bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vestibulo‐ocular and optokinetic reactions to rotation and their interaction in the rabbit
Authors: Baarsma E. A. , Collewijn H. 
Published: December 2014

1. Compensatory eye movements due to sinusoidal yaw movements on a torsion swing were measured in alert rabbits. A range of combinations of frequencies (0·048–1·8 Hz) and amplitudes (1–25°) were used. Gain (cumulative slow phase eye movement amplitude/swing amplitude) and phase (eye position vs. swing position — 180°) were calculated from averaged records.2. Eyes were either closed (canal‐ocular reactions only), open in earth‐fixed visual surroundings (natural interaction of vestibular and optokinetic reactions), or looking at platform‐fixed surroundings, which rotated with the animal (conflict situation). In some rabbits, the same stimulus programme was applied a month after bilateral destruction of the labyrinths (optokinetic reactions only).3. For canal‐ocular reactions, no true threshold was found. Yet the system showed a small but systematic non‐linearity which is tentatively explained by an acceleration‐dependence of gain. For the higher frequencies (0·40–1·8 Hz) used, gain was 0·55–0·75, with a decrease at the lower frequencies, down to 0·16–0·33 at 0·048 Hz. The response showed a phase‐lead of about 45° at 0·048 Hz and was nearly in phase at 1–1·8 Hz. The long time constant of the cupula‐endolymph system was estimated at about 3·3 sec.4. With earth‐fixed visual surroundings a temperature‐independent gain (range 0·55–0·82) with negligible phase error was found for the entire stimulus range tested. This natural combination of canal‐ocular and optokinetic systems appears to function very efficiently, with mutual correction of the defects of the systems apart.5. With platform‐fixed visual surroundings the canal‐ocular system was severely inhibited and its non‐linearities were markedly enhanced by the optokinetic system, especially when the torsion swing moved slowly.6. The general shape of input—output relations of optokinetic reactions after labyrinthectomy were similar to those found earlier in normal animals, but gain was subnormal for the entire stimulus range tested.
Centre and surround influences on the proximal negative response of the pigeon retina
Authors: Brooks Barbara , Holden A. L. 
Published: December 2014

1. Extracellular field potentials were recorded with micro‐electrodes in the inner plexiform layer of the pigeon retina. Stimulus patterns were projected on a tangent screen.2. Maximal responses to a 1° spot were produced from a receptive area 2–3° in extent. Annuli centred over this area produced a different response wave form.3. The responses to centred spots and annuli presented synchronously do not superpose: they interact in a way suggesting transient mutual antagonism. The response to spot onset and offset can be suppressed either by annulus onset or by annulus offset.4. A steady annulus has little effect on the response to spot stimuli, but a steady centred spot enhances the response to annular stimulation.5. The results suggest that the PNR results from convergence of on‐centre and off‐centre pathways, which are embedded in a widespread suppressive surround.
Physiological and morphological identification of hypothalamic magnocellular neuroendocrine cells in goldfish preoptic nucleus*
Authors: Hayward James N. 
Published: December 2014

1. Intracellular recordings were made from antidromically identified neurones in the goldfish preoptic nucleus and Procion Yellow was ejected from the recording pipette, marking these magnocellular neuroendocrine cells diffusely, for histological identification.2. In confirmation of earlier studies these preoptic neuroendocrine cells showed resting membrane potentials of 47 mV, action potentials up to 85 mV, action potentials of long duration (3·9 msec) occurring in two steps, long‐lasting hyperpolarizing after‐potentials and orthodromic driving from olfactory input.3. Magnocellular neuroendocrine cells exhibited all‐or‐none jumps to shorter antidromic latencies as pituitary stimulus strength increased, suggesting multiple branching of the ‘axones’ either near the preoptic nucleus or within the neural lobe.4. I find three morphological types of neuroendocrine cells throughout the magnocellular part of the preoptic nucleus. Cell Type I is a large (37 μm), multipolar neurone, 48 μm from the ependyma, with fine ‘dendrites’ projecting into the lateral hypothalamus and within the preoptic nucleus, with multiple branched ‘axones’. Cell Type II is a large (31 μm), multipolar neurone, 24 μm from the ependyma, with a coarse ‘dendrite’ to the ependyma and fine ‘dendrites’ within the preoptic nucleus, with limited ‘axonal’ branching. Cell Type III is a small (18 μm), multipolar neurone, 46 μm from the ependyma, with fine ‘dendritic’ processes distributed within the preoptic nucleus, with limited ‘axonal’ branching.5. I conclude that magnocellular neuroendocrine cells show electrical membrane properties of other central neurones with both physiological and morphological evidence for multiple ‘axonal’ branching. The three identifiable neuroendocrine cell types (I, II, III) are distributed widely within the anatomical limits of the preoptic nucleus, pars magnocellularis, with each type receiving ‘specific’ input connexions and with unique output pathways. I suggest that these three types of neuroendocrine cells may be related to the ‘cellular’ secretion of ‘specific’ neurohypophysial hormones and neurophysins.
Reflex control of discharge in motor fibres to the larynx
Authors: Głogowska Maria , Stransky A. , Widdicombe J. G. 
Published: December 2014

1. Action potentials have been recorded from single laryngeal motor fibres, with expiratory or inspiratory phases, in cats anaesthetized with pentobarbitone and breathing through a tracheal cannula.2. Pneumothorax increased the discharge of both inspiratory and expiratory units, the inspiratory response being greatly reduced by bilateral vagotomy below the origin of the recurrent laryngeal nerves.3. Addition of a ‘viscous’ resistance to breathing, or asphyxial rebreathing through an added dead space, increased the activity of inspiratory units and decreased that of expiratory units.4. Induction of pulmonary oedema decreased the discharge of inspiratory units and increased that of expiratory units. After vagotomy the response of inspiratory units was reversed.5. Intravenous injections of potassium cyanide increased the activity of both types of unit.6. Chemical irritation of the laryngeal mucosa decreased the discharge of inspiratory units and increased that of expiratory units, whether the vagi were intact or cut.7. It is concluded that expiratory unit discharge can be correlated with expiratory laryngeal resistance, but that inspiratory unit discharge does not correlate so well with inspiratory laryngeal resistance.8. The relationship between laryngeal motor‐fibre activity and the contractions of the inspiratory and expiratory muscles of breathing is discussed.
The forces generated at the human elbow joint in response to imposed sinusoidal movements of the forearm
Authors: Joyce G. C. , Rack Peter M. H. , Ross H. F. 
Published: December 2014

1. The mechanical resistance of the human forearm has been measured during imposed sinusoidal flexion‐extension movements of the elbow joint.2. The force required to move the limb can be divided into components required to move the mass, and components required to overcome the resistance offered by elastic and frictional properties of the muscles and other soft tissues.3. When during a vigorous flexing effort the limb was subjected to a small amplitude sinusoidal movement each extension was followed by a considerable reflex contraction of the flexor muscles. At low frequencies of movement this reflex provided an added resistance to extension, but at 8–12 Hz the delay in the reflex pathway was such that the reflex response to extension occurred after the extension phase of the movement was over and during the subsequent flexion movement. The reflex activity then assisted the movement whereas at other frequencies it impeded it.4. The reflex response to movement increased as the subject exerted a greater flexing force.5. Small movements generated a relatively larger reflex response than big ones.6. Even with large amplitudes of movement when the reflex activity was relatively small, the limb resisted extension with a high level of stiffness; this was comparable with the short range stiffness of muscles in experimental animals.7. The fact that at some frequencies the reflex response assisted the movement implies that with appropriate loading the limb could undergo a self‐sustaining oscillation at those frequencies.
The effect of firing rate on preoptic neuronal thermosensitivity
Authors: Boulant J. A. 
Published: December 2014

1. In anaesthetized rabbits, preoptic single units were recorded having positive or negative thermal coefficients (impulses/sec. ° C) for changes in preoptic temperature.2. A population of forty‐two positive coefficient units was divided into four groups based on their level of firing rate at 38° C. In each group, the average thermoresponse curve was determined by averaging the firing rates of the units at 1° C intervals over the 33–43° C range of preoptic temperatures.3. A population of twenty‐six negative coefficient units was divided into three groups based on their firing rates at 38° C. Similar average thermoresponse curves were determined for each group.4. As the level of firing rate increased in the positive coefficient units, the preoptic thermosensitivity progressively decreased at temperatures above 39° C, but generally increased at temperatures below 39° C.5. In the negative coefficient units, preoptic thermosensitivity generally increased (especially above 39° C) as the firing rate at 38° C increased.6. The results indicate that in positive coefficient units the level of firing rate determines the temperature range in which units are most thermosensitive. This range reflects whether a neurone is more likely to function in heat‐loss or heat‐production responses.7. Since peripheral thermal input affects the level of firing rate of positive coefficient units, a neuronal model is suggested to explain the role of peripheral and central thermal signals in temperature regulation.
Excitability changes in crayfish motor neurone terminals
Authors: Zucker Robert S. 
Published: December 2014

1. Changes in the post‐activation excitability of crayfish motor nerve terminals were used to measure afterpotentials that might be related to facilitation of transmitter release.2. The refractory period is followed by a period of supernormal excitability in which the threshold of nerve terminals drops to about 70% of its pre‐activation level at about 15 msec following an impulse. The threshold returns exponentially to its pre‐activation level with a time constant of about 25 msec at 13° C. Such a supernormal excitability is rarely seen in pre‐terminal nerve branches or in the main axon.3. Following a brief high‐frequency tetanus the peak of the supernormal excitability is greater than that following a single impulse. At low temperature this peak is reduced and delayed, and the decay rate of the supernormal excitability is prolonged with a Q10 of about 2·5.4. Depolarization of nerve terminals decreases, and hyperpolarization increases, the magnitude of the post‐activation supernormal excitability.5. The magnitude of the supernormal excitability depends on the external potassium concentration, but not on sodium. In low calcium the peak supernormal excitability is often reduced. High calcium concentration and manganese ions have no effect, but cobalt abolishes the supernormal excitability, and its effects are only slightly reversible. Both cobalt and manganese reversibly block neuromuscular transmission.6. Strophanthidin has no effect on the post‐activation supernormal excitability, but proteolytic enzymes reduce or abolish it, and hyperosmotic solutions also affect it.7. It is suggested that the action potential is followed by a depolarizing afterpotential in nerve terminals which is caused by a transient increase in the potassium concentration around the terminals. There is no evidence that afterpotentials in nerve terminals are related to facilitation in any way.
Physiological characteristics of re‐innervation of skeletal muscle in the mouse
Authors: Tonge D. A. 
Published: December 2014

1. Re‐innervation of soleus was studied in the mouse after either crushing the sciatic nerve or re‐implanting the nerve to soleus outside the original end‐plate region.2. During the early stages of re‐innervation subthreshold end‐plate potentials (e.p.p.s) were recorded in muscle fibres in response to nerve stimulation. Later the e.p.p.s became large enough to evoke action potentials in muscle fibres.3. The rate of recovery of the release of acetylcholine (ACh) as estimated from the quantal content of e.p.p.s was faster when nerves re‐innervated the old end‐plate region after nerve crush than after re‐implantation so that new neuromuscular junctions were formed.4. During re‐innervation soleus fatigued more rapidly than normal during repetitive nerve stimulation. The fatigue was due to failure of neuromuscular transmission associated with an impaired release of ACh.5. During re‐innervation soleus was supersensitive to ACh until nerve stimulation was capable of evoking action potentials in muscle fibres.
Is spatial adaptation an after‐effect of prolonged inhibition?
Authors: Dealy R. S. , Tolhurst D. J. 
Published: December 2014

1. The elevation of the thresholds for sinusoidal gratings of 4 c/deg and 6·7 c/deg was examined after adapting to gratings of 4 c/deg. Threshold elevation was determined as a function of the adapting contrast.2. It was confirmed that, when the adapting and testing spatial‐frequencies were the same, the threshold elevation curve extrapolated to zero elevation at an adapting contrast equal to the pre‐adaptation threshold for the adapting grating.3. It was found that the threshold elevation curve for 6·7 c/deg gratings also extrapolated to zero elevation at the pre‐adaptation threshold for the adapting grating, even though the testing and adapting frequencies were different.4. It is argued that the latter result shows that adaptation is not simply an after‐effect of prolonged excitation of a channel. Threshold elevation curves may represent the bandwidths of inhibitory interactions between channels.
The effects of physostigmine on synaptic transmission in the inferior mesenteric ganglion of guinea‐pigs
Authors: Bornstein J. C. 
Published: December 2014

1. Synaptic potentials were recorded with intracellular electrodes from cells in the inferior mesenteric ganglion of the guinea‐pig.2. Half‐widths of the synaptic potentials recorded fell into two groups: type L cells had long synaptic potentials (11·6–15·2 msec) and low thresholds (14·6 mV mean), type S cells had short synaptic potentials (6·1–9·3 msec) and high thresholds (29·9 mV mean).3. Physostigmine (1·2 × 10−6
M) caused a significant increase in the half‐width of both types of synaptic potential.4. Physostigmine caused a significant increase in the half‐width of spontaneous synaptic potentials and an increase in their amplitude.5. Repetitive preganglionic stimulation, in the presence of physostigmine, led to a marked and prolonged depolarization in all cells. In most cells repetitive spontaneous firing of action potentials was then observed. This effect was blocked by atropine (1·4 × 10−7
M).6. The effect of atropine on the half‐width in a physostigmine‐treated cell was inconsistent: although synaptic potentials in some cells were slightly shortened their half‐widths were always greater than the control.7. It is concluded that cholinesterase plays a role in limiting the time course of the synaptic potential, by limiting the duration of action of acetylcholine.
Active transport of sodium and potassium by the choroid plexus of the rat
Authors: Johanson Conrad E. , Reed Donal J. , Woodbury Dixon M. 
Published: December 2014

1. Choroid plexus from the lateral ventricle in the adult rat was found to contain approximately 54 m‐equiv Na+ and 89 m‐equiv K+ per kg wet tissue.2. The total water (79%), the extracellular space (21%) and the red blood cell volume (8–9%) in choroid plexus were quantified separately by analysing the distribution of [14C]antipyrine, [14C]inulin and 51Cr‐tagged erythrocytes, respectively, between this tissue and plasma water.3. The tissue electrolyte data together with the compartmental (space) data were used to calculate an average concentration of Na+ (39 m‐equiv/kg cell H2O) and of K+ (144) in the choroid cell.4. Under various experimental conditions known to stimulate or inhibit the Na+—K+ transport system in other tissues, there were significant changes (10–40 m‐equiv/kg cell H2O) in the concentrations of both these cations in the plexus epithelial cells.5. Choroid cell K+ was not independent of the concentration of K+ in plasma since substantial fluctuations in cell K+ occurred in rats rendered either hypo‐ or hyperkalaemic; also, the choroid cell apparently cannot maintain a constant gradient between itself and c.s.f. in the face of kalaemic disturbances.6. Evidence is offered to support the hypothesis that the choroid plexus of the lateral ventricle has a Na+—K+ pump, the operation of which contributes to the maintenance of K+ homoeostasis in the
C.N.S.
Structural and functional asymmetries of myelinated branches in the frog muscle spindle
Authors: Ito F. , Kanamori N. , Kuroda H. 
Published: December 2014

1. Most of the axons innervating single‐type muscle spindles in the frog sartorius muscle divide into myelinated branches at a node; one of the branches subdivides (Bs) and the other does not (Bn).2. Electrical responses at the afferent nerve terminal of the isolated spindles were recorded extracellularly and intracellularly with micro‐electrodes, concurrently with the terminal responses by the paraffin gap method.3. By recording spontaneous orthodromic and provoked antidromic impulses and by stimulating the nerve terminals with micro‐electrodes and inactivating the terminals with micro‐application of potassium ion, it was deduced that propagated and abortive spikes are almost always generated at the terminal of Bn (Tn), not at the terminals of Bs (Ta and Tb).4. The site of impulse initiation, as determined in (3), was found, after measurement of the lengths of the myelinated branches in each preparation, to be essentially the terminal nearest the parent axon.5. Selective inactivation of Tn by far‐ultra‐violet light removed both propagated and abortive spikes. Both types of spikes survived after irradiation of Ta and Tb, although the relationship between spike frequency and spindle stretch was altered. The same results were obtained after transection of the branches with a laser microbeam.
Cat retinal ganglion cells: size and shape of receptive field centres
Authors: Hammond P. 
Published: December 2014

1. Receptive field centres of 144 sustained and transient retinal ganglion cells were mapped in cats under light pentobarbitone anaesthesia.2. Sustained on‐centre, sustained off‐centre, transient on‐centre and transient off‐centre cells had different mean sizes of receptive field centre, with some overlap between their distributions.3. For each class of cell, central fields had the smallest field‐centres; progressively larger field‐centres were encountered more peripherally.4. All classes of ganglion cells tended to have slightly elliptical receptive field centres. Major axes of over half of all receptive fields were oriented within 20° of horizontal. These trends were independent of pupil dimensions, or of receptive field eccentricity or position in the visual field. The results almost certainly reflect asymmetry in retinal wiring.5. Two cells of thirty‐nine tested were sensitive to axis of motion; in both cases the preferred and major axis were horizontal. A further cell was orientation specific.
Membrane potential and input resistance in acinar cells from cat and rabbit submaxillary glands in vivo: effects of autonomic nerve stimulation
Authors: Kagayama M. , Nishiyama A. 
Published: December 2014

1. Membrane potential and input resistance measurements were made from acinar cells of cat and rabbit submaxillary glands in vivo, using intracellular glass micro‐electrodes.2. The mean resting cell membrane potential was higher than previously reported, but ranged widely from −15 to −80 mV.3. Single shock electrical stimulation of the parasympathetic nerve fibres evoked characteristic potential changes. In some cases monophasic hyperpolarizations, in others biphasic responses (depolarization — hyperpolarization) were observed.4. The latency of the hyperpolarizing response was considerably longer (300–550 msec) than the latency of the biphasic response (about 150 msec).5. Hyperpolarizing and biphasic responses could be observed in the same cell at different levels of membrane potential. The initial depolarization of the biphasic response was dependent on the magnitude of the resting potential in such a manner that it was very small or absent at the lowest potentials and increased gradually with increasing level of the resting potential.6. Single‐shock stimulation of the sympathetic nerve fibres to the gland did not evoke any response. In the cat, repetitive stimulation evoked hyperpolarizing or biphasic responses similar to those seen after repetitive stimulation of the parasympathetic nerve fibres. In the rabbit small hyperpolarizations were seen in a few cells only; mostly there was no response. Repetitive stimulation of the parasympathetic nerve fibres to the rabbit submaxillary gland evoked complex potential changes mostly of the depolarization—hyperpolarization type.7. Both single shock and repetitive stimulation of the parasympathetic nerve fibres evoked marked reductions in cell input resistance. In the hyperpolarizing cell type the conductance change sometimes preceded the potential change whereas they always occurred simultaneously in the biphasic cell type.8. It is concluded that both the hyperpolarizing and the biphasic secretory potentials are derived from the same type of acinar cells. The neurotransmitter released by the parasympathetic nerve endings (ACh) acts on the acinar cell membrane by increasing the ion permeability.