Properties of the trochanteral hair plate and its function in the control of walking in the cockroach

1976 ◽  
Vol 64 (1) ◽  
pp. 233-249 ◽  
Author(s):  
R. K. Wong ◽  
K. G. Pearson
Keyword(s):  
Inhibitory Effect ◽  
Short Latency ◽  
Inhibitory Influence ◽  
Type I ◽  
Type Ii ◽  
Step Cycle ◽  
Excitatory Effect ◽  
Physiological Properties ◽  
Hair Sensilla ◽  
Leg Movement

1. The physiological properties of the group of long hair sensilla of the trochanteral hair plate in the cockroach metathoracic leg were studied. The sensilla were divided into type I and type II according to their responses to imposed displacements. 2. Type I hair sensilla responded to dynamic displacements whereas type II hair sensilla responded to both dynamic and static displacements. The hair sensilla are normally excited by phasic flexion movements of the femur near the end of leg protraction. 3. Activity in the trochanteral hair plate afferents had a short latency excitatory effect on the motoneurone producing slow extension movements of the femur and an inhibitory effect on the femur flexor motoneurones. 4. Removal of the trochanteral hair plate in one leg caused overstepping of that leg in a walking animal due to exaggerated flexion of the femur. This change in leg movement can be explained by the removal of the inhibitory influence from the hair plate afferents to the femur flexor motoneurones. 5. We conclude that one function of the trochanteral hair plate is to limit femur flexion during a step cycle.

Two separate inhibitory mechanisms shape the responses of dorsal cochlear nucleus type IV units to narrowband and wideband stimuli

1994 ◽  
Vol 71 (6) ◽  
pp. 2446-2462 ◽  
Author(s):  
I. Nelken ◽  
E. D. Young
Keyword(s):  
Firing Rate ◽  
Cochlear Nucleus ◽  
Inhibitory Effect ◽  
Broadband Noise ◽  
Dorsal Cochlear Nucleus ◽  
Inhibitory Input ◽  
Inhibitory Influence ◽  
Type Ii ◽  
Rate Level ◽  
Type Iv

1. The principal cells of the dorsal cochlear nucleus (DCN) are mostly inhibited by best frequency (BF) tones but are mostly excited by broadband noise (BBN), producing the so-called type IV response characteristic. The narrowband inhibitory responses can be explained by the inhibitory influence of interneurons with type II response characteristics. However, it is not clear that all the details of the type IV responses can be accounted for by this neural circuit. In particular, many type IV units are inhibited by band-reject noise (notch noise); type II units tend to be only weakly excited by these stimuli, if at all. In this paper we study the relationships between the narrowband, inhibitory and the wideband, excitatory regimens of the type IV responses and present the case for the existence of a second inhibitory source in DCN, called the wideband inhibitor (WBI) below. 2. Type IV units were studied using pure tones, noise bands arithmetically centered on BF, notch noise centered on BF, and BBN. We measured the rate-level function (response rate as function of stimulus level) for each stimulus. This paper is based on the responses of 28 type IV units. 3. Evidence for low-threshold inhibitory input to type IV units is derived from analysis of rate-level functions at sound levels just above threshold. Notch noise stimuli of the appropriate notch width produce inhibition at threshold in this regime. When BBN is presented, this inhibition appears to summate with excitation produced by energy in the band of noise centered on BF, resulting in BBN rate-level functions with decreased slope and maximum firing rate. A range of slopes and maximal firing rates is observed, but these variables are strongly correlated and they are negatively correlated with the strength of the inhibition produced by notch noise; this result supports the conclusion that a single inhibitory source is responsible for these effects. 4. By contrast, there is a weak (nonsignificant) positive correlation between the strength of the inhibitory effect of notch noise and the slope/maximal firing rate in response to narrowband stimuli, including BF tones. The contrast between this positive nonsignificant correlation and the significant negative correlation mentioned above suggests that more than one inhibitory effect operates: specifically, the type II input is responsible for inhibition by narrowband stimuli and a different inhibitory source, the WBI, produces inhibition by notch stimuli. 5. Several lines of evidence are given to show that type II units cannot produce the inhibition seen with notch noise stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Sympathetic effects on spontaneous activity in bovine mesenteric lymphatics

1984 ◽  
Vol 247 (4) ◽  
pp. H610-H615
Author(s):  
T. Ohhashi ◽  
T. Azuma
Keyword(s):  
Spontaneous Activity ◽  
Inhibitory Effect ◽  
Lymph Vessel ◽  
Autonomic Nerves ◽  
Inhibitory Influence ◽  
Nerve Terminals ◽  
Pacemaker Cells ◽  
Excitatory Effect ◽  
Transmural Stimulation ◽  
Spontaneous Contractions

To investigate the effects of autonomic nerves on the spontaneous activity, responses of valvular and intervalvular segments of isolated bovine mesenteric lymphatics to 60-strains of pulses (50 V for 0.5 ms at 2 Hz) have been studied under the influence of various drugs. There was a marked difference in response to transmural stimulation between the valvular and intervalvular segments. In the valvular segment, the stimulation arrested the spontaneous activity. However, the rhythm of spontaneous contractions was markedly accelerated during the stimulation in the intervalvular segment. Both inhibitory and excitatory effects were completely blocked by tetrodotoxin and guanethidine, potentiated by cocaine, and unaffected by hexamethonium and atropine. Propranolol blocked the inhibitory effect of the stimulation in the valvular segment. Pretreatment of the intervalvular segment with phentolamine converted the normal excitatory effect of the stimulation into an inhibitory influence. No change in rhythm was brought about by the stimulation in the presence of propranolol and phentolamine in either segment. These results suggest that transmural electrical stimulation causes the release of norepinephrine from postganglionic sympathetic nerve terminals in the vicinity of pacemaker cells and that beta-adrenoceptors are predominant in the valvular region of the lymph vessel.

scholarly journals Excitability and Threshold Mechanism for Enhanced Neuronal Response Induced by Inhibition Preceding Excitation

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Hanqing Ma ◽  
Bing Jia ◽  
Yuye Li ◽  
Huaguang Gu
Keyword(s):  
Steady State ◽  
Neuronal Response ◽  
Inhibitory Effect ◽  
Type I ◽  
Type Ii ◽  
Neural Firing ◽  
Firing Activity ◽  
Subthreshold Oscillations ◽  
Auditory Nervous System ◽  
Threshold Mechanism

Postinhibitory facilitation (PIF) of neural firing presents a paradoxical phenomenon that the inhibitory effect induces enhancement instead of reduction of the firing activity, which plays important roles in sound location of the auditory nervous system, awaited theoretical explanations. In the present paper, excitability and threshold mechanism for the PIF phenomenon is presented in the Morris-Lecar model with type I, II, and III excitabilities. Firstly, compared with the purely excitatory stimulations applied to the steady state, the inhibitory preceding excitatory stimulation to form pairs induces the firing rate increased for type II and III excitabilities instead of type I excitability, when the interval between the inhibitory and excitatory stimulation within each pair is suitable. Secondly, the threshold mechanism for the PIF phenomenon is acquired. For type II and III excitabilities, the inhibitory stimulation induces subthreshold oscillations around the steady state. During the middle and ending phase of the ascending part and the beginning phase of the descending part within a period of the subthreshold oscillations, the threshold to evoke an action potential by an excitatory stimulation becomes weaker, which is the cause for the PIF phenomenon. Last, a theoretical estimation for the range of the interval between the inhibitory and excitatory stimulation for the PIF phenomenon is acquired, which approximates half of the intrinsic period of the subthreshold oscillations for the relatively strong stimulations and becomes narrower for the relatively weak stimulations. The interval for the PIF phenomenon is much shorter for type III excitability, which is closer to the experiment observation, due to the shorter period of the subthreshold oscillations. The results present the excitability and threshold mechanism for the PIF phenomenon, which provide comprehensive and deep explanations to the PIF phenomenon.

Physiological Properties of Neurons in the Ventral Nucleus of the Lateral Lemniscus of the Rat: Intrinsic Membrane Properties and Synaptic Responses

1999 ◽  
Vol 81 (6) ◽  
pp. 2862-2874 ◽  
Author(s):  
Shu Hui Wu
Keyword(s):  
Membrane Properties ◽  
Type I ◽  
Type Ii ◽  
Lateral Lemniscus ◽  
Positive Current ◽  
Physiological Properties ◽  
Current Voltage ◽  
Ventral Nucleus ◽  
Intrinsic Membrane Properties ◽  
Synaptic Responses

Physiological properties of neurons in the ventral nucleus of the lateral lemniscus of the rat: intrinsic membrane properties and synaptic responses. The physiological properties including current-voltage relationships, firing patterns, and synaptic responses of the neurons in the ventral nucleus of the lateral lemniscus (VNLL) were studied in brain slices taken through the young rat’s (17–37 days old) auditory brain stem. Intracellular recordings were made from VNLL neurons, and synaptic potentials were elicited by electrical stimulation of the lateral lemniscus ventral to the VNLL. Current-voltage relations and firing patterns were tested by recording the electrical potentials produced by intracellular injection of positive and negative currents. There were two types of VNLL neurons (type I and II) that exhibited different current-voltage relationships. In response to negative current, both type I and II neurons produced a graded hyperpolarization. Type I neurons responded to positive current with a graded depolarization and multiple action potentials the number of which was related to the strength of the current injected. The current-voltage relations of type I neurons were nearly linear. Type II neurons responded to positive current with a limited depolarization and only one or a few action potentials. The current-voltage relations of type II neurons were nonlinear near the resting potential. The membrane properties of the type II VNLL neurons may play an important role for processing information about time of onset of a sound. Type I neurons showed three different firing patterns, i.e., regular, onset-pause and adaptation, in response to small positive current. The onset-pause and adaptation patterns could become sustained when a large current was injected. The regular, onset-pause, and adaptation patterns in type I neurons and the onset pattern in type II neurons resemble “chopper,” “pauser,” “primary-like,” and “on” responses, respectively, as defined in in vivo VNLL studies. The results suggest that different responses to acoustic stimulation could be attributed to intrinsic membrane properties of VNLL neurons. Many VNLL neurons responded to stimulation of the lateral lemniscus with excitatory or inhibitory responses or both. Excitatory and inhibitory responses showed interaction, and the output of the synaptic integration depended on the relative strength of excitatory and inhibitory responses. Neurons with an onset-pause firing pattern were more likely to receive mixed excitatory and inhibitory inputs from the lower auditory brain stem.

scholarly journals Does the Type II Glucocorticoid Receptor Mediate Cortisol-Induced Suppression in Pituitary Responsiveness to Gonadotropin-Releasing Hormone?

Endocrinology ◽  
2004 ◽  
Vol 145 (6) ◽  
pp. 2739-2746 ◽  
Author(s):  
Kellie M. Breen ◽  
Catherine A. Stackpole ◽  
Iain J. Clarke ◽  
Andrew V. Pytiak ◽  
Alan J. Tilbrook ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Mineralocorticoid Receptor ◽  
Plasma Cortisol ◽  
Pulse Amplitude ◽  
Suppressive Effect ◽  
Inhibitory Effect ◽  
Gonadotropin Releasing Hormone ◽  
Type I ◽  
Type Ii ◽  
Pulsatile Gnrh

Abstract Stress-like elevations in plasma cortisol suppress LH pulse amplitude in ovariectomized ewes by inhibiting pituitary responsiveness to GnRH. Here we sought to identify the receptor mediating this effect. In a preliminary experiment GnRH and LH pulses were monitored in ovariectomized ewes treated with cortisol plus spironolactone, which antagonizes the type I mineralocorticoid receptor (MR), or with cortisol plus RU486, which antagonizes both the type II glucocorticoid receptor (GR) and the progesterone receptor (PR). Cortisol alone reduced LH pulse amplitude, but not pulsatile GnRH secretion, indicating that it reduced pituitary responsiveness to endogenous GnRH. RU486, but not spironolactone, reversed this suppression. We next tested whether RU486 reverses the inhibitory effect of cortisol on pituitary responsiveness to exogenous GnRH pulses of fixed amplitude, frequency, and duration. Hourly GnRH pulses were delivered to ovariectomized ewes in which endogenous GnRH pulses were blocked by estradiol during seasonal anestrus. Cortisol alone reduced the amplitude of LH pulses driven by the exogenous GnRH pulses. RU486, but not an antagonist of PR (Organon 31710), prevented this suppression. Thus, the efficacy of RU486 in blocking the suppressive effect of cortisol is attributed to antagonism of GR, not PR. Together, these observations imply that the type II GR mediates cortisolinduced suppression of pituitary responsiveness to GnRH.

scholarly journals Type I and Type II Neuron Models Are Selectively Driven by Differential Stimulus Features

2008 ◽  
Vol 20 (10) ◽  
pp. 2418-2440 ◽  
Author(s):  
Germán Mato ◽  
Inés Samengo
Keyword(s):  
Normal Forms ◽  
Type I ◽  
Type Ii ◽  
Neuron Models ◽  
Scale Free ◽  
Differential Stimulus ◽  
Physiological Properties ◽  
Dynamical Properties ◽  
Stimulus Features ◽  
Type Ii Neuron

Neurons in the nervous system exhibit an outstanding variety of morphological and physiological properties. However, close to threshold, this remarkable richness may be grouped succinctly into two basic types of excitability, often referred to as type I and type II. The dynamical traits of these two neuron types have been extensively characterized. It would be interesting, however, to understand the information-processing consequences of their dynamical properties. To that end, here we determine the differences between the stimulus features inducing firing in type I and type II neurons. We work with both realistic conductance-based models and minimal normal forms. We conclude that type I neurons fire in response to scale-free depolarizing stimuli. Type II neurons, instead, are most efficiently driven by input stimuli containing both depolarizing and hyperpolarizing phases, with significant power in the frequency band corresponding to the intrinsic frequencies of the cell.

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.

Comparative surface and ultrastructural views of methylotrophic bacteria by TEM, STEM, SE, and freeze-etch electron microscopy.

1987 ◽  
Vol 45 ◽  
pp. 792-793
Author(s):  
T.A. Fassel ◽  
M.J. Schaller ◽  
M.E. Lidstrom ◽  
C.C. Remsen
Keyword(s):  
Cytoplasmic Membrane ◽  
Structural Features ◽  
Methylotrophic Bacteria ◽  
Type I ◽  
Type Ii ◽  
Membrane Complex ◽  
Oxidation Of Methane ◽  
Methane Oxidizing Bacteria ◽  
Wall Structures ◽  
Methylomonas Albus

Methylotrophic bacteria play an Important role in the environment in the oxidation of methane and methanol. Extensive intracytoplasmic membranes (ICM) have been associated with the oxidation processes in methylotrophs and chemolithotrophic bacteria. Classification on the basis of ICM arrangement distinguishes 2 types of methylotrophs. Bundles or vesicular stacks of ICM located away from the cytoplasmic membrane and extending into the cytoplasm are present in Type I methylotrophs. In Type II methylotrophs, the ICM form pairs of peripheral membranes located parallel to the cytoplasmic membrane. Complex cell wall structures of tightly packed cup-shaped subunits have been described in strains of marine and freshwater phototrophic sulfur bacteria and several strains of methane oxidizing bacteria. We examined the ultrastructure of the methylotrophs with particular view of the ICM and surface structural features, between representatives of the Type I Methylomonas albus (BG8), and Type II Methylosinus trichosporium (OB-36).

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