bluuebunny/crossref_metadata_2025 huggingface dataset:
On the mechanism of halothane anaesthesia
Authors: Richards C. D.
Published: December 2014

1. The effects of halothane on the evoked potentials of in vitro preparations of guinea‐pig olfactory cortex were studied.

2. The evoked potentials recorded from the cortical surface comprised an initial diphasic wave — the lateral olfactory tract (l.o.t.) compound action potential — followed by a negative wave of 1–3 mV amplitude and about 10 msec duration. Superimposed on the negative wave was a number of positive peaks. The negative wave has been identified as an extracellularly recorded, monosynaptic, excitatory post‐synaptic potential (e.p.s.p.) and the positive peaks have been shown to reflect the discharge of the cortical cell population in response to the evoked e.p.s.p. and are therefore termed ‘population spikes’.

3. When halothane (0·4–1·5%) was added to the gas stream that superfused the surface of the preparation the evoked e.p.s.p.s became smaller in amplitude and the size of the population spikes diminished. The l.o.t. compound action potential was unaffected by these levels of halothane. Higher levels of halothane (above 2%) further reduced the amplitude of the evoked e.p.s.p.s, abolished the population spikes, decreased the amplitude of the l.o.t. compound action potential and slowed its time course. The effects of halothane on the evoked potentials were dose‐related and were independent (after the first 10 min of treatment) of the duration of the exposure to halothane.

4. The decrease in the size of the population spike caused by the exposure to halothane implied that transmission through the cortical relay had been impaired. This was also shown by the decrease in the evoked activity of units in the prepiriform cortex. Of eleven units, eight were depressed by halothane (0·5–1·5%) two were unaffected and one showed a transient increase in the number of spikes generated in response to a l.o.t. volley.

5. Halothane (up to 1·5%) had no effect on the threshold of the l.o.t. fibres to electrical stimulation or on that of the post‐synaptic cells to synaptic excitation.

6. Post‐tetanic potentiation and frequency potentiation of the evoked e.p.s.p.s were enhanced in the presence of 1% halothane.

7. It is concluded that halothane reduces excitatory synaptic transmission not by an increase in the electrical threshold of the post‐synaptic cells to synaptic excitation but by interference with the process of chemical transmission either by reducing the output of transmitter from the pre‐synaptic nerve terminal or by reducing the sensitivity of the post‐synaptic membrane to the released transmitter substance.
Retention of the original topographic polarity by the 180° rotated tectal reimplant in young adult goldfish
Authors: Yoon Myong G.
Published: December 2014

1. The pattern of visual projection from the retina on to the optic tectum was studied with neurophysiological mapping methods following reimplantation of the optic tectum in young adult goldfish.

2. When a rectangular piece of the tectum was dissected out and then reimplanted to the same tectum in situ, the restored visual projection showed a normal retinotopic order over the area of the tectal reimplant.

3. If the tectal tissue was reimplanted after rotation by 180°, the visual projection from that part of the retina which innervated the 180° rotated tectal reimplant was found to be organized in a completely reverse retinotopic order within the reimplanted area in contrast to the normal projection from the other part of the retina on to the intact surrounding area of the same optic tectum.

4. The results indicate that a piece of reimplanted tectal tissue retains its original topographic polarity regardless of whether the tectal tissue was rotated or not.

5. The retention of original topographic polarity by a small fraction of the tectal tissue suggests that the optic tectum is not a passive receiver of incoming optic fibres but an active accommodator which selects appropriate optic fibres to make proper synaptic connexions in a consistent topographic order.
Effect of pyrogen and antipyretics on prostaglandin activity in cisternal c.s.f. of unanaesthetized cats
Authors: Feldberg W. , Gupta K. P. , Milton A. S. , Wendlandt Sabine
Published: December 2014

1. Samples of cisternal cerebrospinal fluid (c.s.f.) were collected from unanaesthetized cats while rectal temperature was continuously recorded. From the same cat, samples were collected during normal body temperature, during pyrogen fever and when the fever was brought down by an
I.P. injection of an antipyretic. Fever was produced by injection of the bacterial pyrogen of Shigella dysenteriae either into the third ventricle, cisterna magna or
I.V. The samples of c.s.f. were assayed for PGE1‐like activity on the rat stomach fundus strip preparation rendered insensitive to 5‐HT.

2. In samples of c.s.f. collected during normal body temperature, usually either no PGE1‐like activity was detected, or its activity was low. Higher values were obtained in only a few cats.

3. In each experiment the PGE1‐like activity increased, often many‐fold, in samples collected during the pyrogen fever, irrespective, of the route of administration of the pyrogen. However, on
I.V. injection, about 1000 times larger doses of the pyrogen were required than on injection into the liquor space to produce fever and the increase in PGE1‐like activity of cisternal c.s.f.

4. The antipyretic drugs indomethacin, paracetamol and aspirin, injected
I.P. during the pyrogen fever, brought down temperature, and the PGE1‐like activity of the cisternal c.s.f. again became low.

5. When samples of cisternal c.s.f. were subjected to thin layer chromatography the prostaglandin‐like activity was solely or mainly found in the zone corresponding to the prostaglandins of the E series.

6. These findings support the theory that pyrogens produce fever by increasing synthesis and release of prostaglandin in the preoptic anterior hypothalamic area, and that antipyretics of the aspirin type bring down this fever because they inhibit this synthesis.

7. It is concluded that pyrogen increases prostaglandin synthesis not only in the preoptic anterior hypothalamic area. When injected into the liquor space increased synthesis of prostaglandin probably occurs in many regions near the surface of the brain stem, and when injected
I.V. may occur in other parts of the
C.N.S. as well. But to produce fever the prostaglandin has to act on the preoptic anterior hypothalamic area.
The composition of maternal plasma and foetal urine after feeding and drinking in chronically catheterized ewes during the last two months of pregnancy
Authors: Mellor D. J. , Slater J. S.
Published: December 2014

1. The fluid sacs and bladders of sixteen foetuses in fourteen ewes were catheterized between 81 and 92 days gestational age and the rumens of four ewes were also catheterized.

2. Between 95 and 145 days gestational age in forty‐six 24 hr experiments hourly samples of maternal plasma and foetal urine were obtained and in fifteen experiments foetal fluid samples were also taken at 4‐ to 6‐hr intervals.

3. The osmolality, pH, and concentrations of sodium, potassium, chloride, glucose, fructose and urea were measured on all samples.

4. During experiment there was no significant variation in the composition of amniotic or allantoic fluid. Marked changes in osmolality occurred in maternal plasma and foetal urine when ewes drank after feeding, but not in ewes that received water intrarumenally via catheter while feeding or in fasting ewes. Post‐prandial changes in maternal plasma osmolality may have altered transplacental water fluxes and as a result foetal plasma volume and osmolality.

5. The results suggest that the foetus alters renal water retention by varying antidiuretic hormone (ADH) secretion in response to changes in blood volume and at later gestational ages plasma osmolality as well.

6. Post‐prandial changes in the [Na+]/[K+] ratio of foetal urine suggested that foetal adrenocorticotrophin (ACTH) secretion is influenced by variations in foetal blood volume and glucose concentrations.

7. The post‐prandial changes in foetal urine composition observed here support previous suggestions (Mellor & Slater, 1972) about the role of foetal urine in foetal fluid formation which were based on gestational changes in the composition of foetal fluids and urine sampled once daily during the post‐absorptive state.
Receptive field organization of bipolar and amacrine cells in the goldfish retina
Authors: Kaneko Akimichi
Published: December 2014

1. Intracellular recordings were made from bipolar and amacrine cells in the isolated goldfish retina. Cells were identified mainly from their response patterns to a spot and an annulus in reference to the knowledge obtained from the previous work of intracellular Procion Yellow injection. Using white light and monochromatic lights receptive field organization of recorded cells were analysed.

2. All bipolar cells had a centre‐surround organization in their receptive fields. The field centre was estimated to be 100–200 μm in diameter, and the surround 1–1·5 mm.

3. Bipolar cells were classified into two types according to the response properties to monochromatic lights. Opponent colour cells received inputs from red and green cones, responding with red on‐centre, red and green off‐surround or vice versa. Cells without colour coding received input from red cones both in the field centre and the surround. In these cells the centre and the surround were well balanced.

4. Amacrine cells were also classified into two types, a sustained type and a transient type. The sustained type amacrine cells responded with a steady potential change and were colour coded. They were hyperpolarized by red and depolarized by green light. The transient type amacrine cells responded with transient depolarization at on and off of light flashes. They received input chiefly from red cones and were not colour coded. Both types of amacrine cells showed a large spatial summation in an area over 2·5 mm; centre‐surround antagonism was not seen.

5. Comparing the size of the receptive field with anatomy, especially with the size of dendritic spread, the field centre of bipolar cells agreed in size with their dendritic spread. Bipolar cell surround clearly exceeded its dendritic field. Since the response properties of the bipolar cell surround was mimicked most closely by the receptive field of external horizontal cells, the input to the bipolar cell surround is thought to be mediated by external horizontal cells.

6. By comparing receptive field properties of various retinal cells it is suggested that both the opponent colour bipolar cells and the colour coded amacrine cells converge on to the double opponent ganglion cells.
Properties of the depolarizing synaptic potential evoked by peripheral illumination in cones of the turtle retina
Authors: O'Bryan P. M.
Published: December 2014

1. Intracellular recordings of cone and horizontal cell responses to circles or annuli of light were made with the purpose of determining the properties of and the mechanisms underlying the horizontal‐cell‐mediated depolarization of cones which is evoked by surround illumination.

2. A comparison of the responses of a cone and a near‐by horizontal cell to a peripheral stimulus revealed a striking similarity in their time courses and amplitudes, indicating that a correlation exists between the depolarizing synaptic potential in the cone and the response of the horizontal cell.

3. The depolarizing synaptic potential in cones was separated from the direct response of the cell to light by illuminating the periphery with an annulus during steady, bright illumination of the central cone. The synaptic potentials were graded with the intensity or area of peripheral illumination. In some cones a spike‐like depolarization, which overshot the dark resting potential, occurred with bright illumination of the periphery.

4. The effects of extrinsic current on the synaptic potential demonstrated that this response was generated by a change in membrane conductance consisting of two separate components with different time‐dependences and reversal levels. The slower of the two components, which often outlasts the stimulus, represents an increase in membrane conductance.

5. The progressive decline in the amplitude of the responses of horizontal cells under a large spot from centre to periphery was found to result in a diminished feed‐back effect in cones near the edge of the spot. This leads to a Mach‐band effect during the plateau phase of cone responses, suggesting that one function of the feed‐back might be to enhance contrast discrimination.
Functional characteristics of mechanoreceptors in sinus hair follicles of the cat
Authors: Gottschaldt K.‐M. , Iggo A. , Young D. W.
Published: December 2014

1. The discharge of impulses in afferent fibres dissected from the infraorbital and ulnar nerves of anaesthetized cats was recorded during controlled movements of the maxillary and carpal sinus hairs.

2. Four main types of afferent units were identified. Two had slowly adapting responses characteristic of the epidermal type I, and dermal type II mechanoreceptors of the hairy skin. Two rapidly adapting responses to movement of the sinus hairs were found, one with a high velocity threshold and another with a low velocity threshold.

3. The slowly adapting units showed a power relationship between the degree of displacement of the hair and the mean interspike interval of the response. Slowly adapting units also exhibited a power relationship between the velocity of displacement of a hair and the mean interspike interval of the response.

4. The conduction velocities of all types of afferent units were measured and fell in the range of the Aα, fast myelinated fibres.

5. Movements of the carpal sinus hairs yielded both types of slowly adapting response recorded in fibres of the ulnar nerve directly innervating the carpal sinus hair follicles, and rapidly adapting responses from Pacinian corpuscles, found in close association with, but external to, these follicles.

6. On the basis of the findings in this study and the results of anatomical investigations of the receptor structures in the sinus hair follicle a correlation between the distinguishable afferent responses and the morphologically identifiable nerve endings has been proposed.
The sequential contractions of the rumen associated with eructation in sheep
Authors: Ruckebusch Y. , Tomov T.
Published: December 2014

1. The orderly sequential movements of the reticulum and the rumen were studied in conscious sheep by electromyography using enamelled stainless‐steel wires implanted in various regions of the stomach wall and by recording mechanical changes within the various parts of the organ. Electrical activity of the rumen and/or pressure changes were related to eructation when the animals were at rest, feeding or ruminating.

2. Secondary contractions of the rumen were found to originate in the ventral blind sac immediately following a primary contraction or independently. The wave of contraction originating in the ventral blind sac was seen to pass in a circular manner to the dorsal blind sac, the dorsal sac, the ventral sac and finally once more to the ventral blind sac. Eructation occurs at the end of the contraction of the dorsal sac. In each case, the time required to initiate the secondary cycle depended on the strength of contraction of the ventral blind sac.

3. Sustained gaseous distension elicited numerous secondary contractions of the rumen concurrent with a lower frequency of reticular contractions. Although some secondary contractions were incomplete, all began with contraction of the ventral blind sac and were associated with eructation.

4. Chemical stimulation of the rumen by fatty acids at pH 5·5–5·9 increased the ratio of secondary to primary contractions of the rumen to a varying extent depending on their initial rate.

5. It was concluded that the seemingly random occurrence of a secondary cycle of the rumen was dependent on the activity of the ventral blind sac and its pattern could be altered by both mechanical and chemical stimulation.
Sweat storage as a factor influencing sweat discharge in sheep
Authors: Johnson K. G.
Published: December 2014

1. Sweat output has been measured continuously from four Welsh Mountain sheep exposed on several occasions for periods of 8 hr to air temperatures of 20, 30 and 40° C. At all temperatures sweat was discharged intermittently. Discharges occurred more frequently at high air temperatures and when the animals were shorn, but not at consistently different frequencies in summer and winter.

2. At 40° C Ta, sweat discharges were initially large, decreased in size during the first 1–3 hr, and then continued at regular intervals and at an approximately constant size for the remainder of the experiments. Most, and probably all, sweat glands in the skin were active at each discharge.

3. The volumes of sweat glands, determined histologically, decreased after prolonged activity in the heat. Comparison of the changes in sweat gland volumes with the amounts of sweat discharged led to conclusions that the decline in sweat output seen on initial exposure to heat was probably due to depletion of secretory fluid from storage within the gland and that the subsequent regular discharge of small amounts of sweat was due to expulsion of newly formed secretion.

4. Examination of serial sections of midside skin revealed that in these sheep sweat glands consisted of a superficial non‐convoluted duct separated from a large ampulla by a region in which the gland was convoluted. After long periods of sweating, the glands decreased in diameter in both the convoluted and non‐convoluted regions but were never found to be empty.

5. The pattern of sweat output from sheep during prolonged exposure to heat appears to be determined not only by processes of secretion and intermittent expulsion but also by the amount and rate of depletion of preformed sweat stored in the gland lumen.
Effect of cations on the blood platelet release reaction
Authors: Sneddon J. M. , Williams K. I.
Published: December 2014

1. Stimulus‐secretion phenomena in blood platelets incubated with trypsin or thrombin have been investigated.

2. Secretion occurs in at least two stages: (a) induction, obtained when the platelets are incubated with proteolytic enzymes in the presence of the chelating agent EDTA, and (b) release, which occurs with the subsequent addition of Ca2+ to the incubation medium.

3. Ca2+ was the only essential divalent cation required for release. Ba2+ and Mg2+ inhibited release and Sr2+ could only partially substitute for Ca2+.

4. Blood platelets exhibited recovery from enzymic perturbation by trypsin or thrombin by a mechanism that was temperature dependent, but did not require the synthesis of new protein.

5. The results are discussed in relationship to stimulus—secretion in other cells.
Saturation of a shared mechanism which transports L‐arginine and L‐lysine into the brain of the living rat
Authors: Baños Guadalupe , Daniel P. M. , Pratt O. E.
Published: December 2014

1. The rate of entry of
L‐arginine and
L‐lysine into the brain of the rat was measured in vivo by a direct method in which the amino acid concentration was at a constant level in the blood plasma over the period of the experiment.

2. Both
L‐arginine and
L‐lysine enter the brain by a transport mechanism which can be saturated by a high concentration of the same amino acid in the bloodstream. The rate of entry can be explained by Michaelis—Menten kinetics.

3. The entry into the brain of
L‐arginine can be inhibited by raised plasma concentrations of
L‐lysine or
L‐ornithine and the entry of
L‐lysine by raised concentrations of
L‐arginine.

4. The inhibition of entry of an amino acid is most severe when its own concentration in the blood plasma is low and that of the inhibitor is high. The inhibition appears to be basically competitive in type, suggesting that common transport systems are shared by three dibasic amino acids.

5. It is suggested that the raised levels of amino acids found in various disorders of amino acid metabolism are likely to reduce the rate of entry into the brain of other amino acids and a way is suggested in which the dietary treatment of hyperlysinaemia may be made more effective.
A study of single axons in the cat's medial lemniscus
Authors: Brown A. G. , Gordon G. , Kay R. H.
Published: December 2014

1. A method was developed for locating the rostral part of the medial lemniscus in anaesthetized cats and then exploring it with a micro‐electrode selective for single axons. Records were made from 165 axons, all shown histologically to lie in the lemniscus.

2. Almost all lemniscal axons responded at short latency to a shock through surface electrodes over the dorsal columns at C2. The great majority probably belonged to the dorsal column‐lemniscal system, though some may have belonged to other (e.g. spinocervicothalamic) systems.

3. Resting discharge was seen in almost all axons in the absence of any stimulation, and must have been generated almost entirely in the relevant relay nuclei, particularly since in many axons it was easily depressed or totally inhibited by appropriately placed mechanical stimulation of skin or a shock to the dorsal columns.

4. For each fibre held for an adequate length of time, the receptive field, if accessible, was classified as accurately as possible. Fifty‐two axons were precisely categorized in this way: many more were studied for long enough to yield useful information.

5. One half (twenty‐six) of the best categorized axons had receptive fields suggesting excitation by only one type of receptor: fifteen by tylotrich hairs, four by rapidly adapting tactile foot pad receptors, two by claw movement, two by cutaneous touch corpuscles and three by Type II cutaneous receptors. Rigidly held probes driven by electromechanical transducers were used to establish stimulus/response relations. Adjacent or surround inhibition was seen in nearly all these fields, except for the Type II category.

6. The other half (twenty‐six) of the best categorized axons showed various degrees of inter‐receptive excitatory convergence. Five responded to all types of hair, twelve to hair movement and foot‐pad displacement, and nine to hair movement combined with inputs from a variety of slowly adapting receptors in skin or deep tissues, thresholds for the latter ranging from light contact to noxious pressure.

7. Forty axons responded with a slowly adapting discharge to joint movement, some with properties suggesting that their receptors did not lie in the joint capsule itself. The high threshold of most of these axons to dorsal column stimulation suggested that the relevant primary axons lay either deep in the dorsal column or in some other tract.

8. Of axons whose receptive fields were accurately located, 88% lay in forelimb or upper trunk — the remainder in lower trunk, hind limb or tail. The forepaw accounted for 41% of the former group. Axons with receptively ‘pure’ properties tended to lie in central or deep parts of the main lemniscal mass at the level studied. Axons responding to joint movement tended to lie deep in the main mass and in the ventromedial lemniscal bundle. There was some clustering of axons with identical receptive properties.
The relationship of choline acetyltransferase activity at the neuromuscular junction to changes in muscle mass and function
Authors: Diamond Ivan , Franklin Gary M. , Milfay Dale
Published: December 2014

1. The role of muscle mass and function in the regulation of choline acetyltransferase activity at the neuromuscular junction has been investigated in the rat.

2. Choline acetyltransferase (ChAc) is located in presynaptic nerve terminals and is a specific enzymatic marker of cholinergic innervation in muscle.

3. ChAc activity increased co‐ordinately with developmental growth of the soleus muscle. However, another form of muscle growth, work hypertrophy, did not produce an increase in ChAc.

4. Growth arrest of muscle by hypophysectomy did not alter the normal development of ChAc activity, and cortisone‐induced muscle atrophy did not reduce ChAc activity in the soleus or plantaris.

5. Tenotomy‐induced muscle atrophy provoked a significant fall in ChAc in the soleus and plantaris.

6. The tonic soleus had significantly greater ChAc activity than the phasic plantaris.

7. These observations suggest that muscle mass per se does not influence the development and regulation of ChAc in muscle but that the quality of muscle contraction may modulate enzyme activity.
Levels of prostaglandins in human endometrium during the normal menstrual cycle
Authors: Downie J. , Poyser N. L. , Wunderlich M.
Published: December 2014

The levels of prostaglandins in the human endometrium throughout the normal menstrual cycle were measured by bioassay. The identity of prostaglandin F2α and prostaglandin E2 in endometrial tissue extracts was established by combined gas chromatography/mass spectrometry.

The levels of prostaglandin F2α and prostaglandin E2 are low during the proliferative phase of the cycle (10–25 ng/100 mg tissue). Prostaglandin F2α rises significantly during the luteal phase to levels of 65–75 ng/100 mg of tissue. Prostaglandin E2 levels are similar to prostaglandin F2α levels in the proliferative phase but remain lower during the luteal phase. The prostaglandin E2 level is highest at menstruation (52 ng/100 mg tissue). The implications of these findings are discussed in relation to the menstrual process and to the steroid hormonal changes during the cycle.
An analysis of the role of calcium in facilitation at the frog neuromuscular junction
Authors: Younkin S. G.
Published: December 2014

1. Under appropriate conditions stimulation of the neuromuscular junction by a single impulse or a brief train causes subsequent impulses to release increased amounts of transmitter. It has been proposed that this facilitation of transmitter release is due to calcium which remains on release sites following the conditioning stimuli. This residual calcium hypothesis is examined in frog cutaneous pectoris muscle in the present study.

2. The second component of facilitation is shown to depend on the amount of calcium present during tetanization as required by the residual calcium hypothesis.

3. The quantitative behaviour of the facilitation accompanying tetani of a number of frequencies and durations is found to be consistent with the residual calcium hypothesis.

4. Quantitative analysis of facilitation leads to a description of the time course of removal of calcium from release sites which is discussed.
Characteristics, specificity, and efferent control of frog cutaneous cold receptors
Authors: Spray David C.
Published: December 2014

1. Thermal stimulation of frog skin produces a discharge in afferents in the dorsocutaneous nerve. The characteristics of this response have been examined with regard to static and dynamic sensitivity to thermal stimuli and to mechanical sensitivity. Frog cutaneous receptors respond only to cooling, with no response to warming through the same thermal range.

2. The static temperature at which these receptors are maximally active is about 24° C for Rana pipiens and about 27° C for R. catesbiana.

3. The dynamic sensitivity of frog cutaneous receptors is linearly related to both stimulus slope and magnitude. Maximum dynamic sensitivity was between −90 and −120 impulses/° C.sec.

4. Antidromic occlusion experiments demonstrate relative insensitivity of these receptors to tonic mechanical stimulation. At high stimulus intensities, however, larger fibres are recruited into the response; this recruitment of action potentials of larger amplitude is a linear function of both stimulus slope and magnitude.

5. Spike heights are linearly related to conduction velocities in the dorsocutaneous nerve; tonic mechanoreceptors have a mean spike height of 28·4±0·6 μV and conduction velocities about 6–8 m/sec, whereas these temperature sensitive receptors have spike heights 15·8±0·4 μV and conduction velocities about 3–4 m/sec.

6. Maximum dynamic sensitivity skin is increased following stimulation of the first or second sympathetic ganglion. This increase is both marked and progressive, reaching a maximal enhancement of about 150–160% control at a stimulus rate of 5 stimuli/train, each train delivered once every 5 sec.

7. Static sensitivity of the cold receptors is also increased following sympathetic stimulation. This increased sensitivity is shown by both increased discharge rate within the same thermal range and by decreased temperature of maximum static sensitivity.

8. Sympathetic modulation of dynamic thermal sensitivity is mimicked by epinephrine and norepinephrine in doses of 10−6‐10−7 g/ml. Ephedrine, another adrenergic agonist, also mimics the enhancement of cold receptors by sympathetic stimulation.

9. Larger fibres are recruited to account for the increased sensitivity of thermoreceptors following sympathetic stimulation and epinephrine application.

10. Propranolol and phentolamine both block the enhancement of the response by sympathetic stimulation, but propranolol blocks the response of the receptor to thermal stimulation as well. Reserpine pre‐treatment blocks the effect of sympathetic stimulation on the cold response.
The effect of visual experience on the development of stimulus specificity by kitten cortical neurones
Authors: Pettigrew J. D.
Published: December 2014

1. 284 single cortical neurones were studied in area seventeen of twenty‐five normal kittens and of fifteen kittens, binocularly deprived, whose first visual experience had been delayed until the experiment by bilateral lid‐suture. Both normal and binocularly deprived kittens ranged in age from 1 to 6 weeks.

2. The optimal, binocularly presented, visual stimulus and receptive fields were determined for each neurone by varying target configuration, speed and direction of movement and the prism‐induced alignment of both eyes. Repetitive, controlled stimulation in eighty‐four cases allowed quantitative estimates to be made of the response selectivity for the target configuration (spot vs. line), the direction of target motion and the prism‐induced disparity between the retinal images of the binocular target.

3. Before the fourth post‐natal week neurones from both normal and binocularly deprived cortex showed similar properties: selectivity for direction of target motion was present in both preparations but both lacked binocular specificity and dependence on target configuration.

4. After the fourth week, normal kittens had increasing numbers of neurones with selective responses which were dependent upon target configuration and the degree of binocular misalignment. The proportion of selective neurones approached the adult value after the fifth week.

5. The cortex of binocularly deprived kittens failed to show an increase of selectivity with age, and of 150 neurones, sixty‐two were visually unresponsive, two showed selectivity which was dependent upon target configuration and none showed selectivity for prism‐induced retinal disparity.

6. The data are not consistent with the hypothesis that the highly specific response properties of visual cortical neurones can develop without appropriate visual experience. Innate mechanisms appear to be sufficient for the development of the excitatory connexions producing motion sensitivity and receptive field location on both retinas, but patterned visual experience is necessary for the ‘fine‐tuning’ which vetoes responses to stimuli with non‐optimal configuration or binocular disparity.
The compliance of contracting skeletal muscle
Authors: Bressler B. H. , Clinch N. F.
Published: December 2014

1. The method of controlled releases was used to obtain tension—extension curves in toad (Bufo bufo) sartorii under a variety of conditions at 0° C.

2. The curves obtained were approximately linear over a considerable range of force (0·4P0 to P0) if the releases were given from the plateau of tetanic tension. The slope of this linear region was little affected by changes of release velocity in the range 10–120 mm/sec.

3. Such changes as did occur with alterations in release velocity could be quantitatively accounted for in terms of the internal shortening predicted by A. V. Hill's two‐component model.

4. As the muscles were stretched above l0, we found that the maximum stiffness of the tetanized muscles fell in much the same way as the maximum developed force, P0.

5. In another series of experiments we found a rapid change in the overall shape of the tension—extension curve during the early phase of force development in an isometric tetanus. The stiffness of the muscle increased with increasing developed force during this period.

6. The force—velocity curve in these muscles was measured by two methods, both giving a similar result. Surprisingly, toad muscle appears to have about the same intrinsic speed as frog muscle at 0° C. The a.b product from our experiments is considerably greater than the reported values for the maintenance heat rate at 0° C in these muscles.

7. The probable site of the variable compliance in active muscle is discussed. It seems most likely that this is within the A‐band, perhaps in the cross‐bridges themselves.
The effects of the production of sodium depletion by peritoneal dialysis with 5% glucose on the volume and composition of the extracellular fluid of dogs
Authors: Rampton D. S. , Ramsay D. J.
Published: December 2014

1. The volumes and compositions of the extracellular and peritoneal fluids were monitored in functionally nephrectomized dogs during a period of 4 hr of peritoneal dialysis with 5% glucose.

2. The extracellular fluid volume ([14C]mannitol space), sodium, potassium and chloride concentrations decreased, while the peritoneal fluid volume, sodium, potassium and chloride concentrations increased.

3. Movement of water from the e.c.f. to non‐extracellular sites occurred, reaching a maximum after 1 hr; thereafter, the movement of water was first reduced, and later reversed.

4. From the volumes and compositions of the extracellular and peritoneal fluids, the total contents of solutes in the two compartments were calculated.

5. There was a mobilization of sodium and chloride from non‐extra‐cellular sites, which became significant after 2 hr of dialysis, and increased throughout the remainder of the period of dialysis.

6. The physiological significance of these changes is discussed.
The sodium‐transporting compartment of the epithelium of frog skin
Authors: Cereijido M. , Rabito C. A. , Boulan E. Rodríguez , Rotunno Catalina A.
Published: December 2014

1. The abdominal frog skin was mounted between two chambers containing Ringer with 1 m
M‐Na on the outside and 115 m
M‐Na on the inside. When the Na concentration of the outer solution ([Na]o) is instantaneously raised from 1 to 50 m
M, the short circuit current (I) increases to a new value in less than a second, and becomes essentially time‐independent. Only in a few experiments was it observed to increase further, although at a much slower rate.

2. At a time t after this increase, the addition of 10−4
M amiloride to the outer solution produces an exponential decrease of I. The area under this exponential curve is generally taken to reflect the existence of a Na‐ transporting compartment (NaTC).

3. The amount of Na represented by NaTC is a function of t: it increases from 1·7 × 10−9 mole. cm−2, at t = 10 sec, to 22·8 × 10−9 mole. cm−2 at t = 10 min.

4. In view of the fact that (a) I is not a function of the size of the ‘NaTC’ and (b) that whereas I reaches a steady value in a fraction of a second the size of NaTC keeps increasing for minutes, it is proposed that the ‘NaTC’ represents an amount of Na which is not located along the main route of transepithelial transport.

5. On the assumption that the NaTC is located in a cellular compartment and that, in order to accumulate in this compartment Na should be accompanied by a permeable anion, a series of experiments were performed with Ringer in which Cl− was replaced by gluconate. It was observed as expected, that NaTC in gluconate is 164 times smaller than in Cl−, but I only decreases to one half its value in Cl− Ringer.
Membrane capacity measurements on frog skeletal muscle in media of low ion content. With an Appendix
Authors: Adrian R. H. , Almers W. , Chandler W. K.
Published: December 2014

1. A voltage‐clamp technique for the measurement of effective membrane capacity is described and its theoretical basis given in an Appendix. Unlike most other methods used so far, the present technique does not depend on the assumption of a particular equivalent circuit for muscle membrane.

2. With this technique, we have re‐examined the effect of media of low ion content on the effective membrane capacity Ceff. In fibres where potassium conductance is blocked by Rb, Ceff failed to show any appreciable dependence on ionic strength (between 0·015 and 0·29
M) or conductivity (between 0·86 and 13·4 mmho/cm) of the bathing medium.

3. Low conductivity can reduce Ceff in fibres of moderately high K‐conductance. However, in all cases explored here, Ceff had values well above the 2 μF/cm2 found in glycerol‐treated fibres, indicating that passive spread of potential displacements from surface into the tubular system could still occur.

4. The changes in Ceff observed under conditions of moderately high K‐conductance are explicable as a result of potential decrements in the transverse tubules, which would be expected when the wall conductance there is high, and the conductivity of the tubule lumen is low.
Analysis of non‐linearity observed in the current—voltage relation of the tunicate embryo
Authors: Miyazaki Shun‐Ichi , Takahashi Kunitaro , Tsuda Kazuko , Yoshii Mitsunobu
Published: December 2014

1. In the gastrula of the tunicate (Halocynthia aurantium) the resting potential of the embryonic membrane was about −70 mV in both std ASW and Na‐free ASW.

2. The potential responses to depolarizing current in the early gastrula embryo showed distinct potential jumps from about −50 to about +40 mV during the application of current and from about 0 to resting level after its cessation thus forming a plateau at about 0 mV. Those jumps were not altered significantly by the removal of both Na and Ca ions from ASW except for the duration of the plateau after the cessation of current.

3. Blastomeres in an embryo were tightly coupled with each other electrotonically at the blastula and gastrula stages. The fact that the coupling ratio was nearly 1·0 made it reasonable to treat an embryo as one cell as far as electrical properties are concerned.

4. The I—V relation of the embryonic membrane consisted of an inward rectifying region, outward rectifying region and transitional zone between the two, resulting in a S‐shaped curve as in the egg cell membrane. But in the gastrula embryo, the transitional zone actually included the discontinuous part of the I—V curve (from about −50 to about +40 mV) due to the potential jump.

5. The ionic current (Ii) during the potential jump in Na‐free ASW was estimated from the slope of the potential response based on the assumption of constant capacitance during the membrane potential changes. The calculated Ii—V curve complemented the interrupted I—V curve smoothly and showed the existence of a negative resistance region from about −50 to about 0 mV in the steady‐state I—V relation.

6. The steady‐state I—V relation was altered significantly by changing the K concentration in ASW, and the existence of the negative resistance can be reasonably explained by the marked inward‐going rectification or anomalous rectification of K conductance.

7. The replacement of K with Rb in ASW produced the marked suppression of the inward‐going rectification of the embryonic membrane.
The influence of centrally applied noradrenaline on shivering and body temperature in the pigeon
Authors: Hissa R. , Rautenberg W.
Published: December 2014

1. Noradrenaline (NA) was injected in a volume of 1·0 μl. through chronically implanted cannula into the hypothalamus of the unanaesthetized pigeon.

2. In doses of 1–15 μg NA caused complete inhibition of shivering of dose‐dependent duration. Histological mapping of the brain showed that NA was exerting its inhibitor action in the region above the optic chiasma bordering on the posterior hypothalamus and the anterior preoptic nucleus.

3. At low ambient temperature, the NA induced inhibition of the cold tremor caused a fall of core temperature which lasted as long as shivering was inhibited. Shivering induced by local cooling of the spinal cord, and by the combined cooling of the skin and the spinal cord, was likewise inhibited by the cerebral application of NA. There was no evidence of an adjustment of the temperature set‐point by NA.

4. A rapid rise in skin temperature of the unfeathered feet, whenever NA was injected indicated a reduction in peripheral vasomotor tone.
Energetics of relaxation in frog muscle
Authors: Curtin Nancy A. , Woledge Roger C.
Published: December 2014

1. Changes in the levels of phosphocreatine (PCr) and ATP during relaxation after tetanic contraction have been observed and compared with the heat + work production during the same period.

2. The results were the same using 2 sec or 15 sec tetani and using 15 or 30 Hz stimulation.

3. During relaxation the mean chemical change (of ATP + PCr) was −0·105 ± 0·078 μmol/g muscle (n = 53). This change is less than would be required to explain the heat + work produced.

4. The PCr split during both 2 sec and 15 sec tetani (up to the last stimulus) was less than would be required to explain the heat + work produced. This confirms previous experiments.

5. It is concluded that the discrepancy between chemical change and heat + work production does not diminish during relaxation but actually increases.
Motor units in cat soleus muscle: physiological, histochemical and morphological characteristics
Authors: Burke R. E. , Levine D. N. , Salcman M. , Tsairis P.
Published: December 2014

1. Physiological properties of motor units in the soleus muscle were studied in anaesthetized cats using intracellular stimulation of motoneurones to ensure functional isolation of single units. The muscle fibres belonging to 6 units were identified by glycogen depletion following prolonged stimulation, permitting analysis of their histochemical profiles and anatomical organization.

2. The studied units in soleus were all classed as type S and were extremely resistant to fatigue during prolonged stimulation. Twitch contraction times ranged from 64 to 131 msec (mean 97·1 msec) and tetanic tensions ranged from 3·5 to 36 g (mean 10·5 g). Most units exhibited depression of twitch tension in the wake of a short high‐frequency tetanus and few of the units showed any significant degree of post‐tetanic twitch potentiation.

3. Muscle fibres belonging to single soleus motor units were found to be scattered through territorial volumes occupying a large fraction of the total muscle volume. The available data suggest that different soleus motoneurones may innervate from less than 50 to more than 400 muscle fibres, with an average innervation ratio between 140 and 190 muscle fibres per unit.

4. The results were compared with observations on type S motor units in the synergist gastrocnemius, obtained under similar conditions. The evidence suggests that soleus units are not equivalent to the type S units of the mixed gastrocnemius but rather constitute a unique population.
Opponent‐colour cells in different layers of foveal striate cortex
Authors: Gouras Peter
Published: December 2014

1. The majority of cells in layer 4B have opponent‐colour properties indicating that colour opponency plays an important role in the early stages of visual processing in foveal striate cortex. In contrast to cells in the lateral geniculate nucleus many of these cells receive centre—surround antagonism from the same cone mechanism. Some cells show this spatial antagonism at threshold; others require suprathreshold stimuli for its demonstration.

2. The majority of cells in layer 4B do not show orientation or directional selectivity. The proportion of cells with orientation and directional selectivity increases and the proportion of opponent‐colour cells decreases with increasing distance above and below layer 4B so that the majority of cells in the outer layers exhibit considerable spatial selectivity without apparent colour opponency. These changing proportions suggest that the latter cells may be receiving their inputs from different types of opponent‐colour cells making them sensitive to different types of colour contrast but not to colour per se.

3. More opponent‐colour cells receive inputs from the red‐ and green‐ sensitive cone mechanisms than from the blue‐sensitive one. This difference is more marked in layer 4B than 3B suggesting that the latter cortical layer may be more involved in colour vision than the former.
Effect of stretching on the elastic characteristics and the contractile component of frog striated muscle
Authors: Cavagna Giovanni A. , Citterio G.
Published: December 2014

1. The force—velocity relationship and the stress—strain curve of the so‐called series elastic component (s.e.c.) of frog sartorius, semitendinosus and gastrocnemius have been determined during shortening against a given force (isotonic quick‐release) and at high speed (controlled release): (a) from a state of isometric contraction and (b) after stretching of the contracted muscle. In both cases the muscle was released from the same length: this was usually slightly greater than the muscle's resting length.

2. The muscle released immediately after being stretched is able to shorten against a constant force, P, equal to or even greater than the isometric force, P0, at the same length. When the force P applied to the muscle is reduced below P0 the velocity of shortening is greater after stretching, and the force—velocity curve is therefore shifted along the velocity axis: the shift is maximal when P is near to P0 and it decreases rapidly with decreasing P.

3. The extent of shortening of the s.e.c. required to make the force fall from P0 to zero is 50–100% greater when the muscle is released immediately after stretching than when it is released from a state of isometric contraction. This difference is found by using either the controlled release method or the isotonic quick‐release method.

4. If a time interval is left between the end of stretching and the onset of shortening of the contracted muscle (controlled release method), the length change of the s.e.c., for a given fall of the force, is reduced and approaches that taking place when the muscle is released from a state of isometric contraction.

5. Curare does not affect the results described above, indicating that these do not depend on modification of the neuromuscular transmission.

6. It is concluded that stretching a contracted muscle modifies temporarily: (a) its elastic characteristics, as shown by the greater amount of mechanical energy released for a given fall of the force at the muscle's extremities, and (b) its contractile machinery, as it is suggested by the change of the force—velocity relationship.