scholarly journals Task-specific roles of local interneurons for inter- and intraglomerular signaling in the insect antennal lobe

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Debora Fusca ◽  
Peter Kloppenburg
Keyword(s):  
Antennal Lobe ◽  
Periplaneta Americana ◽  
Morphological Properties ◽  
Primary Role ◽  
Tuning Curves ◽  
Complex Interactions ◽  
Local Interneurons ◽  
Whole Cell Patch Clamp ◽  
Functional Analog ◽  
Cell Type Specific

Local interneurons (LNs) mediate complex interactions within the antennal lobe, the primary olfactory system of insects, and the functional analog of the vertebrate olfactory bulb. In the cockroach Periplaneta americana, as in other insects, several types of LNs with distinctive physiological and morphological properties can be defined. Here, we combined whole-cell patch-clamp recordings and Ca2+ imaging of individual LNs to analyze the role of spiking and nonspiking LNs in inter- and intraglomerular signaling during olfactory information processing. Spiking GABAergic LNs reacted to odorant stimulation with a uniform rise in [Ca2+]i in the ramifications of all innervated glomeruli. In contrast, in nonspiking LNs, glomerular Ca2+ signals were odorant specific and varied between glomeruli, resulting in distinct, glomerulus-specific tuning curves. The cell type-specific differences in Ca2+ dynamics support the idea that spiking LNs play a primary role in interglomerular signaling, while they assign nonspiking LNs an essential role in intraglomerular signaling.

scholarly journals Task-specific roles of local interneurons for inter -and intraglomerular signaling in the insect antennal lobe

2020 ◽  
Author(s):  
Debora Fusca ◽  
Peter Kloppenburg
Keyword(s):  
Antennal Lobe ◽  
Periplaneta Americana ◽  
Morphological Properties ◽  
Primary Role ◽  
Tuning Curves ◽  
Complex Interactions ◽  
Local Interneurons ◽  
Whole Cell Patch Clamp ◽  
Functional Analog ◽  
Cell Type Specific

AbstractLocal interneurons (LNs) mediate complex interactions within the antennal lobe, the primary olfactory system of insects, and the functional analog of the vertebrate olfactory bulb. In the cockroach Periplaneta Americana, as in other insects, several types of LNs with distinctive physiological and morphological properties can be defined. Here, we combined whole-cell patch clamp recordings and Ca2+ imaging of individual LNs to analyze the role of spiking and nonspiking LNs in inter- and intraglomerular signaling during olfactory information processing. Spiking GABAergic LNs reacted to odorant stimulation with a uniform rise in [Ca2+]i in the ramifications of all innervated glomeruli. In contrast, in nonspiking LNs, glomerular Ca2+ signals were odorant specific and varied between glomeruli, resulting in distinct, glomerulus-specific tuning curves. The cell type-specific differences in Ca2+ dynamics support the idea that spiking LNs play a primary role in interglomerular signaling, while they assign nonspiking LNs an essential role in intraglomerular signaling.

Distinct Electrophysiological Properties in Subtypes of Nonspiking Olfactory Local Interneurons Correlate With Their Cell Type–Specific Ca2+ Current Profiles

2009 ◽  
Vol 102 (5) ◽  
pp. 2834-2845 ◽  
Author(s):  
Andreas Husch ◽  
Moritz Paehler ◽  
Debora Fusca ◽  
Lars Paeger ◽  
Peter Kloppenburg
Keyword(s):  
Periplaneta Americana ◽  
Membrane Properties ◽  
Type Ii ◽  
Diverse Population ◽  
Cell Type ◽  
Cellular Mechanisms ◽  
Electrophysiological Properties ◽  
Local Interneurons ◽  
Cell Type Specific ◽  
Process Structure

A diverse population of local interneurons (LNs) helps to process, structure, and spatially represent olfactory information in the insect antennal lobe. In Periplaneta americana, we identified two subtypes of nonspiking local interneurons (type II LNs) by their distinct morphological and intrinsic electrophysiological properties. As an important step toward a better understanding of the cellular mechanisms that mediate odor information processing, we present a detailed analysis of their distinct voltage-activated Ca2+ currents, which clearly correlated with their distinct intrinsic electrophysiological properties. Both type II LNs did not posses voltage-activated Na+ currents and apparently innervated all glomeruli including the macroglomerulus. Type IIa LNs had significant longer and thicker low-order neurites and innervated each glomerulus entirely and homogeneously, whereas type IIb LNs innervated only parts of each glomerulus. All type II LNs were broadly tuned and responded to odorants of many chemical classes with graded changes in the membrane potential. Type IIa LNs responded with odor-specific elaborate patterns of excitation that could also include “spikelets” riding on the depolarizations and periods of inhibition. In contrast, type IIb LNs responded mostly with sustained, relatively smooth depolarizations. Consistent with the strong active membrane properties of type IIa LNs versus type IIb LNs, the voltage-activated Ca2+ current of type IIa LNs activated at more hyperpolarized membrane potentials and had a larger transient component.

Physiological and Morphological Characterization of Local Interneurons in the Drosophila Antennal Lobe

2010 ◽  
Vol 104 (2) ◽  
pp. 1007-1019 ◽  
Author(s):  
Yoichi Seki ◽  
Jürgen Rybak ◽  
Dieter Wicher ◽  
Silke Sachse ◽  
Bill S. Hansson
Keyword(s):  
Antennal Lobe ◽  
Neural Circuit ◽  
Three Dimensional ◽  
Morphological Characterization ◽  
Morphological Properties ◽  
Electrophysiological Properties ◽  
Local Interneurons ◽  
Enhancer Trap Line ◽  
Almost All

The Drosophila antennal lobe (AL) has become an excellent model for studying early olfactory processing mechanisms. Local interneurons (LNs) connect a large number of glomeruli and are ideally positioned to increase computational capabilities of odor information processing in the AL. Although the neural circuit of the Drosophila AL has been intensively studied at both the input and the output level, the internal circuit is not yet well understood. An unambiguous characterization of LNs is essential to remedy this lack of knowledge. We used whole cell patch-clamp recordings and characterized four classes of LNs in detail using electrophysiological and morphological properties at the single neuron level. Each class of LN displayed unique characteristics in intrinsic electrophysiological properties, showing differences in firing patterns, degree of spike adaptation, and amplitude of spike afterhyperpolarization. Notably, one class of LNs had characteristic burst firing properties, whereas the others were tonically active. Morphologically, neurons from three classes innervated almost all glomeruli, while LNs from one class innervated a specific subpopulation of glomeruli. Three-dimensional reconstruction analyses revealed general characteristics of LN morphology and further differences in dendritic density and distribution within specific glomeruli between the different classes of LNs. Additionally, we found that LNs labeled by a specific enhancer trap line (GAL4-Krasavietz), which had previously been reported as cholinergic LNs, were mostly GABAergic. The current study provides a systematic characterization of olfactory LNs in Drosophila and demonstrates that a variety of inhibitory LNs, characterized by class-specific electrophysiological and morphological properties, construct the neural circuit of the AL.

scholarly journals Transient voltage-activated K+ currents in central antennal lobe neurons: cell type-specific functional properties

2017 ◽  
Vol 117 (5) ◽  
pp. 2053-2064 ◽  
Author(s):  
Lars Paeger ◽  
Viktor Bardos ◽  
Peter Kloppenburg
Keyword(s):  
Functional Properties ◽  
Antennal Lobe ◽  
Projection Neurons ◽  
Cell Type ◽  
Electrophysiological Properties ◽  
Olfactory Information ◽  
Local Interneurons ◽  
Cell Type Specific ◽  
Transient Voltage ◽  
Marked Cell

In this study we analyzed transient voltage-activated K+ currents ( IA) of projection neurons and local interneurons in the antennal lobe of the cockroach Periplaneta americana. The antennal lobe is the first synaptic processing station for olfactory information in insects. Local interneurons are crucial for computing olfactory information and form local synaptic connections exclusively in the antennal lobe, whereas a primary task of the projection neurons is the transfer of preprocessed olfactory information from the antennal lobe to higher order centers in the protocerebrum. The different physiological tasks of these neurons require specialized physiological and morphological neuronal phenotypes. We asked if and how the different physiological phenotypes are reflected in the functional properties of IA, which is crucial for shaping intrinsic electrophysiological properties of neurons. Whole cell patch-clamp recordings from adult male P. americana showed that all their central antennal lobe neurons can generate IA. The current exhibited marked cell type-specific differences in voltage dependence of steady-state activation and inactivation, and differences in inactivation kinetics during sustained depolarization. Pharmacological experiments revealed that IA in all neuron types was partially blocked by α-dendrotoxin and phrixotoxin-2, which are considered blockers with specificity for Shaker- and Shal-type channels, respectively. These findings suggest that IA in each cell type is a mixed current generated by channels of both families. The functional role of IA was analyzed in experiments under current clamp, in which portions of IA were blocked by α-dendrotoxin or phrixotoxin-2. These experiments showed that IA contributes significantly to the intrinsic electrophysiological properties, such as the action potential waveform and membrane excitability. NEW & NOTEWORTHY In the insect olfactory system, projection neurons and local interneurons have task-specific electrophysiological and morphological phenotypes. Voltage-activated potassium channels play a crucial role in shaping functional properties of these neurons. This study revealed marked cell type-specific differences in the biophysical properties of transient voltage-activated potassium currents in central antennal lobe neurons.

scholarly journals Odor processing in the cockroach antennal lobe—the network components

2021 ◽  
Vol 383 (1) ◽  
pp. 59-73
Author(s):  
Debora Fuscà ◽  
Peter Kloppenburg
Keyword(s):  
Antennal Lobe ◽  
Periplaneta Americana ◽  
Experimental System ◽  
Projection Neurons ◽  
Odor Processing ◽  
Local Interneurons ◽  
Physiological Properties ◽  
Functional Equivalent ◽  
The Central Nervous System ◽  
Physiological Tasks

AbstractHighly interconnected neural networks perform olfactory signal processing in the central nervous system. In insects, the first synaptic processing of the olfactory input from the antennae occurs in the antennal lobe, the functional equivalent of the olfactory bulb in vertebrates. Key components of the olfactory network in the antennal lobe are two main types of neurons: the local interneurons and the projection (output) neurons. Both neuron types have different physiological tasks during olfactory processing, which accordingly require specialized functional phenotypes. This review gives an overview of important cell type-specific functional properties of the different types of projection neurons and local interneurons in the antennal lobe of the cockroach Periplaneta americana, which is an experimental system that has elucidated many important biophysical and cellular bases of intrinsic physiological properties of these neurons.

Ca2+ Currents in Central Insect Neurons: Electrophysiological and Pharmacological Properties

1997 ◽  
Vol 77 (1) ◽  
pp. 186-199 ◽  
Author(s):  
Dieter Wicher ◽  
Heinz Penzlin
Keyword(s):  
Periplaneta Americana ◽  
Low Voltage ◽  
Fast Time ◽  
Channel Blockers ◽  
Pharmacological Properties ◽  
Patch Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Blocking Effects ◽  
Dum Neurons ◽  
Maximal Peak

Wicher, Dieter, and Heinz Penzlin. Ca2+ currents in central insect neurons: electrophysiological and pharmacological properties. J. Neurophysiol. 77: 186–199, 1997. Ca2+ currents in dorsal unpaired median (DUM) neurons isolated from the fifth abdominal ganglion of the cockroach Periplaneta americana were investigated with the whole cell patch-clamp technique. On the basis of kinetic and pharmacological properties, two different Ca2+ currents were separated in these cells: mid/low-voltage-activated (M-LVA) currents and high-voltage-activated (HVA) currents. M-LVA currents had an activation threshold of −50 mV and reached maximal peak values at −10 mV. They were sensitive to depolarized holding potentials and decayed very rapidly. The decay was largely Ca2+ dependent. M-LVA currents were effectively blocked by Cd2+ median inhibiting concentration (IC50 = 9 μM), but they also had a remarkable sensitivity to Ni2+ (IC50 = 19 μM). M-LVA currents were insensitive to vertebrate LVA channel blockers like flunarizine and amiloride. The currents were, however, potently blocked by ω-conotoxin MVIIC (1 μM) and ω-agatoxin IVA (50 nM). The blocking effects of ω-toxins developed fast (time constant τ = 15 s) and were fully reversible after wash. HVA currents activated positive to −30 mV and showed maximal peak currents at +10 mV. They were resistant to depolarized holding potentials up to −50 mV and decayed in a less pronounced manner than M-LVA currents. HVA currents were potently blocked by Cd2+ (IC50 = 5 μM) but less affected by Ni2+ (IC50 = 40 μM). These currents were reduced by phenylalkylamines like verapamil (10 μM) and benzothiazepines like diltiazem (10 μM), but they were insensitive to dihydropyridines like nifedipine (10 μM) and BAY K 8644 (10 μM). Furthermore, HVA currents were sensitive to ω-conotoxin GVIA (1 μM). The toxin-induced reduction of currents appeared slowly (τ ∼ 120 s) and the recovery after wash was incomplete in most cases. The dihydropyridine insensitivity of the phenylalkylamine-sensitive HVA currents is a property the cockroach DUM cells share with other invertebrate neurons. Compared with Ca2+ currents in vertebrates, the DUM neuron currents differ considerably from the presently known types. Although there are some similarities concerning kinetics, the pharmacological profile of the cockroach Ca2+ currents especially is very different from profiles already described for vertebrate currents.

scholarly journals Protective Low-Density Polyethylene Residues from Prepreg for the Development of New Nanocomposites with Montmorillonite: Recycling and Characterization

Recycling ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 45
Author(s):  
Pamela Rodrigues Passos Severino ◽  
Thaís Larissa do Amaral Montanheiro ◽  
Orestes Ferro ◽  
Fábio Roberto Passador ◽  
Larissa Stieven Montagna
Keyword(s):  
Carbon Fiber ◽  
Extrusion Process ◽  
Morphological Properties ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Primary Role ◽  
Protective Films ◽  
And Storage ◽  
Compatibilizer Agent ◽  
The Ideal

A sustainable alternative to the destination of polyethylene (PE) residue from the prepreg package was established. This work intends to develop nanocomposites for packaging containing neat low-density polyethylene (LDPE), a compatibilizer agent (maleic anhydride grafted-LDPE, LDPE-g-MA), recycled LDPE obtained from the protective films of prepreg (rLDPE) and montmorillonite (MMT). The rLDPE, from the prepreg shield, has a primary role during the transport and storage of prepreg, which can be composed of epoxy resin and carbon fiber or glass fiber. However, this rLDPE is withdrawn and discarded, besides, it is estimated that tons of this material are discarded monthly by the company Alltec Materiais Compostos Ltd. (São José dos Campos-SP, Brazil). Due to several factors, including the lack of technology for recycling, the majority of this material is incinerated. In this context, this work presents a technical and ecologically viable alternative for the use of this discarded material. Nanocomposites of LDPE/rLDPE blends and montmorillonite (MMT) with different contents (0.0, 1.0, and 3.0 wt%) and with the addition of compatibilizer agent (LDPE-g-MA) were prepared by extrusion process. Test specimens were obtained by hot pressing in a hydropneumatic press followed by die-cutting. The nanocomposites produced using rLDPE presented good mechanical, thermal, and morphological properties, being the ideal concentration of 1 wt% MMT. Thus, the results obtained confirmed the viability of recycling LDPE from the prepreg package which contributes to the reduction of waste and the use of this material in technological applications.

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