bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arginine vasotocin, an endogenous neuropeptide of Aplysia, suppresses the gill withdrawal reflex and reduces the evoked synaptic input to central gill motor neurons
Authors: Thornhill J. A. , Lukowiak K. , Cooper K. E. , Veale W. L. , Edstrom J. P. 
Published: January 2005

AbstractThe superfusion (15 min) of arginine vasotocin (AVT; 10−9–10−12M) over the abdominal ganglion of Aplysia californica suppressed the amplitude of the gill withdrawal reflex evoked by tactile stimulation of the siphon, increased the rate of gill reflex habituation, and decreased the evoked synaptic activity to central gill motor neurons. The suppressive effects of AVT on gill reflex behaviors were not due to toxic effects of the hormone since the effects were completely reversible following washout and 3 h rest. The results obtained with AVT were similar to those previously found using the mammalian neuropeptide arginine vasopressin. AVT may act by increasing the activity of central neurons which exert suppressive control over both gill reflex behaviors and evoked activity to central gill motor neurons.
Cerebral motoneurons mediating tentacle retraction in the land slug Ariolimax columbianus
Authors: Chan Christopher Y. , Moffett Stacia 
Published: January 2005

Abstract(1) Tentacle retraction in the land slug Ariolimax columbianus can be elicited by stimulation of all nerves and connectives of the ipsi‐ and contralateral cerebral ganglia. (2) Six neurons in the left cerebral ganglion were classified as tentacle retraction motoneurons because their action potentials are followed one‐for‐one with constant delay by action potentials in the left tentacle retractor nerve and their depolarization causes retraction of the ipsilateral tentacle. The motoneurons can be identified by size, pattern of pigmentation, position, and physiological characteristics. (3) Each retractor motoneuron discharges at a rather constant rate and has more than one source of excitatory input, but no IPSPs were observed. No synaptic connections between the six retractor motoneurons were found. The nerve action potentials that correspond to each motoneurons are distinguishable by waveform and size rank. (4) Each motoneuron elicits visible contractions in a particular region of the ipsilateral retractor muscle, but the motor fields of some motoneurons overlap. Some motoneurons mediate relatively rapid contractions while others cause slower responses. (5) There is one‐for‐one correspondence between action potentials of the largest unit recorded extracellularly in the retractor nerve and exciatory junction potentials recorded from the retractor muscle. No evidence of a peripheral neural plexus was found in serial sections of the retractor muscle.
Na+ ‐ and Ca2+ ‐dependent components in action potentials of the ovulation hormone producing caudo‐dorsal cells in Lymnaea stagnalis (Gastropoda)
Authors: Kits K. S. , Bos N. P. A. 
Published: January 2005

AbstractAction potentials in the afterdischarge of the ovulation hormone producing caudo–dorsal cells (CDC) of Lymnaea stagnalis are strikingly different from electrically evoked spikes in the silent resting and inhibited states of these cells. Spikes evoked in the silent states consist of one fast peak (80–100 mV; 10–15 ms). The overshoot is Na+ ‐ and Ca2+ ‐dependent. Spikes are blocked in Na+ ‐free saline and by TTX. Repolarization is retarded by TEA. Co2+ increases the overshoot. Active state action potentials (60–80 mV) last up to 125 ms, due to activation of a slow component following the TTX‐sensitive spike. The slow component is Na+ ‐ and Ca2+ ‐dependent. In normal saline it is blocked by Co2+ and La3+. In Ca2+ ‐free saline the remaining part of the slow component is blocked by La3+ only. The slow component is voltage‐dependent in a graded fashion. Activation is bound to the active state in which the CDC are depolarized by 20 mV. TEA and Ca2+ ‐free saline greatly increase spike duration in the active state. This suggests that, in addition to the classical TEA‐sensitive channel, a Ca2+ ‐dependent K+ channel is involved in repolarization of active state action potentials. The underlying membrane properties and the functional significance are discussed in relation to the pacemaking mechanism of the CDC.
The rise and fall of pineal N‐acetyltransferase in vitro: Neural regulation in the developing rat
Authors: Brammer Mildred , Binkley Sue , Mosher Karen 
Published: January 2005

AbstractIn rats, the pineal gland has a rhythm in the activity of the enzyme, N‐acetyltransferase (NAT), which is thought responsible for daily cycles of melatonin synthesis. Neonatal rat pineal glands, but not those of adult rats, have a single cycle that is observed in vitro during the first day of organ culture. The neural regulation of the cycle was investigated using neonatal rats with adult rats used for comparison. Prior treatment of rat pups with constant light did not abolish the cycle in vitro though it did abolish the in vivo rhythm. Removal of the superior cervical ganglia did not abolish the in vivo rhythm that was measured the first day after surgery, but ablation of the ganglia did abolish the rhythm if several days or more elapsed after surgery. Extirpation of the superior cervical ganglia abolished the in vitro NAT cycle in pup pineal glands as did the pharmacological equivalent, injection of 6‐hydroxydopamine. Propranolol, a beta blocking agent, prevented the occurrence of the cycle in vitro.
A quantitative study of visual cortex synapses during the postnatal development of dark‐reared rats
Authors: Albanese Alfonso , Albanese Eduardo , Brusco Alicia , Saavedra Jorge Pecci 
Published: January 2005

AbstractThe method of Aghajanian and Bloom (1967) was applied to the visual cortex of normal and neonatally visually deprived rats. The rats were kept with their mothers in total darkness since birth, in a ventilated and temperature‐controlled animal quarter. Controls were rats from the same stock, maintained in a regular 12‐h‐light/12‐h‐dark rhythm. The animals were killed at 15, 23, 40, and 65 days of age, and the visual cortices fixed in 4% glutaraldehyde and processed for electron micrography with ethanol‐phosphotungstic acid. A total of 6249 synaptic profiles were counted and their numerical density (DS) determined in both conditions. Features of the presynaptic grid were used for classifying the synaptic profiles in: type A [with one presynaptic dense projection (PsDP)]; type B (with two or three PsDPS); and type C (with four or more PsDPS). In the visually deprived rats the DS increases with a rate similar to controls, but the values for each age are slightly lower (P > 0.01). Type B synapses predominate in the visually deprived group while types A and C are scarcer. The differences found between types were maximal at 65 days of age and the results were highly significant (P > 0.001). It is concluded that major effects of dark‐rearing are manifested when the individual features of the presynaptic grid are considered. It seems that a selected population of synapses is affected by the alteration of the normal epigenetic influence of early visual experience.
A neurochemical description of the dopaminergic innervation of the stomatogastric ganglion of the spiny lobster
Authors: Kushner Pinky Drosten , Barker David L. 
Published: January 2005

AbstractThe spiny lobster stomatogastric ganglion has been shown to be innervated by catecholaminergic processes which derive from cells of large central ganglia (Kushner and Maynard, 1977). Biochemical evidence had indicated that the stomatogastric system synthesizes dopamine and not norepinephrine from tritiated tyrosine (Barker, Kushner, and Hooper, 1979). Studies reported here document that the stomatogastric ganglion itself contains dopamine, as measured with a sensitive endogenous assay. Moreover, the ganglion can synthesize dopamine from tritiated tyrosine or DOPA. Additionally, when incubated in tritiated dopamine, the ganglion takes up dopamine and protects it from degradation; this process is inhibited by cocaine. When incubated with 3H‐tyrosine, small but measurable amounts of tritiated dopamine were detected in the medium surrounding the ganglion.
Serotonin‐activated adenylate cyclase and the possible role of cyclic amp in modulation of buccal muscle contraction in aplysia
Authors: Ram Jeffrey L. , Gole Dilip , Shukla Umesh , Greenberg Laurence 
Published: January 2005

AbstractThe possible role of cyclic AMP in mediating opposite modulatory effects of serotonin (5‐HT) on Aplysia buccal mass muscles E1 and E2 was examined. Serotonin enhances E1 contractions and inhibits E2 contractions. Adenylate cyclase in membranes of both E1 and E2 is stimulated approximately 180% by 10−6M 5‐HT and 300% by 10−3M 5‐HT. Dibutyryl cyclic AMP and 8‐benzylthio cyclic AMP mimicked the effect of 5‐HT on E1 but had no effect on E2. Theophylline (Th) and isobutylmethylxanthine (IBMX) mimicked the effect of 5‐HT on E1 at high concentrations. Concentrations of Th and IBMX low enough not to have any direct effect on contraction increased both the magnitude and duration of the effect of 5‐HT on E1 contraction. Neither Th nor IBMX had a direct effect on E2 contraction, although Th produced a small increase in the effect of 5‐HT on E2. These data are consistent with the hypothesis that cyclic AMP mediates the enhancement effect of 5‐HT on E1 contraction. Other mechanisms probably mediate the effect of 5‐HT on E2 contraction.
Defense posture and leg‐position learning in a primitive insect utilize catchlike tension
Authors: Hoyle Graham , Field Laurence H. 
Published: January 2005

AbstractThe capability for conditioning of leg position, using loud sound as an aversive natural reinforcement, was examined in a primitive New Zealand insect, the weta (Orthoptera: Stenopelmatidae). Electromyographic recordings were made during the conditioning. A majority of wetas tested came to occupy stably a metathoracic tibial position window, coupled to turning off the sound, set in either flexion or extension away from the preferred rest position. Steady tensions of up to 7 g in extension and 5 g in flexion were produced. However, no electromyographic activity accompanied the tension. It is concluded that the insects are using a peripheral catchlike mechanism to adjust posture.
The effects of salines and fixatives upon the size of an identified neuron
Authors: Wilson John A. , Phillips Christine E. , Steinbrecht R. A. , Müller B. 
Published: January 2005

AbstractBecause accurate neuronal dimensions are essential for mathematical modeling of neuronal properties, the effects of a number of salines and fixative procedures on neuronal size were compared, including the non‐chemical, freeze substitution method. Using an identified neuron we compared diameters and found some of the fixative‐saline combinations caused shrinkage by as much as a factor of four from our best estimates of the in vivo size from the quick frozen preparations. A glutaraldehyde based fixation procedure was found which gives results in good agreement with the frozen tissue.
Differential backfilling of interneuron populations based upon axon projections in a lobster abdominal ganglion
Authors: Jones Kenneth A. , Page Charles H. 
Published: January 2005

AbstractIntersegmental interneurons in the lobster second abdominal ganglion were differentially stained by simultaneously backfilling their axons in the anterior and posterior hemiconnectives with nickel and cobalt ions. When precipated with rubeanic acid the nickel and cobalt formed different colors in the cell bodies depending upon the location of the axon(s) in the connectives. In the most completely stained preparations 55 ascending, 56 descending, and 25 bidirectional interneurons were observed. Soma diameters ranged from 157ndash;120 μm. One of the somata was located in the connective. The differential staining technique has advantages over conventional backfilling techniques for examining the morphological relationships of populations of neurons having different axon projections.
Leg position learning by an insect. I. A heat avoidance learning paradigm
Authors: Forman Robin R. 
Published: January 2005

AbstractA new learning paradigm which employs a natural aversive stimulus, tightly constrains learned behavior and demonstrates learning in individual animals is described. Locusts were restrained so that only the femoro‐tibial joint of a single metathoracic leg was free to move. Animals were required to maintain a particular range of femoro‐tibial joint angle to avoid heating of the head. The position of the tibia was sampled by an on‐line computer which set the limits of joint angle and controlled the aversive stimulus while storing data for further analysis. Control animals received patterns of aversive stimuli identical to those received by experimental animals but independent of their own joint position. Quantitative evaluation of the learned behavior of individual animals allowed the identification of three different behavioral strategies by which learning was achieved.
Proprioceptor distribution and control of a muscle reflex in the tibia of spider legs
Authors: Seyfarth Ernst‐August , Pflüger Hans‐Joachim 
Published: January 2005

AbstractIn spiders, retrograde cobalt staining was used to clarify the distribution and detailed innervation of the three types of proprioceptors in the tibiometatarsal leg joint: internal joint receptors, lyriform slit sense organs, and cuticular spines and hairs. The axons of all these receptors run in just two lateral, ascending nerves, which had previously been associated only with the internal receptors. Each nerve contains several hundred axons ranging in diameter from 0.1 μm to ca. 10 μm. Each slit of the four tibial lyriform organs is innervated by two bipolar sensory neurons. The lateral nerves are entirely sensory and run just beneath the cuticle, a convenient site for electrophysiological recording. We demonstrate simultaneous nerve and muscle recordings from intact spiders; these, in combination with selective sensory ablations, show that a resistance reflex in the flexor metatarsi muscles is elicited by internal joint‐receptor units.
Generation of specific behaviors in a locust by local release into neuropil of the natural neuromodulator octopamine
Authors: Sombati Sompong , Hoyle Graham 
Published: January 2005

AbstractThe natural insect neuromodulator octopamine (OCT) was released iontophoretically into regions of neuropil in locust metathoracic ganglia. A narrowly‐defined site was found on one side of the ganglion at which release caused a prolonged bout of repetitive flex‐extend‐flex movements of the tibia on the injected side, at a frequency of from 2–3.5 Hz. When a bout had terminated, repetition of the OCT release caused an extremely similar bout to occur, and again with further treatments, indefinitely. OCT iontophoresis at the equivalent site on the contralateral side caused the contralateral flexor to make stepping movements. Two sites were found, in each half of the ganglion, at which similar OCT release evoked a bout of flight motor activity at 10 Hz. The flight bout involved both sides synchronously and nearly equally, except for a slightly greater motor output on the injected side. Evoked bouts lasted from 20 sec to 25 min depending on the preparation and amount of OCT released. At a site in the 6th abdominal ganglion of mature female locusts OCT release suppressed ongoing rhythmic oviposition digging evoked by severing the ventral nerve cord. A number of previously undescribed DUM neurons was encountered and their dendritic patterns, which are distinctive, determined following dye injection. A hypothesis, termed the Orchestration Hypothesis is presented, which considers how modulator neurons such as locust octopaminergic neurons, might be involved in the generation of specific behaviors.
Glutamatergic central nervous transmission in locusts
Authors: Sombati Sompong , Hoyle Graham 
Published: January 2005

AbstractIt is generally believed that neural transmission in the central nervous systems of insects is cholinergic, on the basis of secondary evidence: the presence of cholinesterase, and sensitivity of a nonsynaptic region of the neuron, its cell body, to iontophoresed acetylcholine. In the present work a preparation has been developed which takes advantage of the availability of identified motor neurons in the locust metathoracic ganglion with known 3‐dimensional geometry of dendritic fields. These neurons transmit at their peripheral neuromuscular junctions with glutamate. The fast extensor tibiae motor neuron also makes excitatory central connections onto its functional antagonists the flexor tibiae motor neurons. Unless Dale's principle is contravened, transmission at these central synapses should also be glutamatergic. This transmission onto flexor motor neurons was found to be attenuated 70% by a glutamatergic blocker. Glutamate iontophoresed into selected areas of neuropil into which the motor neurons have dendritic branches caused the neurons to be depolarized, in a dose‐dependent manner. Individual motor neurons were directly excited to spike with suprathreshold iontophoretic current. With long durations of release they were desensitized, but recovered quickly with rest. The data provide evidence that central transmission onto motor neurons in the locust metathoracic ganglion is glutamatergic.
Dorsal unpaired median neurons of the cockroach metathoracic ganglion
Authors: Arikawa Kentaro , Washio Hiroshi , Tanaka Yoshitaka 
Published: January 2005

AbstractOn the dorsal surface in the metathoracic ganglion of the cockroach Periplaneta americana, eight large and a number of small somata described by Crossman et al., (1971) were reexamined. These eight large cells (40–60 μm in diameter) could be divided into three different types by Lucifer yellow or nickel injection, depending on the branching of their axons. No neuron was found which sent axons into either the anterior or posterior connectives. In the mesothoracic ganglion an interganglionic H‐shaped DUM neuron was found which had four axons, one into each anterior and posterior connective.
Control of swimming in the hydrozoan jellyfish Aequorea aequorea: Direct activation of the subumbrella
Authors: Satterlie Richard A. 
Published: January 2005

AbstractThe epithelial cells that overlie the inner nerve ring of the hydrozoan jellyfish Aequorea aequorea were investigated ultrastructurally and electrophysiologically. The structurally unspecialized epithelial cells are interconnected by gap junctions and are electrically active during swimming as a single, long‐duration action potential was recorded during each swim contraction. Intercellular electrical‐ and dye‐coupling was demonstrated within the epithelial region extending into the velum and subumbrellar regions.Excitatory post‐synaptic potentials were recorded from epithelial cells following swim motorneuron spikes with a short latency. Psps were up to 60 mV in amplitude and, when triggered in bursts, showed summation provided the interpulse interval was less than 25–35 ms. The initial psp in each of a series of bursts showed facilitation with the first few swim contractions following a period of inactivity. In actively swimming medusae, psp amplitude was relatively constant. The reversal potential for epithelial psps was estimated at between 0 and +20 mV.Spontaneous psps spread throughout the epithelial region electronically, but the amplitude decrease with conducting distance was less than that for current pulses injected into individual epithelial cells. This presumably represents the effect of widespread synaptic activation of epithelial cells via multiple input sites throughout the inner nerve ring as opposed to point‐source input in current injection experiments.During a radial response, action potential amplitude was decreased and rise time increased due to decremental conduction through the inhibited region. It is postulated that conduction of a full action potential requires that electrotonic current spread from adjacent, active epithelial cells occur in synchrony with synaptic input from swim motoneurons.
Chronic exposure to lead causes persistent alterations in the electric membrane properties of neurons in cell culture
Authors: Scott Brian , Lew James 
Published: January 2005

AbstractThe effects of chronic lead (Pb) exposure on neuronal electric membrane properties (EMP) were determined using neural cell cultures of adult mouse dorsal root ganglia (DRG). Cultures were exposed to Pb concentrations ranging from 0 to 100 μM for 12 days (8 DIV to 20 DIV). EMP were determined in Pb‐free medium either immediately after withdrawal (IWD), or 6 days after withdrawal (6WD) from Pb.For IWD, regression analysis indicated that a number of EMP varied significantly with increasing Pb concentration. The largest such change occurred for electrical excitability which decreased significantly with increasing Pb (P = 0.000), being reduced by approximately two‐thirds for neurons exposed to 100 μM Pb; resting membrane potential increased with Pb (P = 0.000); membrane time constant decreased with Pb (P = 0.007); action potential afterhyperpolarization decreased with Pb (P = 0.023). There was also evidence that the time course of action potentials was accelerated with increasing Pb concentrations, the rate of fall of neurons with biphasic falling phases being particularly increased (P = 0.047). This general pattern of altered EMP was observed for the 6WD condition also, indicating that chronic exposure to Pb caused persistent abnormalities in neuronal membranes even after 6 days of cultivation in Pb‐free medium.The patterns of alterations in EMP suggested that chronic Pb exposure caused a prolonged increase in potassium permeability. It was proposed that the latter was mediated through a Pb‐induced increase in intracellular ionic calcium and the associated disruption of calcium homeostasis.
Effects of octopamine, dopamine, and serotonin on production of flight motor output by thoracic ganglia of Manduca sexta
Authors: Claassen Dale E. , Kammer Ann E. 
Published: January 2005

AbstractEffects of biogenic amines on a centrally generated motor pattern in Manduca sexta were examined by pressure injecting nanomole to micromole amounts of octopamine, dopamine or serotonin into thoracic ganglia. Motor output was recorded extracellularly from a pair of antagonistic flight muscles and their motor neurons. The monoamines were found to alter production of a motor pattern that produces rhythmic wing flapping (10 Hz) and exhibits phase relationships similar to those in the flight pattern of intact moths.In mesothoracic ganglia with sensory nerves intact, octopamine (4 × 10−9 mol) injected into lateral regions evoked regular firing of a single motor neuron, whereas a higher dose (4 × 10−8 mol) often elicited the flight motor pattern. In the absence of sensory input, these doses of octopamine had little effect. Low doses (10−10 mol) greatly enhanced motor responses to electrical stimulation of a wing sensory nerve.Dopamine (2 × 10−10 mol) injected into the medial region of the mesothoracic ganglion elicited the flight motor pattern in the presence or absence of sensory input. Rhythmic output induced by dopamine (5 × 10−10 mol) was suppressed by injecting serotonin (5 × 10−10 mol) into the same region.These findings demonstrate that dopamine, octopamine, and serotonin have different effects on motor output in Manduca and suggest that these amines are involved in initiating, maintaining and terminating flight behavior, respectively. Octopamine may elicit flight production by enhancing the efficacy of sensory transmission thereby increasing excitability or arousal. Dopamine may act on interneurons involved in generating the flight motor pattern.