bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regenerations of the noradrenergic innervation of the cardiovascular system of the chick following treatment with 6‐hydroxydopamine
Authors: Bennett T. , Malmfors T. 
Published: December 2014

1. Fluorescence histochemical and pharmacological studies were made of the noradrenergic innervation of inferior venae cavae and left atria from 2‐ and 6‐week‐old chicks before, and following, treatment with 6‐hydroxydopamine.2. Noradrenergic nerves in the younger animals appeared to be relatively resistant to the toxic effects of 6‐hydroxydopamine.3. In the older animals, the time course of recovery from the effects of 6‐hydroxydopamine appeared to reflect the rate of regeneration of destroyed noradrenergic nerves.4. Marked presynaptic supersensitivity to adrenaline and noradrenaline was observed in left atria and inferior venae cavae following treatment with 6‐hydroxydopamine.
The distribution, activity, and function of the cilia in the frog brain
Authors: Nelson Deborah J. , Wright Ernest M. 
Published: December 2014

1. The distribution, activity, and function of the cilia in the brain was studied using in vitro preparations of the frog choroid plexuses and ependyma.2. Scanning electron microscopy revealed that twenty to forty cilia, about 20 μm long, project from the cells of the choroidal epithelium and ependyma into the ventricular system of the brain.3. These cilia beat at a constant frequency which ranged from 5 to 20 c/s. Ciliary activity was enhanced by ATP, cyclic AMP, theophylline, and acetylcholine, and was depressed by DNP, IAA, Ni2+, La3+, and Co2+.4. Ciliary motion produced a flow of c.s.f. over the surface of the cells lining the ventricles, and in the choroid plexus this flow reduced the effective thickness of the unstirred layer adjacent to the epithelium by about 100 μm.5. These results are discussed in relation to the factors that control the frequency of ciliary beating, and the role of the cilia in the circulation of the c.s.f.
The postural response of normal dogs to sinusoidal displacement
Authors: Brookhart John M. , Talbott Richard E. 
Published: December 2014

1. Normal dogs were trained to adopt a laterally symmetric stance on a horizontal platform. Sinusoidal oscillation of the platform in the cephalocaudal direction caused the dogs to adopt a strategy of response which would keep them from falling down during the period of imposed motion or perturbation.2. A Fourier analysis of the response variables provided a quantitative measure of the distortion in the induced movement at the various hind leg joints and in the motion of the body. Certain aspects of the distortion could be accounted for by recognized random events such as drift and panting. The remainder of the distortion was task related and therefore provided evidence that the dog's postural control system behaved essentially as a non‐linear system.3. The motion of the body was less distorted than the motion at the joints. The frequency response of the body motion resembled that of a second order linear system, but the amplitude of the body motion did not vary in constant proportion with changes in the amplitude of the input. Further, the phase relation between body motion and platform motion was not constant when the amplitude of the input was changed. Therefore, it was concluded that the control of the body position was probably non‐linearly related to the input disturbance but that the low pass filter characteristics tended to minimize the appearance of distortion in that system output.4. Control of the position of the hind limb is related to the control of the torque generated at the hind limb joints. To the extent that joint angle and change in joint angle are related to the torque at a joint, the distortion of the motion at the joints clearly demonstrates that control of the hind limb during this postural task was non‐linearly related to the sinusoidal input.5. The uniformity of the response parameters, as assessed from the Fourier coefficients, indicated that all of the tested dogs adopted the same or nearly the same strategy for solving the problem of adjusting their postural control in response to the perturbation. Therefore, a reasonable hypothesis for future testing is that the central programme which generates this particular postural response will be structured similarly from one dog to the next.
Ionic mechanisms and receptor properties underlying the responses of molluscan neurones to 5‐hydroxytryptamine
Authors: Gerschenfeld H. M. , Tritsch Danièle Paupardin 
Published: December 2014

1. Molluscan neurones have been found to show six different types of response (three excitatory and three inhibitory) to the iontophoretic application of 5‐hydroxytryptamine (5‐HT). The pharmacological properties of the receptors and the ionic mechanisms associated with these responses have been analysed.2. Four of the responses to 5‐HT (named A, A′, B and C) are consequent upon an increase in membrane conductance whereas the other two (named α and β) are caused by a decrease in membrane conductance.3. The A‐response to 5‐HT consists of a ‘fast’ depolarization due to an increase mainly in Na+‐conductance; the A′‐response is a ‘slow’ depolarization also associated with a Na+‐conductance increase. Receptors mediating the A‐ and A′‐depolarizations have different pharmacological properties and may exist side by side on the same neurone.4. Both the B‐ and C‐responses are inhibitory. The B‐response is a ‘slow’ hyperpolarization due to an increase in K+‐conductance, the C‐response is a fast hyperpolarization associated with an increase in Cl−‐conductance.5. The α‐response to 5‐HT is a depolarization which becomes reduced in amplitude with cell hyperpolarization and reverses at −75 mV; it is caused by a decrease in K+‐conductance. The β‐response is an hyperpolarization which increases in amplitude with cell hyperpolarization and reverses at −20/−30 mV. It results from a decrease in conductance to both Na+ and K+ ions.6. The receptors involved in the 5‐HT responses associated with a conductance increase may be recognized by the action of specific antagonists: 7‐methyltryptamine blocks only the A‐receptors, 5‐methoxygramine only the B‐receptors and neostigmine only the C‐receptors. Curare blocks the A‐ and C‐receptors and bufotenine, the A‐, A′‐ and B‐receptors. No specific antagonists have yet been found for the 5‐HT responses caused by a conductance decrease.7. The significance of the multiplicity of receptors is discussed. Their functional significance at synapses is analysed in the following paper.
Phosphenes produced by electrical stimulation of human occipital cortex, and their application to the development of a prosthesis for the blind
Authors: Dobelle W. H. , Mladejovsky M. G. 
Published: December 2014

1. To explore the feasibility of a visual prosthesis for the blind, human visual cortex has been stimulated during a series of surgical procedures on conscious volunteers undergoing other occipital lobe surgery.2. Area no. 17 seems the most effective locus for such stimulation, at least in sighted or recently hemianopic patients.3. Changes in electrode size and configuration, or in stimulus parameters, have little effect on subjective sensation.4. Thresholds do vary depending on parameters, but not electrode size, and these effects have been studied.5. Painful effects are associated with stimulation of the dura, but not of the calcarine artery and associated vessels.6. Stimulation of a single electrode usually produces one phosphene, whose size ranges from tiny punctate sensations like ‘a star in the sky’ up to a large coin at arm's length. Very large elongated phosphenes, like those seen by Brindley's second patient, have not been reported despite the number of patients, electrodes, and combinations of stimulus parameters tested. These large phosphenes may be an effect of prolonged blindness.7. Stimulation substantially above threshold may produce a second conjugate phosphene, inverted about the horizontal meridian.8. Stimulation of a single electrode may also produce multiple phosphenes with no differential threshold.9. Chromatic effects and/or phosphene flicker may, or may not occur. This can vary from point to point on the same patient.10. Phosphenes fade after 10–15 sec of continuous stimulation.11. All phosphenes move proportionately with voluntary eye movements, within the accuracy of our mapping techniques.12. Brightness modulation can easily be achieved by changing pulse amplitude.13. The position of phosphenes in the visual field corresponds only roughly with expectations based on classical maps showing the projection of the visual field onto the cortex.14. Patients can usually discriminate phosphenes produced by 1 mm2 electrodes on 3 mm centres, although this seems to be close to the limit of resolution.15. Patterns of up to four phosphenes produced by four electrodes have been recognized. However, a variety of complex interactions have been reported.16. Multiple phosphenes are co‐planar, although patients are unable to estimate their distance.17. Phosphenes appear immediately when stimulation is begun, and disappear immediately upon cessation of stimulation.18. Future work must concentrate on blind volunteers to explore possible differences in subjective sensation produced after prolonged blindness, and to explore more complex pattern presentation which requires substantial periods of time with any given patient.
Response patterns of amphibian olfactory bulb neurones to odour stimulation
Authors: Kauer John S. 
Published: December 2014

1. Responses of 199 single olfactory bulb neurones in the frog were observed with odour stimulation.2. To effect control over the concentration, flow rate and time course of the stimulus application, a simple olfactometer was developed and calibrated using a gas chromatograph. The stimulus pulses were monitored by recording the electro‐olfactogram from the olfactory mucosa.3. Several categories of unit activity became evident after delivering many odour applications (637). Some odour applications did not cause any change in the spontaneous activity of the unit. This was classified as type N (no response) activity. Some applications caused a suppression of ongoing activity (type S activity). Some applications caused an excitation during the rising concentration phase of the stimulus pulse (type E activity). Three temporal patterns of excitatory responses were seen and these were categorized as subgroups of activity type E.4. Since each response type was seen with about the same frequency regardless of the odour used, this suggested that the temporal patterns of response per se were not coding for odour type.5. When odour concentration was manipulated for a unit showing suppressive (type S) activity at one concentration, then the unit tended to show qualitatively similar suppression at other concentrations as long as they were above threshold.6. When peak concentrations were manipulated for units showing excitatory (type E) activity, the temporal patterns of response could change dramatically. In many cases the units fired after one level of concentration had been reached and were subsequently suppressed with increase in concentration. Such ‘concentration tuning’ suggested that excitatory temporal patterns, in contrast to suppressive ones, were coding odour concentration information.7. The significance of the changes in temporal response patterns seen here, for experiments examining the relationships between odours using single unit response data, is discussed.
Optical quality of the living cat eye
Authors: Bonds A. B. 
Published: December 2014

1. The optical quality of the living cat eye was measured under conditions similar to those of cat retinal ganglion cell experiments by recording the aerial image of a nearly monochromatic thin line of light.2. Experiments were performed to assess the nature of the fundal reflexion of the cat eye, which was found to behave essentially as a diffuser.3. The optical Modulation Transfer Function (MTF) was calculated from the measured aerial linespread using Fourier mathematics; the MTF of a ‘typical’ cat eye was averaged from data collected from ten eyes.4. The state of focus of the optical system, the pupil size and the angle of the light incident on the eye were all varied to determine their effect on image quality.5. By using an image rotator, the aerial linespread was measured for several orientations of the line; these measurements yielded an approximation of the two‐dimensional pointspread completely characterizing the optical system.6. Evidence is reviewed to show that the optical resolution of the cat, albeit some 3‐5 times worse than that of human, appears to be better than the neural resolution of its retina and its visual system as a whole.
Pancreatic acinar cells: effects of lanthanum ions on amylase release and calcium ion fluxes
Authors: Chandler D. E. , Williams J. A. 
Published: December 2014

1. The effect of La3+ on amylase release and Ca2+ fluxes in mouse pancreatic fragments in vitro was studied.2. Amylase release was increased by 0·1 m
M‐La3+ and progressively inhibited by 1·0–10 m
M‐La3+. Non‐stimulated and bethanecol stimulated secretion were altered in an identical manner. Inhibition of amylase release was rapid and reversible.3. Uptake of 45Ca2+ was multiphasic with equilibrium with stable Ca2+ still not complete after 2 hr. La3+ (10 m
M) limited uptake of 45Ca2+ to the extracellular space and slightly decreased total Ca2+ content. Lower concentrations of La3+ affected 45Ca2+ uptake and total Ca2+ content in a biphasic manner which paralleled effects on amylase release.4. La3+ restricted washout of 45Ca2+ to isotope in the extracellular space and abolished the bethanecol‐stimulated increase in 45Ca2+ efflux.5. Uptake of 45Ca2+ into intracellular space, as measured by the ‘lanthanum’ method, was not affected by bethanecol.6. Tissue ultrastructure and Na+ and K+ content were not affected by La3+.7. It is concluded that an influx of extracellular Ca2+ is not important for triggering of secretion and that La3+ may inhibit amylase release by acting on the release process rather than on Ca2+ influx.
Voltage gradients across the receptor layer of the isolated rat retina
Authors: Arden G. B. 
Published: December 2014

1. The electroretinogram (e.r.g.) of the isolated rat retina has been investigated by recording potential differences developed between two micropipettes.2. In the uniformly illuminated receptor layer, voltage gradients at 90° to the long axes of the receptors are negligible in comparison with the radial voltage gradients.3. When all transsynaptic neural activity has been abolished, the photoresponse recorded across the receptor layer is very different from the photoresponse recorded across the inner retinal layer.4. The photoresponse developed across the inner retinal layers, slow P III, develops slowly and the peak voltage is approximately proportional to log. flash energy.5. The photovoltage across the receptor layer rises rapidly to its peak, before a significant fraction of slow P III has developed.6. The faster photovoltage (receptor potential) increases with flash intensity according to the hyperbolic function characteristic of photo‐receptors.7. The faster photovoltage can be split into two components. Between the tips of the outer limbs and the bases of the inner limbs, it has a simple wave form. In the region between the bases of the inner limbs and the receptor synapses, there is an additional peak (nose) to the photovoltage.8. In the scleral portion of the receptor layer, the photovoltage approximately equals the dark voltage. In the remaining, vitreal portion of the receptor layer the photovoltage exceeds the dark voltage.9. Photocurrent divergence has been measured and the results indicate that the source of photocurrent extends further vitreally than the base of the outer limb.10. The results suggest that the photoresponse generated in the outer limb is modified by an active process which occurs in portions of the rods which are nearer the synapse.
Chloride distribution in Aplysia neurones
Authors: Ascher P. , Kunze Diana , Neild T. O. 
Published: December 2014

1. The intracellular Cl− concentration (Cli) and the membrane potential (Em) were measured in the medial pleural neurones of Aplysia under various experimental conditions designed to determine the Cl− conductance of the neurones and investigate the possibility of an active Cl− transport.2. The magnitude of the Cl− conductance of the cell depends on the experimental conditions.3. In normal sea water, large changes of Em produced by passing current across the cell membrane caused no change of Cli, suggesting that the Cl− conductance was low. Similarly, moderate changes of ECl produced by decreasing Clo or increasing Cli had little or no effect on Em.4. A high Cl− conductance was observed in high Ko or very low Clo. It was greatly reduced if the external Ca2+ was replaced by Co2+, or in the presence of tubocurarine, or if the experiment was performed on an isolated cell soma. The high Cl− conductance is therefore attributed to the release of ACh and perhaps other transmitters from synaptic terminals.5. High concentrations of tetraethylammonium ions or procaine induced a depolarization of the cell, but a decrease of Cli. The rate of fall of Cli was increased by lowering external K+ or raising external Ca2+, and was decreased by replacing external Ca2+ by Co2+.6. NH4+ ions applied externally had effects similar to those of K+ ions. In situations in which intracellular NH4+ might be increased a fall in Cli was observed.7. The changes of Cli caused by TEA, procaine, or internal NH4+ occur against the driving force for passive Cl− movements. They are still observed in isolated cell bodies, and cannot be attributed to the activation of synaptic channels.8. Some interpretations of these anomalous Cl− movements are discussed which could also account for the difference between ECl and Em observed under normal conditions.
Detection of light‐induced changes of intracellular ionized calcium concentration in Limulus ventral photoreceptors using arsenazo III
Authors: Brown J. E. , Brown P. K. , Pinto L. H. 
Published: December 2014

1. The metallochromic indicator dye, arsenazo III, was injected intracellularly into Limulus ventral photoreceptor cells to concentrations greater than 1 m
M.2. The absorption spectrum (450‐750 nm) of the dye in single dark‐adapted cells was measured by a scanning microspectrophotometer. When a cell was light‐adapted, the absorption of the dye changed; the difference spectrum had two maxima at about 610 and 660 nm, a broad minimum at about 540 nm and an isosbestic point at about 585 nm.3. When intracellular calcium concentration was raised in dark‐adapted cells previously injected with arsenazo III, the difference spectum had two maxima at about 610 and 660 nm, a broad minimum at about 530 nm and an isosbestic point at about 585 nm. The injection of Mg2+ into dark‐adapted cells previously injected with the dye induced a difference spectrum that had a single maximum at about 620 nm. Also, decreasing the intracellular pH of cells previously injected with the dye induced a difference spectrum that had a minimum at about 620 nm. The evidence suggests that there is a rise of intracellular ionized calcium when a Limulus ventral photoreceptor is light‐adapted.4. The intracellular calcium concentration, [Ca2+]1, in light‐adapted photoreceptors was estimated to reach at least 10−4
M by compaing the light‐induced difference spectra measured in ventral photoreceptors with a standard curve determined in microcuvettes containing 2m
M arsenazo III in 400 m
M‐KCl, 1 m
M‐MgCl2 and 25 m
M MOPS at pH 7·0.5. In cells injected to less than 3 m
M arsenazo III, light induced a transient decrease in optical transmission at 660 nm (T660). This decrease in T660 indicates that illumination of a ventral photoreceptor normally causes a transient increase of [Ca2+]1.6. Arsenazo III was found to be sensitive, selective and rapid enough to measure light‐induced changes of intracellular ionized calcium in Limulus ventral photoreceptor cells.
The effect of temperature on the potential difference and input resistance of rat seminiferous tubules
Authors: Gladwell R. T. 
Published: December 2014

1. The p.d. of rat seminiferous tubules was 5·86 ± 0·15 mV, lumen negative, at 33° C and varied linearly with temperature between 24 and 37° C, exhibiting an apparent Q1025-35° C of 2·0 with a slope of 0·43 mV/° C. Exposing testes to a temperature of 37‐43° C resulted in an initial hyperpolarization followed by depolarization of the tubules. These changes were more rapid in testes exposed to 41‐43° C than in testes exposed to 37‐39° C.2. The Rin of seminiferous tubules was 198 ± 7·8 kΩ at a testis temperature of 33° C. The Rin decreased when testes were maintained at 37 and 41° C, the rate of decrease being similar to the rate of depolarization.3. Exposing testes to deep body temperature by unilateral surgical cryptorchidism caused a reduction of 30 and 64% in tubular p.d. and Rin respectively when measured 24 hr after surgery. Exposure to deep body temperature for up to 4 days did not cause any further change in either parameter.4. There was no evidence that lanthanum penetrated through the Sertoli cell tight junctions after exposing testes to 41° C for up to 30 min.5. The results indicate that the seminiferous tubule p.d. is maintained by a temperature‐sensitive, cellular mechanism. Exposing testes to deep body temperature or above depolarized the tubules and increased their permeability.
Oscillation of the human ankle joint in response to applied sinusoidal torque on the foot
Authors: Agarwal Gyan C. , Gottlieb Gerald L. 
Published: December 2014

1. Low‐frequency (3‐30 Hz) oscillatory rotation of the ankle joint in plantarflexion—dorsiflexion was generated with a torque motor. Torque, rotation about the ankle and electromyograms (e.m.g.s) for the gastrocnemius—soleus and the anterior tibial muscles were recorded.2. Fourier coefficients at each drive frequency were used to calculate the effective compliance (ratio of rotation and torque). The compliance has a sharp resonance when tonic, voluntary muscle activity is present.3. The resonant frequency of compliance is between 3 and 8 Hz. The location of the resonant frequency and the magnitude of the compliance at resonance depend upon both the degree of tonic muscle activity and the amplitude of the driving torque. The resonant frequency increases with increasing tonic activity.4. With tonic muscle activity, the compliance in the frequency range below resonance increases with increasing amplitudes of driving torque.5. The e.m.g., when evoked by the rhythmic stretch, lags the start of stretching by between 50 and 70 msec.6. When tonic muscle activity is present, the resonant frequency of the stretch reflex is between 5 and 6·5 Hz.7. Following the start of driven oscillation at frequencies near resonance, slowly increasing amplitudes of angular rotation (to a limit) are observed.8. Distortion (from the sinusoidal wave shape) of angular rotation is frequently observed with drive frequencies between 8 and 12 Hz during which there sometimes occur spontaneous recurrences of oscillation at the drive frequency. For the angular rotation, a significant portion of the power may be in subharmonic frequency components of the drive frequency when that frequency is between 8 and 12 Hz.9. Self‐sustaining oscillation (clonus) near the resonant frequency of the compliance is sometimes observed after the modulation signal to the motor is turned off. This is most often seen when the gastrocnemius—soleus muscles are fatigued. Clonus may be evoked by driven oscillation at any frequency.10. The hypothesis that physiological tremor, which occurs between 8 and 12 Hz, is a consequence of stretch reflex servo properties seems to be at odds with the observations of resonance in the compliance and of self‐generated clonus both occurring in the 5‐8 Hz region.