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Current Biology : CB Jan 2019Animals can smell odors from the external environment or from their mouth via two routes: orthonasal and retronasal, respectively. Little is known about how the brain...
Animals can smell odors from the external environment or from their mouth via two routes: orthonasal and retronasal, respectively. Little is known about how the brain processes orthonasal and retronasal odors associated with taste, but a new study has revealed an important role for the gustatory cortex in such odor processing.
Topics: Animals; Mouth; Odorants; Smell; Taste; Time Perception
PubMed: 30620909
DOI: 10.1016/j.cub.2018.11.038 -
The Journal of Experimental Biology Jan 2023Odors released from mates and resources such as a host and food are often the first sensory signals that an animal can detect. Changes in locomotion in response to odors... (Review)
Review
Odors released from mates and resources such as a host and food are often the first sensory signals that an animal can detect. Changes in locomotion in response to odors are an important mechanism by which animals access resources important to their survival. Odor-modulated changes in locomotion in insects constitute a whole suite of flexible behaviors that allow insects to close in on these resources from long distances and perform local searches to locate and subsequently assess them. Here, we review changes in odor-mediated locomotion across many insect species. We emphasize that changes in locomotion induced by odors are diverse. In particular, the olfactory stimulus is sporadic at long distances and becomes more continuous at short distances. This distance-dependent change in temporal profile produces a corresponding change in an insect's locomotory strategy. We also discuss the neural circuits underlying odor modulation of locomotion.
Topics: Animals; Odorants; Insecta; Behavior, Animal; Locomotion; Algorithms; Smell
PubMed: 36637433
DOI: 10.1242/jeb.200261 -
Philosophical Transactions of the Royal... Feb 2023The usual puzzle raised about olfaction is that of a deficit of abstraction: smells, by contrast notably with colours, do not easily lend themselves to abstract...
The usual puzzle raised about olfaction is that of a deficit of abstraction: smells, by contrast notably with colours, do not easily lend themselves to abstract categories and labels. Some studies have argued that the puzzle is culturally restricted and that abstraction is more common outside urban Western societies. Here, I argue that the puzzle is misconstrued and should be reversed: given that odours are constantly changing and that their commonalities are difficult for humans to identify, what is surprising is not that abstract terms are rare, but that they should be used at all for olfaction. Given the nature of the olfactory environment and our cognitive equipment, concrete labels referring to sources seem most adaptive. To explain the use and presence of abstract terms, we need to examine their social and communicative benefits. Here these benefits are spelt out as securing a higher agreement among individuals varying in their olfactory experiences as well as the labels they use, as well as feeling a heightened sense of confidence in one's naming capacities. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.
Topics: Humans; Smell; Metacognition; Communication; Odorants; Emotions
PubMed: 36571118
DOI: 10.1098/rstb.2021.0369 -
Proceedings of the National Academy of... Jul 2020Human navigation relies on inputs to our paired eyes and ears. Although we also have two nasal passages, there has been little empirical indication that internostril...
Human navigation relies on inputs to our paired eyes and ears. Although we also have two nasal passages, there has been little empirical indication that internostril differences yield directionality in human olfaction without involving the trigeminal system. By using optic flow that captures the pattern of apparent motion of surface elements in a visual scene, we demonstrate through formal psychophysical testing that a moderate binaral concentration disparity of a nontrigeminal odorant consistently biases recipients' perceived direction of self-motion toward the higher-concentration side, despite that they cannot verbalize which nostril smells a stronger odor. We further show that the effect depends on the internostril ratio of odor concentrations and not the numeric difference in concentration between the two nostrils. Taken together, our findings provide behavioral evidence that humans smell in stereo and subconsciously utilize stereo olfactory cues in spatial navigation.
Topics: Adult; Cues; Female; Humans; Male; Mental Navigation Tests; Nasal Cavity; Odorants; Olfactory Perception; Optic Flow; Photic Stimulation; Smell; Young Adult
PubMed: 32571945
DOI: 10.1073/pnas.2004642117 -
Cell Reports Nov 2022The evolution of feeding habits leads to speciation in insects. Bactrocera true fruit flies display diverse feeding habits across species. We combine behavioral and...
The evolution of feeding habits leads to speciation in insects. Bactrocera true fruit flies display diverse feeding habits across species. We combine behavioral and functional genomic studies to probe the divergence between the specialist B. minax and the generalist B. dorsalis. We find that both vision and olfaction contribute to their respective host preferences, with a dominant effect of vision over the olfaction in short range. Correspondingly, host location-related genes are significantly enriched in the phototransduction pathway, of which the long-wavelength rhodopsin confers the color preference in both species and has been subject to selection in the specialist. We also find a massive expansion of olfactory receptors in the generalist, along with signatures of conditional expression and positive selection. The phylogenetic context suggests an ancestrally important role of vision in the host location of Bactrocera, as well as the increased performance and plasticity of olfaction alongside the arising of generalism.
Topics: Animals; Phylogeny; Genomics; Tephritidae; Receptors, Odorant; Smell
PubMed: 36384127
DOI: 10.1016/j.celrep.2022.111654 -
Journal of Comparative Physiology. A,... Sep 2017In this review, I give a first-person account of surprising insights that have come from the behavioral dimension of neuroethological studies in my laboratory. These... (Review)
Review
In this review, I give a first-person account of surprising insights that have come from the behavioral dimension of neuroethological studies in my laboratory. These studies include the early attempts to understand the function of the nose in star-nosed moles and to explore its representation in the neocortex. This led to the discovery of a somatosensory fovea that parallels the visual fovea of primates in several ways. Subsequent experiments to investigate the assumed superiority of star-nosed moles to their relatives when locating food led to the unexpected discovery of stereo olfaction in common moles. The exceptional olfactory abilities of common moles, in turn, helped to explain an unusual bait-collecting technique called "worm-grunting" in the American southeast. Finally, the predatory behavior of tentacled snakes was best understood not by exploring their nervous system, but rather by considering fish nervous systems. These experiences highlight the difficulty of predicting the abilities of animals that have senses foreign to the investigator, and also the rewards of discovering the unexpected.
Topics: Animals; Biological Evolution; Escape Reaction; Lateral Line System; Moles; Predatory Behavior; Smell; Touch
PubMed: 28260189
DOI: 10.1007/s00359-016-1143-7 -
Cell Reports Dec 2023Co-transmission of multiple neurotransmitters from a single neuron increases the complexity of signaling information within defined neuronal circuits. Superficial...
Co-transmission of multiple neurotransmitters from a single neuron increases the complexity of signaling information within defined neuronal circuits. Superficial short-axon cells in the olfactory bulb release both dopamine and γ-aminobutyric acid (GABA), yet the specific targets of these neurotransmitters and their respective roles in olfaction have remained unknown. Here, we implement intersectional genetics in mice to selectively block GABA or dopamine release from superficial short-axon cells to identify their distinct cellular targets, impact on circuit function, and behavioral contribution of each neurotransmitter toward olfactory behaviors. We provide functional and anatomical evidence for divergent superficial short-axon cell signaling onto downstream neurons to shape patterns of mitral cell firing that contribute to olfactory-related behaviors.
Topics: Mice; Animals; Olfactory Bulb; Smell; Dopamine; Interneurons; gamma-Aminobutyric Acid; Neurotransmitter Agents
PubMed: 37980561
DOI: 10.1016/j.celrep.2023.113471 -
Kulak Burun Bogaz Ihtisas Dergisi : KBB... 2015Of the five senses, the sense of smell is the most complex and unique in structure and organization. As diagnostic and therapeutic modalities are often underdeveloped,... (Review)
Review
Of the five senses, the sense of smell is the most complex and unique in structure and organization. As diagnostic and therapeutic modalities are often underdeveloped, the sense of smell has been inadequately studied. Olfactory disorders may result from benign pathologies such as sinusitis as well as several diseases including Parkinson's disease, temporal lobe epilepsy, schizophrenia and Alzheimer disease. In this article, we aim to instruct the otorhinolaryngology specialists and residents regarding the tests which measure odor subjectively.
Topics: Humans; Odorants; Olfaction Disorders; Olfactometry; Olfactory Perception; Smell
PubMed: 25934410
DOI: 10.5606/kbbihtisas.2015.27136 -
Journal of the American Geriatrics... Dec 2019Given the need to detect subclinical changes in brain health that sometimes occur with aging in apparently healthy older adults, we assessed whether bimanual gesture...
OBJECTIVES
Given the need to detect subclinical changes in brain health that sometimes occur with aging in apparently healthy older adults, we assessed whether bimanual gesture imitation performance, simple to assess clinically, can detect age effects and alterations in cognition, olfaction, and movement.
DESIGN
Cross-sectional study.
SETTING
Baltimore Longitudinal Study of Aging.
PARTICIPANTS
Men and women, aged 22 to 101 years, without cognitive impairment, dementia, stroke, Parkinson disease, resting tremor, abnormal muscle tone, or abnormal coordination (N = 507).
MEASUREMENTS
Bimanual gesture imitation was measured using a test validated in older adults. We assessed (1) cognition, including verbal memory, executive function, attention, visuospatial ability, visuoperceptual speed, and language; (2) manual dexterity with the Purdue Pegboard Test; (3) olfaction, using the 16-item Sniffin' Sticks Identification Test; (4) upper extremity motor function, using a computer-based finger tapping test; and (5) lower extremity motor function, including 6-meter usual and rapid gait speeds, 400-meter walk time, Health ABC Physical Performance Battery, and total standing balance time. Cross-sectional associations between bimanual gesture imitation performance and each measure were examined using linear regression after adjustment for age, sex, race, education, and body mass index. Models with mobility measures also adjusted for height.
RESULTS
Higher gesture imitation performance was associated with younger age. After adjustment, a worse score was associated with worse olfaction, executive function, and visuospatial ability. Gesture imitation score was not associated with other cognitive measures or motor function.
CONCLUSION
In persons without clinically detectable neurological conditions, poor bimanual gesture imitation is associated with other indicators of brain health, including olfaction and selected cognitive function domains. Bimanual gesture imitation may be useful clinically to detect subtle brain changes in apparently healthy older adults. J Am Geriatr Soc 67:2581-2586, 2019.
Topics: Age Factors; Aged; Aging; Baltimore; Cognition; Cross-Sectional Studies; Female; Gestures; Humans; Imitative Behavior; Longitudinal Studies; Male; Movement; Neuropsychological Tests; Smell; Upper Extremity
PubMed: 31441513
DOI: 10.1111/jgs.16151 -
Anatomical Record (Hoboken, N.J. : 2007) Nov 2014This special issue of The Anatomical Record is the outcome of a symposium entitled "Inside the Vertebrate Nose: Evolution, Structure and Function." The skeletal... (Review)
Review
This special issue of The Anatomical Record is the outcome of a symposium entitled "Inside the Vertebrate Nose: Evolution, Structure and Function." The skeletal framework of the nasal cavity is a complicated structure that often houses sinuses and comprises an internal skeleton of bone or cartilage that can vary greatly in architecture among species. The nose serves multiple functions, including olfaction and respiratory air-conditioning, and its morphology is constrained by evolution, development, and conflicting demands on cranial space, such as enlarged orbits. The nasal cavity of vertebrates has received much more attention in the last decade due to the emergence of nondestructive methods that allow improved visualization of the internal anatomy of the skull, such as high-resolution x-ray computed tomography and magnetic resonance imaging. The 17 articles included here represent a broad range of investigators, from paleontologists to engineers, who approach the nose from different perspectives. Key topics include the evolution and development of the nose, its comparative anatomy and function, and airflow through the nasal cavity of individual species. In addition, this special issue includes review articles on anatomical reduction of the olfactory apparatus in both cetaceans and primates (the vomeronasal system), as well as the molecular biology of olfaction in vertebrates. Together these articles provide an expansive summary of our current understanding of vertebrate nasal anatomy and function. In this introduction, we provide background information and an overview of each of the three primary topics, and place each article within the context of previous research and the major challenges that lie ahead.
Topics: Animals; Biological Evolution; Humans; Nasal Cavity; Nose; Smell; Vertebrates
PubMed: 25312359
DOI: 10.1002/ar.23021