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Bezares-Calderón LA, Berger J, Jékely G. Diversity of cilia-based mechanosensory systems and their functions in marine animal behaviour. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190376. [PMID: 31884914 PMCID: PMC7017336 DOI: 10.1098/rstb.2019.0376] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2019] [Indexed: 12/12/2022] Open
Abstract
Sensory cells that detect mechanical forces usually have one or more specialized cilia. These mechanosensory cells underlie hearing, proprioception or gravity sensation. To date, it is unclear how cilia contribute to detecting mechanical forces and what is the relationship between mechanosensory ciliated cells in different animal groups and sensory systems. Here, we review examples of ciliated sensory cells with a focus on marine invertebrate animals. We discuss how various ciliated cells mediate mechanosensory responses during feeding, tactic responses or predator-prey interactions. We also highlight some of these systems as interesting and accessible models for future in-depth behavioural, functional and molecular studies. We envisage that embracing a broader diversity of organisms could lead to a more complete view of cilia-based mechanosensation. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
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Affiliation(s)
| | - Jürgen Berger
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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Balaban PM, Malyshev AY, Ierusalimsky VN, Aseyev N, Korshunova TA, Bravarenko NI, Lemak MS, Roshchin M, Zakharov IS, Popova Y, Boyle R. Functional changes in the snail statocyst system elicited by microgravity. PLoS One 2011; 6:e17710. [PMID: 21479267 PMCID: PMC3066201 DOI: 10.1371/journal.pone.0017710] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 02/11/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The mollusk statocyst is a mechanosensing organ detecting the animal's orientation with respect to gravity. This system has clear similarities to its vertebrate counterparts: a weight-lending mass, an epithelial layer containing small supporting cells and the large sensory hair cells, and an output eliciting compensatory body reflexes to perturbations. METHODOLOGY/PRINCIPAL FINDINGS In terrestrial gastropod snail we studied the impact of 16- (Foton M-2) and 12-day (Foton M-3) exposure to microgravity in unmanned orbital missions on: (i) the whole animal behavior (Helix lucorum L.), (ii) the statoreceptor responses to tilt in an isolated neural preparation (Helix lucorum L.), and (iii) the differential expression of the Helix pedal peptide (HPep) and the tetrapeptide FMRFamide genes in neural structures (Helix aspersa L.). Experiments were performed 13-42 hours after return to Earth. Latency of body re-orientation to sudden 90° head-down pitch was significantly reduced in postflight snails indicating an enhanced negative gravitaxis response. Statoreceptor responses to tilt in postflight snails were independent of motion direction, in contrast to a directional preference observed in control animals. Positive relation between tilt velocity and firing rate was observed in both control and postflight snails, but the response magnitude was significantly larger in postflight snails indicating an enhanced sensitivity to acceleration. A significant increase in mRNA expression of the gene encoding HPep, a peptide linked to ciliary beating, in statoreceptors was observed in postflight snails; no differential expression of the gene encoding FMRFamide, a possible neurotransmission modulator, was observed. CONCLUSIONS/SIGNIFICANCE Upregulation of statocyst function in snails following microgravity exposure parallels that observed in vertebrates suggesting fundamental principles underlie gravi-sensing and the organism's ability to adapt to gravity changes. This simple animal model offers the possibility to describe general subcellular mechanisms of nervous system's response to conditions on Earth and in space.
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Affiliation(s)
- Pavel M. Balaban
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Aleksey Y. Malyshev
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Victor N. Ierusalimsky
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Nikolay Aseyev
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Tania A. Korshunova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Natasha I. Bravarenko
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - M. S. Lemak
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Matvey Roshchin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Igor S. Zakharov
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - Yekaterina Popova
- NASA Ames Research Center, Moffett Field, California, United States of America
| | - Richard Boyle
- NASA Ames Research Center, Moffett Field, California, United States of America
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Abstract
Three days of training consisting of trials of light paired with rotation produces a long-term modification of photopositive behavior in Hermissenda crassicornis. The behavioral modification depends on the temporal association of light and rotation. For animals that received light paired with rotation, significant increases in the spontaneous activity of type B photoreceptors were correlated with changes in photopositive behavior after training. A persistent tonic depolarization of type B photoreceptors can explain the cellular changes correlated with the long-term behavioral modification produced by the temporal association of light and rotation.
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Crow T, Tian LM. Polysensory interneuronal projections to foot contractile pedal neurons in Hermissenda. J Neurophysiol 2009; 101:824-33. [PMID: 19073803 PMCID: PMC2657075 DOI: 10.1152/jn.91079.2008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Accepted: 12/01/2008] [Indexed: 11/22/2022] Open
Abstract
A Pavlovian-conditioning procedure may produce modifications in multiple behavioral responses. As an example, conditioning may result in the elicitation of a specific somatomotor conditioned response (CR) and, in addition, other motor and visceral CRs. In the mollusk Hermissenda conditioning produces two conditioned responses: foot-shortening and decreased locomotion. The neural circuitry supporting ciliary locomotion is well characterized, although the neural circuit underlying foot-shortening is poorly understood. Here we describe efferent neurons in the pedal ganglion that produce contraction or extension of specific regions of the foot in semi-intact preparations. Synaptic connections between polysensory type Ib and type Is interneurons and identified foot contractile efferent neurons were examined. Type Ib and type Is interneurons receive synaptic input from the visual, graviceptive, and somatosensory systems. Depolarization of type Ib interneurons evoked spikes in identified tail and lateral foot contractile efferent neurons. Mechanical displacement of the statocyst evoked complex excitatory postsynaptic potentials (EPSPs) and spikes recorded from type Ib and type Is interneurons and complex EPSPs and spikes in identified foot contractile efferent neurons. Depolarization of type Ib interneurons in semi-intact preparations produced contraction and shortening along the rostrocaudal axis of the foot. Depolarization of Is interneurons in semi-intact preparations produced contraction of the anterior region of the foot. Taken collectively, the results suggest that type Ib and type Is polysensory interneurons may contribute to the neural circuit underlying the foot-shortening CR in Hermissenda.
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Affiliation(s)
- Terry Crow
- Department of Neurobiology and Anatomy, University of Texas Medical School, 6431 Fannin Street, Houston, TX 77030, USA.
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Crow T, Tian LM. Pavlovian conditioning in Hermissenda: a circuit analysis. THE BIOLOGICAL BULLETIN 2006; 210:289-97. [PMID: 16801502 DOI: 10.2307/4134565] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
An understanding of associative learning requires (1) an adequate description of the experimental conditions under which learning is produced, (2) a knowledge of what is learned or the determination of the content of learning, and (3) an explanation of how learning generates changes in behavior (Rescorla, 1980). These basic issues are being addressed at both the behavioral and cellular/molecular levels by the analysis of associative learning in animals with relatively uncomplex nervous systems. Use of Pavlovian conditioning of invertebrates as a model for associative learning has led to the identification of cellular and synaptic mechanisms underlying the formation of basic associations. However, an understanding of the associative processes that form the basis for Pavlovian conditioning requires an explanation not only of the mechanisms of temporal contiguity or predictability between the conditioned stimulus (CS) and the unconditioned stimulus (US), but also of how changes produced in the nervous system by conditioning are expressed in behavior. Studies with invertebrates have provided the opportunity to examine how associative learning is expressed in the neural circuitry that supports the generation of learned behavior.
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Affiliation(s)
- Terry Crow
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas 77030, USA.
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6
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Crow T. Pavlovian conditioning of Hermissenda: current cellular, molecular, and circuit perspectives. Learn Mem 2004; 11:229-38. [PMID: 15169851 DOI: 10.1101/lm.70704] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The less-complex central nervous system of many invertebrates make them attractive for not only the molecular analysis of the associative learning and memory, but also in determining how neural circuits are modified by learning to generate changes in behavior. The nudibranch mollusk Hermissenda crassicornis is a preparation that has contributed to an understanding of cellular and molecular mechanisms of Pavlovian conditioning. Identified neurons in the conditioned stimulus (CS) pathway have been studied in detail using biophysical, biochemical, and molecular techniques. These studies have resulted in the identification and characterization of specific membrane conductances contributing to enhanced excitability and synaptic facilitation in the CS pathway of conditioned animals. Second-messenger systems activated by the CS and US have been examined, and proteins that are regulated by one-trial and multi-trial Pavlovian conditioning have been identified in the CS pathway. The recent progress that has been made in the identification of the neural circuitry supporting the unconditioned response (UR) and conditioned response (CR) now provides for the opportunity to understand how Pavlovian conditioning is expressed in behavior.
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Affiliation(s)
- Terry Crow
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas 77030, USA.
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7
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Crow T, Tian LM. Statocyst Hair Cell Activation of Identified Interneurons and Foot Contraction Motor Neurons in Hermissenda. J Neurophysiol 2004; 91:2874-83. [PMID: 14985407 DOI: 10.1152/jn.00028.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pavlovian conditioning of Hermissenda produces both light-elicited inhibition of normal positive phototactic behavior and conditioned stimulus (CS)-elicited foot-shortening. Rotation, the unconditioned stimulus (US) elicits foot-shortening and reduced forward ciliary locomotion. The neural circuit supporting ciliary locomotion and its modulation by light is known in some detail. However, the neural circuits responsible for rotation-elicited foot-shortening and reduced forward ciliary locomotion are not known. Here we describe components of the neural circuit in Hermissenda that produce anterior foot contraction and ciliary activation mediated by statocyst hair cells. We have characterized in semi-intact preparations newly identified pedal ventral contraction motor neurons (VCMNs) and interneurons (Ib). Type Ib interneurons receive polysynaptic input from statocyst hair cells and project directly to VCMNs and cilia-activating motor neurons. Depolarization of VCMNs with extrinsic current in normal artificial seawater (ASW) and high-divalent cation ASW, and under conditions where central synaptic transmission was suppressed with 5 mM Ni2+ ASW, elicited a contraction of the ipsilateral anterior foot measured from videotape recordings. Mechanical displacement of the statocyst or depolarization of identified statocyst hair cells with extrinsic current elicited spikes and complex excitatory postsynaptic potentials (EPSPs) in type Ib interneurons and complex EPSPs and spikes recorded in VCMNs. Type Ib interneurons are electrically coupled and project to VCMNs and VP1 cilia-activating motor neurons located in the contralateral pedal ganglia. The results indicate that statocyst hair-cell-mediated anterior foot contraction and graviceptive ciliary locomotion involve different interneuronal circuit components from the circuit previously identified as supporting light modulated ciliary locomotion.
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Affiliation(s)
- Terry Crow
- Department of Neurobiology and Anatomy, University of Texas Medical School, PO Box 20708, Houston, TX 77030, USA.
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Blackwell KT. Calcium waves and closure of potassium channels in response to GABA stimulation in Hermissenda type B photoreceptors. J Neurophysiol 2002; 87:776-92. [PMID: 11826046 DOI: 10.1152/jn.00867.2000] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Classical conditioning of Hermissenda crassicornis requires the paired presentation of a conditioned stimulus (light) and an unconditioned stimulus (turbulence). Light stimulation of photoreceptors leads to production of diacylglycerol, an activator of protein kinase C, and inositol triphosphate (IP(3)), which releases calcium from intracellular stores. Turbulence causes hair cells to release GABA onto the terminal branches of the type B photoreceptor. One prior study has shown that GABA stimulation produces a wave of calcium that propagates from the terminal branches to the soma and raises the possibility that two sources of calcium are required for memory storage. GABA stimulation also causes an inhibitory postsynaptic potential (IPSP) followed by a late depolarization and increase in input resistance, whose cause has not been identified. A model was developed of the effect of GABA stimulation on the Hermissenda type B photoreceptor to evaluate the currents underlying the late depolarization and to evaluate whether a calcium wave could propagate from the terminal branches to the soma. The model included GABA(A), GABA(B), and calcium-sensitive potassium leak channels; calcium dynamics including release of calcium from intracellular stores; and the biochemical reactions leading from GABA(B) receptor activation to IP(3) production. Simulations show that it is possible for a wave of calcium to propagate from the terminal branches to the soma. The wave is initiated by IP(3)-induced calcium release but propagation requires release through the ryanodine receptor channel where IP(3) concentration is small. Wave speed is proportional to peak calcium concentration at the crest of the wave, with a minimum speed of 9 microM/s in the absence of IP(3). Propagation ceases when peak concentration drops below 1.2 microM; this occurs if the rate of calcium pumping into the endoplasmic reticulum is too large. Simulations also show that both a late depolarization and an increase in input resistance occur after GABA stimulation. The duration of the late depolarization corresponds to the duration of potassium leak channel closure. Neither the late depolarization nor the increase in input resistance are observed when a transient calcium current and a hyperpolarization-activated current are added to the model as replacement for closure of potassium leak channels. Thus the late depolarization and input resistance elevation can be explained by a closure of calcium-sensitive leak potassium currents but cannot be explained by a transient calcium current and a hyperpolarization-activated current.
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MESH Headings
- Adenosine Triphosphatases/metabolism
- Animals
- Calcium Channels/physiology
- Calcium Signaling/physiology
- Conditioning, Classical/physiology
- Endoplasmic Reticulum, Smooth/metabolism
- Inositol 1,4,5-Trisphosphate Receptors
- Ion Channel Gating/drug effects
- Ion Channel Gating/physiology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Models, Molecular
- Mollusca
- Muscle Fibers, Skeletal/physiology
- Neural Inhibition/physiology
- Photoreceptor Cells, Invertebrate/physiology
- Potassium Channels/physiology
- Receptors, Cytoplasmic and Nuclear/physiology
- Receptors, GABA-A/physiology
- Receptors, GABA-B/physiology
- Ryanodine Receptor Calcium Release Channel/physiology
- gamma-Aminobutyric Acid/pharmacology
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Affiliation(s)
- K T Blackwell
- School of Computational Sciences and the Krasnow Institute for Advanced Study, George Mason University, MS 281, Fairfax, Virginia 22030, USA.
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9
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Chrachri A, Williamson R. Voltage-dependent conductances in cephalopod primary sensory hair cells. J Neurophysiol 1997; 78:3125-32. [PMID: 9405532 DOI: 10.1152/jn.1997.78.6.3125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cephalopods, such as sepia, squid, and octopus, show a well-developed and sophisticated control of balance particularly during prey capture and escape behaviors. There are two separate areas of sensory epithelium in cephalopod statocysts, a macula/statolith system, which detects linear accelerations (gravity), and a crista/cupula system, which detects rotational movements. The aim of this study is to characterize the ionic conductances in the basolateral membrane of primary sensory hair cells. These were studied using a whole cell patch-clamp technique, which allowed us to identify five ionic conductances in the isolated primary hair cells; an inward sodium current, an inward calcium current, and three potassium outward currents. These outward currents were distinguishable on the basis of their voltage-dependence and pharmacological sensitivities. First, a transient outward current (IA) was elicited by depolarizing voltage steps from a holding potential of -60 mV, was inactivated by holding the cell at -40 mV, and was blocked by 4-aminopyridine. A second, voltage-sensitive, outward current with a sustained time course was identified. This current was not blocked by 4-aminopyridine nor inactivated at a holding potential of -40 mV and hence could be separated from IA using these protocols. A third outward current that depended on Ca2+ entry for its activation was detected, this current was identified by its sensitivity to Ca2+ channel blockers such as Co2+ and Cd2+ and by the N-shaped profile of its current-voltage curve. Inward currents were studied using cesium aspartate solution in the pipette to block the outward currents. Two inward currents were observed in the primary sensory hair cells. A fast transient inward current, which is presumably responsible for spike generation. This inward current appeared as a rapidly activating inward current; this was strongly voltage dependent. Three lines of evidence suggest that this fast transient inward current is a Na+ current (INa). First, it was blocked by tetrodotoxin (TTX); second, it also was blocked by Na+-free saline; and third, it was inactivated when primary hair cells were held at a potential more than -40 mV. The sustained inward current was not affected by TTX and was increased in amplitude 5 min after equimolar Ba2+ replaced Ca2+ as a charge carrier. This inward current also was blocked after external application of 2 mmol/l Co2+ or Cd2+. Furthermore, this current was reduced significantly in a dose-dependent manner by nifedipine, suggesting that it is an L-type Ca2+ current (ICa).
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Affiliation(s)
- A Chrachri
- The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
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10
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Abstract
Apart from their primary function as balance sensors, Hermissenda hair cells are presynaptic neurons involved in the Ca(2+)-dependent neuronal plasticity in postsynaptic B photoreceptors that accompanies classical conditioning. With a view to beginning to understand presynaptic mechanisms of plasticity in the vestibulo-visual system, a locus for conditioning-induced neuronal plasticity, outward currents that may govern the excitability of hair cells were recorded by means of a whole-cell patch-clamp technique. Three K+ currents were characterized: a 4-aminopyridine-sensitive transient outward K+ current (IA), a tetraethyl ammonium-sensitive delayed rectifier K+ current (IK,V), and a Ca(2+)-activated K+ current (IK,Ca). IA activates and decays rapidly; the steady-state activation and inactivation curves of the current reveal a window current close to the apparent resting voltage of the hair cells, suggesting that the current is partially activated at rest. By modulating firing frequency and perhaps damping membrane oscillations, IA may regulate synaptic release at baseline. In contrast, IK,V and IK,Ca have slow onset and exhibit little or no inactivation. These two K+ currents may determine the duration of the repolarization phase of hair-cell action potentials and hence synaptic release via Ca2+ influx through voltage-gated Ca2+ channels. In addition, IK,Ca may be responsible for the afterhyperpolarization of hair cell membrane voltage following prolonged stimulation.
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Affiliation(s)
- E N Yamoah
- Department of Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.
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11
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Alkon DL, Anderson MJ, Kuzirian AJ, Rogers DF, Fass DM, Collin C, Nelson TJ, Kapetanovic IM, Matzel LD. GABA-mediated synaptic interaction between the visual and vestibular pathways of Hermissenda. J Neurochem 1993; 61:556-66. [PMID: 8336142 DOI: 10.1111/j.1471-4159.1993.tb02159.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The synaptic convergence of the eyes and the vestibular hair cells in the nudibranch mollusc Hermissenda has been shown previously to mediate the learning of simple visual-vestibular associations. The neurotransmitter mediating this interaction between the visual and vestibular organs was characterized. HPLC chromatography, confirmed by mass spectroscopic analysis, demonstrated endogenous GABA in the statocysts, in a concentration approximately 150 times greater than in the whole CNS. Additional confirmation was provided by immunocytochemical localization of GABA in hair cell axons and branches that converge with photoreceptor terminal branches. Depolarization of the hair cells in the caudal region of the statocyst in response to positive current injection or vibratory stimulation caused a hyperpolarization and a cessation of the type B photoreceptor impulse activity. The inhibition of the B cell was unaffected by addition to the artificial sea water bath of the adrenergic antagonist yohimbine (250 microM), the cholinergic antagonist atropine (250 microM), and the serotonergic antagonist imipramine (50 microM). In contrast, the GABAA antagonist bicuculline (250 microM) significantly reduced the inhibitory interaction. Moreover, the GABA reuptake inhibitor guvisine (250 microM) increased the hyperpolarization. Pressure microapplication of GABA (12.5 or 25 microM) onto the terminal branches of the B cell resulted in a concentration-dependent hyperpolarization and cessation of spikes in the B cell. Depolarization of the caudal hair cell, or direct GABA application, decreased input resistance across the B cell soma membrane. Moreover, removal of chloride from the extracellular solution reduced inhibition of the B cell induced by GABA application or hair cell stimulation. Furthermore, application of the GABAB agonist baclofen hyperpolarized the type B cell and reduced or eliminated spontaneous impulse activity at the resting membrane potential. The reversal potentials for inhibition induced in all three procedures ranged from -70 to -80 mV and were consistent with mixed Cl- and K+ conductances. These results implicate GABA as the endogenous neurotransmitter mediating visual-vestibular interactions in this animal, and suggest a possible role of GABA in visual-vestibular associative learning.
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Affiliation(s)
- D L Alkon
- Neural Systems Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
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12
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Hodgson TM, Crow T. Cellular correlates of classical conditioning in identified light responsive pedal neurons of Hermissenda crassicornis. Brain Res 1992; 570:267-71. [PMID: 1617416 DOI: 10.1016/0006-8993(92)90590-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cellular correlates of classical conditioning were examined in two recently identified light responsive pedal neurons. The correlates of conditioning consisted of significant decreases in the pedal cells' responses to light (conditioned stimulus) recorded from conditioned animals compared to random controls. Pedal cell P7, which exhibits an inhibitory response to light in naive animals, showed significantly less inhibition during a 5 min light step in conditioned animals as compared to random controls. Pedal neuron P9, which exhibits an excitatory response to light in naive animals, showed significantly less excitation during a 10 s light step in conditioned animals as compared to random controls. The changes in the response to light recorded from pedal neurons P7 and P9 in conditioned animals were not accompanied by any significant changes in membrane potential, action potential amplitude or dark-adapted spike frequency.
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Affiliation(s)
- T M Hodgson
- Department of Neurobiology and Anatomy, University of Texas, School of Medicine, Houston 77225
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13
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Hodgson TM, Crow T. Characterization of 4 light-responsive putative motor neurons in the pedal ganglia of Hermissenda crassicornis. Brain Res 1991; 557:255-64. [PMID: 1747756 DOI: 10.1016/0006-8993(91)90142-i] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
As part of the analysis of the circuitry underlying phototaxis, 4 light-responsive pedal neurons were identified and characterized. The 4 newly identified neurons have been designated as pedal neurons P7, P8, P9 and P10. Pedal cell P7 has an inhibitory response to light, lasting several minutes. Pedal cells P8, P9 and P10 exhibit excitatory 'on' responses to light that last for a few seconds after light onset. Lucifer yellow fills showed that each identified pedal cell has only one process which exits the nervous system through one of the pedal nerves. Various procedures were used to investigate the responses to illumination expressed by the 4 identified pedal neurons. The results indicate that: (1) the light responses are not intrinsic, but are due to synaptic input from other light-responsive cell(s), and (2) the sources of the synaptic input to the pedal cells are the photoreceptors of the eye, and not extraocular photoreceptors or light sensitive neurons within the circumesophageal nervous system.
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Affiliation(s)
- T M Hodgson
- Department of Physiology, School of Medicine, University of Pittsburgh, PA 15261
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14
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Richards WG, Farley J. Motor correlates of phototaxis and associative learning in Hermissenda crassicornis. Brain Res Bull 1987; 19:175-89. [PMID: 3664278 DOI: 10.1016/0361-9230(87)90083-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Motor correlates of Hermissenda phototactic behavior and their modification by associative training were examined. Anatomical studies indicated the posterior three-fourths of the foot to be innervated by nerve P1 while the anterior portion was innervated by nerve P2. Bilateral lesions of either P1 or P2 pedal nerves in untrained animals reduced phototactic behavior. Extracellular recordings of pedal nerves from untrained animals revealed significant increases in total multi-unit activity (MUA) during a light presentation. Prominent components of nerve P2 activity were synchronous bursts apparent in peri-stimulus time (PST) histograms. Burst frequency was increased by light. Associative training resulted in significant decreases in light-evoked MUA frequency in P1 and light-evoked burst frequency in P2. Intracellular recordings were obtained from three classes of putative motoneurons with axons in P2. These were located using cobalt backfills and verified for each preparation by simultaneous extracellular recording from P2. The characteristic pattern of activity of these cells in the dark and its modulation by light was established.
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Affiliation(s)
- W G Richards
- Department of Psychology, Princeton University, NJ 08544
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15
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Doroshenko PA, Zhadan PM. Role of calcium ions in response generation by the scallop abdominal sensory organ. NEUROPHYSIOLOGY+ 1985. [DOI: 10.1007/bf01053491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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An electrophysiological study of the mechanoreceptory function of abdominal sense organ of the scallop Patinopecten yessoensis (JAY). ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0300-9629(84)90647-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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17
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Grossman Y, Alkon DL. Voltage noise power spectra reflect ciliary movement frequencies in statocyst hair cells. Neurosci Lett 1982; 31:135-40. [PMID: 7133549 DOI: 10.1016/0304-3940(82)90105-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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18
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Kuzirian AM, Alkon DL, Harris LG. An infraciliary network in statocyst hair cells. JOURNAL OF NEUROCYTOLOGY 1981; 10:497-514. [PMID: 7310462 DOI: 10.1007/bf01262418] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ultrastructural analysis of the statocyst, a primitive vestibular organ, of the nudibranch mollusc Hermissenda crassicornis, indicates that in addition to the basal foot, there is an infraciliary rootlet system between basal bodies of adjacent sensory cilia. These rootlets project perpendicularly from the basal bodies and parallel to the cell surface in an astral array. A polarity within the network also appears to exist; the array is longest and most extensive on the side of the basal body directed away from the cell centre, but the overall arrangement of the basal bodies indicates a multidirectional sensitivity for each of the 13 sensory cells. This rootlet system, in conjunction with the attachment system of the basal bodies to the cell membrane (button anchors), may serve an integrative function for the mechanical stimuli experienced by sensory cells and/or be involved with their transductive processes by maximizing the stress to, and membrane distortion of, the transductive site caused by weighting of the cilia. Evidence was also obtained for the intracellular synthesis of statoconia by the nonsensory supporting cells.
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Stommel EW, Stephens RE, Alkon DL. Motile statocyst cilia transmit rather than directly transduce mechanical stimuli. J Biophys Biochem Cytol 1980; 87:652-62. [PMID: 7462319 PMCID: PMC2110788 DOI: 10.1083/jcb.87.3.652] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We have investigated the role of motile cilia in mechanotransduction by statocysts of the nudibranch mollusk Hermissenda crassicornis. Movement of the cilia that experience the weight of statoconia causes increased variance of voltage noise and membrane depolarization of the statocyst hair cell. Two complementary approaches were used to immobilize the cilia. Vanadate anion was iontophoretically injected into hair cells. This reversible inhibitor of vibratile form and to assume a more classic, pliable beat pattern. Voltage noise decreased as the cilia slowed and bent more extremely, nearly disappearing as motility was lost. When the intracellular vanadate concentration approached 10(-5) M, the cilia were arrested in an effective stroke against the cell membrane. The cell no longer depolarized upon gravitational or local mechanical stimulation. Rapid reversal of ciliary inhibition by norepinephrine or slow reversal with time restored both the voltage noise and depolarization response. Cilia were rendered rigid and upright by covalent cross-linkage of their membrane "sleeve" to the 9 + 2 axoneme, using the photoactivated, lipophilic, bifunctional agent 4,4'-dithiobisphenyl azide. In the initial stages of cross-linkage, the cilia remained vibratile but slowed and moved through wider excursions. Voltage noise decreased in frequency but increased in amplitude. When the cilia were fully arrested, voltage noise was minimized while the resting potential and membrane resistance remained essentially constant. Mechanical stimulation of the rigid cilia, normal to the cell membrane, elicited a generator potential of the same amplitude but of greater duration than before treatment. Because cilia that are partially arrested by vanadate undergo increased bending, although the hair cell shows decreased noise, neither the axoneme nor the ciliary membrane proper would appear to be sites of direct transduction. In cells with beating but stiffened cilia, however, the voltage noise becomes amplified, implying an increased efficiency of transduction. We suggest that active but rigid flexure of the axoneme is involved in amplification and continuous signal detection. The basal insertion area is the most likely transduction site, being the terminal leverage point through which force is applied to the plasma membrane via the flexing ciliary shaft.
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Crow T, Harrigan JF. Reduced behavioral variability in laboratory-reared Hermissenda crassicornis (Eschscholtz, 1831) (Opisthobranchia: nudibranchia). Brain Res 1979; 173:179-84. [PMID: 487082 DOI: 10.1016/0006-8993(79)91110-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Grossman Y, Alkon DL, Heldman E. A common origin of voltage noise and generator potentials in statocyst hair cells. J Gen Physiol 1979; 73:23-48. [PMID: 438764 PMCID: PMC2215231 DOI: 10.1085/jgp.73.1.23] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage noise, generator potentials, and hair movements in the Hermissenda statocyst were analyzed. Motile hairs on the cyst's luminal surface moved as rods through +/- 10 degrees Hz when free and at 7 Hz when loaded with the weight of the statoconia (at 120 degrees C). For hair cells oriented opposite to a centrifugal force vector, rotation caused depolarization and increase of voltage noise variance. The depolarizing generator potential and the increase in voltage noise variance were similarly reduced by perfusion with zero external sodium or chloral hydrate. Cooling, perfusion with zero external sodium or chloral hydrate reduced the movement frequencies of the hairs but increased their range of motion. The same treatments reduced voltage noise variance and increased input resistance of the hair cell membrane. The results indicate that voltage noise and hair cell generator potential have a common origin: exertion of force on statocyst hairs by the weight of statoconia. The collision of statoconia with the motile hairs, not the hairs' bending, produces most of the voltage noise.
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Abstract
The nudibranch mollusk Hermissenda crassicornis is normally attracted to a test light. Three days of training consisting of 50 trials per day of light paired with a rotational stimulus led to a significant increase, lasting for days, in the animal's response latency to enter a test light. The group that received light associated with rotation was significantly different from groups subjected to nonassociative control procedures. Modifications of well-known sensory networks may be related to a behavioral change that shares several operational features with associative learning.
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Alkon DL, Akaike T, Harrigan J. Interaction of chemosensory, visual, and statocyst pathways in Hermissenda crassicornis. J Gen Physiol 1978; 71:177-94. [PMID: 641519 PMCID: PMC2215704 DOI: 10.1085/jgp.71.2.177] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Neurons in the cerebropleural ganglia (CPG), photoreceptors in the eye, optic ganglion cells, and statocyst hair cells of the nudibranch mollusk Hermissenda crassicornis responded in specific ways, as recorded intracellularly, to stimulation of the chemosensory pathway originating at the tentacular chemoreceptors as well as to stimulation of the visual pathway originating at the photoreceptors. Synaptic inhibition of photoreceptors occurs via the chemosensory pathway. The possible significance of such intersensory interaction is discussed with reference to preliminary investigation of the animal's gustatory behavior and possible neural mechanisms of behavioral choice.
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Abstract
1. The electrical responses of Aplysia statocyst receptor cells were investigated using intracellular micro-electrodes. These ciliated mechanoreceptor cells were stimulated by downward tilting about a horizontal axis. 2. Tilting so that the receptor cell was excited produced a depolarizing receptor potential which, if large enough, could generate action potentials. 3. Large fluctuations in membrane potential were evident during depolarizing receptor potentials and were reduced or sometimes absent when a cell was tilted upward. Power-density spectra of the noise voltage revealed that most of the energy added by downward tilt is contained in frequency components below 3 Hz. 4. Removing synaptic input to the receptor cells by cutting the statocyst nerve or adding excess Mg2+ to the bath did not abolish the increase in fluctuations caused by downward, excitatory tilts. 5. The depolarizing receptor potential was often associated with a decrease in membrane resistance as measured with constant current pulses using a bridge circuit. 6. Replacing most of the Na+ in the bath with either Tris or Mg2+ abolished both potential and resistance changes caused by downward tilt. These results indicate that an increased permeability to Na+ underlies the receptor potential.
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Abstract
Rotation of the isolated nervous system of Hermissenda in a caudal orientation causes a synaptic hyperpolarization accompanied by elimination of impulse activity during the steady-state phase of type A but not type B photoreceptors' responses to light. Rotation of the isolated nervous system in a cephalic orientation causes a synaptic depolarization with increase of impulse activity during the steady-state phase of both type A and type B photoreceptors' responses to light. These effects of rotation on photorecptors are explained by known synaptic interactions. Sufficient redundancy is found to be provided by the neural organization of the visual system and its interaction with the statocyst to preserve much of the visual information in spite of signal transformation in specific photorecptors resulting from pairing of rotation with light.
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Abstract
A new technique is described for stimulating hair cells of the Hermissenda statocyst. The preparation and recording apparatus can be rotated at up to 78 rpm while recording intracellular potentials. Hair cells in front of the centrifugal force vector depolarize in response to rotation. Hair cells in back of the centrifugal force vector hypoerpolarize in response to rotation. Mechanisms by which the hair cell generator potential might arise are examined.
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Abstract
Responses to mechanical stimulation were recorded from hair cells in the statocyst of Hermissenda crassicornis. The response to a brief stimulus is a depolarizing wave which reaches peak in about 25 msec and decays slowly. 2. Hyperpolarization by extrinsic currents increases the amplitude of the response; depolarization decreases it and eventually reverses its polarity. It is inferred from these results that the primary outcome of the transduction process is an increase of membrane conductance and that the voltage change (generator potential) follows as a secondary event. 3. The features of the conductance change were reconstructed from the time course of the generator potential and the passive properties of the membrane. It was found that the increase of membrane conductance develops slowly and is roughly proportional to the energy delivered by the stimulus. 4. The time course of the conductance change required to reproduce the generator potential is similar to the output of a model involving a sequence of transformations. 5. The generator potential is sensitive to temperature, becoming faster as temperature is raised. This effect is reproduced by the model if the transition rates are assumed to be temperature-dependent, with a Q10 of about 2. 6. It is concluded that a chain of temperature-sensitive processes is interposed between the stimulus and the increase of membrane conductance.
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Abstract
Type A photorecptors can produce an initial hyperpolarizing wave followed by a delayed long-lasting increase in firing which is usually accompanied by a small depolarizing wave. The initial hyperpolarizing wave arises from an increase in conductance while the depolarizing wave was shown to arise from a decrease in conductance. The data presented indicate that both effects produced by the type A photoreceptors in ipsilateral hair cells are synaptic.
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Abstract
Hair cells in Hermissenda respond to illumination of the ipsilateral and contralateral eyes. These responses are modified by associative training of the animal. The observed electrophysiological changes appear to result from changes in the photoreceptors' synaptic input to the hair cells.
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Abstract
Reflex behavior of Hermissenda in response to visual and rotational stimuli is described. It is shown that repeated association of light with rotation modifies the subsequent responses of the animals to light. This modification does not occur after the same period of light or rotation alone. The effect of the associative training is strongly dependent on the amount of daily light with which the animals are maintained.
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The Perception of Gravity and of Angular Acceleration in Invertebrates. HANDBOOK OF SENSORY PHYSIOLOGY 1974. [DOI: 10.1007/978-3-642-65942-3_2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Peretz B, Moller R. Control of habituation of the withdrawal reflex by the gill ganglion in Aplysia. JOURNAL OF NEUROBIOLOGY 1974; 5:191-212. [PMID: 4835399 DOI: 10.1002/neu.480050303] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
Hair cells in the statocyst of Hermissenda crassicornis respond to mechanical stimulation with a short latency (<2 ms) depolarizing generator potential that is followed by hyperpolarization and inhibition of spike activity. Mechanically evoked hyperpolarization and spike inhibition were abolished by cutting the static nerve, repetitive mechanical stimulation, tetrodotoxin (TTX), and Co(++). Since none of these procedures markedly altered the generator potential it was concluded that the hyperpolarization is an inhibitory synaptic potential and not a component of the mechanotransduction process. Intracellular recordings from pairs of hair cells in the same statocyst and in statocysts on opposite sides of the brain revealed that hair cells are connected by chemical and/or electrical synapses. All chemical interactions were inhibitory. Hyperpolarization and spike inhibition result from inhibitory interactions between hair cells in the same and in opposite statocysts.
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Abstract
Hair cells of the Hermissenda statocyst respond to photic stimulation. This response requires the presence of at least one of the two eyes. Two principal hair cell responses to light were observed. The activity of photoreceptors in response to a light step is interrupted during firing of contralateral hair cells. The intersensory interactions between the statocyst and visual pathway underlying these responses were examined with simultaneous intracellular recordings. Evidence is presented that the statocyst of Hermissenda is an important channel for visual information.
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