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Cell Jun 2023Animals with complex nervous systems demand sleep for memory consolidation and synaptic remodeling. Here, we show that, although the Caenorhabditis elegans nervous...
Animals with complex nervous systems demand sleep for memory consolidation and synaptic remodeling. Here, we show that, although the Caenorhabditis elegans nervous system has a limited number of neurons, sleep is necessary for both processes. In addition, it is unclear if, in any system, sleep collaborates with experience to alter synapses between specific neurons and whether this ultimately affects behavior. C. elegans neurons have defined connections and well-described contributions to behavior. We show that spaced odor-training and post-training sleep induce long-term memory. Memory consolidation, but not acquisition, requires a pair of interneurons, the AIYs, which play a role in odor-seeking behavior. In worms that consolidate memory, both sleep and odor conditioning are required to diminish inhibitory synaptic connections between the AWC chemosensory neurons and the AIYs. Thus, we demonstrate in a living organism that sleep is required for events immediately after training that drive memory consolidation and alter synaptic structures.
Topics: Animals; Odorants; Caenorhabditis elegans; Smell; Sleep; Synapses
PubMed: 37269832
DOI: 10.1016/j.cell.2023.05.006 -
Frontiers in Neuroscience 2023Cognitive loss in older adults is a growing issue in our society, and there is a need to develop inexpensive, simple, effective in-home treatments. This study was... (Review)
Review
OBJECTIVE
Cognitive loss in older adults is a growing issue in our society, and there is a need to develop inexpensive, simple, effective in-home treatments. This study was conducted to explore the use of olfactory enrichment at night to improve cognitive ability in healthy older adults.
METHODS
Male and female older adults ( = 43), age 60-85, were enrolled in the study and randomly assigned to an Olfactory Enriched or Control group. Individuals in the enriched group were exposed to 7 different odorants a week, one per night, for 2 h, using an odorant diffuser. Individuals in the control group had the same experience with amounts of odorant. Neuropsychological assessments and fMRI scans were administered at the beginning of the study and after 6 months.
RESULTS
A statistically significant 226% improvement was observed in the enriched group compared to the control group on the Rey Auditory Verbal Learning Test and improved functioning was observed in the left uncinate fasciculus, as assessed by mean diffusivity.
CONCLUSION
Minimal olfactory enrichment administered at night produces improvements in both cognitive and neural functioning. Thus, olfactory enrichment may provide an effective and low-effort pathway to improved brain health.
PubMed: 37554295
DOI: 10.3389/fnins.2023.1200448 -
Cell Jun 2023In Drosophila, a dedicated olfactory channel senses a male pheromone, cis-vaccenyl acetate (cVA), promoting female courtship while repelling males. Here, we show that...
In Drosophila, a dedicated olfactory channel senses a male pheromone, cis-vaccenyl acetate (cVA), promoting female courtship while repelling males. Here, we show that separate cVA-processing streams extract qualitative and positional information. cVA sensory neurons respond to concentration differences in a 5-mm range around a male. Second-order projection neurons encode the angular position of a male by detecting inter-antennal differences in cVA concentration, which are amplified through contralateral inhibition. At the third circuit layer, we identify 47 cell types with diverse input-output connectivity. One population responds tonically to male flies, a second is tuned to olfactory looming, while a third integrates cVA and taste to coincidentally promote female mating. The separation of olfactory features resembles the mammalian what and where visual streams; together with multisensory integration, this enables behavioral responses appropriate to specific ethological contexts.
Topics: Animals; Female; Male; Drosophila melanogaster; Drosophila Proteins; Sexual Behavior, Animal; Receptors, Odorant; Pheromones; Smell; Drosophila; Mammals
PubMed: 37236194
DOI: 10.1016/j.cell.2023.04.038 -
Journal of Comparative Physiology. A,... Jul 2023Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to... (Review)
Review
Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to navigate toward odor sources-such as integrating flow information with odor information, comparing odor concentration across sensors, and integrating odor information over time. Because arthropods share many homologous brain structures-antennal lobes for processing olfactory information, mechanosensors for processing flow, mushroom bodies (or hemi-ellipsoid bodies) for associative learning, and central complexes for navigation, it is likely that these closely related behaviors are mediated by conserved neural circuits. However, differences in the types of odors they seek, the physics of odor dispersal, and the physics of locomotion in water, air, and on substrates mean that these circuits must have adapted to generate a wide diversity of odor-seeking behaviors. In this review, we discuss common strategies and specializations observed in olfactory navigation behavior across arthropods, and review our current knowledge about the neural circuits subserving this behavior. We propose that a comparative study of arthropod nervous systems may provide insight into how a set of basic circuit structures has diversified to generate behavior adapted to different environments.
Topics: Animals; Arthropods; Olfactory Pathways; Smell; Odorants; Brain
PubMed: 36658447
DOI: 10.1007/s00359-022-01611-9 -
Biosensors Nov 2023Animals can easily detect hundreds of thousands of odors in the environment with high sensitivity and selectivity. With the progress of biological olfactory research,... (Review)
Review
Animals can easily detect hundreds of thousands of odors in the environment with high sensitivity and selectivity. With the progress of biological olfactory research, scientists have extracted multiple biomaterials and integrated them with different transducers thus generating numerous biosensors. Those biosensors inherit the sensing ability of living organisms and present excellent detection performance. In this paper, we mainly introduce odor biosensors based on substances from animal olfactory systems. Several instances of organ/tissue-based, cell-based, and protein-based biosensors are described and compared. Furthermore, we list some other biological materials such as peptide, nanovesicle, enzyme, and aptamer that are also utilized in odor biosensors. In addition, we illustrate the further developments of odor biosensors.
Topics: Animals; Odorants; Receptors, Odorant; Smell; Peptides; Biosensing Techniques
PubMed: 38131760
DOI: 10.3390/bios13121000 -
Behavioural Processes Apr 2024It is generally believed that termites can't learn and are not "intelligent". This study aimed to test whether termites could have any form of memory. A Y-shaped test...
It is generally believed that termites can't learn and are not "intelligent". This study aimed to test whether termites could have any form of memory. A Y-shaped test device with one release chamber and two identical test chambers was designed and constructed by 3D printing. A colony of damp wood termites was harvested from the wild. Worker termites were randomly selected for experiment. Repellent odors that could mimic the alarm pheromone for termites were first identified. Among all substances tested, a tea tree oil and lemon juice were found to contain repellent odors for the tested termites, as they significantly reduced the time that termites spent in the chamber treated with these substances. As control, a trail pheromone was found to be attractive. Subsequently, a second cohort of termites were operant conditioned by punishment using both tea tree oil and lemon juice, and then tested for their ability to remember the path that could lead to the repellant odors. The test device was thoroughly cleaned between trials. It was found that conditioned termites displayed a reduced tendency to choose the path that led to expectant punishment as compared with naïve termites. Thus, it is concluded that damp wood termites are capable of learning and forming "fear memory", indicative of "intelligence" in termites. This result challenges established presumption about termites' intelligence.
Topics: Isoptera; Animals; Odorants; Conditioning, Operant; Pheromones; Memory; Learning; Tea Tree Oil; Citrus; Insect Repellents; Behavior, Animal; Punishment
PubMed: 38493970
DOI: 10.1016/j.beproc.2024.105012 -
Chimia Jun 2023To support perfumers in their creation of olfactive signatures resulting in unique and instantly recognizable perfumes, there is a constant demand for the development of... (Review)
Review
To support perfumers in their creation of olfactive signatures resulting in unique and instantly recognizable perfumes, there is a constant demand for the development of new odorant molecules and of novel processes for their production. Increasing the sustainability of both the molecules and the processes is a crucial activity at Givaudan. Biocatalysis has the potential to positively influence metrics applied at Givaudan that drive and measure our ambition to innovate responsibly, which is summarized in the FiveCarbon Path™. It targets an increased use of renewable carbon, carbon efficiency in synthesis, and the production of powerful and biodegradable odorant molecules while maximizing the use of upcycled carbon available from waste and side streams. This review illustrates with some examples how enzymes selected from the oxidoreductase and isomerase enzyme classes are applied at Givaudan for the preparation of odorant molecules both at laboratory and industrial scale.
Topics: Odorants; Biotechnology; Biocatalysis; Carbon; Industry; Perfume
PubMed: 38047777
DOI: 10.2533/chimia.2023.384 -
Sensors (Basel, Switzerland) Jul 2023Among the five human senses, light, sound, and force perceived by the eye, ear, and skin, respectively are physical phenomena, and therefore can be easily measured and... (Review)
Review
Among the five human senses, light, sound, and force perceived by the eye, ear, and skin, respectively are physical phenomena, and therefore can be easily measured and expressed as objective, univocal, and simple digital data with physical quantity. However, as taste and odor molecules perceived by the tongue and nose are chemical phenomena, it has been difficult to express them as objective and univocal digital data, since no reference chemicals can be defined. Therefore, while the recording, saving, transmitting to remote locations, and replaying of human visual, auditory, and tactile information as digital data in digital devices have been realized (this series of data flow is defined as DX (digital transformation) in this review), the DX of human taste and odor information is not yet in the realization stage. Particularly, since there are at least 400,000 types of odor molecules and an infinite number of complex odors that are mixtures of these molecules, it has been considered extremely difficult to realize "human olfactory DX" by converting all odors perceived by human olfaction into digital data. In this review, we discuss the current status and future prospects of the development of "human olfactory DX", which we believe can be realized by utilizing odor sensors that employ the olfactory receptors (ORs) that support human olfaction as sensing molecules (i.e., human OR sensor).
Topics: Humans; Odorants; Receptors, Odorant; Smell; Nose; Tongue
PubMed: 37448013
DOI: 10.3390/s23136164