scholarly journals On the Function of a Locust Flight Steering Muscle and its Inhibitory Innervation

1990 ◽  
Vol 150 (1) ◽  
pp. 55-80 ◽  
Author(s):  
HARALD WOLF
Keyword(s):  
Action Potentials ◽  
Excitatory Input ◽  
Efferent Nerve ◽  
Common Inhibitor ◽  
Horizontal Flight ◽  
Segmental Ganglion ◽  
The Common ◽  
Flight Steering ◽  
Aerodynamic Angle ◽  
Fine Adjustment

1. In tethered flying locusts, the pleuroalar (or pleuroaxillary) muscle of the forewing (M85) was stimulated via its efferent nerve. The effect on the angular setting of the wing was observed using photogrammetry. Maximal tetanic contraction of the muscle reduced downstroke pronation and upstroke supination by more than 25°. A more physiological stimulus regime resulted in angular changes of about 7°, which is near the range observed during steering manoeuvres. This confirms that the pleuroalar muscle plays an important role in adjusting the wing's aerodynamic angle of attack, as proposed in anatomical studies by Pfau (1978). 2. Unit a of the pleuroalar muscle was found to be innervated by the common inhibitor neurone 1 (CI) of the segmental ganglion. IJPs with amplitudes between 2 and 10mV were elicited by action potentials in CI. 3. A basic tonus was observed in the pleuroalar muscle in the absence of activity in excitatory motoneurones. CI input reduced this basic contracture but did not affect EJPs or muscle twitches elicited by excitatory input. 4. Activity of the common inhibitor was recorded intracellularly and with nerve electrodes in tethered flying locusts. Tonic discharges were observed with spike frequencies ranging from 5 to 35 Hz, 25 Hz being a typical value. 5. EMG recordings from the two units of the pleuroalar muscle showed that only unit a was active during most horizontal flight sequences. While its discharge was modulated in response to imposed roll movements, unit b was recruited primarily during ipsilateral roll. These results indicate functional specialization between pleuroalar muscle units a and b and suggest that the inhibitory innervation of unit a functions in the fine adjustment of wing pronation.

scholarly journals Apical length governs computational diversity of L5 pyramidal neurons

2019 ◽  
Author(s):  
Alessandro R. Galloni ◽  
Aeron Laffere ◽  
Ede Rancz
Keyword(s):  
Action Potentials ◽  
Pyramidal Neurons ◽  
Apical Dendrite ◽  
Common Assumption ◽  
Dendritic Excitability ◽  
Visual Cortices ◽  
The Common ◽  
Channel Dependent ◽  
Apical Dendrites ◽  
The Brain

AbstractAnatomical similarity across the neocortex has led to the common assumption that the circuitry is modular and performs stereotyped computations. Layer 5 pyramidal neurons (L5PNs) in particular are thought to be central to cortical computation because of their extensive arborisation and nonlinear dendritic operations. Here, we demonstrate that computations associated with dendritic Ca2+ plateaus in L5PNs vary substantially between the primary and secondary visual cortices. L5PNs in the secondary visual cortex show reduced dendritic excitability and smaller propensity for burst firing. This reduced excitability is correlated with shorter apical dendrites. Using numerical modelling, we uncover a universal principle underlying the influence of apical length on dendritic backpropagation and excitability, based on a Na+ channel-dependent broadening of backpropagating action potentials. In summary, we provide new insights into the modulation of dendritic excitability by apical dendrite length and show that the operational repertoire of L5 neurons is not universal throughout the brain.

Unit Activity in the Abdominal Nerve Cord of a Dragonfly NYMPH

1962 ◽  
Vol 39 (1) ◽  
pp. 31-44
Author(s):  
ANN FIELDEN ◽  
G. M. HUGHES
Keyword(s):  
Action Potentials ◽  
The Body ◽  
Peripheral Stimulus ◽  
Inhibitory Effects ◽  
Nerve Fibres ◽  
Dragonfly Nymph ◽  
Peripheral Area ◽  
Segmental Ganglion ◽  
Peripheral Areas ◽  
Stimulation Of

1. Electrical activity of single units has been studied in small bundles of nerve fibres split off from the connectives between abdominal ganglia of the dragonfly nymph. Many units showed a resting discharge but activity of other units was only found when the insect was stimulated mechanically. 2. In some fibres the resting discharge was unaffected by mechanical stimulation and such spontaneous activity showed different patterns. These units were identified as interneurones and a prominent feature of their discharge was an irregular firing over long periods and the formation of characteristic intermittent bursts. 3. Responses to tactile or proprioceptive stimulation were investigated in primary sensory fibres and interneurones. The latter showed excitatory and inhibitory effects which were often related to the site of the peripheral stimulus. 4. Primary sensory fibres generally gave action potentials of smaller amplitude and were excited by stimulation of more localized areas. Many fibres traverse at least one connective after they enter a segmental ganglion and most ascend or descend ipsilaterally, but some crossing-over of sensory fibres occurs in the ganglia. 5. Interneurones were classified according to the nature of the peripheral areas from which they received their input. Ipsilateral, contralateral, and bilateral fibres have all been found but so far there is no evidence for any asymmetric fibres. Fibres responding to stimulation of a single segment or of many segments were found. Some of the latter extended over the whole length of the body and it is clear that spikes may be initiated in many of the ganglia through which an interneurone passes. 6. It is evident from this work that a given peripheral area is represented centrally by many interneurones and a great deal of convergence from different areas may occur on individual interneurones.

Innervation of the Anterior and Posterior Levator Muscles of the Fifth Leg of the Crab Carcinus Maenas

1987 ◽  
Vol 127 (1) ◽  
pp. 229-248
Author(s):  
STACIA MOFFETT ◽  
DANIEL P. YOX ◽  
LINDA B. KAHAN ◽  
RICHARD L. RIDGWAY
Keyword(s):  
Muscle Fibre ◽  
Electron Micrographs ◽  
Carcinus Maenas ◽  
Levator Muscle ◽  
Muscle Fibres ◽  
Motor Innervation ◽  
Postsynaptic Potentials ◽  
Common Inhibitor ◽  
The Common ◽  
Nerve Recordings

In the fifth pair of legs, the anterior levator muscle of the basi-ischiopodite (AL) consists of a dorsal thoracic head (ALd), two closely aligned ventral thoracic heads (ALv) and a small coxal head (ALc). Major thoracic subdivisions are separately innervated, whereas the nerve innervating the coxal head projects from ALd. The posterior levator (PL) is located in the coxa and is separately innervated. Nerve recordings, dye backfilling, muscle fibre recordings and nerve crosssections yielded somewhat different estimates for the levator motor innervation. Nerve backfills reveal at least 10 motoneurones supplying AL: six shared by ALd and ALv, one unique to ALv and three unique to ALd. Nerve recordings reveal six motoneurones supplying ALd and five supplying ALv. Four (including the common inhibitor) are shared by ALd and ALv and six project from ALd to ALc. Most AL muscle fibres are innervated by two or three motoneurones, but fibres innervated by five were encountered. Postsynaptic potentials ranging from small (<1-5 mV) to large (15–25 mV) were found distributed throughout AL. PL is innervated by two excitors not shared with AL and by the common inhibitor. Electron micrographs reveal more axons than any of the methods for counting motoneurones. Neurones with axon diameters below 3 μm are likely to be sensory.

Peripheral neural input to neurons of the middle cervical ganglion in the cat

1984 ◽  
Vol 246 (3) ◽  
pp. R354-R358
Author(s):  
Z. J. Bosnjak ◽  
J. P. Kampine
Keyword(s):  
Electrical Stimulation ◽  
Synaptic Input ◽  
Action Potentials ◽  
Efferent Nerve ◽  
Neural Input ◽  
Central Origin ◽  
Cervical Ganglion ◽  
Intracellular Action ◽  
Peripheral Origin

In vitro studies were conducted on the middle cervical ganglion (MCG) of the cat by recording intracellular action potentials from its neurons. The purpose of this study was to examine the possibility of a peripheral synaptic input to the MCG. Preganglionic electrical stimulation, via the ventral ansa (VA) and dorsal ansa (DA) subclavia, and post-ganglionic electrical stimulation, via the ventrolateral cardiac nerve (VCN), evoked graded synaptic responses that led to the discharge of one or more action potentials in the 14 ganglia studied. The conduction velocity of these pathways ranged from 0.4 to 0.9 m/s. Ten percent of the cells impaled were inexcitable, even with direct intracellular depolarizing current, whereas 80% of the neurons studied received a synaptic input from fibers of both central and peripheral origin. In addition, subthreshold synaptic inputs from peripheral and central origin sum to discharge the cell, suggesting an integration of neural inputs in the MCG. These responses were blocked by d-tubocurarine chloride. This evidence indicates that sympathetic efferent nerve activity can be modified by peripheral excitatory inputs and that these inputs may function as pathways for a peripheral reflex at the level of the MCG.

Circulatory mechanoreceptors in the pond turtle Pseudemys scripta

1982 ◽  
Vol 242 (3) ◽  
pp. R216-R219 ◽  
Author(s):  
F. M. Faraci ◽  
H. W. Shirer ◽  
J. A. Orr ◽  
J. W. Trank
Keyword(s):  
Blood Pressure ◽  
Pulmonary Artery ◽  
Action Potentials ◽  
Arterial Occlusion ◽  
Physiological Role ◽  
Vascular Occlusion ◽  
Saline Injection ◽  
Heart Cycle ◽  
The Common ◽  
Pseudemys Scripta

This study was undertaken to characterize cardiovascular receptors in the turtle, Pseudemys scripta, with particular attention being given to neural activity changes associated with alterations in blood pressure. Vagal afferent nerve traffic, synchronous with heart contractions, was recorded in anesthetized artificially ventilated turtles. Action potentials, from receptors that fired regularly during each heart cycle, occurred during ventricular systole. Mechanical probing and vascular occlusion indicated that these receptors were located in the proximal common pulmonary artery including the bulbus cordis region. Bolus injections of saline into the ventricle or the common pulmonary artery caused immediate but transient increases in cardiac synchronous traffic. Prolonged elevation of arterial and ventricular blood pressure, by either saline injection or arterial occlusion, caused increases in receptor discharge of the same duration as the pressure increases. Although these receptors could participate in the regulation of the systemic and the pulmonary circulation, the physiological role for them is presently unknown.

Properties of the Common Inhibitor Binding Domain in Mitochondrial NADH-Dehydrogenase (Complex I)

1999 ◽  
Vol 27 (3) ◽  
pp. A82-A82
Author(s):  
Jürgen G. Okun ◽  
Volker Zickermann ◽  
Hermann Schägger ◽  
Ulrich Brandt
Keyword(s):  
Complex I ◽  
Nadh Dehydrogenase ◽  
Binding Domain ◽  
Inhibitor Binding ◽  
Common Inhibitor ◽  
The Common ◽  
Dehydrogenase Complex

scholarly journals Reduction of Dendritic Inhibition in CA1 Pyramidal Neurons in Amyloidosis Models of Early Alzheimer’s Disease

2020 ◽  
Vol 78 (3) ◽  
pp. 951-964
Author(s):  
Marvin Ruiter ◽  
Lotte J. Herstel ◽  
Corette J. Wierenga
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Action Potentials ◽  
Pyramidal Neurons ◽  
Early Stage ◽  
Brain Slices ◽  
Pyramidal Cells ◽  
Excitatory Input ◽  
Aβ Oligomers ◽  
Ca1 Pyramidal Neurons

Background: In an early stage of Alzheimer’s disease (AD), before the formation of amyloid plaques, neuronal network hyperactivity has been reported in both patients and animal models. This suggests an underlying disturbance of the balance between excitation and inhibition. Several studies have highlighted the role of somatic inhibition in early AD, while less is known about dendritic inhibition. Objective: In this study we investigated how inhibitory synaptic currents are affected by elevated Aβ levels. Methods: We performed whole-cell patch clamp recordings of CA1 pyramidal neurons in organotypic hippocampal slice cultures after treatment with Aβ-oligomers and in hippocampal brain slices from AppNL-F-G mice (APP-KI). Results: We found a reduction of spontaneous inhibitory postsynaptic currents (sIPSCs) in CA1 pyramidal neurons in organotypic slices after 24 h Aβ treatment. sIPSCs with slow rise times were reduced, suggesting a specific loss of dendritic inhibitory inputs. As miniature IPSCs and synaptic density were unaffected, these results suggest a decrease in activity-dependent transmission after Aβ treatment. We observed a similar, although weaker, reduction in sIPSCs in CA1 pyramidal neurons from APP-KI mice compared to control. When separated by sex, the strongest reduction in sIPSC frequency was found in slices from male APP-KI mice. Consistent with hyperexcitability in pyramidal cells, dendritically targeting interneurons received slightly more excitatory input. GABAergic action potentials had faster kinetics in APP-KI slices. Conclusion: Our results show that Aβ affects dendritic inhibition via impaired action potential driven release, possibly due to altered kinetics of GABAergic action potentials. Reduced dendritic inhibition may contribute to neuronal hyperactivity in early AD.

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