bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some observations on habituation of the flexor reflex in the rat: The influence of strychnine, bicuculline, spinal transection, and decerebration
Authors: MacDonald J. F. , Pearson J. A. 
Published: January 2005

AbstractThe involvement of inhibition in habituation of the flexor reflex was investigated in intact, spinal, and decerebrate rats. Strychnine and bicuculline were administered in order to determine the contribution of certain forms of central inhibition to the development of habituation. Both strychnine and bicuculline reduced habituation in the intact rat but did not do so in the spinal preparation. Strychnine, in fact, caused a facilitation of habituation in the spinal rat. The impairment of habituation by strychnine was related to the intensity of stimulation used to elicit the reflex. Thus, the effect of strychnine was only demonstrable when relatively high intensities were used. Flexor reflex habituation was shown to be more pronounced in the decerebrate than in the spinal preparation. This difference could be demonstrated only when stimuli of high intensity were given. It is concluded that, in the absence of supraspinal influences, habituation of the flexor reflex does not require inhibitory mechanisms. However, inhibition may play a role in habituation of the component of the reflex that utilizes descending influences.
Motor innervation of the pharynx levator muscle of the snail, Helix pomatia: Physiological and histological properties
Authors: Peters M. 
Published: January 2005

Abstract
(1) Motor innervation of the pharynx levator muscle of Helix pomatia was investigated with intracellular recording and axonal iontophoresis of cobalt chloride.
Muscle fibers respond to direct electrical stimulation of the muscle with active graded responses or non‐overshooting spike potentials.
Each fiber is innervated via the external and internal lip nerves by several (mostly 3) excitatory nerve fibers each. Two types of EPSPs can be distinguished according to amplitude, duration, and facilitation.
Axonal CoCl2‐staining via an external lip nerve branch revealed many nerve fibers entering the muscle and branching there into a rich network of blebbed fibers of various diameters.
The structure and function of serially homologous leg motor neurons in the locust. II. Physiology
Authors: Wilson John A. 
Published: January 2005

AbstractSimultaneous intracellular recordings were made from pairs of motor neurons in the pro‐ or mesothoracic ganglion of the locust. Though central connections were sought between pairs of motor neurons, none were found. This is in sharp contrast to the findings that flexor and extensor tibiae neurons in the metathoracic ganglion make certain connections between themselves (Hoyle and Burrows, 1973; Heitler and Burrows, 1977a). As the previously mentioned authors believed that the metathoracic flexor‐extensor connections were used as part of the motor program for jumping and kicking, the present results strongly support their hypothesis.Common PSPs have been found in a variety of pairs of motor neurons. Of note are common PSPs of the same sign to antagonists. Different innervation patterns have been found for the flexor and extensor muscles.It is proposed that serially homologous motor neurons serving similar functions are, to a first approximation, similar in the locust. Serially homologous motor neurons serving different functions will, in most cases, have altered structures and/or functions.
Catecholamine‐rich cells and varicosities in bovine splenic nerve, vesicle contents and evidence for exocytosis
Authors: Thureson‐Klein Åsa , Klein Richard L. , Johansson Olie 
Published: January 2005

AbstractThe bovine splenic nerve trunk contins mast cells, ganglion cells, small intensely flurescent (SIF) cells, and varicosities which exhibit a brilliant fluorescence characteristic for noradrenaline (NA) and dopamine (DA) after formaldehyde exposure. All these catecholamine‐rich structure could contribute particles to isolated nerve vesicle fractions. Mast cells are recognized ultrastructurally by their large (300–800nm) dense granules. SIF cells may be represented by cells and processes containing dense cored vesicles (120–140 nm) which are larger than the typical vesicles in axons and terminals. Terminal‐like areas with typical large dense cored vesicles (LDV, 75 nm) and small dense cored vesicles (SDV, 45–55 nm) probably correspond to the fluorescent varicosities. The LDV constitute about 40% of all vesicle in terminal‐like areas and terminals. Their staining properties indicate the presence of protein, phospholipids, and ATP. Tyramine depletes NA without loss of matrix density. The LDV can fuse with the terminal membrane, and released material outside omega profiles is interpreted to depict exocytosis. Large and small vesicles are easily distinguished from the very large mast cell granules and the moderately dense Schwann cell vesicles. Neither appear to contaminate the LDV fractions but the latter may contain a small population of SIF cell vesicles. Golgi vesicles from the Schwann cells mainly occur in the lighter zones of the gradient.
Primitive nervous system: Electrophysiology of inhibitory events in flatworm nerve cords
Authors: Koopowitz Harold , Keenan Larry , Bernardo Kerry 
Published: January 2005

AbstractEvoked potentials from the major longitudinal nerve cords of Notoplana acticola are potentiated if the preparation is decerebrated or if certain nerves in the ventral submuscular plexus are severed. Concomitant with an increase in amplitude of the response (in some preparations over fourfold) is a decrease in latency of the response and a decrease in the threshold stimulus intensity needed to evoke activity. Evoked activity can also be depressed with moderate increases in stimulus intensity and is induced some distance from the recording site. The depressant effects can be lifted if the brain is bisected, if the contralateral nerve VI is severed close to the brain, and if the commissures between the two nerves VI are cut. The depressant effects of nerves V and VI are additive. Depression and the subsequent lifting of the inhibition occur in Ringer baths containing either normal sea water or equal mixtures of sea water and isotonic MgCl2. The possibility of inhibitory synapses immune to high concentrations of magnesium ions is discussed.
Multiple innervation of purkinje cells by climbing fibers in the cerebellum of the adult staggerer mutant mouse
Authors: Mariani Jean , Changeux Jean‐Pierre 
Published: January 2005

AbstractIntracellular recordings from Purkinje cells (PC) in the cerebellum of adult staggerer mutant mice revealed that the orthodromic response of PCs to juxtafastigial (JF) stimulation closely resembled a climbing fiber response (CFR). However, for most of the PCs studied, these responses were graded in a stepwise manner when the stimulus strength was increased. The underlying excitatory synaptic potentials (EPSPs) had the typical shape of EPSPs mediated through climbing fibers (CFs), but their size fluctuated in discrete steps, the highest one reaching the firing level. In the same PCs, the size of the spontaneous EPSPs fluctuated in a similar fashion and the frequency of each step was in the range of CF‐mediated EPSPs. These results strongly suggest that in staggerer mice several CFs synapse with each PC instead of a single CF as in normal adults. Furthermore, the activation through some of these CFs does not reach the firing level of the corresponding PC.
Calmodulin in mammalian nerve
Authors: Iqbal Zafar , Ochs Sidney 
Published: January 2005

AbstractCalmodulin, a calcium‐dependent regulatory protein has been isolated from mammalian nerve. The protein has similarities to the calcium‐binding protein earlier shown to be transported at a fast rate in the nerve fibers. The implication is that calmodulin, which has been shown to be involved in various key cellular processes, may have a relation to axoplasmic transport.
Heterogeneity of excitatory synapses at the ends of single muscle fibers in lobster, Homarus americanus
Authors: Meiss D. E. , Govind C. K. 
Published: January 2005

AbstractCrustacean neuromuscular synapses arising from a single excitor axon are known to be well differentiated among different muscle fibers but little is known about their condition along single fibers. Focal recording techniques were used to examine the quantal transmitter release and facilitation properties of synapses in the single excitatory innervated distal accessory flexor muscle of the lobster, Homarus americanus. Synapses were reliably differentiated with respect to quantal output so that those located near the tendon end were 1.15–4.12 times greater than those at the opposite, exoskeletal end (p < 0.01, paired t‐test). Regional differences were also seen in the amount of facilitation determined from twin pulse experiments. The fine structural basis for these differences was determined by serial section electron microscopy of 10‐μm segments at each end to ensure that the area of focal recording was sampled. No quantitative differences were found in the terminals or synapses in the two regions. Instead, the physiological diversity was correlated with number and size of presynaptic dense bars. Thus, the tendon end had a greater number and larger mean surface area of dense bars compared to the exoskeletal end. This heterogeneity of excitatory multiterminal innervation is correlated with the axonal branching pattern. Thus, the main axon and the larger primary axon branches lie in close proximity to the tendon end of the muscle fibers, whereas the exoskeletal end is innervated by smaller secondary and tertiary axonal branches. This proximity to the large axonal branches of the higher quantal output synapses at the tendon end may be regulated by some neural influence including a timing of innervation and/or access to greater amounts of metabolites in the larger branches which may be conducive to forming high‐output synapses.
L‐Proline as a glutamate antagonist at a crustacean neuromuscular junction
Authors: van Harreveld A. 
Published: January 2005

AbstractThe fast as well as the slow contractions of the adductor muscle in the claw of Procambarus clarkii are inhibited by L‐proline. This inhibition is dose dependent and decreases with increasing frequency of stimulation of the “slow” fiber. Contractions caused by perfusing the adductor muscle with L‐glutamate solutions are also inhibited by L‐proline. The inhibiting potency of L‐proline is small; the effective concentration of this amino acid is 50–100 times that of the L‐glutamate applied. It was postulated that the inhibitory effect of L‐proline is based on competition for excitatory receptor sites of L‐glutamate, which causes depolarization and contraction, and L‐proline, which lacks these actions. Theoretical considerations suggested a linear relationship between the stimulating L‐glutamate and the just‐inhibiting L‐proline concentrations. Experimental evidence supported this model.
Axonal transport: A quantitative study of retained and transported protein fraction in the cat
Authors: Muñoz‐Martínez E. J. , Núñez R. , Sanderson A. 
Published: January 2005

AbstractThe fast axoral transport of proteins was studied in the cat sciatic nerve after injection of [3H] leucine into the spinal ganglion or the ventral horn of the seventh lumbar segment. The amount of transported proteins after ganglion injection was linearly related to the amount of label present at the ganglion. At variable intervals after ganglion or spinal cord injection, the sciatic nerves were sectioned in some experiments. The transport of proteins continued in the peripheral nerve stump in a wavelike manner, but the advancing wave leaves a labeled trail behind. A fraction of this trail corresponds to proteins moving at slower velocities than thevelocity of proteins in the wave front. Another fraction of the trail corresponds to molecules retained by the axons. Each nerve segment of 5 mm in lenth retains 1.5% of the transported proteins, and the profile of retained proteins along the sciatic nerves follows a single exponential function. From the proportion of retained proteins, the concentration of transported proteins at the terminals of branching axons as a function of the branching ratio was estimated. In the case of motor axons innervating the soleus muscle of the cat, the concentration of recently transported proteins at the nerve terminals would be approximately 0.83% of the proteins leaving the spinal cord. This low concentration of transported proteins at the nerve terminals may explain the lability of neuromuscular synapses when axonal transport is decreased or interrupted.
The shadow response of the cockroach periplaneta americana
Authors: Meyer David J. , Margiotta Joseph F. , Walcott Benjamin 
Published: January 2005

AbstractWe show that the “escape response” (running) of the cockroach Periplaneta americana is interrupted when the insect runs through a shadow. Shadows were cast by holding an opaque plastic sheet so that the cockroach ran beneath it. In control experiments, a similarly positioned clear plastic sheet was ineffective. Removal of the shadow stimulus allowed running to continue. The likelihood that cockroaches would resume running after removal of the shadow stimulus decreased with the time they were allowed to remain in shadow.
Is octopamine a transmitter mediating hormone release in insects?
Authors: Orchard I. , Loughton B. G. 
Published: January 2005

AbstractThe release of hyperlipemic hormone from the glandular cells of the corpus cardiacum (CC) of Locusta migratoria is under the synaptic control of axons in nervus corpus cardiacum II (NCC II). The effects of aminergic agonists and antagonists on the release of the hyperlipemic hormone induced by electrical stimulation of NCC II have been examined. CC isolated from reserpine‐injected locusts did not release hormone when subjected to electrical stimulation of NCC II but continued to release hormone in response to high‐potassium saline. The electrically stimulated release of hormone from isolated CC was abolished by the α‐adrenergic blocking agent, phenoxybenzamine, but potentiated by the ß‐adrenergic blocking agent, propranolol. Phenoxybenzamine did not interfere with release induced by high‐potassium saline. It is suggested that the postsynaptic receptors on the glandular cells are similar to the β‐adrenergic receptors of vertebrates. Octopamine was found to be present in the glandular lobe of the CC at concentrations of 0.62 pmole per gland pair. Reserpine depleted the content to 0.3 pmole per pair. Bathing the CC in 10−7 M octopamine resulted in the release of hyperlipemic hormone, and this release was blocked by phenoxybenzamine. It is concluded that the neurotransmitter involved in the synapse between axons of NCC II and the cells releasing hyperlipemic hormone is aminergic, possibly octopaminergic. Octopamine may well be a transmitter mediating hormone release in insects.
The effect of antiserum to S 100 protein on behavior and amount of S 100 in brain cells
Authors: Hydén H. , Lange P. W. 
Published: January 2005

AbstractSince antiserum raised against the S 100 protein has an impairing effect on acquisition in behavioral tests, when interacting with S 100 on hippocampal cells, the effect of S 100 antiserum was studied in rats on the S 100 content of the hippocampus and thalamus, as well as on behavior. The operant reversal of handedness test and a light discrimination test were used. S 100 antiserum, 2 × 30 μl, was injected intraventricularly before and during the sessions of two different learning tests. The S 100 protein was determined by quantitative immunoelectrophoresis. In the antiserum‐injected animals, the levels of S 100 protein was increased by up to 30%, the incorporation values of 3H‐valine increased in proteins of high molecular weight. Further acquisition was inhibited compared to controls, in which antiserum absorbed with pure S 100 protein was injected intraventricularly. The stimulation of S 100 synthesis, probably by the glia, may have occurred by a negative feedback effect, as has been observed in thymocytes.
Organization of motor neurons to a multiply innervated insect muscle
Authors: Phillips Christine E. 
Published: January 2005

AbstractNine excitatory motor neurons have been identified as innervating the locust metathoracic flexor tibiae. The anatomical organization of the flexor motor neurons within the ganglion was examined with both light and electron microscopy. Flexor motor neurons were physiologically identified prior to intracellular staining with Procion or cobalt. Some of the cobalt‐stained neurons were then silver intensified. The reliability of soma location and variability of neurite branching were examined. While the position of a soma could vary within its cluster by up to one radius, the anterior, posterior, and lateral soma clusters bore a consistent relationship to each other. The density of neurite branching varied greatly for any particular flexor. The ultrastructure of the tract containing the flexor neurites revealed the individual neurites to be glial wrapped, while the tract itself was isolated from the neuropil by additional glia. The hypothesis that subsets of the flexor motor neuron pool are recruited for different behaviors is discussed in light of the last two findings.
Effects of furosemide on neural mechanisms in aplysia
Authors: Scappaticci Karen A. , Dretchen Kenneth L. , Carpenter David O. , Pellmar Terry C. 
Published: January 2005

AbstractThe effects of furosemide on action potentials and responses to several neurotransmitters have been studied in the neurons of Aplysia. Furosemide (10−7 and 10−3M) does not visibly affect the normal action potential in R15 neurons. However, when TTX (30μM) is used to block the sodium component in R15, the remaining spike (presumably the calcium component) is increased in amplitude in the presence of furosemide. Furosemide also alters transmitter‐induced conductances. Furosemide greatly reduces the amplitude and shifts, in a depolarizing direction, the reversal potential of chloride‐dependent responses to γ‐aminobutyric acid (GABA) and acetylcholine (ACh). This suggests that furosemide both blocks the chloride channel and inhibits a chloride pump. ACh‐induced sodium responses were also reduced by furosemide but to a lesser extent than chloride responses. The potassium response to ACh and a voltage‐dependent calcium response to serotonin were not altered. These results indicate that furosemide could alter synaptic responses both presynaptically by enhancement of calcium flux during the action potential and postsynaptically by blockade of chloride and sodium conductances.
Mechanical properties of a slow muscle in the cockroach
Authors: Chesler Mitchell , Fourtner Charles R. 
Published: January 2005

AbstractThe mechanical properties of the metacoxal muscle, 177d, in the cockroach, Periplaneta americana, was investigated. The muscle exhibited a mean resting tension of 2.6 ± 1.3g SD. Neurally evoked tension summed with the resting tension and the relaxation phase of the evoked tension varied from less than 1 s to several minutes. This residual tension varied not only in duration but also in amplitude. Stimulation of inhibitory axons increased the rate of relaxation and thereby abolished the residual tension. However, inhibitory stimulation never reduced the resting tension. Stimulation of the main leg nerve at several times the threshold of the inhibitory axons could evoke residual tension. Recording of synaptic potentials from the two histochemically different fiber types (dorsal and ventral groups) revealed large hyperpolarizations in the ventral fibers and decreased duration and amplitude of excitatory potentials in the dorsal fibers. These results suggest that there are a variety of ways in which tension can be evoked, maintained, and controlled in these muscles.
Increased effectiveness of a motorneuron after partial denervation of its target muscle in the cricket Teleogryllus oceanicus
Authors: Donaldson P. Lynn , Josephson Robert K. 
Published: January 2005

AbstractFibers of the metathoracic extensor tibia muscle of the cricket Teleogryllus oceanicus are innervated by a slow excitatory axon (slow fibers), a fast excitatory axon (fast fibers), or by both slow and fast axons (dual fibers). Sectioning metathoracic nerve 5 removes the fast axon input to the muscle but not that of the slow axon. Following such partial denervation, the mechanical responses initiated by the slow axon increase progressively for at least 30 days; twitch tensions reach 5–10 times those of control muscles and tetanic tensions 10–30 times control values. After sectioning nerve 5, resting membrane potentials decrease in those fibers which originally received fast axon input and the input resistance of all fiber types increases, including that of slow fibers which are not innervated through nerve 5. Excitatory junctional potentials (EJPs) initiated by the slow axon become larger following partial denervation, accounting in part for the larger contraction amplitudes. The increased input resistance is adequate to account for the larger EJPs in slow fibers but not for the proportionally greater increase in EJP amplitude in fibers which were formerly dually innervated. The change in EJP amplitude is abrupt in slow fibers and gradual in formerly dual fibers.
Dynamic analysis of cockroach giant interneuron activity evoked by forced displacement of cercal thread‐hair sensilla
Authors: Buño W. , Crispino L. , Monti‐Bloch L. , Mateos A. 
Published: January 2005

AbstractThis investigation involved extracellular recordings of cockroach abdominal giant interneuron (GI) action potentials evoked by cercal “threadlike” hair sensilla (THS) stimulation with a galvanometric device, by controlled displacements of about seven THS. Small and large GIs, distinguished by their amplitudes, were studied simultaneously. Only the small GIs were spontaneously active. Responses to sine, pulse, and ramp stimulation of sensilla produced phasic responses in both GI types. Some GIs were directionally sensitive and had shorter response latencies in the direction of best sensitivity while others were omnidirectional. Contralateral stimulation decreased responses to homolateral stimuli. In experiments using paired pulses (less than 50‐ms intervals) there is a period of hyperexcitability, in large GIs, in which the response to the second stimulus is greater. Repeated stimulation caused an exponential decline in the response which was steeper in all GIs at higher stimulating frequencies and had a faster time course in large GIs. Because of this last property GIs function as low‐pass filters limiting the flow of information, with large GIs having a lower frequency “cutoff” than smaller GIs.
Physiology and in situ identification of putative aminergic neurotransmitters in the nervous system of Gyrocotyle fimbriata, a parasitic flatworm
Authors: Keenan Larry , Koopowitz Harold 
Published: January 2005

AbstractThe longitudinal nerve cords (LNC) in Gyrocotyle fimbriata do not change their activity in response to catecholamines but are excited by the amino acids glutamate and aspartate at concentrations less than 10−5M. This activity can be blocked by application of 2‐amino‐4‐phosphonobutyrate (APB), an aminergic blocking agent. In situ measurements of fluorescent spectra from LNC neurites have a λmax at 513.6 nm. Treatment with HCl shifts the peak to 510 nm. Both glutamate and aspartate fluoresce and behave similarly with peak emissions of 512.5 nm before HCl treatment and 511 nm and 509 nm, respectively, after treatment. Dopamine and norepinephrine both fluoresce at 512.2 nm but the peaks shifts to 516.5 and 528, respectively, following acid treatment. These experiments indicate that the fluorescing substance in the neurons is not a known catecholamine and could be an amino acid.