| 1. |
- Arvidsson, Josefin, et al.
(författare)
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Successful acquisition of an olfactory discrimination test by Asian elephants,Elephas maximus
- 2012
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Ingår i: Physiology and Behavior. - : Elsevier. - 0031-9384 .- 1873-507X. ; 105:3, s. 809-814
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Tidskriftsartikel (refereegranskat)abstract
- The present study demonstrates that Asian elephants, Elephas maximus, can successfully be trained to cooperatein an olfactory discrimination test based on a food-rewarded two-alternative instrumental conditioningprocedure. The animals learned the basic principle of the test within only 60 trials and readily mastered intramodalstimulus transfer tasks. Further, they were capable of distinguishing between structurally related odorstimuli and remembered the reward value of previously learned odor stimuli after 2, 4, 8, and 16 weeks ofrecess without any signs of forgetting. The precision and consistency of the elephants' performance in testsof odor discrimination ability and long-term odor memory demonstrate the suitability of this method forassessing olfactory function in this proboscid species. An across-species comparison of several measuresof olfactory learning capabilities such as speed of initial task acquisition and ability to master intramodalstimulus transfer tasks shows that Asian elephants are at least as good in their performance as mice, rats,and dogs, and clearly superior to nonhuman primates and fur seals. The results support the notion thatAsian elephants may use olfactory cues for social communication and food selection and that the sense ofsmell may play an important role in the control of their behavior.
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| 2. |
- Cranford, Ted W., et al.
(författare)
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A New Acoustic Portal into the Odontocete Ear and Vibrational Analysis of the Tympanoperiotic Complex
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:8, s. e11927-
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Tidskriftsartikel (refereegranskat)abstract
- Global concern over the possible deleterious effects of noise on marine organisms was catalyzed when toothed whales stranded and died in the presence of high intensity sound. The lack of knowledge about mechanisms of hearing in toothed whales prompted our group to study the anatomy and build a finite element model to simulate sound reception in odontocetes. The primary auditory pathway in toothed whales is an evolutionary novelty, compensating for the impedance mismatch experienced by whale ancestors as they moved from hearing in air to hearing in water. The mechanism by which high-frequency vibrations pass from the low density fats of the lower jaw into the dense bones of the auditory apparatus is a key to understanding odontocete hearing. Here we identify a new acoustic portal into the ear complex, the tympanoperiotic complex (TPC) and a plausible mechanism by which sound is transduced into the bony components. We reveal the intact anatomic geometry using CT scanning, and test functional preconceptions using finite element modeling and vibrational analysis. We show that the mandibular fat bodies bifurcate posteriorly, attaching to the TPC in two distinct locations. The smaller branch is an inconspicuous, previously undescribed channel, a cone-shaped fat body that fits into a thin-walled bony funnel just anterior to the sigmoid process of the TPC. The TPC also contains regions of thin translucent bone that define zones of differential flexibility, enabling the TPC to bend in response to sound pressure, thus providing a mechanism for vibrations to pass through the ossicular chain. The techniques used to discover the new acoustic portal in toothed whales, provide a means to decipher auditory filtering, beam formation, impedance matching, and transduction. These tools can also be used to address concerns about the potential deleterious effects of high-intensity sound in a broad spectrum of marine organisms, from whales to fish.
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| 3. |
- Laska, Matthias, et al.
(författare)
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Olfactory Discrimination of Aliphatic Odorants in South African Fur Seals (Arctocephalus pusillus)
- 2010
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Ingår i: JOURNAL OF COMPARATIVE PSYCHOLOGY. - : American Psychological Association. - 0735-7036 .- 1939-2087. ; 124:2, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- Using a food-rewarded, two-choice, instrumental conditioning paradigm we assessed the ability of South African fur seals, Arctocephalus pusillus, to discriminate between members of five chemical classes of aliphatic odorants presumed to differ in their abundance in the marine chemical environment. We found that the fur seals were able to distinguish between 24 of the 25 odor pairs presented and thus have a well-developed ability to discriminate between structurally related odorants, that aliphatic n-acetic esters were significantly more poorly discriminated by the fur seals than aliphatic n-aldehydes and n-carboxylic acids, and a lack of correlations between discrimination performance and structural similarity of odorants in terms of differences in carbon chain length. These results suggest that the sense of smell may play an important and hitherto underestimated role in regulating the behavior of fur seals. Further, they support the notion that regular connections between the perceived quality of odorants and their molecular structural properties are not a general phenomenon but appear to be odorant class- and species-specific. Our data support the hypothesis that a species chemical environment may affect its olfactory capabilities.
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| 4. |
- Nilsson, Sara, 1981-, et al.
(författare)
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Behavioral Responses to Mammalian Blood Odor and a Blood Odor Component in Four Species of Large Carnivores
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Only little is known about whether single volatile compounds are as efficient in eliciting behavioral responses in animals asthe whole complex mixture of a behaviorally relevant odor. Recent studies analysing the composition of volatiles inmammalian blood, an important prey-associated odor stimulus for predators, found the odorant trans-4,5-epoxy-(E)-2-decenal to evoke a typical ‘‘metallic, blood-like’’ odor quality in humans. We therefore assessed the behavior of captiveAsian wild dogs (Cuon alpinus), African wild dogs (Lycaon pictus), South American bush dogs (Speothos venaticus), andSiberian tigers (Panthera tigris altaica) when presented with wooden logs that were impregnated either with mammalianblood or with the blood odor component trans-4,5-epoxy-(E)-2-decenal, and compared it to their behavior towards a fruityodor (iso-pentyl acetate) and a near-odorless solvent (diethyl phthalate) as control. We found that all four species displayedsignificantly more interactions with the odorized wooden logs such as sniffing, licking, biting, pawing, and toying, whenthey were impregnated with the two prey-associated odors compared to the two non-prey-associated odors. Mostimportantly, no significant differences were found in the number of interactions with the wooden logs impregnated withmammalian blood and the blood odor component in any of the four species. Only one of the four species, the SouthAmerican bush dogs, displayed a significant decrease in the number of interactions with the odorized logs across the fivesessions performed per odor stimulus. Taken together, the results demonstrate that a single blood odor component can beas efficient in eliciting behavioral responses in large carnivores as the odor of real blood, suggesting that trans-4,5-epoxy-(E)-2-decenal may be perceived by predators as a ‘‘character impact compound’’ of mammalian blood odor. Further, the resultssuggest that odorized wooden logs are a suitable manner of environmental enrichment for captive carnivores.
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| 5. |
- Rizvanovic, Alisa, et al.
(författare)
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Olfactory Discrimination Ability of Asian Elephants (Elephas maximus) forStructurally Related Odorants
- 2013
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Ingår i: Chemical Senses. - Oxford : Oxford University Press. - 0379-864X .- 1464-3553. ; 38:2, s. 107-118
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Tidskriftsartikel (refereegranskat)abstract
- Using a food-rewarded two-choice instrumental conditioning paradigm, we assessed the ability of Asian elephants, Elephasmaximus, to discriminate between 2 sets of structurally related odorants. We found that the animals successfully discriminatedbetween all 12 odor pairs involving members of homologous series of aliphatic 1-alcohols, n-aldehydes, 2-ketones,and n-carboxylic acids even when the stimuli differed from each other by only 1 carbon. With all 4 chemical classes, the elephantsdisplayed a positive correlation between discrimination performance and structural similarity of odorants in terms ofdifferences in carbon chain length. The animals also successfully discriminated between all 12 enantiomeric odor pairs tested.An analysis of odor structure–activity relationships suggests that a combination of molecular structural properties rather thana single molecular feature may be responsible for the discriminability of enantiomers. Compared with other species testedpreviously on the same sets of odor pairs (or on subsets thereof), the Asian elephants performed at least as well as miceand clearly better than human subjects, squirrel monkeys, pigtail macaques, South African fur seals, and honeybees. Furthercomparisons suggest that neither the relative nor the absolute size of the olfactory bulbs appear to be reliable predictors ofbetween-species differences in olfactory discrimination capabilities. In contrast, we found a positive correlation between thenumber of functional olfactory receptor genes and the proportion of discriminable enantiomeric odor pairs. Taken together,the results of the present study support the notion that the sense of smell may play an important role in regulating thebehavior of Asian elephants.
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| 6. |
- Starkhammar, Josefin, et al.
(författare)
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Design and benchmark tests of a hydrophone array system for whale echolocation recordings
- 2012
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Ingår i: Open Journal of Acoustics. - : Scientific Research Publishing, Inc.. - 2162-5794 .- 2162-5786. ; 2:3, s. 121-130
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes in depth the design and application considerations of a computer based measurement system enabling 1 MS/s simultaneous sampling of 47 hydrophones for cross sectional recordings of echolocation beams of toothed whales (Odontocetes). An earlier prototype version of the system has previously only been presented as a brief proof of principle that did not offer a complete description of the software and hardware solution. Crucial hardware and software design considerations of the further developed system include the re-arm times of the burst mode sampling and the dual-core distributed execution of the software components. The rearm time was measured to 283 µs, using a 550 µs long sample window around each click. This enables burst mode sampling of clicks with an inter-click interval as short as 833 µs. It is shown through both synthetic benchmark tests of the system and through field measurements of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) that it is capable of acquiring, analyzing and visualizing data in run-time. It operates effectively also in highly reverberant surroundings like concrete pools and shallow waters. Burst mode sampling allows the system to block reflections with 0.3 - 0.5 m longer propagation paths than the direct path. It is suggested that the system’s compliance to reverberant recording sites makes it valuable in future dolphin echolocation studies.
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| 7. |
- Starkhammar, Josefin, et al.
(författare)
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Separating overlapping click trains originating from multiple individuals in echolocation recordings
- 2011
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Ingår i: JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA. - : Acoustical Society of America. - 0001-4966 .- 1520-8524. ; 129:1, s. 458-466
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Tidskriftsartikel (refereegranskat)abstract
- Recordings of the acoustic activity of free-swimming groups of echolocating dolphins increase the likelihood of collecting overlapping click trains, originating from multiple individuals, in the same set of data. In order to evaluate the click properties of each individual based on such recordings it is necessary to identify which clicks originate from which animal. This paper suggests a computationally efficient strategy to separate overlapping click trains originating from multiple free-swimming bottlenose dolphins, enabling echolocation analysis at an individual level on several animals. This technique is based on sequential matching of the frequency spectra of successive clicks. The clicks are grouped together as individual click trains if the correlation coefficients between clicks are higher than a pre-set threshold level. The robustness of the algorithm is tested by adding artificially generated white Gaussian noise and comparing the results with other comparable commonly used methods based on inter-click intervals, centroid frequencies, and amplitude levels. The described method is applicable to a variety of experimental and observational contexts, e. g., those regarding echolocation development of calves, the hypothesized acoustic "etiquette" among dolphins when investigating the same object, and the possible occurrence of eavesdropping in large dolphin pods.
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| 8. |
- Sunghee, Kim, et al.
(författare)
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Olfactory discrimination ability of South African fur seals (Arctocephalus pusillus) for enantiomers
- 2013
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer. - 0340-7594 .- 1432-1351. ; 199:6, s. 535-544
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Tidskriftsartikel (refereegranskat)abstract
- Using a food-rewarded two-choice instrumentalconditioning paradigm we assessed the ability of SouthAfrican fur seals, Arctocephalus pusillus, to discriminatebetween 12 enantiomeric odor pairs. The results demonstratethat the fur seals as a group were able to discriminatebetween the optical isomers of carvone, dihydrocarvone,dihydrocarveol, menthol, limonene oxide, a-pinene,fenchone (all p\0.01), and b-citronellol (p\0.05),whereas they failed to distinguish between the (?)- and(-)-forms of limonene, isopulegol, rose oxide, and camphor(all p[0.05). An analysis of odor structure–activityrelationships suggests that a combination of molecularstructural properties rather than a single molecular featuremay be responsible for the discriminability of enantiomericodor pairs. A comparison between the discrimination performanceof the fur seals and that of other species testedpreviously on the same set of enantiomers (or subsetsthereof) suggests that the olfactory discrimination capabilitiesof this marine mammal are surprisingly well developedand not generally inferior to that of terrestrial mammalssuch as human subjects and non-human primates. Further,comparisons suggest that neither the relative nor the absolutesize of the olfactory bulbs appear to be reliable predictorsof between-species differences in olfactorydiscrimination capabilities. Taken together, the results ofthe present study support the notion that the sense of smellmay play an important and hitherto underestimated role inregulating the behavior of fur seals.
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