bluuebunny/crossref_metadata_2025 huggingface dataset:
Dorsal root recording relevant for mating reflexes in female rats: Identification of receptive fields and effects of peripheral denervation
Authors: Kow Lee‐Ming , Pfaff Donald W.
Published: January 2005

Cutaneous receptive fields of dorsal roots T11 through S3 in rats were mapped by recording dorsal root multiple unit activity. The receptive fields, having the shape of transverse bands on the skin, are arranged in order according to their dorsal roots, and there are extensive overlaps between adjacent fields. Routes followed by peripheral sensory innervation of skin were also studied by observing effects of various methods of skin denervation on dorsal root responses to cutaneous stimulation. The results are discussed with respect to the somatosensory control of female rat mating reflexes.
The site of anoxic block in the spinal monosynaptic pathway
Authors: Carregal Enrique J. A.
Published: January 2005

Asphyxiation of the spinal cord for periods of 2–4 min leads to block of the monosynaptic pathway. At about the same time this blockage takes place, the afferent action potentials fail to invade the presynaptic terminals. Asphyxiation also interferes with the antidromic invasion of motoneurons, and the failure of the antidromic action potentials to invade the motoneuron dendrites coincides with the time of the disappearance of the orthodromic monosynaptic responses. During reoxygenation, both the presynaptic terminals and the dendrites recover their function, or rather their polarization, in a few seconds and yet synaptic transmission reappears only after several minutes. It is postulated that failure of synaptic transmission during asphyxia is due to depolarization of both the presynaptic terminals and the dendrites of the postsynaptic elements. However, repolarization of these elements during reoxygenation, is not sufficient to reestablish synaptic transmission, but recovery of some unidentified biochemical process is apparently necessary.
Dissociation of field potential from neuronal activity in the isolated retina: Failure of the b‐wave with normal ganglion cell response
Authors: Masland Richard H. , Ames Adelbert
Published: January 2005

The b‐wave of the isolated rabbit retina was compared with the ganglion cell response to light before and after modification of the retina's incubating medium. Marked diminution of the b‐wave, with no reduction in ganglion cell response, was observed under three experimental conditions: (1) following a short period of anoxia; (2) following a short period in 0.2 mM Ca++; (3) in a small percentage of preparations, simply as a result of prolonged incubation in control medium. In contrast, a short period in 50 mM K+ led to a parallel fall and parallel recovery of both responses. It is apparent that under selected conditions the field potentials which constitute the b‐wave are poorly correlated with the retina's neural activity.
Integration in the crayfish antennal neuropile: Topographic representation and multiple‐channel coding of mechanoreceptive submodalities
Authors: Taylor Robert C.
Published: January 2005

Response patterns of interneuron populations in the antennal neuropile of the crayfish have been investigated by extracellular recordings made with a single electrode. Mechanical stimuli of the antennae are divided into submodalities and topographically represented. The submodalities include large movements of the entire antenna, directional aspects of movements and vibrations, and vibratory stimulation up to click repetition rates of 100.

Interneuron output is always patterned, ranging from simple bimodal types to complex multimodal patterns that extend over 40 msec. The interneuron output is “noisy” due to short‐ and long‐term fluctuations in sensitivity producing temporal fluctuations in both output probability and output patterns. The response latencies both within and between populations cluster around several fixed latencies.

The axons of a group of neurons, sensitive to the same submodality, are located together and consequently can be recorded with a single electrode. Responses from the interneurons composing a population are similar in response to nonoptimal stimulation, but are synchronized and of high probability to optimal stimulation.
Temperature‐dependence of rapid axonal transport in sympathetic nerves of the rabbit
Authors: Cosens Barry , Thacker David , Brimijoin Stephen
Published: January 2005

Stop‐flow techniques were used to determine how temperature affected the axonal transport of dopamine‐β‐hydroxylase (DBH) activity in rabbit sciatic nerves in vitro. These nerves were cooled locally to 2°C for 1.5 hr, which caused a sharp peak of DBH activity to accumulate above the cooled region. Accumulated DBH was then allowed to resume migration at various temperatures. From direct measurements of the rate of migration, we found that the axonal transport velocity of DBH was a simple exponential function of temperature between 13°C and 42°C. Over this range of temperatures, the results were well described by the equation: V = 0.546(1.09)T, where V is velocity in mm/hr, and T is temperature in degrees centigrade. The Q10 between 13°C and 42°C was 2.33, and an Arrhenius plot of the natural logarithm of velocity versus the reciprocal of absolute temperature yielded an apparent activation energy of 14.8 kcal. Transport virtually halted when temperature was raised to 47°C, although only about half of the DBH activity disappeared during incubation at this temperature. Another transition occurred at 13°C; below this temperature, velocity fell precipitously. This was not an artifact peculiar to the stop‐flow system since the rate of accumulation of DBH activity proximal to a cold‐block also decreased abruptly when the temperature above the block was reduced below 13°C.
Electrophysiological studies of fetal mouse olfactory bulb explants during development of synaptic functions in culture
Authors: Corrigall William A. , Crain Stanley M. , Bornstein Murray B.
Published: January 2005

Explants of 18‐ or 19‐day fetal mouse olfactory bulb have been maintained in culture for periods up to 5 weeks. Compound action potentials can be evoked in the bulb explants by 1 day in vitro, and by 3–4 days, synaptically mediated slow wave discharges can be demonstrated in bicuculline (10−5 M). The capability of the bulb explants to generate these slow‐wave discharges has also been revealed by the introduction of picrotoxin (10−5 M), d‐tubocurarine (10−4 M) and chloride‐free medium, but not of strychnine (up to 3 × 10−5 M). The data indicate early functional development of inhibitory, as well as excitatory, synaptic systems. In addition, the selective and reversible depression of these slow wave potentials by GABA (1–5 × 10−4 M), but not by glycine (up to 3 × 10−3 M), indicates a GABA‐ergic component in the inhibitory network. Single unit extracellular recordings have been obtained from the presumptive mitral cells which, in culture, are spontaneously active even as early as 1–2 days after explantation. Correlative Bodian silver‐impregnations demonstrate the presence of neurons in these explants which resemble typical mitral cells. Studies of mitral cells using paired stimuli suggest the development in vitro of an inhibitory system analogous to that known to suppress the excitability of their in situ counterparts following orthodromic or antidromic activation. These data, as well as the pharmacological sensitivities of the mitral cells in culture to GABA (5 × 10−4 M) and bicuculline (10−5 M), indicate that granule‐to‐mitral synapses may develop characteristic functions in olfactory bulb explants.
Effects of imprinting on lysine uptake and incorporation into protein in chick brain
Authors: Hambley J. W. , Haywood J. , Rose S. P. R. , Bateson P. P. G.
Published: January 2005

One‐day old chicks were exposed for either 30, 60, or 120 min to an imprinting stimulus or kept in darkness in similar conditions. At the end of this time they were injected peripherally with 14C‐lysine and killed 20 min later. The radioactivity of free lysine and that incorporated into protein was measured; incorporation was found to differ between exposed and dark birds only in the anterior part of the forebrain roof after 60‐min treatment (E/D = 1.25). However, more free radioactive lysine was found in all brain regions of exposed birds at this time. When the specific radioactivity of the free lysine (dpm/nmol lysine) was measured there were no differences between the two types of birds, indicating that the incorporation difference was not due to a change in precursor radioactivity. The use of 14C‐2‐aminoisobutyrate confirmed that even with a nonincorporated amino acid pool size changes still occurred. The greater lysine incorporation in anterior forebrain roof was largely restricted to the cytoplasmic soluble fraction.
Functional development in the mauthner cell system of embryos and larvae of the zebra fish
Authors: Eaton Robert C. , Farley R. D. , Kimmel C. B. , Schabtach E.
Published: January 2005

In the embryonic zebra fish as early as 40 hr after fertilization, the Mauthner cells (M‐cells) initiate an escape response, elicited by tactile‐vibrational stimulation. The initial part of this behavior is similar to the acoustic startle reflex seen during the larval stage which begins at 96 hr. The embryonic response is directional and is followed by a series of strong tail flexures which are more pronounced than those during swimming. In the embryo the M‐cell fired at the beginning of the response and rarely fired again during subsequent contractions; in our experiments the M‐cell did not mediate iterative movements of the tail. The M‐cell system is probably involved in evoked hatching behavior, as the tactile response is sufficient to rupture the egg membrane and allow the animal to escape. The M‐cell sometimes fired spontaneously, which suggests that it might function also in spontaneous hatching behavior which occurs in the absence of phasic stimulation. At 48 hr the M‐cell has morphologically mature synapses on its soma and dendrites, but its cytoplasm is relatively undifferentiated; it has few oriented neurofilaments and no distinct axon hillock. During these stages the extracellular M‐spike is longer in duration and smaller in amplitude than at later times when the cell is more mature morphologically. Our data suggest that long‐term inhibitory control of the M‐cell system begins to function at about the time of hatching. At this time the cell is morphologically mature and is richly supplied with synaptic endings over its soma and dendrites.
Diurnal rhythms in cyclic nucleotide metabolism in Helix nervous system
Authors: Levitan Irwin B. , Treistman Steven N.
Published: January 2005

Concentrations of cAMP (cyclic adenosine 3′,5′‐monophosphate) and cGMP (cyclic guanosine 3′,5′‐monophosphate), in ganglia from the garden snail Helix pomatia, vary considerably over the course of the day. There is a maximum in the concentration of both cyclic nucleotides between 08:00 and 12:00 (lights on 06:00 to 18:00), with the cAMP maximum occurring slightly later than that in cGMP. In addition there can be several smaller maxima in cAMP and cGMP levels; the timing of these can be markedly different from experiment to experiment, with cAMP and cGMP sometimes in and sometimes out of phase with each other. This pattern is observed in Helix which had been activated from the dormant state 4–6 days earlier, but is not present in dormant or in long‐active animals. The cyclic nucleotide rhythm can be seen in ganglia maintained in organ culture, and persists for at least 24 hours after removal of the tissue from the animal. There appears to be little change in the level of basal or Na Fstimulated adenylate cyclase activity in Helix ganglia over the course of the day. On the other hand, both cAMP and cGMP phosphodiesterase activities exhibit rhythms which are consistent with the rhythms in cAMP and cGMP concentrations.
Adult mouse dorsal root ganglia neurons in cell culture
Authors: Scott Brian S.
Published: January 2005

A method has been developed for the long‐term culture of dissociated adult mouse dorsal root ganglia (DRG). Of critical importance to the success of this technique was a three‐hour incubation in collagenase which softened the DRG and permitted gentle dissociation. The morphological and electrophysiological features of the dissociated adult DRG were similar to those observed in previous studies of immature (i.e., embryonic and newborn) DRG in culture and also to those of adult DRG in situ.

With regard to electrophysiological work, the adult DRG neurons are superior to embryonic and newborn neurons because of their larger size and greatly increased survival in culture (no degeneration for first six days, and thereafter a relatively slow decrease). The adult neurons regenerated nerve fibers to an extent comparable to that of immature neurons. Therefore, the adult DRG cultures might be useful to study factors influencing regeneration in the adult mammalian nervous system. The adult cultures might also be useful to investigate factors influencing the aging process.
The dorsal, unpaired, median neurons of the locust metathoracic ganglion
Authors: Hoyle Graham
Published: January 2005

Neurons having large cell bodies in the anterior dorsal median cluster in the metathoracic ganglion of the locust Schistocerca gregaria and the grasshopper Romalea microptera were studied by direct dye injection and reverse filling combined with electrical stimulation and recording. Eight, possibly nine, are of the unpaired type, with a T branch leading into left and right axons that leave the ganglion to terminate in muscles. Another six are probably paired, and may be interneurons. Five of the 8 or 9 unpaired neurons have one axonal branch in both N4 and N5, on both sides: the others have but a single branch. One of the nine, DUMETi, has left and right axons exclusively innervating the jumping muscles, and another, DUMDL, has left and right axons exclusively innervating the dorsal longitudinal flight muscles. Neither the locations, sizes or numbers of somata, nor their locations were as constant as is the case for ordinary ventral motorneurons.
Membrane‐potential‐sensitive dyes for optical monitoring of activity in Aplysia neurons
Authors: Woolum John C. , Strumwasser Felix
Published: January 2005

Two membrane‐associated dyes (WW375 and NK2367) which change their absorption of light when the membrane potential changes have been studied using several preparations from Aplysia. Action potentials are easily observed in nerve trunks (from a number of axons), in bag cell clusters, in some of the larger single cells of the parietovisceral ganglion, and in the optic nerve. Physiological effects of the dyes on the circadian rhythm of activity in the eye are described.
A biochemical comparison of Xenopus laevis and mammalian myelin from the central and peripheral nervous systems
Authors: Quarles R. H. , Sakuragawa N. , Everly J. L. , Pasnak C. F. , Webster H. deF. , Trapp B. D.
Published: January 2005

Myelin purified from the central nervous system of Xenopus laevis contained the same major lipid and protein components as human myelin. However, some minor differences in the myelin proteins were noted. The Xenopus basic protein had a higher apparent mol wt. on sodium dodecyl sulfate gels than the corresponding mammalian protein. The absolute specific activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase in the Xenopus myelin was considerably higher than in mammals. There were differences in the high mol wt. proteins, and the glycoproteins in Xenopus myelin were more heterogeneous than those in mammals. Peripheral myelin from Xenopus sciatic nerve was compared with that from the rat. The lipids in the two types of myelin were similar. There was a major glycoprotein in the Xenopus myelin corresponding to the P0 protein and a basic protein of slightly larger mol wt. than the P1 protein of rat myelin.
Calcium‐dependent increase in spike duration during repetitive firing of Aplysia axon in the presence of TEA
Authors: Horn Richard , Miller Jeffrey J.
Published: January 2005

Repetitive stimulation was studied in the axon of the giant neuron, R2, of Aplysia in the presence of TEA. In 25 or 50 mM extracellular TEA, a plateau develops on the axon spike during repetitive stimulation at frequencies greater than 3/sec. The plateau in extracellular TEA is inhibited by 30 mM CoCl2 or 1 mM CdCl2, and is enhanced by raising the Ca concentration. Intracellular TEA induces a plateau on the axon spike at frequencies less than 1/30sec. This plateau increases in duration with repetitive stimulation at higher frequencies and is inhibited by 30 mM CoCl2 or 1 mM CdCl2. The increase in spike duration during repetitive firing in the presence of TEA is indicative of an increased entry of Ca during the spike train.
Hyperpolarizing potentials induced by Ca‐mediated K‐conductance increase in hamster submandibular ganglion cells
Authors: Suzuki Takashi , Kusano Kiyoshi
Published: January 2005

The mechanisms of three types of hyperpolarizing electrogenesis in hamster submandibular ganglion cells were analyzed with intracellular microelectrodes. These included (1) spike‐induced hyperpolarizing afterpotential (S‐HAP), (2) spontaneous transient hyperpolarizing potential (HP), and (3) the hyperpolarizing (H) phase of postsynaptic potential (PSP). Most of these hyperpolarizing potentials were due to conductance increases and reversed polarity at membrane potential (Em) between −70 and −85 mV, which was close to the K‐equilibrium potential. The average resting potential of ganglion cells was −53 mV. Action potential overshoot increased slightly in high [Ca2+]0 and decreased in low [Ca2+]0. In most neurons action potentials were completely suppressed by 10−7 M tetrodotoxin (TTX). The S‐HAP has an initial component due to delayed rectification and a late component. The late component is enhanced by increasing [Ca2+]0, or by applying Ca‐ionophore (A23187), TEA, caffeine, or dibutyryl cyclic (DBc‐) AMP; it is suppressed by decreasing [Ca2+]0, or by applying Mn2+. Perfusion with Cl−‐free saline reduced membrane potential slightly but did not modify the S‐HAP. Depolarizing pulses also induced hyperpolarizing afterpotential (D‐HAP), similar to the S‐HAP. Spontaneous transient HPs occurred in some neurons at irregular intervals. HPs were insensitive to TTX but were suppressed by Mn2+. Caffeine induced low frequency rhythmic HPs in many neurons, often alternating with periods of repetitive spiking. The PSP was a monophasic depolarizing (D‐) potential in some neurons, but in others the D‐phase was followed by a small H‐phase. Perfusion with A23187, caffeine or DBc‐AMP increased the H‐phase of the PSP. Perfusion with K+‐free saline or treatment with 10−5M ouabain did not abolish the H‐phase of PSPs. These membrane potential‐dependent phenomena appear to be induced mainly by Ca‐mediated K‐conductance increases. This mechanism contributes to the regulation of low‐frequency repetitive firing in submandibular ganglion cells.
Autophosphorylation of chick brain synaptic polypeptides. Phosphorylation of proteins during incubation of intact synaptosomes with 32PO4
Authors: Breithaupt Thomas B. , Babitch Joseph A.
Published: January 2005

Chick brain synaptosomes incorporated phosphate into proteins when incubated in physiological buffer containing energy sources. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that three synaptosomal polypeptides were significantly phosphorylated after 15 sec incubation while at least fifteen polypeptides were active kinase substrates after 15 min incubation. Labeled synaptosomes were hypotonically lysed and separated by centrifugation into soluble, membrane, and mitochondrial fractions. Every fraction exhibited significant phosphate incorporation. Electrophoresis revealed that each fraction had several unique phosphorylated polypeptides and a distinctive phosphorylation pattern. The same polypeptides appear to be labeled whether MgATP was added to synaptic plasma membranes or synaptic plasma membranes were isolated after synaptosomal autophosphorylation.
An endogenous motor program for sand crab uropods
Authors: Paul Dorothy Hayman
Published: January 2005

A stereotyped pattern of spontaneous, rhythmic bursting in motoneurons of three prinicipal uropod muscles in the sand crab Emerita analoga has been recorded from a deafferented chain of the foru most‐posterior abdominal ganglia. This endogenous motor program resembles the electromyogram pattern recorded from return‐stroke and power‐stroke muscles in swimming crabs in that (1) latencies of power‐stroke bursts and burst periods are positively correlated with each other and (2) durations of power‐stroke bursts are brief and mearly invarient. The endogenous program differs from the electromyogram pattern in having longer periods and return‐stroke bursts which are brief and sporadic. The neural oscillator underlying the endogenous motor program, therefore, appears to drive the power stroke. Circumstantial evidence suggests that it may also inhibit return‐stroke motoneurons concurrently with excitation of the power‐stroke excitor.
Primitive nervous systems: Action of aminergic drugs and blocking agents on activity in the ventral nerve cord of the flatworm Notoplana acticola
Authors: Keenan Larry , Koopowitz Harold , Bernardo Kerry
Published: January 2005

Electrically evoked activity in the submuscular ventral longitudinal nerve cords of Notoplana acticola is depressed by GABA and glycine in the presence of high magnesium concentrations. This inhibition occurs with 0.001–0.01 millimolar concentrations of these putative aminergic neurotransmitters and is reversible when washed out. The action of GABA and glycine was reversed nonspecifically by picrotoxin, bucuculline, and strychnine. PTZ (Pentylenetetrazole) was shown to mimic the effects that these blocking agents had on evoked activity when they were tested alone. The release of inhibition by these blocking agents is similar to that of decerebration. Three possible mechanisms responsible for synaptic activity in high Mg2+ concentrations are discussed and the possibility that the effector site of interaction may be the chloride ionophore is explored.
Plasticity of feeding behavior in the opisthobranch mollusc Navanax
Authors: Susswein A. J. , Bennett M. V. L.
Published: January 2005

Several forms of plasticity of feeding behavior were investigated in Navanax. Navanax is a gastropod mollusc which lacks a radula, and ingests prey with suction caused by rapid pharyngeal expansion. Feeding is little affected by handling or posture and is resistant to the noxious stimulus of cutting through the body wall. Feeding is affected by arousal, as shown by a decrease in latency following initial exposure to food. The feeding response also habituates, as shown by an increase in latency when feeding responses are elicited without allowing animals to engulf food. The latency increase is not likely to be due to motor fatigue, since it can be partially reversed by dishabituation with an alternate prey species. Continued feeding causes satiation, as shown by increased feeding latencies and eventual cessation of feeding after a mean weight gain of 42.0% of initial animal weight (N = 12). Another form of plasticity occurs when Navanax are presented with food too large to swallow whole. Navanax either cease to respond after a few presentations, perhaps due to habituation, or maintain suction on the partially swallowed prey for an extended period of time. During extended sucks, the more deeply ingested portions are digested.
Fine structure of an octopaminergic neuron and its terminals
Authors: Hoyle G. , Colquhoun W. , Williams M.
Published: January 2005

The large octopaminergic dorsal unpaired median neuron of the locust that innervates the extensor tibiae muscle, DUMETi, was examined electronmicroscopically. Its soma contains many Golgi complexes apparently making dense‐core vesicles similar to those found in peripheral branches and terminals. There are also larger stores of the dense material in the soma, especially near the exit of the principal neurite, that are not in vesicular form. Since the neurons can readily be penetrated and stimulated by microelectrodes, they form favorable subjects for direct studies of the control of neurosecretion. Preterminal fine branches of the neuron were located in proximal outer bundles of muscle fibers into which they had been traced electrophysiologically. They contain numerous large dense‐core vesicles arrayed in rows near microtubules. These fine branches have a thick layer of collagenous connective tissue between the axon and the muscle fiber. Final terminals have varicosities containing many vesicles, lying inside the outer layers of the sarcolemmal complex of muscle fibers. They do not form synaptic structures. Terminals of another DUM neuron, one that innervates the dorsal longitudinal flight muscles (DUMDL), were similar in detail to those of DUMETi. DUMETi swelled about 20‐fold in cross‐sectional area above a ligature, in a 12‐hr period, indicating that there is an extensive centrifugal flow of material in it, and sprouted a branch.
Axonal transport in rats rendered paraplegic following a single subarachnoid injection of either batrachotoxin or 6‐aminonicotinamide into the spinal cord
Authors: Boegman R. J. Boegman , Albuquerque E. X.
Published: January 2005

Batrachotoxin (BTX) or 6‐aminonicotinamide (6‐AN) when injected into the subarachnoidal space of the lumbar spinal cord block fast axonal transport of 3H‐protein in motor nerves. Axonal transport recovers partially within one day after administering BTX while the effect of 6‐AN lasts for more than 21 days. These observations are discussed in relation to the onset and recovery of membrane depolarization observed in the extensor muscle.
Drosophila clock mutations affect the morphology of a brain neurosecretory cell group
Authors: Konopka Ronald J. , Wells Steven
Published: January 2005

Mutations that eliminate circadian rhythmicity in two species of Drosophila affect the location of cells in a neurosecretory cell group. This is the first example of mutations which affect the morphology of an identifiable cell group in the Drosophila brain.
Control of gill reflex habituation and the rate of EPSP decrement of L7 by a common source in the CNS of Aplysia
Authors: Lukowiak Ken , Peretz Bertram
Published: January 2005

It was found in older Aplysia that the rate of decrement of the EPSP evoked in L7 by repeated tactile stimulation of the gill was dependent on the strength of the applied stimulus and that the rate of decrement paralleled the rate of gill reflex habituation. As the stimulus intensity was increased both rates slowed. In contrast, it was found in young Aplysia that the rate of EPSP decrement and the rate of gill reflex habituation were independent of the strength of the stimulus applied to the gill. Neither rate changed as the stimulus intensity was changed. Moreover, L7's of young animals are more responsive to tactile stimuli applied to the gill than are L7's of older animals and the difference in excitability is not due to any differences in passive membrane properties between the L7's in young and older Aplysia. These findings are fully consistent with and supportive of the proposal that a common neuronal source in the parieto‐visceral ganglion of Aplysia controls the rate of gill reflex habituation, the synaptic input to L7, and the rate of decrement of this input, evoked by repeated tactile stimulation of the gill. Additinally, it was proposed that this common source is developed in completely in the young. As a consequence of this incomplete development, young Aplysia exhibit less adaptability to changing stimulus conditions and, in general, less ability to suppress their behavior. It may thus be possible to study directly developmental changes in the nervous system which act to transform juvenile behavior to adult behavior.
Changes in the composition of labeled protein transported in motor axons during their regeneration
Authors: Bisby M. A.
Published: January 2005

Labeled proteins transported in rat sciatic nerve axons after application of L‐(35S) methionine to motoneuron cell bodies were characterized by SDS‐polyacrylamide gel electrophoresis. During nerve regeneration following a crush injury, changes were observed in the composition of the fast‐transported proteins. The major change was an increase in relative amount of a 18,000‐dalton polypeptide (S2). Less dramatic changes occurred in a 66,000‐dalton polypeptide (N) which also increased, and in a 13,000‐dalton polypeptide (T) which decreased. The increase in S2 and N was significant by three days after injury and all changes were maximal between 7 and 14 days. A return to normal proportions was reached between 21 and 42 days. It is concluded that axonal injury produces, among its other effects, an alteration in the proportions of proteins transported into the axon. It remains to be determined whether these changes are prerequisites for axonal regeneration, or facilitate regeneration, or are incidental to it.
Interommatidial sensilla of the praying mantis: Their central neural projections and role in head‐cleaning behavior
Authors: Zack Sheldon , Bacon Jon
Published: January 2005

The compound eye of the praying mantis is covered with approximately 600 bristles and campaniform sensilla. Their afferents project to the brain, and to the suboesophageal and prothoracic ganglia. Cutting the eye branch of the dorsal tegumentary nerve (DTN), the peripheral nerve innervating the corneal sensilla, makes it impossible to initiate head grooming by tactile stimulation of the eye. This stimulus is a strong releaser of grooming behavior in normal animals. Head grooming can be initiated, after cutting the eye branch of the DTN, by stimulation of the frons (the operation leaves the sensory innervation of this part of the cuticle intact). Frame‐by‐frame analysis of films of head grooming after cutting the nerve reveals a reduction of the speed at which the forelimb is brushed across the surface of the head and eye. The significance of this finding is discussed in terms of a putative feedback loop from the corneal sensilla to the motor neurons controlling the grooming movements.
Action of colchicine on membrane currents and synaptic transmission in Aplysia ganglion cells
Authors: Baux G. , Simonneau M. , Tauc L.
Published: January 2005

The action of colchicine, a drug known to disrupt microtubules, on synaptic transmission and voltage‐dependent phenomena was studied. Colchicine depressed transmission in both cholinergic and noncholinergic Aplysia ganglionic synapses. In some synapses, this effect was partly due to the curare like properties of the alkaloid. Ca2+ currents, analyzed by voltage clamp techniques, were rapidly depressed by intracellular injection of colchicine and more slowly depressed by external application. Injected colchicine acted at much lower concentrations than required extracellularly. The implication of the reduced calcium influx in synaptic transmission is discussed. Colchicine caused a shift in the reversal potential of acetylcholine‐activated chloride channels in a direction consistent with an increased intracellular chloride activity. It was concluded that the wide range of actions of colchicine on membrane properties should be taken into account when this drug is used in biological research.
Vertical motion detectors and their synaptic relations in the third optic lobe of the fly
Authors: Bishop Cynthia A. , Bishop Lewis G.
Published: January 2005

The synaptic relations of the giant vertical cells in the lobula plate of the fly were investigated using electron microscopical procedures and Lucifer yellow dye backfill and injection techniques. Histological features of the giant vertical cells are described. The giant vertical cells are exclusively postsynaptic in the lobula plate. They function to integrate input from dense arrays of chemical synapses and have a wide spatial input from the lobula plate. The giant vertical cells are postsynaptic to perpendicularly occurring cells. There are two classes of cells presynaptic to the vertical cells, one of which contains large dense‐core vesicles. The giant vertical cells are not the only cells postsynaptic to these two classes of perpendicualr cells. A second group of smaller tangential cells, the twin vertical cells, were also found postsynaptic to many of the same cells that synapsed with the giant vertical cells. The twin vertical cells and the giant vertical cells are therefore integrating some of the same information in the lobula plate.
Cyclic AMP, 5‐HT, and the modulation of transmitter release at the crayfish neuromuscular junction
Authors: Enyeart John
Published: January 2005

In this study it was found that several agents which elevate cAMP levels in cells also increase dramatically the quantity of transmitter released from crayfish excitatory nerve terminals in response to a stimulus. With respect to time course and magnitude, the increase produced by one of these agents, the cyclic nucleotide phosphodiesterase inhibitor Squibb 20,009 (SQ 20,009), is unlike any reported for such a drug at a synapse. Additionally, SQ 20,009 potentiated the facilitation of transmitter release produced by serotonin (5‐HT) at this synapse. These results establish a possible role for cAMP in the control and modulation of transmitter release at the crayfish neuromuscular junction (NMJ). They further suggest that 5‐HT functions here by activation of a presynaptically located adenylate cyclase.
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

The 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

(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

Action 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

In 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

The 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

The 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

The 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

The 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

Because 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

Intersegmental 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

A 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

In 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.