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Tolnai S, Weiß M, Beutelmann R, Bankstahl JP, Bovee S, Ross TL, Berding G, Klump GM. Age-Related Deficits in Binaural Hearing: Contribution of Peripheral and Central Effects. J Neurosci 2024; 44:e0963222024. [PMID: 38395618 PMCID: PMC11026345 DOI: 10.1523/jneurosci.0963-22.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/25/2024] Open
Abstract
Pure-tone audiograms often poorly predict elderly humans' ability to communicate in everyday complex acoustic scenes. Binaural processing is crucial for discriminating sound sources in such complex acoustic scenes. The compromised perception of communication signals presented above hearing threshold has been linked to both peripheral and central age-related changes in the auditory system. Investigating young and old Mongolian gerbils of both sexes, an established model for human hearing, we demonstrate age-related supra-threshold deficits in binaural hearing using behavioral, electrophysiological, anatomical, and imaging methods. Binaural processing ability was measured as the binaural masking level difference (BMLD), an established measure in human psychophysics. We tested gerbils behaviorally with "virtual headphones," recorded single-unit responses in the auditory midbrain and evaluated gross midbrain and cortical responses using positron emission tomography (PET) imaging. Furthermore, we obtained additional measures of auditory function based on auditory brainstem responses, auditory-nerve synapse counts, and evidence for central inhibitory processing revealed by PET. BMLD deteriorates already in middle-aged animals having normal audiometric thresholds and is even worse in old animals with hearing loss. The magnitude of auditory brainstem response measures related to auditory-nerve function and binaural processing in the auditory brainstem also deteriorate. Furthermore, central GABAergic inhibition is affected by age. Because the number of synapses in the apical turn of the inner ear was not reduced in middle-aged animals, we conclude that peripheral synaptopathy contributes little to binaural processing deficits. Exploratory analyses suggest increased hearing thresholds, altered binaural processing in the brainstem and changed central GABAergic inhibition as potential contributors.
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Affiliation(s)
- Sandra Tolnai
- Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg 26111, Germany
- Cluster of Excellence "Hearing4all", Oldenburg 26111, Germany
| | - Mariella Weiß
- Cluster of Excellence "Hearing4all", Hannover 30625, Germany
- Department of Nuclear Medicine, Hannover Medical School, Hannover 30625, Germany
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
| | - Rainer Beutelmann
- Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg 26111, Germany
- Cluster of Excellence "Hearing4all", Oldenburg 26111, Germany
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover 30625, Germany
| | - Sonny Bovee
- Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg 26111, Germany
- Cluster of Excellence "Hearing4all", Oldenburg 26111, Germany
| | - Tobias L Ross
- Department of Nuclear Medicine, Hannover Medical School, Hannover 30625, Germany
| | - Georg Berding
- Cluster of Excellence "Hearing4all", Hannover 30625, Germany
- Department of Nuclear Medicine, Hannover Medical School, Hannover 30625, Germany
| | - Georg M Klump
- Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg 26111, Germany
- Cluster of Excellence "Hearing4all", Oldenburg 26111, Germany
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2
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Nabel AL, Teich L, Wohlfrom H, Alexandrova O, Heß M, Pecka M, Grothe B. Development of myelination and axon diameter for fast and precise action potential conductance. Glia 2024; 72:794-808. [PMID: 38174817 DOI: 10.1002/glia.24504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/05/2024]
Abstract
Axons of globular bushy cells in the cochlear nucleus convey hyper-accurate signals to the superior olivary complex, the initial site of binaural processing via comparably thick axons and the calyx of the Held synapse. Bushy cell fibers involved in hyper-accurate binaural processing of low-frequency sounds are known to have an unusual internode length-to-axon caliber ratio (L/d) correlating with higher conduction velocity and superior temporal precision of action potentials. How the L/d-ratio develops and what determines this unusual myelination pattern is unclear. Here we describe a gradual developmental transition from very simple to complex, mature nodes of Ranvier on globular bushy cell axons during a 2-week period starting at postnatal day P6/7. The molecular composition of nodes matured successively along the axons from somata to synaptic terminals with morphologically and molecularly mature nodes appearing almost exclusively after hearing onset. Internodal distances are initially coherent with the canonical L/d-ratio of ~100. Several days after hearing onset, however, an over-proportional increase in axon caliber occurs in cells signaling low-frequency sounds which alters their L/d ratio to ~60. Hence, oligodendrocytes initially myelinating axons according to their transient axon caliber but a subsequent differential axon thickening after hearing onset results in the unusual myelination pattern.
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Affiliation(s)
- Alisha L Nabel
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
| | - Laurin Teich
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
- Division of Neurobiology, Faculty of Biology, Munich Cluster for Systems Neurology (SyNergy), Martinsried, Germany
| | - Hilde Wohlfrom
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
| | - Olga Alexandrova
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
| | - Martin Heß
- Division of Systematic Zoology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
| | - Michael Pecka
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
| | - Benedikt Grothe
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-Universität in Munich, Martinsried, Germany
- Division of Neurobiology, Faculty of Biology, Munich Cluster for Systems Neurology (SyNergy), Martinsried, Germany
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Mowery TM, Wackym PA, Nacipucha J, Dangcil E, Stadler RD, Tucker A, Carayannopoulos NL, Beshy MA, Hong SS, Yao JD. Superior semicircular canal dehiscence and subsequent closure induces reversible impaired decision-making. Front Neurol 2023; 14:1259030. [PMID: 37905188 PMCID: PMC10613502 DOI: 10.3389/fneur.2023.1259030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 09/14/2023] [Indexed: 11/02/2023] Open
Abstract
Background Vestibular loss and dysfunction has been associated with cognitive deficits, decreased spatial navigation, spatial memory, visuospatial ability, attention, executive function, and processing speed among others. Superior semicircular canal dehiscence (SSCD) is a vestibular-cochlear disorder in humans in which a pathological third mobile window of the otic capsule creates changes to the flow of sound pressure energy through the perilymph/endolymph. The primary symptoms include sound-induced dizziness/vertigo, inner ear conductive hearing loss, autophony, headaches, and visual problems; however, individuals also experience measurable deficits in basic decision-making, short-term memory, concentration, spatial cognition, and depression. These suggest central mechanisms of impairment are associated with vestibular disorders; therefore, we directly tested this hypothesis using both an auditory and visual decision-making task of varying difficulty levels in our model of SSCD. Methods Adult Mongolian gerbils (n = 33) were trained on one of four versions of a Go-NoGo stimulus presentation rate discrimination task that included standard ("easy") or more difficult ("hard") auditory and visual stimuli. After 10 days of training, preoperative ABR and c+VEMP testing was followed by a surgical fenestration of the left superior semicircular canal. Animals with persistent circling or head tilt were excluded to minimize effects from acute vestibular injury. Testing recommenced at postoperative day 5 and continued through postoperative day 15 at which point final ABR and c+VEMP testing was carried out. Results Behavioral data (d-primes) were compared between preoperative performance (training day 8-10) and postoperative days 6-8 and 13-15. Behavioral performance was measured during the peak of SSCD induced ABR and c + VEMP impairment and the return towards baseline as the dehiscence began to resurface by osteoneogenesis. There were significant differences in behavioral performance (d-prime) and its behavioral components (Hits, Misses, False Alarms, and Correct Rejections). These changes were highly correlated with persistent deficits in c + VEMPs at the end of training (postoperative day 15). The controls demonstrated additional learning post procedure that was absent in the SSCD group. Conclusion These results suggest that aberrant asymmetric vestibular output results in decision-making impairments in these discrimination tasks and could be associated with the other cognitive impairments resulting from vestibular dysfunction.
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Affiliation(s)
- Todd M. Mowery
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
- Rutgers Brain Health Institute, New Brunswick, NJ, United States
| | - P. Ashley Wackym
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
- Rutgers Brain Health Institute, New Brunswick, NJ, United States
| | - Jacqueline Nacipucha
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Evelynne Dangcil
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Ryan D. Stadler
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Aaron Tucker
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Nicolas L. Carayannopoulos
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Mina A. Beshy
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Sean S. Hong
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Justin D. Yao
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
- Rutgers Brain Health Institute, New Brunswick, NJ, United States
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4
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Jüchter C, Beutelmann R, Klump GM. Speech sound discrimination by Mongolian gerbils. Hear Res 2022; 418:108472. [DOI: 10.1016/j.heares.2022.108472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 02/16/2022] [Accepted: 02/22/2022] [Indexed: 11/04/2022]
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Kozhevnikova JD, Volodin IA, Zaytseva AS, Ilchenko OG, Volodina EV. Pup ultrasonic isolation calls of six gerbil species and the relationship between acoustic traits and body size. ROYAL SOCIETY OPEN SCIENCE 2021; 8:201558. [PMID: 33959325 PMCID: PMC8074943 DOI: 10.1098/rsos.201558] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/10/2021] [Indexed: 05/04/2023]
Abstract
Among Gerbillinae rodents, ultrasonic calls of adults of small-sized species are typically higher frequency than those of adults of large-sized species. This study investigates whether a similar relationship can be found in pups of six gerbil species (Dipodillus campestris, Gerbillus perpallidus, Meriones unguiculatus, Meriones vinogradovi, Sekeetamys calurus and Pachyuromys duprasi). We compared the average values of acoustic variables (duration, fundamental and peak frequency) of ultrasonic calls (20 calls per pup, 1200 in total) recorded from 6- to 10-day-old pups (10 pups per species, 60 in total) isolated for 2 min at 22°C and then weighed and measured for body variables. The longest calls (56 ± 33 ms) were found in the largest species, and the highest frequency calls (74.8 ± 5.59 kHz) were found in the smallest species. However, across species, call duration (ranging from 56 to 159 ms among species) did not display a significant relationship with pup body size; and, among frequency variables, only the minimum fundamental frequency depended on pup body size. Discriminant analysis assigned 100% of calls to the correct species. The effect of species identity on the acoustics was stronger than the effect of body size. We discuss these results with the hypotheses of acoustic adaptation, social complexity, hearing ranges and phylogeny.
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Affiliation(s)
- Julia D. Kozhevnikova
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 1/12, 119234 Moscow, Russia
| | - Ilya A. Volodin
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 1/12, 119234 Moscow, Russia
- Department of Behaviour and Behavioural Ecology, A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow 119071, Russia
| | - Alexandra S. Zaytseva
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 1/12, 119234 Moscow, Russia
- Department of Small Mammals, Moscow Zoo, Moscow, Russia
| | | | - Elena V. Volodina
- Department of Behaviour and Behavioural Ecology, A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow 119071, Russia
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6
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Eipert L, Klump GM. Uncertainty-based informational masking in a vowel discrimination task for young and old Mongolian gerbils. Hear Res 2020; 392:107959. [PMID: 32330738 DOI: 10.1016/j.heares.2020.107959] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/13/2020] [Accepted: 04/01/2020] [Indexed: 11/25/2022]
Abstract
Informational masking emerges with processing of complex sounds in the central auditory system and can be affected by uncertainty emerging from trial-to-trial variation of stimulus features. Uncertainty can be non-informative but confusing and thus mask otherwise salient stimulus changes resulting in increased discrimination thresholds. With increasing age, the ability for processing of such complex sound scenes degrades. Here, 6 young and 4 old gerbils were tested behaviorally in a vowel discrimination task. Animals were trained to discriminate between sequentially presented target and reference vowels of the vowel pair/I/-/i/. Reference and target vowels were generated shifting the three formants of the reference vowel in steps towards the formants of the target vowels. Non-informative but distracting uncertainty was introduced by random changes in location, level, fundamental frequency or all three features combined. Young gerbils tested with uncertainty for the target or target and reference vowels showed similar informational masking effects for both conditions. Young and old gerbils were tested with uncertainty for the target vowels only. Old gerbils showed no threshold increase discriminating vowels without uncertainty in comparison with young gerbils. Introducing uncertainty, vowel discrimination thresholds increased for young and old gerbils and vowel discrimination thresholds increased most when presenting all three uncertainty features combined. Old gerbils were more susceptible to non-informative uncertainty and their thresholds increased more than thresholds of young gerbils. Gerbils' vowel discrimination thresholds are compared to human performance in the same task (Eipert et al., 2019).
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Affiliation(s)
- Lena Eipert
- Cluster of Excellence Hearing4all, Division Animal Physiology and Behavior, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, D-26111, Oldenburg, Germany
| | - Georg M Klump
- Cluster of Excellence Hearing4all, Division Animal Physiology and Behavior, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, D-26111, Oldenburg, Germany.
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7
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Li K, Chan CHK, Rajendran VG, Meng Q, Rosskothen-Kuhl N, Schnupp JWH. Microsecond sensitivity to envelope interaural time differences in rats. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 145:EL341. [PMID: 31153346 DOI: 10.1121/1.5099164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 04/03/2019] [Indexed: 06/09/2023]
Abstract
Currently, there is controversy around whether rats can use interaural time differences (ITDs) to localize sound. Here, naturalistic pulse train stimuli were used to evaluate the rat's sensitivity to onset and ongoing ITDs using a two-alternative forced choice sound lateralization task. Pulse rates between 50 Hz and 4.8 kHz with rectangular or Hanning windows were delivered with ITDs between ±175 μs over a near-field acoustic setup. Similar to other mammals, rats performed with 75% accuracy at ∼50 μs ITD, demonstrating that rats are highly sensitive to envelope ITDs.
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Affiliation(s)
- Kongyan Li
- Department of Biomedical Sciences, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong , ,
| | - Chloe H K Chan
- Department of Biomedical Sciences, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong , ,
| | - Vani G Rajendran
- Department of Biomedical Sciences, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong , ,
| | - Qinglin Meng
- Acoustics Lab, School of Physics and Optoelectronics, South China University of Technology, Guangzhou,
| | - Nicole Rosskothen-Kuhl
- Department of Biomedical Sciences, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong ,
| | - Jan W H Schnupp
- Department of Biomedical Sciences, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong ,
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8
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Barone CM, Douma S, Reijntjes DOJ, Browe BM, Köppl C, Klump G, Park TJ, Pyott SJ. Altered cochlear innervation in developing and mature naked and Damaraland mole rats. J Comp Neurol 2019; 527:2302-2316. [PMID: 30861124 PMCID: PMC6767702 DOI: 10.1002/cne.24682] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 01/04/2023]
Abstract
Compared to many other rodent species, naked mole rats (Heterocephalus glaber) have elevated auditory thresholds, poor frequency selectivity, and limited ability to localize sound. Because the cochlea is responsible for encoding and relaying auditory signals to the brain, we used immunofluorescence and quantitative image analysis to examine cochlear innervation in mature and developing naked mole rats compared to mice (Mus musculus), gerbils (Meriones unguiculatus), and Damaraland mole rats (Fukomys damarensis), another subterranean rodent. In comparison to mice and gerbils, we observed alterations in afferent and efferent innervation as well as their patterns of developmental refinement in naked and Damaraland mole rats. These alterations were, however, not always shared similarly between naked and Damaraland mole rats. Most conspicuously, in both naked and Damaraland mole rats, inner hair cell (IHC) afferent ribbon density was reduced, whereas outer hair cell afferent ribbon density was increased. Naked and Damaraland mole rats also showed reduced lateral and medial efferent terminal density. Developmentally, naked mole rats showed reduced and prolonged postnatal reorganization of afferent and efferent innervation. Damaraland mole rats showed no evidence of postnatal reorganization. Differences in cochlear innervation specifically between the two subterranean rodents and more broadly among rodents provides insight into the cochlear mechanisms that enhance frequency sensitivity and sound localization, maturation of the auditory system, and the evolutionary adaptations occurring in response to subterranean environments.
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Affiliation(s)
- Catherine M Barone
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Sytse Douma
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Daniël O J Reijntjes
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Brigitte M Browe
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Christine Köppl
- Cluster of Excellence "Hearing4All", Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Georg Klump
- Cluster of Excellence "Hearing4All", Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Thomas J Park
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois
| | - Sonja J Pyott
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Nengovhela A, Braga J, Denys C, de Beer F, Tenailleau C, Taylor PJ. Associated tympanic bullar and cochlear hypertrophy define adaptations to true deserts in African gerbils and laminate-toothed rats (Muridae: Gerbillinae and Murinae). J Anat 2019; 234:179-192. [PMID: 30474264 PMCID: PMC6326829 DOI: 10.1111/joa.12906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2018] [Indexed: 10/27/2022] Open
Abstract
Hearing capabilities in desert rodents such as gerbils and heteromyids have been inferred from both anatomical and ecological aspects and tested with experiments and theoretical models. However, very few studies have focused on other desert-adapted species. In this study, a refined three-dimensional morphometric approach was used on three African rodent tribes (Otomyini, Taterillini and Gerbillini) to describe the cochlear and tympanic bullar morphology, and to explore the role of phylogeny, allometry and ecology to better understand the underlying mechanism of any observed trends of hypertrophy in the bulla and associated changes in the cochlea. As a result, desert-adapted species could be distinguished from mesic and semi-arid taxa by the gross cochlear dimensions, particularly the oval window, which is larger in desert species. Bullar and cochlear modifications between species could be explained by environment (bulla and oval window), phylogeny (cochlear curvature gradient) and/or allometry (cochlear relative length, oval window and bulla) with some exceptions. Based on their ear anatomy, we predict that Desmodillus auricularis and Parotomys brantsii should be sensitive to low-frequency sounds, with D. auricularis sensitive to high-frequency sounds, too. This study concludes that in both arid and semi-arid adapted laminate-toothed rats and gerbils there is bulla and associated cochlea hypertrophy, particularly in true desert species. Gerbils also show tightly coiled cochlea but the significance of this is debatable and may have nothing to do with adaptations to any specific acoustics in the desert environment.
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Affiliation(s)
- Aluwani Nengovhela
- Laboratoire d'Anthropologie Moléculaire et Imagerie de SynthèseUMR 5288CNRSUniversité de Toulouse (Paul Sabatier)ToulouseFrance
- South African Research Chair in Biodiversity and Change and Centre for Invasion BiologySchool of Mathematical and Natural SciencesUniversity of VendaThohoyandouSouth Africa
| | - José Braga
- Laboratoire d'Anthropologie Moléculaire et Imagerie de SynthèseUMR 5288CNRSUniversité de Toulouse (Paul Sabatier)ToulouseFrance
- Evolutionary Studies InstituteUniversity of the WitwatersrandJohannesburgSouth Africa
| | - Christiane Denys
- Institut de Systématique, Evolution, BiodiversitéUMR 7205, CNRS, MNHN, UPMC, EPHESorbonne UniversitésParisFrance
| | - Frikkie de Beer
- South African Nuclear Energy CorporationPelindabaNorth West ProvinceSouth Africa
| | - Christophe Tenailleau
- Centre Inter‐Universitaire de Recherche et d'Ingénierie des MatériauxUMR 5085CNRSUniversité de Toulouse (Paul Sabatier)ToulouseFrance
| | - Peter J. Taylor
- South African Research Chair in Biodiversity and Change and Centre for Invasion BiologySchool of Mathematical and Natural SciencesUniversity of VendaThohoyandouSouth Africa
- Core Team Member of the Centre of Invasion BiologyStellenbosch UniversityStellenboschSouth Africa
- School of Life SciencesUniversity of KwaZulu‐NatalDurbanSouth Africa
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10
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Eipert L, Klinge-Strahl A, Klump GM. Processing of interaural phase differences in components of harmonic and mistuned complexes in the inferior colliculus of the Mongolian gerbil. Eur J Neurosci 2018; 47:1242-1251. [PMID: 29603825 DOI: 10.1111/ejn.13922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 02/19/2018] [Accepted: 03/22/2018] [Indexed: 11/30/2022]
Abstract
Harmonicity and spatial location provide eminent cues for the perceptual grouping of sounds. In general, harmonicity is a strong grouping cue. In contrast, spatial cues such as interaural phase or time difference provide for strong grouping of stimulus sequences but weak grouping for simultaneously presented sounds. By studying the neuronal basis underlying the interaction of these cues in processing simultaneous sounds using van Rossum spike train distance measures, we aim at explaining the interaction observed in psychophysical experiments. Responses to interaural phase differences imposed on single components of harmonic and mistuned complex tones as well as noise delay functions were recorded as multiunit responses from the inferior colliculus of Mongolian gerbils. Results revealed a better representation of interaural phase differences if imposed on a harmonic rather than a mistuned frequency component of a complex tone. The representation of interaural phase differences was better for long integration-time windows approximately reflecting firing rates rather than short integration-time windows reflecting the temporal pattern of the stimulus-driven response. We found only a weak impact of interaural phase differences if combined with mistuning of a component in a harmonic tone complex.
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Affiliation(s)
- Lena Eipert
- Animal Physiology and Behavior Group, Department for Neuroscience, School for Medicine and Health Sciences, Carl-von-Ossietzky University Oldenburg, 26111, Oldenburg, Germany.,Cluster of Excellence Hearing4all, Carl-von-Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Astrid Klinge-Strahl
- Animal Physiology and Behavior Group, Department for Neuroscience, School for Medicine and Health Sciences, Carl-von-Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Georg M Klump
- Animal Physiology and Behavior Group, Department for Neuroscience, School for Medicine and Health Sciences, Carl-von-Ossietzky University Oldenburg, 26111, Oldenburg, Germany.,Cluster of Excellence Hearing4all, Carl-von-Ossietzky University Oldenburg, 26111, Oldenburg, Germany
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11
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Interaction of interaural cues and their contribution to the lateralisation of Mongolian gerbils (Meriones unguiculatus). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2018; 204:435-448. [PMID: 29476321 DOI: 10.1007/s00359-018-1253-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 02/15/2018] [Indexed: 10/18/2022]
Abstract
The main sound localisation cues in the horizontal plane are interaural time and level differences (ITDs and ILDs, respectively). ITDs are thought to be the dominant cue in the low-frequency range, ILDs the dominant cue in the high-frequency range. ITDs and ILDs co-occur. Their interaction and contribution to the lateralisation of pure tones by Mongolian gerbils was investigated behaviourally using cross-talk cancellation techniques for presenting ITDs and ILDs independently. First, ITDs were applied to pure tones with frequencies ≤ 2 kHz to the ongoing waveform, at the onsets and offsets, or in both the ongoing waveform and at the onsets and offsets. Gerbils could lateralise tones only if ongoing ITDs were present indicating that ongoing ITDs are decisive for the lateralisation of low-frequency tones. Second, an ITD was added to 2-to-6-kHz tones with varying ILD. Gerbils' lateralisation was unaffected by the ITD indicating that a large ILD provides a strong lateralisation cue at those frequencies. Finally, small ILDs were applied to 2-kHz tones with an ongoing ITD, pointing either to the same or opposing sides as the ITD. Gerbils' lateralisation was driven by the ITD but strongly affected by the ILD indicating that both interaural cues contribute to the lateralisation.
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