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O'Leary TP, Brown RE. Age-related changes in species-typical behaviours in the 5xFAD mouse model of Alzheimer's disease from 4 to 16 months of age. Behav Brain Res 2024; 465:114970. [PMID: 38531510 DOI: 10.1016/j.bbr.2024.114970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/12/2024] [Accepted: 03/23/2024] [Indexed: 03/28/2024]
Abstract
Alzheimer's disease (AD) patients show age-related decreases in the ability to perform activities of daily living and the decline in these activities is related to the severity of neurobiological deterioration underlying the disease. The 5xFAD mouse model of AD shows age-related impairments in sensory- motor and cognitive function, but little is known about changes in species-typical behaviours that may model activities of daily living in AD patients. Therefore, we examined species-typical behaviours used as indices of exploration (rearing) and compulsivity (grooming) across six tests of anxiety-like behaviour or motor function in female 5xFAD mice from 3 to 16 months of age. Robust decreases in rearing were found in 5xFAD mice across all tests after 9 months of age, although few differences were observed in grooming. A fine-scale analysis of grooming, however, revealed a previously unresolved and spatially restricted pattern of grooming in 5xFAD mice at 13-16 months of age. We then examined changes in species-typical behaviours in the home-cage, and show impaired nest building in 5xFAD mice at all ages tested. Lastly, we examined the relationship between reduced species typical behaviours in 5xFAD mice and the presentation of freezing behaviour, a commonly used measure of memory for conditioned fear. These results showed that along with cognitive and sensory-motor behaviour, 5xFAD mice have robust age-related impairments in species-typical behaviours. Therefore, species typical behaviours in 5xFAD mice may help to model the decline in activities of daily living observed in AD patients, and may provide useful behavioural phenotypes for evaluating the pre-clinical efficacy of novel therapeutics for AD.
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Affiliation(s)
- Timothy P O'Leary
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Richard E Brown
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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2
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Mesoscopic Mapping of Visual Pathway in a Female 5XFAD Mouse Model of Alzheimer's Disease. Cells 2022; 11:cells11233901. [PMID: 36497159 PMCID: PMC9740259 DOI: 10.3390/cells11233901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/25/2022] [Accepted: 12/01/2022] [Indexed: 12/11/2022] Open
Abstract
Amyloid-β (Aβ) deposition and Aβ-induced neurodegeneration appear in the retina and retinorecipient areas in the early stages of Alzheimer's disease (AD). Although these Aβ-related changes in the retina cause damage to the visual functions, no studies have yet revealed the alterations in the visual pathways of AD. Therefore, we investigated the alterations of visual circuits in the AD mouse model using anterograde tracer cholera toxin β subunits (CTβ). Moreover, we investigated the Aβ accumulation in the retina and retinorecipient areas and the neuronal loss, and synaptic degeneration in retinorecipient areas by immunofluorescent staining of 4- and 12-month-old female 5XFAD transgenic mice. Our results demonstrated that Aβ accumulation and neurodegeneration occurred in the retina and retinorecipient regions of early and late stages of the 5XFAD mice. Retinal efferents to the suprachiasmatic nucleus and lateral geniculate nucleus were impaired in the early stage of AD. Moreover, retinal connections to the dorsal lateral geniculate nucleus and superior colliculus were degenerated in the late-stage of AD. These findings reveal the Aβ-related pathology induced visual circuit disturbances at the mesoscale level in both the early and late stages of AD and provide anatomical and functional insights into the visual circuitry of AD.
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Aranđelović J, Santrač A, Batinić B, Todorović L, Stevanović V, Tiruveedhula VVNPB, Sharmin D, Rashid F, Stanojević B, Cook JM, Savić MM. Effects of α5 GABA A receptor modulation on social interaction, memory, and neuroinflammation in a mouse model of Alzheimer's disease. CNS Neurosci Ther 2022; 28:1767-1778. [PMID: 35822698 PMCID: PMC9532908 DOI: 10.1111/cns.13914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/08/2022] [Accepted: 06/21/2022] [Indexed: 12/24/2022] Open
Abstract
Aims GABAergic modulation involved in cognitive processing appears to be substantially changed in Alzheimer's disease (AD). In a widely used 5xFAD model of AD, we aimed to assess if negative and positive allosteric modulators of α5 GABAA receptors (NAM and PAM, respectively) would affect social interaction, social, object and spatial memory, and neuroinflammation. Methods After 10‐day treatment with PAM, NAM, or solvent, 6‐month‐old transgenic and non‐transgenic 5xFAD mice underwent testing in a behavioral battery. Gene expressions of IL‐1β, IL‐6, TNF‐α, GFAP, and IBA‐1 were determined in hippocampus and prefrontal cortex by qPCR. Results PAM treatment impaired spatial learning in transgenic females compared to solvent‐treated transgenic females, and social recognition in transgenic and non‐transgenic males. NAM treatment declined social interaction in transgenic and non‐transgenic males, while had beneficial effect on cognitive flexibility in non‐transgenic males compared to solvent‐treated non‐transgenic males. Transgenic animals have not fully displayed cognitive symptoms, but neuroinflammation was confirmed. NAM reduced proinflammatory gene expressions in transgenic females and astrogliosis in transgenic males compared to pathological controls. Conclusion PAM and NAM failed to exert favorable behavioral effects in transgenic animals. Suppression of neuroinflammation obtained with NAM calls for more studies with GABAergic ligands in amyloid beta‐ and/or tau‐dependent models with prominent neuroinflammation.
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Affiliation(s)
- Jovana Aranđelović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Anja Santrač
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Bojan Batinić
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Lidija Todorović
- Laboratory for Radiobiology and Molecular Genetics, Vinča Institute of Nuclear Sciences, National Institute of thе Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Vladimir Stevanović
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | | | - Dishary Sharmin
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
| | - Farjana Rashid
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
| | - Boban Stanojević
- Laboratory for Radiobiology and Molecular Genetics, Vinča Institute of Nuclear Sciences, National Institute of thе Republic of Serbia, University of Belgrade, Belgrade, Serbia.,Comprehensive Cancer Centre, Faculty of Life Sciences & Medicine, King's College London, Rayne Institute, London, UK
| | - James M Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
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Simanaviciute U, Brown RE, Wong A, Fertan E, Grant RA. Abnormal whisker movements in the 3xTg-AD mouse model of Alzheimer's disease. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12813. [PMID: 35733405 PMCID: PMC9744487 DOI: 10.1111/gbb.12813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 04/27/2022] [Accepted: 04/27/2022] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease is the most frequent form of dementia in elderly people. The triple transgenic (3xTg-AD) mouse model of Alzheimer's Disease is important in biomedical research as these mice develop both neuropathological and behavioural phenotypes. However, their behavioural phenotype is variable, with findings depending on the specific task, as well as the age and sex of the mice. Whisker movements show motor, sensory and cognitive deficits in mouse models of neurodegenerative disease. Therefore, we examined whisker movements in 3, 12.5 and 17-month-old female 3xTg-AD mice and their B6129S/F2 wildtype controls. Mice were filmed using a high-speed video camera (500 fps) in an open arena during a novel object exploration task. Genotype and age differences were found in mice exploring the arena prior to object contact. Prior to whisker contact, the 3-month-old 3xTg-AD mice had smaller whisker angles compared with the wildtype controls, suggesting an early motor phenotype in these mice. Pre-contact mean angular position at 3 months and whisking amplitude at 17 months of age differed between the 3xTg-AD and wildtype mice. During object contact 3xTg-AD mice did not reduce whisker spread as frequently as the wildtype mice at 12.5 and 17 months, which may suggest sensory or attentional deficits. We show that whisker movements are a powerful behavioural measurement tool for capturing behavioural deficits in mouse models that show complex phenotypes, such as the 3xTg-AD mouse model.
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Affiliation(s)
- Ugne Simanaviciute
- Department of Natural SciencesManchester Metropolitan UniversityManchesterUK
| | - Richard E. Brown
- Department of Psychology and NeuroscienceDalhousie UniversityHalifaxNova ScotiaCanada
| | - Aimee Wong
- Department of Psychology and NeuroscienceDalhousie UniversityHalifaxNova ScotiaCanada
| | - Emre Fertan
- Department of Psychology and NeuroscienceDalhousie UniversityHalifaxNova ScotiaCanada
| | - Robyn A. Grant
- Department of Natural SciencesManchester Metropolitan UniversityManchesterUK
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Roddick KM, Fertan E, Schellinck HM, Brown RE. A Signal Detection Analysis of Olfactory Learning in 12-Month-Old 5xFAD Mice. J Alzheimers Dis 2022; 88:37-44. [DOI: 10.3233/jad-220049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Although Alzheimer’s disease is most often studied in terms of memory impairments, olfactory dysfunction begins in the early stages. We tested olfactory learning, sensitivity, and response bias using signal detection methods in 12-month-old male and female 5xFAD mice and their wildtype controls in the operant olfactometer. Odor detection was not reduced in the 5xFAD mice, but learning was, which was worse in female 5xFAD mice than in males. Female mice were more conservative in their response strategy. Signal detection analysis allows us to discriminate between cognitive and sensory deficits of male and female mouse models of AD.
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O'Leary TP, Brown RE. Visuo-spatial learning and memory impairments in the 5xFAD mouse model of Alzheimer's disease: Effects of age, sex, albinism, and motor impairments. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12794. [PMID: 35238473 PMCID: PMC9744519 DOI: 10.1111/gbb.12794] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 12/19/2021] [Indexed: 12/17/2022]
Abstract
The 5xFAD mouse model of Alzheimer's disease (AD) rapidly develops AD-related neuro-behavioral pathology. Learning and memory impairments in 5xFAD mice, however, are not always replicated and the size of impairments varies considerably across studies. To examine possible sources of this variability, we analyzed the effects of age, sex, albinism due to background genes (Tyrc , Oca2p ) and motor impairment on learning and memory performance of wild type and 5xFAD mice on the Morris water maze, from 3 to 15 months of age. The 5xFAD mice showed impaired learning at 6-9 months of age, but memory impairments were not detected with the test procedure used in this study. Performance of 5xFAD mice was profoundly impaired at 12-15 months of age, but was accompanied by slower swim speeds than wild-type mice and a frequent failure to locate the escape platform. Overall female mice performed worse than males, and reversal learning impairments in 5xFAD mice were more pronounced in females than males. Albino mice performed worse than pigmented mice, confirming that albinism can impair performance of 5xFAD mice independently of AD-related transgenes. Overall, these results show that 5xFAD mice have impaired learning performance at 6-9 months of age, but learning and memory performance at 12-15 months is confounded with motor impairments. Furthermore, sex and albinism should be controlled to provide an accurate assessment of AD-related transgenes on learning and memory. These results will help reduce variability across pre-clinical experiments with 5xFAD mice, and thus enhance the reliability of studies developing new therapeutics for AD.
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Affiliation(s)
- Timothy P. O'Leary
- Department of Psychology and NeuroscienceDalhousie UniversityHalifaxNova ScotiaCanada
| | - Richard E. Brown
- Department of Psychology and NeuroscienceDalhousie UniversityHalifaxNova ScotiaCanada
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Fertan E, Brown RE. Age-Related Deficits in Working Memory in 5xFAD Mice in the Hebb-Williams Maze. Behav Brain Res 2022; 424:113806. [DOI: 10.1016/j.bbr.2022.113806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/10/2022] [Accepted: 02/14/2022] [Indexed: 11/02/2022]
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Ramamurthy DL, Dodson HK, Krubitzer LA. Developmental plasticity of texture discrimination following early vision loss in the marsupial Monodelphis domestica. J Exp Biol 2021. [PMCID: PMC8181249 DOI: 10.1242/jeb.236646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Behavioral strategies that depend on sensory information are not immutable; rather they can be shaped by the specific sensory context in which animals develop. This behavioral plasticity depends on the remarkable capacity of the brain to reorganize in response to alterations in the sensory environment, particularly when changes in sensory input occur at an early age. To study this phenomenon, we utilize the short-tailed opossum, a marsupial that has been a valuable animal model to study developmental plasticity due to the extremely immature state of its nervous system at birth. Previous studies in opossums have demonstrated that removal of retinal inputs early in development results in profound alterations to cortical connectivity and functional organization of visual and somatosensory cortex; however, behavioral consequences of this plasticity are not well understood. We trained early blind and sighted control opossums to perform a two-alternative forced choice texture discrimination task. Whisker trimming caused an acute deficit in discrimination accuracy for both groups, indicating the use of a primarily whisker-based strategy to guide choices based on tactile cues. Mystacial whiskers were important for performance in both groups; however, genal whiskers only contributed to behavioral performance in early blind animals. Early blind opossums significantly outperformed their sighted counterparts in discrimination accuracy, with discrimination thresholds that were lower by ∼75 μm. Our results support behavioral compensation following early blindness using tactile inputs, especially the whisker system.
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Affiliation(s)
- Deepa L. Ramamurthy
- Center for Neuroscience, University of California, Davis, Davis, CA 95618, USA
| | - Heather K. Dodson
- Center for Neuroscience, University of California, Davis, Davis, CA 95618, USA
| | - Leah A. Krubitzer
- Center for Neuroscience, University of California, Davis, Davis, CA 95618, USA
- Department of Psychology, University of California, Davis, Davis, CA 95618, USA
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Landreth K, Simanaviciute U, Fletcher J, Grayson B, Grant RA, Harte MH, Gigg J. Dissociating the effects of distraction and proactive interference on object memory through tests of novelty preference. Brain Neurosci Adv 2021; 5:23982128211003199. [PMID: 35392130 PMCID: PMC8981243 DOI: 10.1177/23982128211003199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/22/2021] [Indexed: 11/16/2022] Open
Abstract
Encoding information into memory is sensitive to distraction while retrieving that memory may be compromised by proactive interference from pre-existing memories. These two debilitating effects are common in neuropsychiatric conditions, but modelling them preclinically to date is slow as it requires prolonged operant training. A step change would be the validation of functionally equivalent but fast, simple, high-throughput tasks based on spontaneous behaviour. Here, we show that spontaneous object preference testing meets these requirements in the subchronic phencyclidine rat model for cognitive impairments associated with schizophrenia. Subchronic phencyclidine rats show clear memory sensitivity to distraction in the standard novel object recognition task. However, due to this, standard novel object recognition task cannot assess proactive interference. Therefore, we compared subchronic phencyclidine performance in standard novel object recognition task to that using the continuous novel object recognition task, which offers minimal distraction, allowing disease-relevant memory deficits to be assessed directly. We first determined that subchronic phencyclidine treatment did not affect whisker movements during object exploration. Subchronic phencyclidine rats exhibited the expected distraction standard novel object recognition task effect but had intact performance on the first continuous novel object recognition task trial, effectively dissociating distraction using two novel object recognition task variants. In remaining continuous novel object recognition task trials, the cumulative discrimination index for subchronic phencyclidine rats was above chance throughout, but, importantly, their detection of object novelty was increasingly impaired relative to controls. We attribute this effect to the accumulation of proactive interference. This is the first demonstration that increased sensitivity to distraction and proactive interference, both key cognitive impairments in schizophrenia, can be dissociated in the subchronic phencyclidine rat using two variants of the same fast, simple, spontaneous object memory paradigm.
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Affiliation(s)
- K. Landreth
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - U. Simanaviciute
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- Department of Natural Sciences, Manchester Metropolitan University, Manchester, UK
| | - J. Fletcher
- Division of Pharmacy, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - B. Grayson
- Division of Pharmacy, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - R. A. Grant
- Department of Natural Sciences, Manchester Metropolitan University, Manchester, UK
| | - M. H. Harte
- Division of Pharmacy, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - J. Gigg
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
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Shansky RM. Sex differences in mechanisms of disease. GENES BRAIN AND BEHAVIOR 2021; 19:e12646. [PMID: 32141220 DOI: 10.1111/gbb.12646] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Rebecca M Shansky
- Department of Psychology, Northeastern University College of Science, Boston, Massachusetts
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11
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Matthews DG, Caruso M, Alcazar Magana A, Wright KM, Maier CS, Stevens JF, Gray NE, Quinn JF, Soumyanath A. Caffeoylquinic Acids in Centella asiatica Reverse Cognitive Deficits in Male 5XFAD Alzheimer's Disease Model Mice. Nutrients 2020; 12:E3488. [PMID: 33202902 PMCID: PMC7698091 DOI: 10.3390/nu12113488] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/04/2020] [Accepted: 11/10/2020] [Indexed: 02/07/2023] Open
Abstract
Centella asiatica (CA) is an edible plant and a popular botanical dietary supplement. It is reputed, in Ayurveda, to mitigate age-related cognitive decline. There is a considerable body of preclinical literature supporting CA's ability to improve learning and memory. This study evaluated the contribution of CA's triterpenes (TT), widely considered its active compounds, and caffeoylquinic acids (CQA) to the cognitive effects of CA water extract (CAW) in 5XFAD mice, a model of Alzheimer's disease. 5XFAD mice were fed a control diet alone, or one containing 1% CAW or compound groups (TT, CQA, or TT + CQA) equivalent to their content in 1% CAW. Wild-type (WT) littermates received the control diet. Conditioned fear response (CFR) was evaluated after 4.5 weeks. Female 5XFAD controls showed no deficit in CFR compared to WT females, nor any effects from treatment. In males, CFR of 5XFAD controls was attenuated compared to WT littermates (p = 0.005). 5XFAD males receiving CQA or TT + CQA had significantly improved CFR (p < 0.05) compared to 5XFAD male controls. CFR did not differ between 5XFAD males receiving treatment diets and WT males. These data confirm a role for CQA in CAW's cognitive effects.
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Affiliation(s)
- Donald G. Matthews
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (D.G.M.); (M.C.); (K.M.W.); (N.E.G.); (J.F.Q.)
| | - Maya Caruso
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (D.G.M.); (M.C.); (K.M.W.); (N.E.G.); (J.F.Q.)
| | - Armando Alcazar Magana
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA; (A.A.M.); (C.S.M.)
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA;
| | - Kirsten M. Wright
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (D.G.M.); (M.C.); (K.M.W.); (N.E.G.); (J.F.Q.)
| | - Claudia S. Maier
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA; (A.A.M.); (C.S.M.)
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA;
| | - Jan F. Stevens
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA;
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA
| | - Nora E. Gray
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (D.G.M.); (M.C.); (K.M.W.); (N.E.G.); (J.F.Q.)
| | - Joseph F. Quinn
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (D.G.M.); (M.C.); (K.M.W.); (N.E.G.); (J.F.Q.)
- Parkinson’s Disease Research Education and Clinical Care Center, Veterans’ Administration Portland Health Care System, Portland, OR 97239, USA
| | - Amala Soumyanath
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; (D.G.M.); (M.C.); (K.M.W.); (N.E.G.); (J.F.Q.)
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Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2020; 206:441-451. [PMID: 32077991 PMCID: PMC7192888 DOI: 10.1007/s00359-020-01408-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 11/10/2022]
Abstract
Whisker touch is an active sensory system. Previous studies in Pinnipeds have adopted relatively stationary tasks to judge tactile sensitivity, which may not accurately promote natural whisker movements and behaviours. This study developed a novel feeding task, termed fish sweeping to encourage whisker movements. Head and whisker movements were tracked from video footage in Harbor seal (Phoca vitulina), California sea lion (Zalophus californianus) and Pacific walrus (Odobenus rosmarus divergens). All species oriented their head towards the moving fish target and moved their whiskers during the task. Some species also engaged in whisker control behaviours, including head-turning asymmetry in the Pacific walrus, and contact-induced asymmetry in the Pacific walrus and California sea lion: behaviours that have only previously been observed in terrestrial mammals. This study confirms that Pinnipeds should be thought of as whisker specialists, and that whisker control (movement and positioning) is an important aspect of touch sensing in these animals, especially in sea lions and walruses. That the California sea lion controls whisker movement in relation to an object, and also had large values of whisker amplitude, spread and asymmetry, suggests that California sea lions are a promising model with which to further explore active touch sensing.
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