Morphological Characteristics and Central Projections of Two Types of Interneurons in the Visual Pathway of Hermissenda

2002 ◽  
Vol 87 (1) ◽  
pp. 322-332 ◽  
Author(s):  
Terry Crow ◽  
Lian-Ming Tian
Keyword(s):  
Motor Neurons ◽  
Synaptic Input ◽  
Morphological Characteristics ◽  
Excitatory Input ◽  
Higher Order ◽  
Inhibitory Input ◽  
Type I ◽  
Type Ii ◽  
Central Projections ◽  
Inhibitory Synaptic Input

The synaptic interactions between photoreceptors in the eye and second-order neurons in the optic ganglion of the nudibranch mollusk Hermissenda are well characterized. However, the higher-order neural circuitry of the visual system, consisting of cerebropleural interneurons that receive synaptic input from photoreceptors and project to pedal motor neurons that mediate visually guided behaviors, is only partially understood. In this report we have examined the central projections of two identified classes of cerebropleural interneurons that receive excitatory or inhibitory synaptic input from identified photoreceptors. The classification of the interneurons was based on both morphological and electrophysiological criteria. Type I interneurons received monosynaptic excitatory or inhibitory synaptic input from identified photoreceptors and projected to postsynaptic targets within the cerebropleural ganglion. Type II interneurons, characterized here for the first time, received polysynaptic excitatory or inhibitory synaptic input from identified photoreceptors and projected to postsynaptic targets in either the ipsilateral pedal ganglion or the contralateral cerebropleural ganglion. Type I interneurons exhibited unique intraganglionic projections to different regions of the cerebropleural ganglion, depending on whether they received excitatory or inhibitory synaptic input from identified photoreceptors. Type I interneurons that received monosynaptic excitatory input from identified B photoreceptors terminated near the cerebropleural commissure and had multiple regions of varicosities located at branches that projected from the primary axon. Type I interneurons that received monosynaptic inhibitory input from identified B photoreceptors projected to the anterior cerebropleural ganglion and exhibited varicosities localized to the terminal region of the primary axonal process. Type II interneurons that received polysynaptic inhibitory input from identified photoreceptors projected to the contralateral cerebropleural ganglion. Most type II interneurons that projected to the pedal ganglia received polysynaptic excitatory input from identified photoreceptors. These results indicate that there is at least one additional interneuron in the higher-order visual circuit between type I interneurons and pedal motor neurons responsible for the generation of phototactic locomotion in Hermissenda.

Physiology of Neuronal Subtypes in the Respiratory–Vocal Integration Nucleus Retroamigualis of the Male Zebra Finch

2005 ◽  
Vol 94 (4) ◽  
pp. 2379-2390 ◽  
Author(s):  
M. F. Kubke ◽  
Y. Yazaki-Sugiyama ◽  
R. Mooney ◽  
J. M. Wild
Keyword(s):  
Motor Neurons ◽  
Zebra Finch ◽  
Synaptic Input ◽  
Cell Types ◽  
Inhibitory Input ◽  
Type I ◽  
Type Ii ◽  
Intracellular Recordings ◽  
Electrophysiological Properties ◽  
Premotor Neurons

Learned vocalizations, such as bird song, require intricate coordination of vocal and respiratory muscles. Although the neural basis for this coordination remains poorly understood, it likely includes direct synaptic interactions between respiratory premotor neurons and vocal motor neurons. In birds, as in mammals, the medullary nucleus retroambigualis (RAm) receives synaptic input from higher level respiratory and vocal control centers and projects to a variety of targets. In birds, these include vocal motor neurons in the tracheosyringeal part of the hypoglossal motor nucleus (XIIts), other respiratory premotor neurons, and expiratory motor neurons in the spinal cord. Although various cell types in RAm are distinct in their anatomical projections, their electrophysiological properties remain unknown. Furthermore, although prior studies have shown that RAm provides both excitatory and inhibitory input onto XIIts motor neurons, the identity of the cells in RAm providing either of these inputs remains to be established. To characterize the different RAm neuron types electrophysiologically, we used intracellular recordings in a zebra finch brain stem slice preparation. Based on numerous differences in intrinsic electrophysiological properties and a principal components analysis, we identified two distinct RAm neuron types (types I and II). Antidromic stimulation methods and intracellular staining revealed that type II neurons, but not type I neurons, provide bilateral synaptic input to XIIts. Paired intracellular recordings in RAm and XIIts further indicated that type II neurons with a hyperpolarization-dependent bursting phenotype are a potential source of inhibitory input to XIIts motor neurons. These results indicate that electrically distinct cell types exist in RAm, affording physiological heterogeneity that may play an important role in respiratory–vocal signaling.

Cellular studies of peripheral neurons in siphon skin of Aplysia californica

1979 ◽  
Vol 42 (2) ◽  
pp. 530-557 ◽  
Author(s):  
C. H. Bailey ◽  
V. F. Castellucci ◽  
J. Koester ◽  
E. R. Kandel
Keyword(s):  
Motor Neurons ◽  
Synaptic Input ◽  
Firing Pattern ◽  
White Cell ◽  
Type I ◽  
Type Ii ◽  
Peripheral Neurons ◽  
Peripheral Neuron ◽  
Type I Neuron ◽  
Kinetics Of

1. To account for the similarity in the kinetics of habituation between the central and peripheral components of siphon withdrawal, we have tested the idea (52) that each centrally located mechanoreceptor sensory neuron sends two branches to siphon motor neurons; one to centrally located siphon motor neurons and a collateral branch that remains in the periphery and innervates the peripheral siphon motor neurons. 2. We have found a group of peripheral siphon motor neurons and tested the connection onto these cells by central mechanoreceptors. In addition, we have defined by various electrophysiological and morphological criteria two general classes of peripheral neurons that lie along the course of the siphon nerve. 3. One class (type I) consists of only a single cell in each animal. This peripheral neuron typically has the largest cell body found lying along the siphon nerve and is the only peripheral nerve cell that appears white when viewed under epi-illumination. The type I neuron often has a highly regular firing pattern, which occurs in the absence of spontaneous synaptic input. The three-dimensional morphology of this neuron suggests a paucity of fine processes, most of which do not arborize and may terminate in the connective tissue sheath. Fine structural observations of the peripheral white cell have revealed the presence of large densecore granules. The peripheral type I neuron is similar in most of its electrophysiological and morphological properties to central neurons postulated to be neurosecretory. The peripheral white cell is, at present, the only peripheral neuron we can identify with certainty as a unique individual. 4. The second class (type II) of peripheral neurons are siphon motor neurons for the peripheral component of the siphon-withdrawal reflex. In contrast to the type I neurons, members of the second class of peripheral neurons possess smaller, more spherical cell bodies that have varying amounts of orange pigmentation and which give rise to a relatively well-developed and arborized dendritic tree. Type II neurons feature an irregular spontaneous firing pattern that is occasionally modulated by a rich spontaneous synaptic input. Peripheral siphon motor neurons have restricted motor fields that produce contraction of the mantle floor and the base of the siphon. Most of the type II neurons were found to be electrically coupled to one another. 5. The peripheral siphon motor neurons resemble the central siphon motor neurons in that they receive a collateral synapse from centrally located mechanoreceptor sensory neurons. This peripheral sensory-to-motor synapse exhibits the same kinetics of decrement as its central counterpart, both of which parallel behavioral habituation. 6. The rich mechanoreceptor input onto the relatively isolated dendritic trees of the peripheral siphon motor neurons provide a uniquely restricted neuropil to study the sensory-to-motor synapse. The peripheral motor neurons may, therefore, be a useful simple preparation for the cellular study of behavioral plasticity.

Relationship between input connectivity, morphology and orientation tuning of layer 2/3 pyramidal cells in mouse visual cortex

2020 ◽  
Author(s):  
Simon Weiler ◽  
Drago Guggiana Nilo ◽  
Tobias Bonhoeffer ◽  
Mark Hübener ◽  
Tobias Rose ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Synaptic Input ◽  
Pyramidal Cells ◽  
Excitatory Input ◽  
Orientation Tuning ◽  
Inhibitory Input ◽  
Layer 2 ◽  
Dendritic Complexity ◽  
Inhibitory Synaptic Input

AbstractNeocortical pyramidal cells (PCs) display functional specializations defined by their excitatory and inhibitory circuit connectivity. For layer 2/3 (L2/3) PCs, little is known about the detailed relationship between their neuronal response properties, dendritic structure and their underlying circuit connectivity at the level of single cells. Here, we ask whether L2/3 PCs in mouse primary visual cortex (V1) differ in their functional intra- and interlaminar connectivity patterns, and how this relates to differences in visual response properties. Using a combined approach, we first characterized the orientation and direction tuning of individual L2/3 PCs with in vivo 2-photon calcium imaging. Subsequently, we performed excitatory and inhibitory synaptic input mapping of the same L2/3 PCs in brain slices using laser scanning photostimulation (LSPS).Our data from this structure-connectivity-function analysis show that the sources of excitatory and inhibitory synaptic input are different in their laminar origin and horizontal location with respect to cell position: On average, L2/3 PCs receive more inhibition than excitation from within L2/3, whereas excitation dominates input from L4 and L5. Horizontally, inhibitory input originates from locations closer to the horizontal position of the soma, while excitatory input arises from more distant locations in L4 and L5. In L2/3, the excitatory and inhibitory inputs spatially overlap on average. Importantly, at the level of individual neurons, PCs receive inputs from presynaptic cells located spatially offset, vertically and horizontally, relative to the soma. These input offsets show a systematic correlation with the preferred orientation of the postsynaptic L2/3 PC in vivo. Unexpectedly, this correlation is higher for inhibitory input offsets within L2/3 than for excitatory input offsets. When relating the dendritic complexity of L2/3 PCs to their orientation tuning, we find that sharply tuned cells have a less complex apical tree compared to broadly tuned cells. These results indicate that the spatial input offsets of the functional input connectivity are linked to orientation preference, while the orientation selectivity of L2/3 PCs is more related to the dendritic complexity.

scholarly journals Hierarchical control of locomotion by distinct types of spinal V2a interneurons in zebrafish

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Evdokia Menelaou ◽  
David L. McLean
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Hierarchical Control ◽  
Higher Order ◽  
Type I ◽  
Type Ii ◽  
Timing Control ◽  
Amplitude Control ◽  
Spinal Interneurons ◽  
Larval Zebrafish

Abstract In all vertebrates, excitatory spinal interneurons execute dynamic adjustments in the timing and amplitude of locomotor movements. Currently, it is unclear whether interneurons responsible for timing control are distinct from those involved in amplitude control. Here, we show that in larval zebrafish, molecularly, morphologically and electrophysiologically distinct types of V2a neurons exhibit complementary patterns of connectivity. Stronger higher-order connections from type I neurons to other excitatory V2a and inhibitory V0d interneurons provide timing control, while stronger last-order connections from type II neurons to motor neurons provide amplitude control. Thus, timing and amplitude are coordinated by distinct interneurons distinguished not by their occupation of hierarchically-arranged anatomical layers, but rather by differences in the reliability and probability of higher-order and last-order connections that ultimately form a single anatomical layer. These findings contribute to our understanding of the origins of timing and amplitude control in the spinal cord.

scholarly journals Catecholaminergic Fiber Innervation of the Vocal Motor System Is Intrasexually Dimorphic in a Teleost with Alternative Reproductive Tactics

2015 ◽  
Vol 86 (2) ◽  
pp. 131-144 ◽  
Author(s):  
Zachary N. Ghahramani ◽  
Miky Timothy ◽  
Gurpreet Kaur ◽  
Michelle Gorbonosov ◽  
Alena Chernenko ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Motor System ◽  
Advertisement Call ◽  
Motor Nucleus ◽  
Type I ◽  
Type Ii ◽  
Fiber Density ◽  
Reproductive Tactics ◽  
Long Duration ◽  
Behavioral Divergence

Catecholamines, which include the neurotransmitters dopamine and noradrenaline, are known modulators of sensorimotor function, reproduction, and sexually motivated behaviors across vertebrates, including vocal-acoustic communication. Recently, we demonstrated robust catecholaminergic (CA) innervation throughout the vocal motor system in the plainfin midshipman fish Porichthys notatus, a seasonal breeding marine teleost that produces vocal signals for social communication. There are 2 distinct male reproductive morphs in this species: type I males establish nests and court females with a long-duration advertisement call, while type II males sneak spawn to steal fertilizations from type I males. Like females, type II males can only produce brief, agonistic, grunt type vocalizations. Here, we tested the hypothesis that intrasexual differences in the number of CA neurons and their fiber innervation patterns throughout the vocal motor pathway may provide neural substrates underlying divergence in reproductive behavior between morphs. We employed immunofluorescence (-ir) histochemistry to measure tyrosine hydroxylase (TH; a rate-limiting enzyme in catecholamine synthesis) neuron numbers in several forebrain and hindbrain nuclei as well as TH-ir fiber innervation throughout the vocal pathway in type I and type II males collected from nests during the summer reproductive season. After controlling for differences in body size, only one group of CA neurons displayed an unequivocal difference between male morphs: the extraventricular vagal-associated TH-ir neurons, located just lateral to the dimorphic vocal motor nucleus (VMN), were significantly greater in number in type II males. In addition, type II males exhibited greater TH-ir fiber density within the VMN and greater numbers of TH-ir varicosities with putative contacts on vocal motor neurons. This strong inverse relationship between the predominant vocal morphotype and the CA innervation of vocal motor neurons suggests that catecholamines may function to inhibit vocal output in midshipman. These findings support catecholamines as direct modulators of vocal behavior, and differential CA input appears reflective of social and reproductive behavioral divergence between male midshipman morphs.

Congenital Dyserythropoietic Anemia

PEDIATRICS ◽  
1973 ◽  
Vol 51 (5) ◽  
pp. 957-958
Author(s):  
G. Bennett Humphrey ◽  
Bahaod-Din Mojab ◽  
Ingomar Mutz
Keyword(s):  
Carbohydrate Metabolism ◽  
Morphological Characteristics ◽  
Type I ◽  
Type Ii ◽  
Congenital Dyserythropoietic Anemia ◽  
The 1950S ◽  
Deja Vu ◽  
Déjà Vu ◽  
Excellent Article

Reading the excellent article by Drs. Murphy and Oski, "Congenital Dyserythropoietic Anemia (CDA)",1 which further defines type II, produced a sense of deja vu. In the 1950s, nonspherocytic, hemolytic anemias (HNHA) were categorized as type I and II based on the in vitro autohemolysis test.2 This group of anemias has subsequently been demonstrated to be due to a series of enzymatic abnormalities in carbohydrate metabolism.3 In CDA, the morphological characteristics which define types I, II, and III probably reflect nuclear rather than cytoplasmic abnormalities.

Convergent Properties of Vestibular-Related Brain Stem Neurons in the Gerbil

2000 ◽  
Vol 83 (4) ◽  
pp. 1958-1971 ◽  
Author(s):  
Galen D. Kaufman ◽  
Michael E. Shinder ◽  
Adrian A. Perachio
Keyword(s):  
Translational Motion ◽  
Stimulus Frequency ◽  
Head Rotation ◽  
Vestibular Nuclei ◽  
Inhibitory Input ◽  
Type I ◽  
Similar Response ◽  
Type Ii ◽  
Response Dynamics ◽  
Related Activity

Three classes of vestibular-related neurons were found in and near the prepositus and medial vestibular nuclei of alert or decerebrate gerbils, those responding to: horizontal translational motion, horizontal head rotation, or both. Their distribution ratios were 1:2:2, respectively. Many cells responsive to translational motion exhibited spatiotemporal characteristics with both response gain and phase varying as a function of the stimulus vector angle. Rotationally sensitive neurons were distributed as Type I, II, or III responses (sensitive to ipsilateral, contralateral, or both directions, respectively) in the ratios of 4:6:1. Four tested factors shaped the response dynamics of the sampled neurons: canal-otolith convergence, oculomotor-related activity, rotational Type (I or II), and the phase of the maximum response. Type I nonconvergent cells displayed increasing gains with increasing rotational stimulus frequency (0.1–2.0 Hz, 60°/s), whereas Type II neurons with convergent inputs had response gains that markedly decreased with increasing translational stimulus frequency (0.25–2.0 Hz, ±0.1 g). Type I convergent and Type II nonconvergent neurons exhibited essentially flat gains across the stimulus frequency range. Oculomotor-related activity was noted in 30% of the cells across all functional types, appearing as burst/pause discharge patterns related to the fast phase of nystagmus during head rotation. Oculomotor-related activity was correlated with enhanced dynamic range compared with the same category that had no oculomotor-related response. Finally, responses that were in-phase with head velocity during rotation exhibited greater gains with stimulus frequency increments than neurons with out-of-phase responses. In contrast, for translational motion, neurons out of phase with head acceleration exhibited low-pass characteristics, whereas in-phase neurons did not. Data from decerebrate preparations revealed that although similar response types could be detected, the sampled cells generally had lower background discharge rates, on average one-third lower response gains, and convergent properties that differed from those found in the alert animals. On the basis of the dynamic response of identified cell types, we propose a pair of models in which inhibitory input from vestibular-related neurons converges on oculomotor neurons with excitatory inputs from the vestibular nuclei. Simple signal convergence and combinations of different types of vestibular labyrinth information can enrich the dynamic characteristics of the rotational and translational vestibuloocular responses.

scholarly journals Antioxidant Gene Expression in Vocal Hindbrain of a Teleost Fish

2018 ◽  
Author(s):  
Clara Liao ◽  
Ni Y. Feng ◽  
Andrew H. Bass
Keyword(s):  
Oxidative Stress ◽  
Breeding Season ◽  
Motor Neurons ◽  
Sound Production ◽  
Cellular Respiration ◽  
Type I ◽  
Type Ii ◽  
Antioxidant Genes ◽  
Long Duration ◽  
Significant Difference

ABSTRACTPlainfin midshipman fish (Porichthys notatus) have a remarkable capacity to generate long duration advertisement calls known as hums, each of which may last for close to two hours and be repeated throughout a night of courtship activity during the breeding season. The midshipman’s striking sound production capabilities provide a unique opportunity to investigate the mechanisms that motor neurons require for withstanding high-endurance activity. The temporal properties of midshipman vocal behaviors are largely controlled by a hindbrain central pattern generator that includes vocal motor neurons (VMN) that directly determine the activity pattern of target sonic muscles and, in turn, a sound’s pulse repetition rate, duration and pattern of amplitude modulation. Of the two adult midshipman male reproductive phenotypes -- types I and II-- only type I males acoustically court females with hums from nests that they build and guard, while type II males do not produce courtship hums but instead sneak or satellite spawn to steal fertilizations from type I males. A prior study using next generation RNA sequencing showed increased expression of a number of cellular respiration and antioxidant genes in the VMN of type I males during the breeding season, suggesting they help to combat potentially high levels of oxidative stress linked to this extreme behavior. This led to the question of whether the expression of these genes in the VMN would vary between actively humming versus non-humming states as well as between male morphs. Here, we tested the hypothesis that to combat oxidative stress, the VMN of reproductively active type I males would exhibit higher mRNA transcript levels for two superoxide dismutases (sod1,sod2) compared to the VMN of type II males and females that do not hum and in general both of which have a more limited vocal repertoire than type I males. The results showed no significant difference insod1transcript expression across reproductive morphs in the VMN and the surrounding hindbrain, and no difference ofsod2across the two male morphs and females in the SH. However, we observed a surprising, significantly lower expression ofsod2transcripts in the VMN of type I males as compared to type II males. We also found no significant difference insod1andsod2expression between actively humming and non-humming type I males in both the VMN and surrounding hindbrain. These findings overall lead us to conclude that increased transcription ofsod1andsod2is not necessary for combatting oxidative stress from the demands of the midshipman high-endurance vocalizations, but warrant future studies to assess protein levels, enzyme activity levels, as well as the expression of other antioxidant genes. These results also eliminate one of the proposed mechanisms that male midshipman use to combat potentially high levels of oxidative stress incurred by motor neurons driving long duration vocalization and provide more insight into how motor neurons are adapted to the performance of extreme behaviors.

scholarly journals Composition and organization of the collagen network produced by fetal bovine chondrocytes cultured at high density.

1993 ◽  
Vol 41 (6) ◽  
pp. 867-875 ◽  
Author(s):  
F Ruggiero ◽  
B Petit ◽  
M C Ronziere ◽  
J Farjanel ◽  
D J Hartmann ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Cell Layer ◽  
Morphological Characteristics ◽  
Culture Cell ◽  
High Density ◽  
Type I ◽  
Type Ii ◽  
High Density Culture ◽  
Entire Cell ◽  
Fetal Bovine

Fetal bovine chondrocytes isolated from the resting zone of epiphyseal cartilage were maintained in high-density culture for 4 weeks. From Day 2 in culture, the chondrocytes deposited an extracellular matrix composed of Types II, IX, and XI collagen. Types IX and XI collagen were restricted to the pericellular domain from Day 5. By 2 weeks the entire cell layer stained for antibodies to Type II and IX collagens. Type XI could be demonstrated throughout the cell layer by pepsinization of the sections. Results from both rotary shadowing and immunochemistry showed that the fibrils formed in culture were heterotypic, with Type IX collagen arranged along the surface and with Type XI collagen buried in Type II fibrils. Nonspecific Type VI collagen and the glycoproteins tenascin and fibrillin, previously described in cartilaginous tissue, were identified by their ultrastructural characteristics in the cell layer homogenate. Although the cells presented morphological characteristics of chondrocytes and still expressed cartilage-specific collagens, the appearance of Type I collagen in the culture cell layer after 4 weeks of culture demonstrates a partial dedifferentiation of the chondrocytes. The culture system described in this report provides an interesting tool for maintaining chondrocytes in a cartilage-like matrix to study the influence of different physical and chemical factors on the expression and differentiation of the cells.

scholarly journals New Aspects of Neotropical Polycystic (Echinococcus vogeli) and Unicystic (Echinococcus oligarthrus) Echinococcosis

2008 ◽  
Vol 21 (2) ◽  
pp. 380-401 ◽  
Author(s):  
Antonio D'Alessandro ◽  
Robert L. Rausch
Keyword(s):  
South America ◽  
Abdominal Cavity ◽  
Geographic Origin ◽  
Morphological Characteristics ◽  
Total Mortality ◽  
Medical Problem ◽  
Sufficient Information ◽  
Type I ◽  
Type Ii ◽  
Characteristic Type

SUMMARY Of the four species of the genus Echinococcus (Cestoda) distinguished by biological and morphological characteristics, two species, E. vogeli and E. oligarthrus, occur widely in the Neotropics. Approximately 200 cases of polycystic echinococcosis (PE) have been recorded from 12 countries in South America. Following early proliferation of E. vogeli in the human host, typically in the liver, the metacestode usually spreads in the peritoneal and pleural cavities, and numerous organs may be invaded. The clinical characteristics of PE in 81 patients with sufficient information are reviewed. Type I disease consists of polycysts in the liver and abdominal cavity (37% of the patients had this characteristic); type II is similar to type I but also includes hepatic insufficiency (26%); type III consists of cysts in liver and chest (14%); type IV consists of cysts only in the mesenteries (16%); and type V consists of cysts calcified in liver and lung (4%). The percentage of patients with polycysts in the liver was 81%, and the percentage of patients with polycysts in the chest was 14%. PE is most ready diagnosed by geographic origin of the patient and by means of ultrasound or computerized tomography scanning showing cysts and calcifications. The highest mortality was for patients with type II disease, due to hepatic failure and its complications. There were five patients who died due to surgical accidents, whereas 35 cases had uncomplicated surgery. Twenty-three patients died of PE, making the total mortality 29% (23 of 78 cases). None of the 13 patients treated only with albendazole, the most efficacious treatment, was completely cured. PE represents a severe medical problem in South America. A reevaluation of the characteristics of the metacestode of E. oligarthrus indicated that it is unicystic. Only three human cases are known (two with infection in the orbit and one with infection in the heart). The metacestode of E. oligarthrus, in contrast with that of E. vogeli, consists of a spherical, fluid-filled vesicle that enlarges concentrically and is not known to undergo exogenous proliferation.

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