bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative aspects of sensitivity and summation in the cat retina
Authors: Cleland B. G. , Enroth-Cugell Christina
Published: December 2014

1. Properties of the central response mechanism of on‐centre ganglion cells in the cat retina were studied by recording, from optic tract fibres, responses evoked by stimuli modulated with time in a sinusoidal or square‐wave fashion.

2. The shape of averaged square‐wave responses resulting from the central mechanism alone was identified. This shape was identical from one cell to another. Such an identification permits the early recognition of peripheral antagonism.

3. Threshold sensitivity for a sinusoidal stimulus was determined for fifty cells along one horizontal and vertical axis, passing through the most sensitive portion of the receptive field. These sensitivity profiles were described in terms of a central segment of constant maximum sensitivity (uniform centre) and sloping outer segments of exponentially decreasing sensitivity (exponential annulus). The dimensions of the uniform centre (horizontal axis × vertical axis) varied from 0·1° × 0·1° to 2·5° × 2·2°, the half width of the exponential annulus ranged from 0·1° to 0·63°.

4. Adapting spots of varying diameter were placed concentric with the receptive field and the (unmodulated) luminance, at each diameter, that reduced a small central (sinusoidal) stimulus to threshold, was determined. The resulting area—adaptation curve, (adapting luminance plotted against diameter) showed that within defined limits the state of adaptation is determined by the flux independent of its distribution.

5. Sinusoidal stimuli of varying diameter were placed concentric with the receptive field and the threshold luminance at each diameter was determined. Suprathreshold square‐wave stimuli indicated that the central mechanism alone contributed to the response. These area‐sensitivity curves did not show any decrease in sensitivity at larger diameters.

6. The shape of the area—sensitivity curve, and hence the extent of the summating area, was found to be independent of the state of adaptation.

7. For any one cell the shapes of the area—adaptation and area—sensitivity curves were shown to be identical, indicating that adapting flux and stimulus flux are independent of distribution over the same defined limits.

8. The sensitivity of combinations of small disconnected areas of the receptive field was found to be equal to the sum of their individual sensitivities.
The effect of 2,4‐dinitrophenol and related compounds on bile secretion
Authors: Pugh Patricia M. , Stone S. L.
Published: December 2014

1. 2,4‐dinitrophenol, 2,4‐dinitrophenetole, 2,4‐dinitronaphthol, 4,6‐dinitro‐o‐cresol, and to a lesser extent picric acid, produced an increase in bile flow and a rise in body temperature in the anaesthetized dog. The total biliary bromsulphalein (BSP) excretion in unit time was either slightly reduced, increased or remained at its pre‐injection level.

2. Picramic acid, the nitrochlorophenols and 2,4‐dinitrobenzaldehyde caused a moderate increase in bile flow without an effect on the temperature of the animal.

3. The three mononitrophenols, the five remaining isomeric dinitrophenols, isopicramic acid, the aminonitrophenols, phenol, 2,4‐dinitroanisole, 2,4‐dinitrobenzoic acid, 2,4‐dinitrobenzene sulphonic acid, 2,4‐dinitroresorcinol and 4‐nitracatechol had little effect on bile secretion or body temperature.

4. It thus appears that, in order for a compound of this type to have a pronounced effect on bile secretion, it is necessary to have nitro groups in positions 2 and 4 of the benzene ring, and a free or potential hydroxyl group.
Shivering and non‐shivering thermogenesis during summit metabolism in young lambs
Authors: Alexander G. , Williams D.
Published: December 2014

1. Summit metabolism of lambs declined steadily from about 3·5 l. O2/kg.hr during the first day of life, to about 2·0 l. O2/kg.hr at 2 months of age.

2. The contributions of shivering and non‐shivering thermogenesis to these changes were estimated by three independent methods; non‐shivering thermogenesis was stimulated by catecholamines in a thermoneutral environment, shivering was suppressed by curariform drugs during summit metabolism, and an attempt was made to suppress non‐shivering thermogenesis during summit metabolism by use of the sympatholytic drugs phentolamine and propranolol. Drugs were given by intravenous infusion during measurement of oxygen consumption in a closed circuit respiration chamber.

3. ‘Resting’ metabolic rate of lambs during the first day of life was increased two to three‐fold, from 1 l. O2/kg.hr, by either adrenaline or noradrenaline infused at 1‐10 μg/kg.min. The increase declined with increasing age of lamb and was virtually absent by 3 weeks. The response to catecholamines appeared maximal at the dose levels used.

4. Muscular paralysis induced by suxamethonium or gallamine reduced summit metabolism by about 2 l. O2/kg.hr in all lambs examined within the first 2 months of life. The residual metabolic rate, and the metabolic response to catecholamines under thermoneutral conditions, declined with age in the same manner, and their magnitudes were similar.

5. Summit metabolism in lambs aged up to 2 months was depressed to varying degrees by the sympathetic inhibitors phentolamine, propranolol and hexamethonium. The depression with propranolol was greater, and the decline with age clearer, than with phentolamine. Hexamethonium and phentolamine depressed blood pressure, propranolol decreased heart rate and phentolamine and propranolol each suppressed shivering in some experiments.

6. In 1 day‐old lambs estimates of non‐shivering thermogenesis, by the various methods, ranged from 0·8 to 1·4 l. O2/kg.hr (mean 1·1 l. or 31% of summit metabolism), and the estimates of shivering ranged from 1·3 to 1·9 l. O2/kg.hr (mean 1·6 l. or 46% of summit metabolism). However, in lambs 1‐month old, estimates of non‐shivering thermogenesis from sympathetic inhibition (0·6 and 0·8 l. O2/kg.hr) were considerably higher than estimates from muscular paralysis or stimulation by catecholamines (0·2 and 0·1 l. O2/kg.hr). It is suggested that the depression of summit metabolism by the sympathetic inhibitors is not solely due to specific inhibition of non‐shivering thermogenesis, at least in the older lambs.

7. The possession of a non‐shivering thermogenic mechanism in addition to shivering is of clear survival value to new‐born lambs.
Vagal control of thermal panting in mammals and birds
Authors: Richards S. A.
Published: December 2014

1. The role of the vagus nerves during normal respiration and thermal polypnoea was examined in four species of mammals and four species of birds by lung/air sac inflation and cervical vagotomy.

2. The Hering—Breuer inflation reflex could be elicited in all of the mammals during both normal respiration and panting; it was present in the fowl and pigeon at normal body temperature only.

3. Section of one vagus during hyperthermia reduced respiratory frequency in most animals and increased depth. Bilateral vagotomy had little further effect in the panting rabbit, lamb and pigeon, but abolished rapid respiration in the rat, guinea‐pig, fowl, duck and quail.

4. Vagotomized lambs and pigeons started panting in response to increasing body temperature, although the rate attained was slower than in intact animals. Guinea‐pig, rat, fowl and quail did not pant under these conditions.

5. Appropriate afferent vagal stimulation in the vagotomized fowl maintained normal respiration or thermal panting.

6. It is concluded that panting can, in some mammals and birds, be controlled by central mechanisms alone, while in others it depends on extrinsic stimuli mediated by way of the vagus nerves.
Oxygen consumption in normally grown, small‐for‐dates and large‐for‐dates new‐born infants
Authors: Hill June R. , Robinson D. C.
Published: December 2014

1. Serial measurements of minimal oxygen consumption (V̇O2) have been obtained from nineteen healthy new‐born infants in order to find out how body weight, gestational age and age after birth affected V̇O2. The first measurement of V̇O2 was done within 12 hr of birth, and further measurements were made at intervals until the baby left hospital.

2. The majority of the infants (seventeen) weighed less than 2·5 kg at birth, and were ‘premature’ according to international definition. Gestational age, calculated from the mother's last menstrual period, was corroborated by clinical data and obstetrical history. The babies were divided into four groups according to birth weight and gestational age combined (see Table 1). Babies in the first two groups were the appropriate weight for dates (i.e. normally grown), babies in the other two groups were either small‐for‐dates or large‐for‐dates.

3. At birth minimal V̇O2 was closely correlated with birth weight in all babies and appeared to be directly proportional to it. The value for V̇O2/kg was similar in all groups. V̇O2 was not related to gestational age per se. However, in the two normally grown groups V̇O2 was roughly related to gestational age because birth weight was related to gestational age.

4. In all babies minimal V̇O2 rose progressively with increasing age after birth; a marked increase in V̇O2 occured in the first week of life, despite a small decline in body weight.

5. At a given age after birth differences in V̇O2/kg between the four groups were mostly less than 10%, and in general the differences were not statistically significant.

Values for minimal V̇O2 in all four groups were roughly:

5 ml. O2/kg.min at < 12 hr of age.

7 ml. O2/kg.min at 7‐14 days of age.

9 ml. O3/kg.min at about 2 months of age.

6. It is concluded that:

(a) At birth minimal V̇O2 is largely determined by birth weight. V̇O2/kg is little affected by either rate of growth in utero or gestational age.

(b) Minimal V̇O2 is a function of age after birth as well as of body weight, and the value for V̇O2/kg increases as the baby gets older.
The effect of local blockage of motor nerve terminals
Authors: Katz B. , Miledi R.
Published: December 2014

1. Electrophoretic application of tetrodotoxin (TTX) was used to study the effect of localized blockage of impulses in motor nerve terminals.

2. Under suitable conditions it can be shown that local production of end‐plate potentials ceases distal to the site of TTX application, while it continues without diminution at proximal sites of the same terminal arborization.

3. It is concluded that electrotonic spread of an action potential wave along a motor nerve terminal is insufficient to elicit transmitter release. Active propagation in the terminals is an essential requirement for neuromuscular transmission.
Three factors limiting the reliable detection of light by retinal ganglion cells of the cat
Authors: Barlow H. B. , Levick W. R.
Published: December 2014

1. Responses of cat retinal ganglion cells have been examined with a view to specifying the characteristics that limit the detection of light stimuli.

2. Threshold is defined as the weakest stimulus that can be reliably detected by examination of the output from a retinal ganglion cell; it depends upon (a) the quantum/spike ratio, which is the mean number of additional quantal absorptions required to produce an additional impulse, (b) the temporal course of the response, which determines the time interval within which the maintained discharge is modified, and (c) the statistical distribution of the number of impulses that occur in this time interval in the absence of the stimulus.

3. The quantum/spike ratio changes greatly when adapting luminance is changed, and this is the predominant factor accounting for changes in increment threshold.

4. The time course of the response changes with adaptation level and area of the stimulus. This may account for the changes in temporal integration that occur in analogous psychophysical experiments.

5. Changes in the irregularity of the maintained discharge also affect the threshold of single ganglion cells. This is only a minor factor in the conditions of most of our experiments, but it may be important when unstabilized images and non‐equilibrium adaptation conditions are encountered.
Flash bleaching of rhodopsin in the human retina
Authors: Ripps H. , Weale R. A.
Published: December 2014

1. Measurements were made of the photo‐sensitivity of rhodopsin in the living human retina following bleaching with (a) a flash less than 1 msec in duration, (b) a continuous exposure lasting 30 sec.

2. The apparatus consisted of a fundus reflectometer coupled to a computer for on‐line processing. Three subjects were studied.

3. The relations between the quantity of pigment bleached and the incident energy are so similar for the flash and continuous exposure tests that the occurrence of photo‐reversal (such as has been reported in similar circumstances for visual pigment in solution) seems to be ruled out.

4. Nonetheless, the two experimental conditions lead qualitatively to two different photo‐chemical states in as much as the density difference spectrum for the flash exposure is displaced toward longer wave‐lengths in comparison with the data obtained with the continuous exposure.

5. The results are discussed with reference to the sequence of events following the bleaching of visual pigments solutions as reported by other workers.
The influence of calcium on sodium efflux in squid axons
Authors: Baker P. F. , Blaustein M. P. , Hodgkin A. L. , Steinhardt R. A.
Published: December 2014

1. Previous work has shown that the sodium efflux from the axons of Loligo forbesi increases when external sodium is replaced by lithium.

2. The increase in efflux in lithium was unaffected by ouabain but was abolished by removal of external calcium; in these respects it differed from the potassium‐dependent sodium efflux which was abolished by ouabain but not reduced by removal of external calcium.

3. Strontium but not magnesium could replace calcium in activating the ouabain‐insensitive sodium efflux; lanthanum had an inhibitory effect.

4. Replacing all the external NaCl by choline chloride or dextrose gave a rise in Na efflux which was abolished by ouabain but not by removal of external calcium.

5. The rise in Na efflux resulting from partial replacement of NaCl by dextrose or choline chloride consisted of two components one of which was ouabain‐insensitive and calcium‐dependent and the other was inhibited by ouabain but calcium‐insensitive.

6. The ouabain‐insensitive component of the Na efflux was activated by low concentrations of Na, Li or K but inhibited by high concentrations of Na and to a lesser extent Li. The inhibiting effect of high Na was of the kind expected if these ions displace calcium from an external site.

7. The ouabain‐insensitive component of the Na efflux was abolished by cyanide, had a Q10 of 2·7; and was roughly proportional to [Na]i2. It was much more variable in magnitude than the ouabain‐sensitive, potassium‐dependent component of the sodium efflux.

8. The calcium influx increased five to fortyfold when external NaCl was replaced by LiCl or dextrose, the increase for Li being larger than the increase for dextrose.

9. The calcium influx from Na, Li or dextrose sea water was increased three to tenfold by increasing the internal Na about fourfold.

10. The experiments provide evidence for a coupling between an inward movement of calcium and an outward movement of sodium.
Motor nerves of salivary myoepithelial cells in dogs
Authors: Emmelin N. , Garrett J. R. , Ohlin P.
Published: December 2014

1. The pressures in the ducts of the parotid and submaxillary glands were recorded in dogs under chloralose‐urethane anaesthesia. A single stimulus applied to the parasympathetic nerve regularly caused a pressure rise of short duration. Usually it did not evoke secretion.

2. In both glands a single stimulus applied to the vagosympathetic trunk usually caused a pressure response of short duration. It had no secretory effect.

3. In the parotid gland, repetitive vagosympathetic stimulation caused a sustained increase of pressure in the duct, usually without inducing secretion.

4. In the submaxillary gland, repetitive vagosympathetic stimulation caused a sustained pressure rise, even when the secretory response had been abolished by propranolol.

5. It is concluded that the salivary myoepithelial cells of dogs are supplied with fibres from both sympathetic and parasympathetic divisions of the autonomic nervous system and both can cause the cells to contract.
Extraocular muscle afferents to the cerebellum of the cat
Authors: Fuchs A. F. , Kornhuber H. H.
Published: December 2014

1. Afferents from the extraocular muscles to the cerebellum of the cat were investigated by evoked potential techniques using muscle stretch as a stimulus.

2. Short (about 4 msec) latency responses occurred in the vermian folia anterior (Larsell's lobule V b, c) and posterior (lobules VI and VII) to the primary fissure under light Nembutal anaesthesia.

3. The location of the cerebellar eye muscle responses coincides with the visual and auditory projections as well as homologous projections from cortical Areas 8 (the frontal eye fields) and 17 in the monkey. It also overlaps the oculomotor area of the cerebellum as revealed by electrical stimulation.

4. Facts 2 and 3 above, together with the selective disturbance of saccadic eye movements in humans with cerebellar atrophy, suggest a cerebellum mediated proprioceptive feed‐back loop for the control of saccadic eye movements.
The molecular dimensions of porcine neurophysin and some thermodynamic parameters of the reaction with lysine vasopressin
Authors: Ginsburg M. , Thomas P. J.
Published: December 2014

1. The molecular weight of porcine neurophysin was estimated by molecular sieve chromatography and by analytical ultracentrifugation and was found to be in the order of 13,000.

2. Internal evidence for the homogeneity of the preparation of neurophysin with respect to molecular weight was obtained in the ultracentrifugation experiments.

3. The frictional ratio of neurophysin was 1·1 which suggests that the molecular form of the protein approximates to a sphere.

4. The molecular weight and frictional ratio were not affected by temperature change (10–34° C) or by twofold change in protein concentration.

5. The binding of [14C]lysine vasopressin to porcine neurophysin was studied at 0, 27 and at 45° C, and double reciprocal plots of the binding were shown to be curvilinear at 27 and at 45° C and rectilinear at 0° C.

6. Concordant estimates for maximum binding capacity were obtained by extrapolations from the data at 27 and 45° C by applying two independent empirical methods of approximation; these agreed with the estimate obtained by extrapolation of the straight line, fitting data obtained at 0° C, being approximately 1 mole lysine vasopressin per 13,000 g protein.

7. The association constant and thermodynamic parameters of the reaction were estimated for near saturation conditions. The reaction is entropy driven.

8. The binding of lysine vasopressin was found to be dependent on protein concentration. No dependence of oxytocin binding on protein concentration was apparent.
Calcium movements across the membrane of human red cells
Authors: Schatzmann H. J. , Vincenzi F. F.
Published: December 2014

1. A study has been made of the cellular content and movement of Ca across the membrane of human red blood cells.

2. The [Ca] in the cellular contents of fresh red cells is 4·09 × 10−2 m
M. The intracellular concentration of free ionic Ca ([Ca2+]) is considered to be less than this value and therefore less than extracellular [Ca2+] under normal conditions.

3. Observation of unidirectional Ca fluxes with 45Ca confirms previous reports of low permeability of the red cell membrane for Ca. After nearly 1 week of loading in the cold, intracellular 45Ca content is 1·8% of extracellular 45Ca content. Appearance in extracellular fluid of 45Ca from coldloaded cells can be considered to arise from two compartments. Efflux of 45Ca from the ‘slower compartment’ is accelerated by the addition of glucose.

4. Starved red cells, incubated at 37° C, after reversible haemolysis for loading with Ca and Mg‐ATP, exhibit an outward net transport of Ca against an electrochemical gradient. The transport is associated with the appearance of inorganic phosphate (Pi). Cells treated similarly, but without ATP show no transport and no appearance of Pi.

5. During the initial phase of transport, 1·3 mole Pi appear per mole Ca transported.

6. The transport of Ca from ATP‐loaded cells is highly temperature‐dependent, with a Q10 of 3·5.

7. Cell membrane adenosine triphosphatase (ATPase) activity of reversibly haemolysed cells is stimulated only by intracellular, and not by extracellular Ca.

8. Neither Ca transport in reversibly haemolysed cells, nor the Ca‐Mg activated ATPase of isolated cell membranes is sensitive to Na, K, ouabain or oligomycin.

9. Mg is not transported under the conditions which reveal Ca transport, but Mg appears to be necessary for Ca transport.

10. Sr is transported from reversibly haemolysed Mg‐ATP‐loaded cells. Sr also can substitute for Ca, but not for Mg, in the activation of membrane ATPase.

11. It is concluded that, in addition to a low passive permeability, an active extrusion mechanism for Ca exists in the human red cell membrane. This extrusion mechanism, in addition to a low passive membrane permeability for Ca, may represent the means by which intracellular Ca content is maintained at a low level. It is suggested that the Ca‐Mg activated membrane ATPase and the active transport of Ca are two manifestations of the same process.
Non‐linear summation of unit synaptic potentials in spinal motoneurones of the cat
Authors: Kuno M. , Miyahara J. T.
Published: December 2014

1. Monosynaptic excitatory post‐synaptic potentials (EPSPs) produced in spinal motoneurones of the cat by stimulation of a single afferent fibre were recorded with intracellular electrodes.

2. In total, seventy‐three triceps surae motoneurones were studied with stimulation of thirty‐six different afferent fibres.

3. The mean amplitude of the EPSPs evoked by single afferent impulses ranged from 0·06 to 2·0 mV with an average of 0·27 mV.

4. The mean number of unit EPSPs responding to a single afferent impulse (m) was calculated from the number of failures. The values ranged from 0·7 to more than 5. About 10% of the sample showed no failure of synaptic response in about 200 consecutive trials. The m values for these synaptic responses were estimated to range from 5 to 15.

5. In the majority of tests, the observed amplitude fluctuations of monosynaptic EPSPs evoked by stimulation of a single fibre were less than those expected from Poisson's law. This discrepancy may be accounted for by non‐linear summation of the unit EPSPs at dendritic synaptic sites.

6. It is suggested that the synaptic responses initiated at different sites of a motoneurone may summate linearly at the soma, although summation of unit EPSPs is non‐linear at individual synaptic sites.
The nature and location of certain phasic mechanoreceptors in the cat's foot
Authors: Lynn Bruce
Published: December 2014

1. The locations of the receptor endings of twenty‐two phasic, primary afferent units which could be excited by small (less than 40 μm) point displacements of cats' large foot pads have been determined by dissection.

2. Eleven of these units had endings located within or immediately below the skin on the plantar surface of the pad; eight had endings located deep within the pad and three had endings on the digits.

3. All the deep and digital endings were of the PC type of Jänig, Schmidt & Zimmermann (1968) whilst five of the superficial endings were definitely of the RA type of Jänig et al. (1968), and another five could have been. One superficial ending had properties intermediate between those of RA and PC receptors.

4. It was shown by dissection that the endings of four of the PC type units were Pacinian corpuscles and such corpuscles were seen within 1 mm of the apparent location of six other PC receptors. Pacinian corpuscles were found close to only two of the eleven superficial receptor locations.

5. It is therefore concluded that of the two functionally distinct types of phasic receptors studied, the PC receptors are Pacinian corpuscles located deep in the pad or on the digits, whilst the RA receptors are located within or immediately below the skin and are not Pacinian corpuscles.
Reflex discharges into thoracic white rami elicited by somatic and visceral afferent excitation
Authors: Coote J. H. , Downman C. B. B. , Weber W. V.
Published: December 2014

1. Reflex discharges in white rami (WR) were elicited by single‐shock stimulation of dorsal roots (DR), splanchnic (SPL) and intercostal nerves (IC).

2. The reflexes have been compared in anaesthetized cats with intact neuraxis, after mid‐brain transection and after high cord transection. The brain stem can maintain moderate inhibition of the WR responses, but strong inhibition of IC responses. After cord transection all reflexes are released again.

3. Stimulation of ventromedial medullary reticular substance could completely, and independently, inhibit maximal SPL‐to‐WR and IC‐to‐WR reflexes.

4. Carotid sinus distension did not reduce WR responses, indicating that the major part of the volley is not in vasoconstrictor fibres.

5. Central delay of DR‐to‐WR responses is longer than delay of DR‐to‐IC responses and is unchanged by transections of the neuraxis at mid‐brain or high spinal levels.

6. There was no facilitation of WR responses by a prior conditioning volley in the visceral or somatic afferent pathway in contrast to early facilitation of the IC responses.
A theory of cerebellar cortex
Authors: Marr David
Published: December 2014

1. A detailed theory of cerebellar cortex is proposed whose consequence is that the cerebellum learns to perform motor skills. Two forms of input—output relation are described, both consistent with the cortical theory. One is suitable for learning movements (actions), and the other for learning to maintain posture and balance (maintenance reflexes).

2. It is known that the cells of the inferior olive and the cerebellar Purkinje cells have a special one‐to‐one relationship induced by the climbing fibre input. For learning actions, it is assumed that:

(a) each olivary cell responds to a cerebral instruction for an elemental movement. Any action has a defining representation in terms of elemental movements, and this representation has a neural expression as a sequence of firing patterns in the inferior olive; and

(b) in the correct state of the nervous system, a Purkinje cell can initiate the elemental movement to which its corresponding olivary cell responds.

3. Whenever an olivary cell fires, it sends an impulse (via the climbing fibre input) to its corresponding Purkinje cell. This Purkinje cell is also exposed (via the mossy fibre input) to information about the context in which its olivary cell fired; and it is shown how, during rehearsal of an action, each Purkinje cell can learn to recognize such contexts. Later, when the action has been learnt, occurrence of the context alone is enough to fire the Purkinje cell, which then causes the next elemental movement. The action thus progresses as it did during rehearsal.

4. It is shown that an interpretation of cerebellar cortex as a structure which allows each Purkinje cell to learn a number of contexts is consistent both with the distributions of the various types of cell, and with their known excitatory or inhibitory natures. It is demonstrated that the mossy fibre‐granule cell arrangement provides the required pattern discrimination capability.

5. The following predictions are made.

(a) The synapses from parallel fibres to Purkinje cells are facilitated by the conjunction of presynaptic and climbing fibre (or post‐synaptic) activity.

(b) No other cerebellar synapses are modifiable.

(c) Golgi cells are driven by the greater of the inputs from their upper and lower dendritic fields.

6. For learning maintenance reflexes, 2(a) and 2(b) are replaced by

2′. Each olivary cell is stimulated by one or more receptors, all of whose activities are usually reduced by the results of stimulating the corresponding Purkinje cell.

7. It is shown that if (2′) is satisfied, the circuit receptor → olivary cell → Purkinje cell → effector may be regarded as a stabilizing reflex circuit which is activated by learned mossy fibre inputs. This type of reflex has been called a learned conditional reflex, and it is shown how such reflexes can solve problems of maintaining posture and balance.

8. 5(a), and either (2) or (2′) are essential to the theory: 5(b) and 5(c) are not absolutely essential, and parts of the theory could survive the disproof of either.
The response of the sweat glands of the new‐born baby to thermal stimuli and to intradermal acetylcholine
Authors: Foster K. G. , Hey E. N. , Katz G.
Published: December 2014

1. Measurements of evaporative sweat loss were made on fifty‐six premature and full‐term babies 1‐67 days after birth with an infra‐red analyser and a ventilated capsule placed on the thigh. Measurements were also made of total evaporative water loss while in a closed metabolic chamber and of the regional distribution of sweating with starch—iodine paper.

2. No sweating to thermal stimuli could be detected in infants of less than 210 days post‐conceptual age, even when rectal temperature rose as high as 37·8° C. In older infants sweat was detected first on the forehead and temple, later on the chest, and usually by 240–260 days post‐conceptual age on the legs (term ∼ 268 days). Generalized sweating on the limbs appeared at an earlier post‐conceptual age in the more prematurely born infants.

3. The response of sweat glands on the thigh to an intradermal injection of 2 μg acetylcholine (ACh) was tested. No sweat response was detected in infants under 225 days post‐conceptual age, while all infants born within 2 weeks of term responded. The response was often augmented after 2‐5 tests at 5‐10 min intervals; all the eight infants born within 2 weeks of term who were examined twice in the first 2 weeks of life showed a greater response on the second occasion.

4. An average of 414 active sweat glands/cm2 were detected on the thigh in eight babies 7–10 days old born within 2 weeks of term. This was 6½ times the number found in adults. The mean peak sweat rate to chemical stimulation was however only 2·4 nl./gland.min, which was 3 times lower than the maximum rate recorded in adults.

5. In five infants with congenital defects of the brain and complete absence of temperature control there was no sweat response to thermal or direct chemical stimulation of the glands.

6. Functional maturation appears to depend on intact central innervation and is marginally hastened by post‐natal factors. Immaturity of the sweat glands can account for the lack of any response to thermal stimuli in premature babies, but not for the modest thermal response obtained in babies at term.
The effect on drinking in the rat of intravenous infusion of angiotensin, given alone or in combination with other stimuli of thirst
Authors: Fitzsimons J. T. , Simons Barbara J.
Published: December 2014

1. Intravenous infusion of angiotensin causes rats which are in water balance to drink water.

2. The mean amount of angiotensin needed to initiate drinking was 29·1 ± 4·6 μg/kg (
S.E. of mean) in twenty normal rats, and 15·7 ± 2·1 μg/kg in thirty‐four nephrectomized rats.

3. The nephrectomized rat is therefore more sensitive to this action of angiotensin than the rat with intact kidneys.

4. The rates of infusion (0·05–3·0 μg/kg−1 min−1) which cause drinking are comparable to those used to produce other effects in rats.

5. Angiotensin restores the drinking response of the nephrectomized rat subjected to caval ligation to a value similar to that obtained in the uninfused normal rat subjected to caval ligation.

6. The effects of angiotensin and hypertonic saline on drinking are additive when both substances are administered to nephrectomized rats.

7. These experiments provide further support for the view that the renin—angiotensin system is concerned in extracellular thirst.
Effect of environmental temperature on the turnover of noradrenaline in hypothalamus and other areas of rat brain
Authors: Simmonds M. A.
Published: December 2014

1. The hypothesis that noradrenaline (NA) may be a transmitter in the temperature regulating centre in the hypothalamus is based on the changes in rectal temperature induced by injection of large doses of NA into the brain. As an alternative approach, the effect of environmental temperature on the rate of turnover of endogenous NA in the hypothalamus has been studied.

2. Small amounts of tritium labelled noradrenaline [3H]NA were injected into the c.s.f. of rats in order to label radioactively the endogenous NA in the brain. The rats were then exposed to environmental temperatures of 9, 17, 24 and 32° C. The rates of disappearance of [3H]NA from discrete areas of brain were taken as indices of the rates of turnover of endogenous NA in those areas.

3. The rate of disappearance of [3H]NA from the hypothalamus was three times as fast at 9 and 32° C as at 17 or 24° C. There were no such significant differences from the pre‐optic area or ‘rest of brain’ (whole brain minus hypothalamus, pre‐optic area, cerebellum and medulla).

4. The endogenous concentrations of NA were not altered by the experimental procedures in any of the areas of brain studied.

5. The rats maintained normal rectal temperatures at environmental temperatures of 9, 17 and 24° C but became 2·8° C hyperthermic at 32° C.

6. It is concluded that mild conditions of both heat and cold resulted in an increased turnover of NA in specific nerve terminals in the hypothalamus. Since the rats were thermoregulating normally, the nerve terminals involved are regarded as forming a part of the central temperature regulating centre.
Some physiological properties of identified mammalian neuroglial cells
Authors: Dennis M. J. , Gerschenfeld H. M.
Published: December 2014

Mammalian glial cells were identified and studied in the optic nerves of anaesthetized rats.

Cells with membrane potentials of 77–85 mV were located in the optic nerve with capillary micropipettes. These were shown to be neuroglia by iontophoretic injection of a fluorescent dye through the recording electrode, followed by histological verification of the location of the dye. No distinction was made between astroglia and oligodendroglia.

Neuroglial cells gave no impulse activity. Their membrane potential was studied in isolated optic nerves by varying the ionic composition of the bathing fluid. The glial membrane potential depends predominantly on a transmembrane gradient of potassium ions.
Spontaneous and evoked activity of motor nerve endings in calcium Ringer
Authors: Katz B. , Miledi R.
Published: December 2014

1. Electrical activity of neuromuscular junctions of the frog was studied in a medium (Ca‐Ringer) whose Na ions had been entirely replaced by Ca.

2. Spontaneous miniature end‐plate potentials (m.e.p.p.s) of reduced amplitude are recorded in this abnormal ionic environment, and graded end‐plate potentials can be elicited by applying depolarizing current pulses to the pre‐junctional parts of the nerve.

3. Addition of 5 m
M tetraethylammonium (TEA) to the Ca‐Ringer causes the appearance, in almost all‐or‐none fashion, of very large e.p.p.s (up to 45 mV in amplitude) in response to nerve stimulation.

4. These ‘giant’ e.p.p.s occur despite the curarizing action of TEA (and its depressing effect on the amplitude of m.e.p.p.s) and they persist after application of tetrodotoxin.

5. After several hours exposure to Ca‐Ringer, spontaneous end‐plate activity gradually declines, and eventually evoked e.p.p. responses fail. On return to normal Na‐Ringer, spontaneous end‐plate activity is quickly resumed, but the potentials have an abnormal, very wide, amplitude distribution.

6. The results are discussed, in conjunction with relevant work on the squid giant synapse, in terms of the ‘calcium hypothesis’ of transmitter release.
Echo‐location of bats after ablation of auditory cortex
Authors: Suga N.
Published: December 2014

1. Echo‐location of blinded Yuma bats (Myotis yumanensis) was studied after ablation of the auditory cortex (A.C.). A task of obstacle‐avoidance was given to the bats. Hits and misses of strands were counted, and orientation sounds emitted by the bats during flight were recorded.

2. After bilateral ablation of A.C., two bats out of six failed to avoid even large obstacles such as 3·7 mm strands and wall. These bats emitted orientation sounds at a rate of 10–15/sec during flight, but did not change that rate before crossing the obstacles and crashed into them. In these bats, other cortical areas in addition to A.C. were probably ablated.

3. In three bats out of six, obstacle‐avoidance performance was quite normal. These bats avoided even 0·2 mm strands with orientation sounds, the repetition rate of which was systematically increased before crossing the obstacles. In two of them, the dorsal half of the inferior colliculus (I.C.) was bilaterally ablated in addition to A.C. But ability to avoid the obstacles was not impaired at all. Their cerebral cortices did not show the normal positive—negative diphasic potential change in response to tonal stimuli, although the normal diphasic potential change was retained in A.C. of bats which could not echo‐locate as a result of bilateral ablation of the main nucleus of I.C. A.C. appeared to be not essential for echo‐location.

4. Unilateral ablation of A.C. and the internal capsule had no effect on echo‐location, but bilateral ablation of them usually resulted in death from operational trauma.

5. It was suggested that A.C. was less important for sound localization in bats than in cats.
The iodide space in rabbit brain
Authors: Ahmed Nawal , Van Harreveld A.
Published: December 2014

1. The iodide space in rabbit brain varies greatly depending on the conditions under which it is determined.

2. When 131I− only is used the iodide space 4 hr after administration of the marker is of the order of 2%. The iodide content of the cerebrospinal fluid (c.s.f.) is about 1% of that of the serum.

3. Depression of the active iodide transport by perchlorate increases the space to 8·2% and the iodide content of the c.s.f. to 26% of that of the serum.

4. The active iodide transport can also be depressed by saturation with unlabelled iodide. Up to a serum iodide concentration of 5 m
M the space determined after 5 hr remained constant at 2·7%. The iodide space grew when the serum iodide content was enhanced from 5 to 20 m
M, to become constant at a value of 10·6% on further increase of the serum iodide (up to 50 m
M). The iodide content of the c.s.f. increased in a similar manner as the space with the iodide concentration of the serum to about 1/3 of the serum concentration. The iodide space of the muscle was independent of the plasma iodide content.

5. From 4 to 8 hr after administration of 131I− alone or with unlabelled iodide (to a serum concentration of 15 m
M) the iodide space remained relatively constant.

6. When 131I− was administered in the fluid with which the ventricles were perfused an iodide space of about 7% was attained after about 5 hr.

7. In experiments in which 131I− was administered intravenously and the sink action of the c.s.f. was eliminated by perfusion of the ventricles with a perfusate containing as much 131I− as the plasma, the iodide space was 10·2%. When in addition active iodide transport was depressed by perchlorate the space increased to 16·8%.

8. Intravenous administration of labelled and unlabelled iodide (to a serum concentration of 20–40 m
M) and ventricle perfusion with the same concentration of 131I− and unlabelled iodide as in the plasma yielded an iodide space of 20·8%. In similar experiments the iodide concentration of the perfusate was so adjusted that after 5 hr perfusion its iodide content hardly changed during the passage through the ventricles. Under these conditions the iodide concentration of the extracellular and perfusion fluids can be considered to be near equal. The iodide space computed on the basis of the iodide content of the outflowing fluid was 22·5%.

9. The large iodide space could be equated with the extracellular space if the iodide remained extracellular. This seems to be the case in the muscle where the iodide space is similar to the inulin space.

10. The large effects on the iodide space of perchlorate and saturation with unlabelled iodide in experiments in which the marker was administered intravenously and in the perfusate (7 and 8) suggests the presence of an active iodide transport from the brain extracellular fluid into the blood over the blood—brain barrier.
The effect of membrane polarization on the time course of the end‐plate current in frog sartorius muscle
Authors: Kordaš M.
Published: December 2014

1. Intracellular recordings of the end‐plate current at different membrane potentials were made, using a voltage‐clamp technique.

2. When the membrane potential is varied between about +40 and −120 mV, the half‐decline time of the end‐plate current increases from about 0·6 msec to about 1·6 msec.

3. It is suggested that the stability of receptor—mediator complex is affected by the membrane potential.
A comparison of the effect of temperature, metabolic inhibitors and of ouabain on the electrogenic component of the sodium pump in mammalian non‐myelinated nerve fibres
Authors: den Hertog A. , Ritchie J. M.
Published: December 2014

1. A comparison has been made of the effect of cooling, metabolic inhibitors and of ouabain on the electrogenic component of the sodium pump in mammalian non‐myelinated nerve fibres.

2. The hyperpolarization that occurs during the potassium‐activated response that is obtained after a brief period of stimulation (5 sec, 30/sec) in potassium‐free solution was taken as an index of the activity of the pump.

3. Cooling decreased the amplitude and rate constant of decay of the potassium‐activated response. The area of the response, which reflects the total amount of sodium that is extruded after activity, remained constant.

4. Exposure to the metabolic inhibitors deoxy‐
D‐glucose and cyanide also decreased the amplitude and rate constant of the response; as with cooling, the area remained relatively constant.

5. Ouabain, however, reduced the amplitude without reducing the rate constant, which was even sometimes increased with small concentrations of ouabain. The area of the response always decreased therefore.

6. The effects applying metabolic inhibitors are thus similar to those obtained on cooling, but differ from those of ouabain.
An electrophysiological analysis of responses from lizard muscle spindles
Authors: Proske Uwe
Published: December 2014

1. Stretch receptor discharges were recorded in the lizard Tiliqua nigrolutea. Responses were identified as coming from muscle spindles by their ‘in parallel’ behaviour during a twitch.

2. Recordings from spindles in the iliofibularis muscle which contains many single innervated fibres revealed spindles which discharged on the rising phase of the muscle contraction. This ‘in series’ response increased in frequency and duration at high resting tensions on the muscle and was attributed to a specific intrafusal contraction.

3. The ‘in series’ discharge could be induced by stimulation of only one small filament of the muscle nerve. This suggested a focal intrafusal motor innervation.

4. Responses from spindles in the semitendinosus muscle, which contains many multiple innervated fibres provided examples of an ‘in series’ response which could be produced by stimulation of several muscle nerve filaments. This was interpreted as being an example of multiple intrafusal motor innervation.

5. Spindles with short or elongated sensory regions were subjected to ‘ramp’ stretches. The presence of distinct phasic and tonic responses from the two types was confirmed and related to the behaviour of mammalian spindles.
Proteolytic activity during the absorption of [131I]γ‐globulin in the new‐born calf
Authors: Hardy R. N.
Published: December 2014

1. Proteolytic activity within the small intestine of unsuckled calves less than 20 hr of age, anaesthetized with sodium pentobarbitone, has been assessed from the break‐down of [131I]bovine serum γ‐globulin infused into the duodenum.

2. Absorption of [131I]γ‐globulin was measured by analysis of venous blood, the levels of radioactivity attained in which were comparable with those when [131I]PVP K.60 (mean mol.wt. 160,000) was administered. When lymph collected from the thoracic duct during the absorption of [131I]γ‐globulin was injected into the femoral vein, the levels of radioactivity in the blood were close to those expected if the labelled material in the lymph had been retained within the plasma. These observations suggested that [131I]γ‐globulin was absorbed into the circulation of the anaesthetized young calf without significant break‐down.

3. Gel‐filtration of lymph and plasma from calves fed [131I]γ‐globulin has confirmed that proteolysis before and during absorption was slight, since little 131I labelled material of low mol.wt. was found.

4. Gel‐filtration of the contents of the alimentary tract from calves fed [131I]γ‐globulin showed that some hydrolysis occurred in the abomasum and duodenum and that this was reduced by barbiturate anaesthesia. Protein break‐down in the terminal ileum was slight both in the conscious animal and in animals anaesthetized with sodium pentobarbitone.
Changes in the composition of rabbit hind limb lymph after thermal injury
Authors: Lewis G. P.
Published: December 2014

1. Lymph was collected directly from the hind limbs of rabbits anaesthetized with pentobarbitone and from unanaesthetized rabbits before and for several days after the hind limb was injured.

2. After the limb was injured with hot water at 60° C for 1 min or at 80° C for 15–20 sec, there was an increase in the concentration of cytoplasmic and mitochondrial enzymes in the lymph.

3. As previously found in cats, it was not until cell destruction was brought about by freezing the limb solid, that there was an increase in the concentration of lysosomal enzymes in the lymph.

4. In rabbits which had a cannula permanently implanted in the femoral lymphatic, it was found that the elevated enzyme levels following a 60° C burn returned to normal at between 24 and 36 hr after injury.

5. The increase in enzyme activities usually occurred in two phases, an initial increase during the first 4‐6 hr after the burn followed by a second increase which reached a maximum between 10 and 16 hr after injury.

6. Even during the second phase which corresponded with the cellular phase of injury there was no increase in lysosomal enzymes.

7. The present results support the earlier conclusion that lysosomes take little or no part in the tissue reaction to thermal injury except in the later scavenging processes after cell break‐down.
Effect of calcium on excitatory neuromuscular transmission in the crayfish
Authors: Bracho H. , Orkand R. K.
Published: December 2014

1. The effects of varying the external Ca concentration from 1·8 to 30 m
M/l. (⅛−2 times normal) have been studied at the in vitro crayfish excitatory neuromuscular junction. Electrophysiological techniques were used to record transmembrane junctional potentials from muscle fibres and extracellular junctional currents from the vicinity of nerve terminals.

2. The excitatory junctional potential amplitude was proportional to [Ca]0n, where n varied between 0·68 and 0·94 (mean 0·82) when [Ca]0 was varied from 1·8 to 15 m
M/l.

3. The increase in junctional potential amplitude on raising [Ca]0 resulted primarily from an increase in the average number of quanta of excitatory transmitter released from the presynaptic nerve terminal by the nerve impulse.

4. The size of the quanta, synaptic delay, presynaptic potential and electrical properties of the muscle membrane were little affected by changes in calcium concentration in the range studied.