scholarly journals Network interneurons underlying ciliary locomotion in Hermissenda

2013 ◽  
Vol 109 (3) ◽  
pp. 640-648 ◽  
Author(s):  
Terry Crow ◽  
Nan Ge Jin ◽  
Lian-Ming Tian
Keyword(s):  
Spike Activity ◽  
Excitatory Postsynaptic Potential ◽  
Type I ◽  
Type Ii ◽  
Visually Guided ◽  
Monosynaptic Connection ◽  
Postsynaptic Potential ◽  
The Neural Network ◽  
Efferent Neurons ◽  
Ciliary Locomotion

In the nudibranch mollusk Hermissenda, ciliary locomotion contributes to the generation of two tactic behaviors. Light elicits a positive phototaxis, and graviceptive stimulation evokes a negative gravitaxis. Two classes of light-responsive premotor interneurons in the network contributing to ciliary locomotion have been recently identified in the cerebropleural ganglia. Aggregates of type I interneurons receive monosynaptic excitatory (Ie) or inhibitory (Ii) input from identified photoreceptors. Type II interneurons receive polysynaptic excitatory (IIe) or inhibitory (IIi) input from photoreceptors. The ciliary network also includes type III inhibitory (IIIi) interneurons, which form monosynaptic inhibitory connections with ciliary efferent neurons (CENs). Illumination of the eyes evokes a complex inhibitory postsynaptic potential, a decrease of Ii spike activity, a complex excitatory postsynaptic potential, and an increase of Ie spike activity. Here, we characterized the contribution of identified I, II, and IIIi interneurons to the neural network supporting visually guided locomotion. In dark-adapted preparations, light elicited an increase in the tonic spike activity of IIe interneurons and a decrease in the tonic spike activity of IIi interneurons. Fluorescent dye-labeled type II interneurons exhibited diverse projections within the circumesophageal nervous system. However, a subclass of type II interneurons, IIe(cp) and IIi(cp) interneurons, were shown to terminate within the ipsilateral cerebropleural ganglia and indirectly modulate the activity of CENs. Type II interneurons form monosynaptic or polysynaptic connections with previously identified components of the ciliary network. The identification of a monosynaptic connection between Ie and IIIi interneurons shown here suggest that they provide a major role in the light-dependent modulation of CEN spike activity underlying ciliary locomotion.

scholarly journals Sensory Regulation of Network Components Underlying Ciliary Locomotion in Hermissenda

2008 ◽  
Vol 100 (5) ◽  
pp. 2496-2506 ◽  
Author(s):  
Terry Crow ◽  
Lian-Ming Tian
Keyword(s):  
Neural Network ◽  
Spike Activity ◽  
Electrical Coupling ◽  
Rhythmic Activity ◽  
Burst Activity ◽  
Type I ◽  
Sensory Regulation ◽  
The Neural Network ◽  
Efferent Neurons ◽  
Ciliary Locomotion

Ciliary locomotion in the nudibranch mollusk Hermissenda is modulated by the visual and graviceptive systems. Components of the neural network mediating ciliary locomotion have been identified including aggregates of polysensory interneurons that receive monosynaptic input from identified photoreceptors and efferent neurons that activate cilia. Illumination produces an inhibition of type Ii (off-cell) spike activity, excitation of type Ie (on-cell) spike activity, decreased spike activity in type IIIi inhibitory interneurons, and increased spike activity of ciliary efferent neurons. Here we show that pairs of type Ii interneurons and pairs of type Ie interneurons are electrically coupled. Neither electrical coupling or synaptic connections were observed between Ie and Ii interneurons. Coupling is effective in synchronizing dark-adapted spontaneous firing between pairs of Ie and pairs of Ii interneurons. Out-of-phase burst activity, occasionally observed in dark-adapted and light-adapted pairs of Ie and Ii interneurons, suggests that they receive synaptic input from a common presynaptic source or sources. Rhythmic activity is typically not a characteristic of dark-adapted, light-adapted, or light-evoked firing of type I interneurons. However, burst activity in Ie and Ii interneurons may be elicited by electrical stimulation of pedal nerves or generated at the offset of light. Our results indicate that type I interneurons can support the generation of both rhythmic activity and changes in tonic firing depending on sensory input. This suggests that the neural network supporting ciliary locomotion may be multifunctional. However, consistent with the nonmuscular and nonrhythmic characteristics of visually modulated ciliary locomotion, type I interneurons exhibit changes in tonic activity evoked by illumination.

Synchrony in Excitatory Neural Networks

1995 ◽  
Vol 7 (2) ◽  
pp. 307-337 ◽  
Author(s):  
D. Hansel ◽  
G. Mato ◽  
C. Meunier
Keyword(s):  
Time Course ◽  
Partial Coherence ◽  
Excitatory Postsynaptic Potential ◽  
Type I ◽  
Type Ii ◽  
Large Coupling ◽  
Postsynaptic Potential ◽  
Synaptic Interactions ◽  
Fully Connected ◽  
Fully Connected Networks

Synchronization properties of fully connected networks of identical oscillatory neurons are studied, assuming purely excitatory interactions. We analyze their dependence on the time course of the synaptic interaction and on the response of the neurons to small depolarizations. Two types of responses are distinguished. In the first type, neurons always respond to small depolarization by advancing the next spike. In the second type, an excitatory postsynaptic potential (EPSP) received after the refractory period delays the firing of the next spike, while an EPSP received at a later time advances the firing. For these two types of responses we derive general conditions under which excitation destabilizes in-phase synchrony. We show that excitation is generally desynchronizing for neurons with a response of type I but can be synchronizing for responses of type II when the synaptic interactions are fast. These results are illustrated on three models of neurons: the Lapicque integrate-and-fire model, the model of Connor et al., and the Hodgkin-Huxley model. The latter exhibits a type II response, at variance with the first two models, that have type I responses. We then examine the consequences of these results for large networks, focusing on the states of partial coherence that emerge. Finally, we study the Lapicque model and the model of Connor et al. at large coupling and show that excitation can be desynchronizing even beyond the weak coupling regime.

scholarly journals Axodendritic versus axosomatic cochlear efferent termination is determined by afferent type in a hierarchical logic of circuit formation

2021 ◽  
Vol 7 (4) ◽  
pp. eabd8637
Author(s):  
Jemma L. Webber ◽  
John C. Clancy ◽  
Yingjie Zhou ◽  
Natalia Yraola ◽  
Kazuaki Homma ◽  
...  
Keyword(s):  
Hair Cells ◽  
Fiber Type ◽  
Afferent Fiber ◽  
Outer Hair Cells ◽  
Type I ◽  
Type Ii ◽  
Efferent Neurons ◽  
Distinct Pair ◽  
Mechanosensory Hair Cells ◽  
Circuit Formation

Hearing involves a stereotyped neural network communicating cochlea and brain. How this sensorineural circuit assembles is largely unknown. The cochlea houses two types of mechanosensory hair cells differing in function (sound transmission versus amplification) and location (inner versus outer compartments). Inner (IHCs) and outer hair cells (OHCs) are each innervated by a distinct pair of afferent and efferent neurons: IHCs are contacted by type I afferents receiving axodendritic efferent contacts; OHCs are contacted by type II afferents and axosomatically terminating efferents. Using an Insm1 mouse mutant with IHCs in the position of OHCs, we discover a hierarchical sequence of instructions in which first IHCs attract, and OHCs repel, type I afferents; second, type II afferents innervate hair cells not contacted by type I afferents; and last, afferent fiber type determines if and how efferents innervate, whether axodendritically on the afferent, axosomatically on the hair cell, or not at all.

Effect of Bone Marrow Stromal Stem Cells (BMSCs) Therapy on the Expression of Sodium Channel, Voltage-Gated, Type I, Alpha Subunit (SCN1A) in Temporal Lobe Epilepsy and Its Mechanism

2021 ◽  
Vol 11 (8) ◽  
pp. 1565-1570
Author(s):  
Gaolin Wang ◽  
Bo Sun ◽  
Xiangpeng Meng ◽  
Bin Ge
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Incubation Period ◽  
Control Group ◽  
Excitatory Postsynaptic Potential ◽  
Type I ◽  
Group Model ◽  
Model Group ◽  
Postsynaptic Potential ◽  
Stromal Stem Cells

SCN1A gene plays an indispensable role in several diseases. Bone marrow stromal stem cells (BMSCs) therapy is a potential target for treating epilepsy, but its therapeutic effect and mechanism is unclear. Our study aims to investigate the mechanism by how BMSCs affect epilepsy. Wistar rats were assigned into control group, model group (pilocarpine-induced TLE model), and BMSCs group followed by measuring the latency of field excitatory postsynaptic potential, pathological changes, SCN1A level by Real time PCR, NF-ĸB and TLR4 expression by Western blot, and HGMB1, TLR4, IL-1β and IL-6 secretion by ELISA. In model group, the incubation period of postsynaptic potential generation was significantly shortened and SCN1A level was significantly decreased, along with increased NF-ĸB expression and secretion of HMGB1, TLR-4, IL-1β and IL-6 (P < 0.05). After BMSCs treatment, the incubation period of postsynaptic potentials can be significantly prolonged and SCN1A was significantly upregulated, with ameliorated epilepsy injury and reduced secretion of related factors (P <0.05). Pilocarpine-induced TLE can reduce SCN1A expression and BMSCs therapy can up-regulate SCN1A expression by regulating NF-ĸB/HGMB1/TLR4 signaling pathway, thereby protecting neurons, reducing pathological damage, and ameliorating the development of epilepsy.

Interneuronal Projections to Identified Cilia-Activating Pedal Neurons in Hermissenda

2003 ◽  
Vol 89 (5) ◽  
pp. 2420-2429 ◽  
Author(s):  
Terry Crow ◽  
Lian-Ming Tian
Keyword(s):  
Synaptic Input ◽  
Visual Processing ◽  
Inhibitory Interneuron ◽  
Type I ◽  
Type Ii ◽  
Synaptic Organization ◽  
Ciliary Movement ◽  
The Neural Network ◽  
Excitatory Synaptic Input

Neural networks have been shown to support the generation of more than one behavioral motor act. In the nudibranch mollusk Hermissenda, Pavlovian conditioning results in light, the conditioned stimulus (CS), evoking both inhibition of locomotion and foot contraction. The synaptic organization of the eyes and optic ganglion is well documented; however, the characterization of the neural network mediating visually modulated behaviors is incomplete. We have now characterized synaptic connections between identified photoreceptors and a newly identified interneuron (IIb), identified synaptic projections from type I and type II interneurons to an inhibitory interneuron (IIIi) and to two newly identified pedal neurons, VP1 and VP2. Here we show that VP1 activates ciliary movement on the anterior foot and VP2 innervates the anterior foot and ventral tentacle. Stimulation of the photoreceptors with light produced two effects on the activity of VP1 and VP2. First, light inhibits type Ii and IIi interneurons and disinhibits VP1 and VP2. Depolarization of type IIe interneurons also disinhibits VP1 and VP2. Second, the light-elicited depolarization and increased tonic activity of VP1 and VP2 is produced by excitatory synaptic input from ipsilateral and contralateral type IIbinterneurons. Pedal neurons VP1 and VP2 receive similar synaptic input from type I, II, and IIIi interneurons; this is in agreement with previous research showing that the visual pathway influences both ciliary locomotion and foot movement. The organization of the visual system in Hermissenda provides for the expression of cellular and synaptic plasticity supporting learning without altering the networks ability to carry out the requirements for normal visual processing.

scholarly journals Efferent synaptic transmission at the vestibular type II hair cell synapse

2020 ◽  
Vol 124 (2) ◽  
pp. 360-374 ◽  
Author(s):  
Zhou Yu ◽  
J. Michael McIntosh ◽  
Soroush G. Sadeghi ◽  
Elisabeth Glowatzki
Keyword(s):  
Hair Cells ◽  
Nerve Fibers ◽  
Type I ◽  
Type Ii ◽  
Vestibular Hair Cells ◽  
Efferent Neurons ◽  
The Brain ◽  
Cell Synapse ◽  
Stimulation Of

Type II vestibular hair cells (HCs) receive inputs from efferent neurons in the brain stem. We used in vitro optogenetic and electrical stimulation of vestibular efferent fibers to study their synaptic inputs to type II HCs. Stimulation of efferents inhibited type II HCs, similar to efferent effects on cochlear HCs. We propose that efferent inputs adjust the contribution of signals from type I and II HCs to vestibular nerve fibers.

Physiology of electrosensory lateral line lobe neurons in Gnathonemus petersii

1999 ◽  
Vol 202 (10) ◽  
pp. 1301-1309 ◽  
Author(s):  
Y. Sugawara ◽  
K. Grant ◽  
V. Han ◽  
C.C. Bell
Keyword(s):  
Lateral Line ◽  
Sensory Input ◽  
Parallel Fiber ◽  
Projection Neurons ◽  
Excitatory Postsynaptic Potential ◽  
Efferent Neuron ◽  
Parallel Fibers ◽  
Postsynaptic Potential ◽  
Efferent Neurons

In mormyrid electric fish, sensory signals from electroreceptors are relayed to secondary sensory neurons in a cerebellum-like structure known as the electrosensory lateral line lobe (ELL). Efferent neurons and interneurons of the ELL also receive inputs of central origin, including electric organ corollary discharge signals, via parallel fibers and via fibers from the juxtalobar nucleus. To understand the cellular mechanisms of the integration of sensory inputs and central inputs in the ELL, the intracellular activity and ionic properties of the efferent projection neurons and interneurons were examined in an in vitro slice preparation.We focus here on the electrophysiological properties of the efferent neurons of the ELL network, the large fusiform cells and large ganglion cells, and on a class of gamma-aminobutyric acid (GABA)-ergic interneurons known as medium ganglion (MG) cells. In response to current injection through a recording pipette, both types of efferent neuron fire a large narrow spike followed by a large hyperpolarizing afterpotential. The MG cells fire a complex spike which consists of small narrow spikes and a large broad spike. Although the forms of the action potentials in efferent neurons and in MG cells are different, all spikes are mediated by tetrodotoxin (TTX)-sensitive Na+ conductances and spike repolarization is mediated by tetraethylammonium (TEA+)-sensitive K+ conductances. In the presence of TEA+, substitution of Ba2+ for Ca2+ in the bath revealed the presence of a high-voltage-activated Ca2+ conductance.Stimulation of parallel fibers conveying descending input to the ELL molecular layer in vitro evokes an excitatory postsynaptic potential (EPSP), generally followed by an inhibitory postsynaptic potential (IPSP), in the efferent neurons. In MG cells, the same stimulation evokes an EPSP, often followed by a small IPSP. Synaptic transmission at parallel fiber synapses is glutamatergic and is mediated via both N-methyl-d-aspartate (NMDA)- and (AMPA)-type glutamate receptors. The inhibitory component of the parallel fiber response is GABAergic. It is probably mediated via the stellate neurons and the MG cells, which are themselves GABAergic interneurons intrinsic to the ELL network.A hypothetical neural circuit of the intrinsic connections of the ELL, based on the known morphology of projection neurons and medium ganglion interneurons, is presented. This circuit includes an excitatory and an inhibitory submodule. The excitatory submodule is centered on a large fusiform cell and appears to relay the sensory input as a positive ‘ON’ image of an object. The inhibitory submodule is centered on a large ganglion cell and relays a negative ‘OFF’ image to the next higher level. We suggest that MG cells exert an inhibitory bias on efferent neuron types and that the ELL network output is modulated by the dynamically plastic integration of central descending signals with sensory input.

scholarly journals Polysensory Interneuronal Projections to Foot Contractile Pedal Neurons in Hermissenda

2009 ◽  
Vol 101 (2) ◽  
pp. 824-833 ◽  
Author(s):  
Terry Crow ◽  
Lian-Ming Tian
Keyword(s):  
Neural Circuit ◽  
Behavioral Responses ◽  
Neural Circuitry ◽  
Type I ◽  
Synaptic Connections ◽  
Pedal Ganglion ◽  
Conditioning Procedure ◽  
Efferent Neurons ◽  
Conditioned Responses ◽  
Ciliary Locomotion

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.

Heat-Etching with a Bullivant Type II Simple Freeze-Cleave Device

1970 ◽  
Vol 28 ◽  
pp. 106-107 ◽  
Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt
Keyword(s):  
New Zealand ◽  
General Hospital ◽  
Massachusetts General Hospital ◽  
Type I ◽  
Type Ii ◽  
Collaborative Effort ◽  
Temperature And Pressure ◽  
The University

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.

Labelling of non-A, non-B hepatitis infected chimpanzee hepatocytes with nuclease-gold conjugates

1984 ◽  
Vol 42 ◽  
pp. 250-251
Author(s):  
G. D. Gagne ◽  
M. F. Miller ◽  
D. A. Peterson
Keyword(s):  
Endoplasmic Reticulum ◽  
Experimental Infection ◽  
Uranyl Acetate ◽  
Type I ◽  
Cellular Injury ◽  
Type Ii ◽  
Tubular Structures ◽  
Type Iii ◽  
Type Iv ◽  
Infected Chimpanzee

Experimental infection of chimpanzees with non-A, non-B hepatitis (NANB) or with delta agent hepatitis results in the appearance of characteristic cytoplasmic alterations in the hepatocytes. These alterations include spongelike inclusions (Type I), attached convoluted membranes (Type II), tubular structures (Type III), and microtubular aggregates (Type IV) (Fig. 1). Type I, II and III structures are, by association, believed to be derived from endoplasmic reticulum and may be morphogenetically related. Type IV structures are generally observed free in the cytoplasm but sometimes in the vicinity of type III structures. It is not known whether these structures are somehow involved in the replication and/or assembly of the putative NANB virus or whether they are simply nonspecific responses to cellular injury. When treated with uranyl acetate, type I, II and III structures stain intensely as if they might contain nucleic acids. If these structures do correspond to intermediates in the replication of a virus, one might expect them to contain DNA or RNA and the present study was undertaken to explore this possibility.

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