surgery have both shown efficacy in improving olfactory outcomes in CRSwNP in the short term; however, the long-term response of these treatments remains uncertain. Newer targeted biologic therapies, such as dupilumab, have also shown remarkable and durable improvement in smell loss for CRSwNP patients.
CONCLUSION
Olfactory dysfunction is highly prevalent in the CRSwNP population. Although significant advances have been made in our understanding of olfactory dysfunction in the setting of CRS, additional studies are needed to elucidate cellular and molecular changes mediated by type 2-mediated inflammation in the olfactory epithelium with potential downstream effects on the central olfactory system. Further identification of these underlying basic mechanisms will be vital for developing future therapies targeted to improve olfactory dysfunction in patients with CRSwNP.
Topics: Humans; Animals; Smell; Anosmia; Inflammation; Models, Animal; Nasal Polyps
PubMed: 36848279
DOI: 10.1177/19458924231153485 -
Current Opinion in Insect Science Apr 2023The focus of bee neuroscience has for a long time been on only a handful of social honeybee and bumblebee species, out of thousands of bees species that have been... (Review)
Review
The focus of bee neuroscience has for a long time been on only a handful of social honeybee and bumblebee species, out of thousands of bees species that have been described. On the other hand, information about the chemical ecology of bees is much more abundant. Here we attempted to compile the scarce information about olfactory systems of bees across species. We also review the major categories of intra- and inter-specific olfactory behaviors of bees, with specific focus on recent literature. We finish by discussing the most promising avenues for bee olfactory research in the near future.
Topics: Animals; Bees; Smell
PubMed: 36842606
DOI: 10.1016/j.cois.2023.101018 -
Chemical Senses Jan 2024Different animals have distinctive anatomical and physiological properties to their chemical senses that enhance detection and discrimination of relevant chemical cues....
Different animals have distinctive anatomical and physiological properties to their chemical senses that enhance detection and discrimination of relevant chemical cues. Humans and other vertebrates are recognized as having 2 main chemical senses, olfaction and gustation, distinguished from each other by their evolutionarily conserved neuroanatomical organization. This distinction between olfaction and gustation in vertebrates is not based on the medium in which they live because the most ancestral and numerous vertebrates, the fishes, live in an aquatic habitat and thus both olfaction and gustation occur in water and both can be of high sensitivity. The terms olfaction and gustation have also often been applied to the invertebrates, though not based on homology. Consequently, any similarities between olfaction and gustation in the vertebrates and invertebrates have resulted from convergent adaptations or shared constraints during evolution. The untidiness of assigning olfaction and gustation to invertebrates has led some to recommend abandoning the use of these terms and instead unifying them and others into a single category-chemical sense. In our essay, we compare the nature of the chemical senses of diverse animal types and consider their designation as olfaction, oral gustation, extra-oral gustation, or simply chemoreception. Properties that we have found useful in categorizing chemical senses of vertebrates and invertebrates include the nature of peripheral sensory cells, organization of the neuropil in the processing centers, molecular receptor specificity, and function.
Topics: Animals; Humans; Smell; Taste; Taste Perception; Fishes; Cues
PubMed: 38422390
DOI: 10.1093/chemse/bjae009 -
Genes Jun 2020The senses dictate how the brain represents the environment, and this representation is the basis of how we act in the world [...].
The senses dictate how the brain represents the environment, and this representation is the basis of how we act in the world [...].
Topics: Brain; Humans; Sensation; Smell
PubMed: 32549403
DOI: 10.3390/genes11060654 -
Neurological Sciences : Official... Jul 2023To date, there are quite a few studies assessing olfaction and gustation in blindness, with great variability in sample size, participants' age, blindness onset and... (Review)
Review
To date, there are quite a few studies assessing olfaction and gustation in blindness, with great variability in sample size, participants' age, blindness onset and smell and taste evaluation methods. Indeed, the evaluation of olfactory and gustatory performance can differ depending on several factors, including cultural differences. Therefore, here we analysed through a narrative review, all the works reporting a smell and taste assessment in blind individuals during the last 130 years, trying to summarize and address the knowledge in this field.
Topics: Humans; Smell; Taste; Olfaction Disorders; Taste Perception; Blindness
PubMed: 36913147
DOI: 10.1007/s10072-023-06734-8