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Jędrychowska J, Vardanyan V, Wieczor M, Marciniak A, Czub J, Amini R, Jain R, Shen H, Choi H, Kuznicki J, Korzh V. Mutant analysis of Kcng4b reveals how the different functional states of the voltage-gated potassium channel regulate ear development. Dev Biol 2024; 513:50-62. [PMID: 38492873 DOI: 10.1016/j.ydbio.2024.03.002] [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: 08/01/2023] [Revised: 03/04/2024] [Accepted: 03/06/2024] [Indexed: 03/18/2024]
Abstract
The voltage gated (Kv) slow-inactivating delayed rectifier channel regulates the development of hollow organs of the zebrafish. The functional channel consists of the tetramer of electrically active Kcnb1 (Kv2.1) subunits and Kcng4b (Kv6.4) modulatory or electrically silent subunits. The two mutations in zebrafish kcng4b gene - kcng4b-C1 and kcng4b-C2 (Gasanov et al., 2021) - have been studied during ear development using electrophysiology, developmental biology and in silico structural modelling. kcng4b-C1 mutation causes a C-terminal truncation characterized by mild Kcng4b loss-of-function (LOF) manifested by failure of kinocilia to extend and formation of ectopic otoliths. In contrast, the kcng4b-C2-/- mutation causes the C-terminal domain to elongate and the ectopic seventh transmembrane (TM) domain to form, converting the intracellular C-terminus to an extracellular one. Kcng4b-C2 acts as a Kcng4b gain-of-function (GOF) allele. Otoliths fail to develop and kinocilia are reduced in kcng4b-C2-/-. These results show that different mutations of the silent subunit Kcng4 can affect the activity of the Kv channel and cause a wide range of developmental defects.
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Affiliation(s)
- Justyna Jędrychowska
- International Institute of Molecular and Cell Biology in Warsaw, Poland; Department of Genetics, Institute of Physiology and Pathology of Hearing, Warsaw, Poland
| | - Vitya Vardanyan
- Institute of Molecular Biology, Armenian Academy of Sciences, Yerevan, Armenia
| | - Milosz Wieczor
- Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland
| | - Antoni Marciniak
- Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland
| | - Jacek Czub
- Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland
| | - Razieh Amini
- International Institute of Molecular and Cell Biology in Warsaw, Poland
| | - Ruchi Jain
- International Institute of Molecular and Cell Biology in Warsaw, Poland
| | - Hongyuan Shen
- Singapore Nuclear Research and Safety Initiative, National University of Singapore, Singapore
| | - Hyungwon Choi
- Cardiovascular Research Institute, National University Health Sciences, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jacek Kuznicki
- International Institute of Molecular and Cell Biology in Warsaw, Poland
| | - Vladimir Korzh
- International Institute of Molecular and Cell Biology in Warsaw, Poland.
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Mougkogiannis P, Adamatzky A. Thermosensory Spiking Activity of Proteinoid Microspheres Cross-Linked by Actin Filaments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:12649-12670. [PMID: 38837748 PMCID: PMC11191697 DOI: 10.1021/acs.langmuir.4c01107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/24/2024] [Accepted: 05/27/2024] [Indexed: 06/07/2024]
Abstract
Actin, found in all eukaryotic cells as globular (G) or filamentous (F) actin, undergoes polymerization, with G-actin units changing shape to become F-actin. Thermal proteins, or proteinoids, are created by heating amino acids (160-200 °C), forming polymeric chains. These proteinoids can swell in an aqueous solution at around 50 °C, producing hollow microspheres filled with a solution, exhibiting voltage spikes. Our research explores the signaling properties of proteinoids, actin filaments, and hybrid networks combining actin and proteinoids. Proteinoids replicate brain excitation dynamics despite lacking specific membranes or ion channels. We investigate enhancing conductivity and spiking by using pure actin, yielding improved coordination in networks compared with individual filaments or proteinoids. Temperature changes (20 short-peptide supramolecular C to 80 °C) regulate conduction states, demonstrating external control over emergent excitability in protobrain systems. Adding actin to proteinoids reduces spike timing variability, providing a more uniform feature distribution. These findings support theoretical models proposing cytoskeletal matrices for functional specification in synthetic protocell brains, promoting stable interaction complexity. The study concludes that life-like signal encoding can emerge spontaneously within biological polymer scaffolds, incorporating abiotic chemistry.
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Affiliation(s)
| | - Andrew Adamatzky
- Unconventional Computing
Laboratory, UWE Bristol, Bristol BS16 1QY, U.K.
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Ricci V, Ronco F, Boileau N, Salzburger W. Visual opsin gene expression evolution in the adaptive radiation of cichlid fishes of Lake Tanganyika. SCIENCE ADVANCES 2023; 9:eadg6568. [PMID: 37672578 PMCID: PMC10482347 DOI: 10.1126/sciadv.adg6568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023]
Abstract
Tuning the visual sensory system to the ambient light is essential for survival in many animal species. This is often achieved through duplication, functional diversification, and/or differential expression of visual opsin genes. Here, we examined 753 new retinal transcriptomes from 112 species of cichlid fishes from Lake Tanganyika to unravel adaptive changes in gene expression at the macro-evolutionary and ecosystem level of one of the largest vertebrate adaptive radiations. We found that, across the radiation, all seven cone opsins-but not the rhodopsin-rank among the most differentially expressed genes in the retina, together with other vision-, circadian rhythm-, and hemoglobin-related genes. We propose two visual palettes characteristic of very shallow- and deep-water living species, respectively, and show that visual system adaptations along two major ecological axes, macro-habitat and diet, occur primarily via gene expression variation in a subset of cone opsin genes.
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Affiliation(s)
- Virginie Ricci
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Fabrizia Ronco
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Nicolas Boileau
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Walter Salzburger
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
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Windmill JFC, Jackson JC, Pook VG, Robert D. Frequency doubling by active in vivo motility of mechanosensory neurons in the mosquito ear. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171082. [PMID: 29410822 PMCID: PMC5792899 DOI: 10.1098/rsos.171082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 11/28/2017] [Indexed: 06/08/2023]
Abstract
Across vertebrate and invertebrate species, nonlinear active mechanisms are employed to increase the sensitivity and acuity of hearing. In mosquitoes, the antennal hearing organs are known to use active force feedback to enhance auditory acuity to female generated sounds. This sophisticated form of signal processing involves active nonlinear events that are proposed to rely on the motile properties of mechanoreceptor neurons. The fundamental physical mechanism for active auditory mechanics is theorized to rely on a synchronization of motile neurons, with a characteristic frequency doubling of the force generated by an ensemble of motile mechanoreceptors. There is however no direct biomechanical evidence at the mechanoreceptor level, hindering further understanding of the fundamental mechanisms of sensitive hearing. Here, using in situ and in vivo atomic force microscopy, we measure and characterize the mechanical response of mechanosensory neuron units during forced oscillations of the hearing organ. Mechanoreceptor responses exhibit the hallmark of nonlinear feedback for force generation, with movements at twice the stimulus frequency, associated with auditory amplification. Simultaneous electrophysiological recordings exhibit similar response features, notably a frequency doubling of the firing rate. This evidence points to the nature of the mechanism, whereby active hearing in mosquitoes emerges from the double-frequency response of the auditory neurons. These results open up the opportunity to directly investigate active cellular mechanics in auditory systems, and they also reveal a pathway to study the nanoscale biomechanics and its dynamics of cells beyond the sense of hearing.
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Du Y, Wang R, Han F, Lu Q, Qu J. Firing pattern and synchronization property analysis in a network model of the olfactory bulb. Cogn Neurodyn 2013; 6:203-9. [PMID: 23543047 DOI: 10.1007/s11571-011-9189-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 12/13/2011] [Accepted: 12/29/2011] [Indexed: 11/29/2022] Open
Abstract
In the olfactory system, both the temporal spike structure and spatial distribution of neuronal activity are important for processing odor information. In this paper, a biophysically-detailed, spiking neuronal model is used to simulate the activity of olfactory bulb. It is shown that by varying some key parameters such as maximal conductances of Ks and Nap the spike train of single neuron can exhibit various firing patterns. Synchronization in coupled neurons is also investigated as the coupling strength varying in the situation of two neurons and network. It is illustrated that the coupled neurons can exhibit different types of pattern when the coupling strength varies. These results may be instructive to understand information transmission in olfactory system.
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Affiliation(s)
- Ying Du
- Institute for Cognitive Neurodynamics, School of Science, East China University of Science and Technology, Shanghai, 200237 China
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Lv P, Rodriguez-Contreras A, Kim HJ, Zhu J, Wei D, Choong-Ryoul S, Eastwood E, Mu K, Levic S, Song H, Yevgeniy PY, Smith PJS, Yamoah EN. Release and elementary mechanisms of nitric oxide in hair cells. J Neurophysiol 2010; 103:2494-505. [PMID: 20220083 DOI: 10.1152/jn.00017.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The enzyme nitric oxide (NO) synthase, that produces the signaling molecule NO, has been identified in several cell types in the inner ear. However, it is unclear whether a measurable quantity of NO is released in the inner ear to confer specific functions. Indeed, the functional significance of NO and the elementary cellular mechanism thereof are most uncertain. Here, we demonstrate that the sensory epithelia of the frog saccule release NO and explore its release mechanisms by using self-referencing NO-selective electrodes. Additionally, we investigated the functional effects of NO on electrical properties of hair cells and determined their underlying cellular mechanism. We show detectable amounts of NO are released by hair cells (>50 nM). Furthermore, a hair-cell efferent modulator acetylcholine produces at least a threefold increase in NO release. NO not only attenuated the baseline membrane oscillations but it also increased the magnitude of current required to generate the characteristic membrane potential oscillations. This resulted in a rightward shift in the frequency-current relationship and altered the excitability of hair cells. Our data suggest that these effects ensue because NO reduces whole cell Ca(2+) current and drastically decreases the open probability of single-channel events of the L-type and non L-type Ca(2+) channels in hair cells, an effect that is mediated through direct nitrosylation of the channel and activation of protein kinase G. Finally, NO increases the magnitude of Ca(2+)-activated K(+) currents via direct NO nitrosylation. We conclude that NO-mediated inhibition serves as a component of efferent nerve modulation of hair cells.
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Affiliation(s)
- Ping Lv
- Center for Neuroscience, Department of Anesthesiology and Pain Medicine, Program in Communication Sciences, University of California, Davis, Davis, CA 95616, USA
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Windmill JFC, Bockenhauer S, Robert D. Time-resolved tympanal mechanics of the locust. J R Soc Interface 2009; 5:1435-43. [PMID: 18522928 DOI: 10.1098/rsif.2008.0131] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A salient characteristic of most auditory systems is their capacity to analyse the frequency of sound. Little is known about how such analysis is performed across the diversity of auditory systems found in animals, and especially in insects. In locusts, frequency analysis is primarily mechanical, based on vibrational waves travelling across the tympanal membrane. Different acoustic frequencies generate travelling waves that direct vibrations to distinct tympanal locations, where distinct groups of correspondingly tuned mechanosensory neurons attach. Measuring the mechanical tympanal response, for the first time, to acoustic impulses in the time domain, nanometre-range vibrational waves are characterized with high spatial and temporal resolutions. Conventional Fourier analysis is also used to characterize the response in the frequency domain. Altogether these results show that travelling waves originate from a particular tympanal location and travel across the membrane to generate oscillations in the exact region where mechanosensory neurons attach. Notably, travelling waves are unidirectional; no strong back reflection or wave resonance could be observed across the membrane. These results constitute a key step in understanding tympanal mechanics in general, and in insects in particular, but also in our knowledge of the vibrational behaviour of anisotropic media.
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Affiliation(s)
- J F C Windmill
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
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Haeberle H, Bryan LA, Vadakkan TJ, Dickinson ME, Lumpkin EA. Swelling-activated Ca2+ channels trigger Ca2+ signals in Merkel cells. PLoS One 2008; 3:e1750. [PMID: 18454189 PMCID: PMC2365925 DOI: 10.1371/journal.pone.0001750] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Accepted: 02/08/2008] [Indexed: 01/26/2023] Open
Abstract
Merkel cell-neurite complexes are highly sensitive touch receptors comprising epidermal Merkel cells and sensory afferents. Based on morphological and molecular studies, Merkel cells are proposed to be mechanosensory cells that signal afferents via neurotransmission; however, functional studies testing this hypothesis in intact skin have produced conflicting results. To test this model in a simplified system, we asked whether purified Merkel cells are directly activated by mechanical stimulation. Cell shape was manipulated with anisotonic solution changes and responses were monitored by Ca2+ imaging with fura-2. We found that hypotonic-induced cell swelling, but not hypertonic solutions, triggered cytoplasmic Ca2+ transients. Several lines of evidence indicate that these signals arise from swelling-activated Ca2+-permeable ion channels. First, transients were reversibly abolished by chelating extracellular Ca2+, demonstrating a requirement for Ca2+ influx across the plasma membrane. Second, Ca2+ transients were initially observed near the plasma membrane in cytoplasmic processes. Third, voltage-activated Ca2+ channel (VACC) antagonists reduced transients by half, suggesting that swelling-activated channels depolarize plasma membranes to activate VACCs. Finally, emptying internal Ca2+ stores attenuated transients by 80%, suggesting Ca2+ release from stores augments swelling-activated Ca2+ signals. To identify candidate mechanotransduction channels, we used RT-PCR to amplify ion-channel transcripts whose pharmacological profiles matched those of hypotonic-evoked Ca2+ signals in Merkel cells. We found 11 amplicons, including PKD1, PKD2, and TRPC1, channels previously implicated in mechanotransduction in other cells. Collectively, these results directly demonstrate that Merkel cells are activated by hypotonic-evoked swelling, identify cellular signaling mechanisms that mediate these responses, and support the hypothesis that Merkel cells contribute to touch reception in the Merkel cell-neurite complex.
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Affiliation(s)
- Henry Haeberle
- Neuroscience Graduate Program, University of California San Francisco, San Francisco, California, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Leigh A. Bryan
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tegy J. Vadakkan
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mary E. Dickinson
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ellen A. Lumpkin
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Verhagen JV. The neurocognitive bases of human multimodal food perception: consciousness. ACTA ACUST UNITED AC 2006; 53:271-86. [PMID: 17027988 PMCID: PMC3373180 DOI: 10.1016/j.brainresrev.2006.09.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 09/04/2006] [Accepted: 09/06/2006] [Indexed: 11/26/2022]
Abstract
This review explores how we become aware of the (integrated) flavor of food. In recent years, progress has been made understanding the neural correlates of consciousness. Experimental and computational data have been largely based on the visual system. Contemporary neurobiological frameworks of consciousness are reviewed, concluding that neural reverberation among forward- and back-projecting neural ensembles across brain areas is a common theme. In an attempt to extrapolate these concepts to the oral-sensory and olfactory systems involved with multimodal flavor perception, the integration of the sensory information of which into a flavor gestalt has been reviewed elsewhere (Verhagen, J.V., Engelen, L., 2006. The neurocognitive bases of human multimodal food perception: Sensory integration. Neurosci. Biobehav. Rev. 30(5): 613_650), I reconceptualize the flavor-sensory system by integrating it into a larger neural system termed the Homeostatic Interoceptive System (HIS). This system consists of an oral (taste, oral touch, etc.) and non-oral part (non oral-thermosensation, pain, etc.) which are anatomically and functionally highly similar. Consistent with this new concept and with a large volume of experimental data, I propose that awareness of intraoral food is related to the concomitant reverberant self-sustained activation of a coalition of neuronal subsets in agranular insula and orbitofrontal cortex (affect, hedonics) and agranular insula and perirhinal cortex (food identity), as well as the amygdala (affect and identity) in humans. I further discuss the functional anatomy in relation essential nodes. These formulations are by necessity to some extent speculative.
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Verhagen JV, Engelen L. The neurocognitive bases of human multimodal food perception: sensory integration. Neurosci Biobehav Rev 2006; 30:613-50. [PMID: 16457886 DOI: 10.1016/j.neubiorev.2005.11.003] [Citation(s) in RCA: 216] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 11/23/2005] [Accepted: 11/23/2005] [Indexed: 11/30/2022]
Abstract
This review addresses a fundamental neuroscientific question in food perception: how multimodal features of food are integrated. Much research and conceptualization has emerged related to multisensory integration in vision, audition and somatosensation, while it remains poorly understood and researched within the chemical and mouth feel senses. This review aims to bridge this gap. We discuss the main concepts in the fields of auditory, visual and somatosensory multisensory integration and relate them to oral-sensory (gustatory and somatosensory) and olfactory (orolfactory) interactions. We systematically review the psychophysical literature pertaining to intra- and intermodal interactions related to food perception, while making explicit distinctions between peripheral and central interactions. As the neural bases of crossmodal orolfaction currently are poorly understood, we introduce several plausible neuroscientific models, which provide a framework for further neuroscientific exploration in this area. We are guided by a new meta-analysis of the odor-taste neuroimaging literature, as well as by single-unit, anatomical and psychophysical studies. Finally, we propose strong involvement of recurrent neural networks in multisensory integration and make suggestions for future research.
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Affiliation(s)
- Justus V Verhagen
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.
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11
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Abstract
PURPOSE This study examined the degree to which birthweight, gestational age, fetal drug exposure, hazardous postnatal medical events, and a mother's predisposition toward touch predicted the likelihood of an infant's tactile vulnerability during nursing care. SUBJECTS The convenience sample included 99 hospitalized infants in their second week of life and their mothers. DESIGN The design was correlational. METHODS A standardized observational assessment was used to code the infant's physiological and behavioral responses to touch during 4 different episodes of nursing care. Chart review was performed to collect information regarding fetal drug exposure, birthweight, gestational age, and postnatal medical events. Mothers completed a questionnaire regarding their own comfort with using touch and being touched. MEASURES The Tactile Vulnerability Assessment measured infant reactivity to and tolerance for touch during nursing care. The Postnatal Complications Scale identified hazardous medical conditions and treatments experienced by the infant during the first 2 weeks of life, and the Physical Contact Assessment evaluated a mother's predisposition toward touch. RESULTS The number of hazardous postnatal medical events experienced by an infant was the primary predictor of tactile vulnerability, accounting for 28% of the variance in the infant's likelihood of developing hyperarousal and distress from touch during care. Illicit fetal drug exposure and maternal predisposition toward touch were also significant predictors. CONCLUSIONS The significant relationship of postnatal medical events to tactile vulnerability suggests that it may be associated with the presence of infant pain or injury to the infant's central nervous system. Symptoms of drug withdrawal and the impact of teratogens on arousal regulation may also be implicated in greater distress from touch by infants. In addition, findings suggest the potential for inherited transmission of a vulnerability to touch. Assessment of infant vulnerability, including discussion with parents about their views of the infant's needs regarding touch, may enhance problem identification and early intervention to reduce infant distress and further medical problems.
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Affiliation(s)
- Sandra J Weiss
- Department of Community Health Systems, School of Nursing, University of California-San Francisco, San Francisco, CA 94143-0608, USA.
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12
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Weiss SJ. Haptic perception and the psychosocial functioning of preterm, low birth weight infants. Infant Behav Dev 2005. [DOI: 10.1016/j.infbeh.2005.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Gollisch T, Herz AMV. Disentangling sub-millisecond processes within an auditory transduction chain. PLoS Biol 2005; 3:e8. [PMID: 15660161 PMCID: PMC539322 DOI: 10.1371/journal.pbio.0030008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Accepted: 10/21/2004] [Indexed: 11/19/2022] Open
Abstract
Every sensation begins with the conversion of a sensory stimulus into the response of a receptor neuron. Typically, this involves a sequence of multiple biophysical processes that cannot all be monitored directly. In this work, we present an approach that is based on analyzing different stimuli that cause the same final output, here defined as the probability of the receptor neuron to fire a single action potential. Comparing such iso-response stimuli within the framework of nonlinear cascade models allows us to extract the characteristics of individual signal-processing steps with a temporal resolution much finer than the trial-to-trial variability of the measured output spike times. Applied to insect auditory receptor cells, the technique reveals the sub-millisecond dynamics of the eardrum vibration and of the electrical potential and yields a quantitative four-step cascade model. The model accounts for the tuning properties of this class of neurons and explains their high temporal resolution under natural stimulation. Owing to its simplicity and generality, the presented method is readily applicable to other nonlinear cascades and a large variety of signal-processing systems. Comparing auditory stimuli that give the same neural response within the framework of a computational model, the authors extract intermediary signal-processing steps with sub- millisecond temporal resolution
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Affiliation(s)
- Tim Gollisch
- Institute for Theoretical Biology, Humboldt University, Berlin Germany.
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Saghatelyan A, Carleton A, Lagier S, de Chevigny A, Lledo PM. Local neurons play key roles in the mammalian olfactory bulb. ACTA ACUST UNITED AC 2004; 97:517-28. [PMID: 15242661 DOI: 10.1016/j.jphysparis.2004.01.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Over the past few decades, research exploring how the brain perceives, discriminates, and recognizes odorant molecules has received a growing interest. Today, olfaction is no longer considered a matter of poetry. Chemical senses entered the biological era when an increasing number of scientists started to elucidate the early stages of the olfactory pathway. A combination of genetic, biochemical, cellular, electrophysiological and behavioral methods has provided a picture of how odor information is processed in the olfactory system as it moves from the periphery to higher areas of the brain. Our group is exploring the physiology of the main olfactory bulb, the first processing relay in the mammalian brain. From different electrophysiological approaches, we are attempting to understand the cellular rules that contribute to the synaptic transmission and plasticity at this central relay. How olfactory sensory inputs, originating from the olfactory epithelium located in the nasal cavity, are encoded in the main olfactory bulb remains a crucial question for understanding odor processing. More importantly, the persistence of a high level of neurogenesis continuously supplying the adult olfactory bulb with newborn local neurons provides an attractive model to investigate how basic olfactory functions are maintained when a large proportion of local neurons are continuously renewed. For this purpose, we summarize the current ideas concerning the molecular mechanisms and organizational strategies used by the olfactory system to encode and process information in the main olfactory bulb. We discuss the degree of sensitivity of the bulbar neuronal network activity to the persistence of this high level of neurogenesis that is modulated by sensory experience. Finally, it is worth mentioning that analyzing the molecular mechanisms and organizational strategies used by the olfactory system to transduce, encode, and process odorant information in the olfactory bulb should aid in understanding the general neural mechanisms involved in both sensory perception and memory. Due to space constraints, this review focuses exclusively on the olfactory systems of vertebrates and primarily those of mammals.
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Affiliation(s)
- Armen Saghatelyan
- Laboratory of Perception and Memory, Centre National de la Recherche Scientifique, Unité de Recherche Associée 2182, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris, France
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15
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Weitzel EK, Tasker R, Brownell WE. Outer hair cell piezoelectricity: frequency response enhancement and resonance behavior. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2003; 114:1462-6. [PMID: 14514199 PMCID: PMC2828812 DOI: 10.1121/1.1596172] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Stretching or compressing an outer hair cell alters its membrane potential and, conversely, changing the electrical potential alters its length. This bi-directional energy conversion takes place in the cell's lateral wall and resembles the direct and converse piezoelectric effects both qualitatively and quantitatively. A piezoelectric model of the lateral wall has been developed that is based on the electrical and material parameters of the lateral wall. An equivalent circuit for the outer hair cell that includes piezoelectricity shows a greater admittance at high frequencies than one containing only membrane resistance and capacitance. The model also predicts resonance at ultrasonic frequencies that is inversely proportional to cell length. These features suggest all mammals use outer hair cell piezoelectricity to support the high-frequency receptor potentials that drive electromotility. It is also possible that members of some mammalian orders use outer hair cell piezoelectric resonance in detecting species-specific vocalizations.
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Affiliation(s)
- Erik K Weitzel
- Bobby R. Alford Department of Otorhinolaryngology and Communicative Sciences, Baylor College of Medicine, Houston, Texas 77030, USA
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Abstract
We investigate the transduction of sound stimuli into neural responses and focus on locust auditory receptor cells. As in other mechanosensory model systems, these neurons integrate acoustic inputs over a fairly broad frequency range. To test three alternative hypotheses about the nature of this spectral integration (amplitude, energy, pressure), we perform intracellular recordings while stimulating with superpositions of pure tones. On the basis of online data analysis and automatic feedback to the stimulus generator, we systematically explore regions in stimulus space that lead to the same level of neural activity. Focusing on such iso-firing-rate regions allows for a rigorous quantitative comparison of the electrophysiological data with predictions from the three hypotheses that is independent of nonlinearities induced by the spike dynamics. We find that the dependence of the firing rates of the receptors on the composition of the frequency spectrum can be well described by an energy-integrator model. This result holds at stimulus onset as well as for the steady-state response, including the case in which adaptation effects depend on the stimulus spectrum. Predictions of the model for the responses to bandpass-filtered noise stimuli are verified accurately. Together, our data suggest that the sound-intensity coding of the receptors can be understood as a three-step process, composed of a linear filter, a summation of the energy contributions in the frequency domain, and a firing-rate encoding of the resulting effective sound intensity. These findings set quantitative constraints for future biophysical models.
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Rabinovich M, Volkovskii A, Lecanda P, Huerta R, Abarbanel HD, Laurent G. Dynamical encoding by networks of competing neuron groups: winnerless competition. PHYSICAL REVIEW LETTERS 2001; 87:068102. [PMID: 11497865 DOI: 10.1103/physrevlett.87.068102] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2000] [Indexed: 05/20/2023]
Abstract
Following studies of olfactory processing in insects and fish, we investigate neural networks whose dynamics in phase space is represented by orbits near the heteroclinic connections between saddle regions (fixed points or limit cycles). These networks encode input information as trajectories along the heteroclinic connections. If there are N neurons in the network, the capacity is approximately e(N-1)!, i.e., much larger than that of most traditional network structures. We show that a small winnerless competition network composed of FitzHugh-Nagumo spiking neurons efficiently transforms input information into a spatiotemporal output.
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Affiliation(s)
- M Rabinovich
- Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093-0402, USA
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