bluuebunny/crossref_metadata_2025 huggingface dataset:
Edge detectors in human vision
Authors: Shapley R. M. , Tolhurst D. J.
Published: December 2014

1. The spatial properties of edge detectors were measured psychophysically with the technique of subthreshold addition. Subthreshold patterns used to add to an edge were lines, sine gratings, Gaussian edges, and ramps.

2. The sensitivity profile, determined from experiments on subthreshold addition of lines to an edge was an antisymmetric function, with peak sensitivity approximately ± 1·5′ from its midpoint. Its total extent was about ± 6′.

3. The spatial frequency response of edge detectors was measured in experiments on subthreshold addition of sine gratings to an edge. The spatial frequency response was peaked at about 3 c/deg, and was broadly tuned in frequency. It was approximately equal to the Fourier transform of the sensitivity profile, implying linearity of edge detectors.

4. The visibility of Gaussian edges and ramps could be explained largely in terms of the activation of edge detector neurones.

5. The role of edge detectors in perception, in creating apparent brightness, and as an explanation of contour illusions, is discussed.
The organization of primary afferent depolarization in the isolated spinal cord of the frog
Authors: Carpenter D. O. , Rudomin P.
Published: December 2014

1. The organization of primary afferent depolarization (PAD) produced by excitation of peripheral sensory and motor nerves was studied in the frog cord isolated with hind limb nerves.

2. Dorsal root potentials from sensory fibres (DR‐DRPs) were evoked on stimulation of most sensory nerves, but were largest from cutaneous, joint and flexor muscle afferents. With single shock stimulation the largest cutaneous and joint afferent fibres gave DR‐DRPs, but potentials from muscle nerves resulted from activation of sensory fibres with thresholds to electrical stimulation higher than 1·2–1·5 times the threshold of the most excitable fibres in the nerve. This suggests that PAD from muscle afferents is probably due to excitation of extrafusal receptors.

3. Dorsal root potentials produced by antidromic activation of motor fibres (VR‐DRPs) were larger from extensor muscles and smaller or absent from flexor muscles. The VR‐DRPs were produced by activation of the lowest threshold motor fibres.

4. Three types of interactions were found between test and conditioning DRPs from the same or different nerves. With maximal responses occlusion was usually pronounced. At submaximal levels linear summation occurred. Near threshold the conditioning stimulus frequently resulted in a large facilitation of the test DRP. All three types of interactions were found with two DR‐DRPs, two VR‐DRPs or one DR‐DRP and one VR‐DRP.

5. The excitability of sensory nerve terminals from most peripheral nerves was increased during the DR‐DRP. The magnitude of the excitability increase varied roughly with the magnitude of the DR‐DRP evoked by the conditioning stimulus.

6. There was a marked excitability increase of cutaneous and extensor muscle afferent terminals during the VR‐DRP. Flexor muscle afferent terminals often showed no excitability changes to ventral root stimulation. In those experiments where afferent terminals from flexor muscles did show an excitability increase, the effects were smaller than those of cutaneous and extensor terminals.

7. The VR‐DRPs appear to reflect activity of a negative feed‐back loop from extensor motoneurones on to sensory fibres from cutaneous and extensor muscles. This system may have a role in modulating the ballistic movement of the frog. DR‐DRPs, on the contrary, are widespread in origin and distribution. PAD from sensory fibres may function to sharpen contrast between incoming afferent information.
On the function of myoepithelial cells in salivary glands
Authors: Emmelin N. , Gjörstrup P.
Published: December 2014

1. In dogs under chloralose‐urethane anaesthesia the submaxillary duct was cannulated and connected either to an open outflow system, in which saliva displaced water, or to a closed pressure recording system.

2. The secretory cells, which are supplied with β‐adrenoreceptors, were stimulated with isoprenaline, adrenaline or sympathetic nerve stimulation. Myoepithelial cells, supplied with α‐receptors, were activated with phenylephrine, adrenaline or sympathetic stimulation, and also with bradykinin. To abolish α‐receptor stimulating effects of adrenaline and sympathetic nerve stimulation, dihydroergotamine, phenoxybenzamine and phentolamine were used.

3. When the secretory cells were activated alone, saliva flowed from the salivary duct, but the flow started late and only a moderately high pressure could be produced in the closed system. Saliva appeared much earlier in the duct when secretion was combined with myoepithelial contraction, and a much higher pressure could be built up in the duct system.

4. It is concluded that rapid emptying of saliva in the mouth and a maintained flow at a high rate of the viscous saliva is promoted by contractions of the myoepithelial cells.
Differential release of acetylcholine from the hypothalamus and mesencephalon of the monkey during thermoregulation
Authors: Myers R. D. , Waller M. B.
Published: December 2014

1. In unanaesthetized monkeys acclimated to primate chairs, 101 isolated sites in the hypothalamus and mesencephalon were perfused at a rate of 30–50 μl./min by means of push—pull cannulae. The perfusate, which contained an anticholinesterase, was assayed for acetylcholine (ACh) activity on the guinea‐pig ileum in the presence of neostigmine.

2. The body temperature of each animal was monitored continuously during an experiment by colonic and brain thermistors. To alter the ambient temperature by 15–20° C, either a stream of warm air was passed over the monkey's trunk or containers of ice were placed in its chair chamber to cool the same region.

3. Assays of the effluent revealed that the release of ACh varied according to the ambient temperature as follows: elevated only during cooling; elevated only during warming; elevated by both thermal stimuli; suppressed only by cooling; suppressed only by warming; suppressed by both thermal stimuli; elevated during cooling but suppressed by warming; and elevated by warming and suppressed by cooling.

4. A composite anatomical ‘mapping’ of all perfusion sites revealed that in response to either peripheral cooling or warming, the output of ACh varied at only 36% of all sites anterior to the mid‐hypothalamic plane, but at 65% of those loci caudal to this coronal plane.

5. In the anterior, preoptic area, cooling enhanced the output of ACh at 88% of the active releasing sites, whereas warming reduced the release of ACh at 80% of these perfusion loci. Posterior to this region, ACh release was elevated by cooling at about half of the active releasing sites, but lowered by warming at nearly every active perfusion locus. Within the mesencephalon, the ratio of the temperature‐induced change in ACh release was similar but in an opposite direction, since the level of ACh in the effluent collected from two out of three sites was augmented by cooling, but diminished by warming.

6. These results provide additional evidence for the neurochemical model of Myers & Yaksh (1969), which suggests that a cholinergic pathway originating in the anterior, preoptic region transmits efferent signals for heat production. Further, within the posterior hypothalamic area as well as in the mesencephalon of the monkey, the characteristics of the ACh releasing sites reflect a function delegated primarily to heat gain, although evidence of a cholinergic pathway for the heat loss system is also presented.
The formation of synapses in reinnervated and cross‐reinnervated adult avian muscle
Authors: Bennett M. R. , Pettigrew A. G. , Taylor R. S.
Published: December 2014

1. A study has been made of the formation of synapses in spontaneously reinnervated and cross‐reinnervated anterior latissimus dorsi (ALD) and posterior latissimus dorsi (PLD) muscles of adult fowls.

2. Denervated ALD and PLD muscle fibres have a uniform and high sensitivity to iontophoretically applied acetylcholine (ACh). During early reinnervation the sensitivity distribution to ACh of the ALD muscle fibres begins to return to normal before synaptic potentials can be evoked. The normal ACh sensitivity distribution of PLD muscle fibres is also restored after reinnervation. After cross‐reinnervation of the ALD and PLD muscles the ACh sensitivity distribution of many of the muscle fibres is again restored to normal.

3. Reinnervating and cross‐reinnervating ALD nerve terminals showed a greater than normal degree of facilitation of transmitter release when a test impulse was applied at various intervals after a conditioning impulse. Cross‐reinnervating PLD nerve terminals showed facilitation of transmitter release rather than the normal depression in a conditioning‐test impulse sequence.

4. The distribution of nerve terminals over the surface of spontaneously reinnervated and cross‐reinnervated ALD and PLD muscle fibres has been determined from an examination of the sensitivity distribution to applied ACh, the graded versus all‐or‐none nature of the evoked potential and the distribution of cholinesterase stained synapses.

5. The results suggest that the innervation pattern of individual ALD and PLD muscle fibres is restored both after spontaneous reinnervation and cross‐reinnervation.
Effects of muscle stretch on transmitter release at end‐plates of rat diaphragm and frog sartorius muscle
Authors: Turkanis S. A.
Published: December 2014

1. Miniature end‐plate potentials (m.e.p.p.s) and end‐plate potentials were recorded intracellularly at neuromuscular junctions of the frog sartorius muscle and the rat diaphragm before, during and after muscle stretch.

2. Stretch increased the frequency of the m.e.p.p.s and the mean quantum content (m) at end‐plates of the sartorius muscle.

3. Stretch enhanced m.e.p.p. frequency of the sartorius muscle in normal Ringer solution as well as in solutions high in magnesium and low in calcium content. In addition, an increase in frequency occurred in the presence of tetrodotoxin and in the absence of neostigmine methylsulphate.

4. The magnitude of the increase in m.e.p.p. frequency in the sartorius muscle was negatively correlated with the control frequency.

5. In contrast to the above findings at sartorius end‐plates, muscle stretch did not affect the frequency of m.e.p.p.s or the m values at end‐plates of the rat diaphragm.
The hypothermic effect of tetrodotoxin in the unanaesthetized cat
Authors: Clark Wesley G. , Coldwell Barbara A.
Published: December 2014

1. The hypothermic effect on unanaesthetized cats of tetrodotoxin injected
I.V. or into the lateral cerebral ventricle was examined.

2. At an ambient temperature (Ta) of 22° C, tetrodotoxin given intraventricularly was over 400 times more potent in lowering body temperature (Tb) than when given
I.V. The magnitude of the hypothermia was dose‐dependent for both routes. Decreases in Tb as great as 6·8° C were induced by infusions or multiple injections of tetrodotoxin into the ventricle.

3. Tetrodotoxin also lowered Tb at Ta = 13, 30 or 35° C. Tachypnoea, which lasted for longer durations and which became more intense the higher the Ta, accompanied development of hypothermia. Shivering was observed only during recovery from hypothermia at 13° C.

4. During the tetrodotoxin‐induced hypothermia, animals were still able to regulate against environmental thermal stresses.

5. EDTA disodium salt, leucocytic pyrogen and prostaglandin E1 antagonized the hypothermic effect of tetrodotoxin when they were administered during recovery from tetrodotoxin.

6. Activation of heat‐loss mechanisms, and the absence of compensatory shivering during development of hypothermia after tetrodotoxin administration, plus lowering of Tb by tetrodotoxin at Ta above as well as below the thermoneutral temperature, indicate that lowering of the thermoregulatory set‐point is the mechanism by which centrally or peripherally administered tetrodotoxin lowers Tb. Further evidence for set‐point lowering after intraventricular administration of tetrodotoxin is provided by persistence of the ability to regulate against both heat and cold stresses during hypothermia. The possibility that the decrease in set‐point could be due to the well known action of tetrodotoxin to block transient increases in membrane sodium ion conductance is discussed in terms of a recent hypothesis regarding ionic control of the thermoregulatory set‐point.
Contrast perception and electrophysiological correlates
Authors: Fiorentini Adriana , Maffei L.
Published: December 2014

1. Previous findings show that the amplitude of the human visual potentials evoked by gratings alternating in phase at several c/s is linearly related to the logarithm of the grating contrast.

2. Similar previous experiments on the cat have shown that both the amplitude of evoked potentials and the amplitude of the response of simple cortical cells to alternating gratings increase linearly with the logarithm of the contrast. No such relation is found for single neurones in the retina or in the lateral geniculate body.

3. In this work the contrast of a grating is evaluated psychophysically by human subjects in a range of more than 10 times above threshold, using a binocular matching technique.

4. The apparent contrast is found to increase linearly with the logarithm of the stimulus contrast.

5. The conclusion is drawn that the linear relation between apparent contrast and the logarithm of the objective contrast might be the outcome of a process of elaboration that is carried out at the simple cell level.
A comparison of the effects of adenosine triphosphate with noradrenaline and with the inhibitory potential of the guinea‐pig taenia coli
Authors: Tomita T. , Watanabe Hisako
Published: December 2014

1. The response of the smooth muscle of the guinea‐pig taenia coli to adenosine triphosphate (ATP) and related substances was compared with that to noradrenaline and dopamine. The effect of these substances on the inhibitory potential was investigated.

2. ATP in concentration of 10−6‐10−5
M suppressed the spontaneous spike and relaxed the preparation. ATP in a concentration higher than 10−4
M hyperpolarized the membrane, reduced the membrane resistance and decreased the inhibitory potential.

3. Effects of noradrenaline (5 × 10−6
M) and of dopamine (5 × 10−4
M) were similar to those of ATP (10−3
M). However, the effects of catecholamines were reduced in Cl‐deficient solution and blocked by phentolamine (3·5 × 10−6
M), while the effects of ATP were unaffected.

4. A high concentration of phentolamine (3·5 × 10−4
M) almost abolished the inhibitory potential as well as the effects of ATP. The inhibitory potential and the effect of high concentration of ATP (10−3
M) were not impaired by imidazole (50 m
M).

5. Adenosine diphosphate, adenosine monophosphate and adenosine produced effects essentially similar to those of ATP. However, their potency was less compared with ATP.

6. These electrophysiological observations support the hypothesis that ATP may be the transmitter of the non‐adrenergic inhibitory nerves in the taenia coli. No evidence against the hypothesis was obtained.
The binding of acetylcholine to receptors and its removal from the synaptic cleft
Authors: Katz B. , Miledi R.
Published: December 2014

1. Acetylcholine (ACh) noise and miniature end‐plate potentials were recorded with focal external micro‐electrodes.

2. The effect of prostigmine on the time course of the ‘molecular’ and ‘quantal’ transmitter actions was studied. Prostigmine (10−6 g/ml.) has little or no effect on the duration of the molecular ‘gating action’, while it greatly prolongs the quantal conductance change.

3. After inhibition of ACh hydrolysis, the removal of the transmitter from the synapse is generally too slow to be accounted for by free diffusion. It is suggested that diffusion is delayed by binding to post‐synaptic receptors. This is consistent with the finding that receptor blockage by curare or α‐bungarotoxin shortens as well as reduces quantal transmitter action.

4. The correlated effects of the receptor‐blocking agents, on size and time course of the miniature end‐plate currents, were subjected to a simple analysis. Its result suggests that after inhibition of cholinesterase about two thrids of the quantal packet of ACh combines with post‐synaptic receptors.

5. During focal external recording the effect of prostigmine on the time course of miniature end‐plate potentials can become exaggerated due to what appears to be a compression artifact which obstructs outward diffusion of the transmitter.
Kinetics of potassium transport across single distal tubules of rat kidney
Authors: de Mello‐Aires Margarida , Giebisch Gerhard , Malnic Gerhard , Curran Peter F.
Published: December 2014

1. The transport of potassium across the distal tubular epithelium was studied in vivo in rats on a normal potassium intake and in rats in which distal tubular potassium secretion was either stimulated by potassium loading or the
I.V. administration of a 5% sodium bicarbonate solution or in which potassium secretion was suppressed by dietary deprivation of potassium or sodium.

2. 42K was used to measure unidirectional fluxes across the luminal and peritubular cell membranes and to assess the magnitude of cellular potassium partaking in the transport process. This was accomplished by the simultaneous perfusion of the peritubular capillary network with 42K‐Ringer and of the distal tubular lumen with initially tracer‐free solution. From the steady‐state flux and the time course of tracer washout into the lumen after discontinuing the peritubular perfusion, unidirectional fluxes, rate coefficients of ion transfer and cellular transport pools could be measured.

3. Transepithelial movement of potassium involves mixing with a variable cellular potassium transport pool. The latter is significantly elevated in conditions of enhanced distal tubular potassium secretion; cellular potassium labelling is reduced in conditions in which potassium secretion has been suppressed by potassium deprivation.

4. Evidence is presented that changes in the peritubular transport pattern are primarily responsible for modifications of potassium translocation. Thus, stimulation of potassium secretion is associated with increased peritubular potassium uptake; a reduced potassium uptake across the peritubular cell membrane accounts for the fall in potassium secretion in potassium‐depleted animals. Whereas passive entry of potassium across the peritubular membrane is augmented in potassium‐loaded animals, the induction of metabolic alkalosis by the administration of 5% sodium bicarbonate stimulates active potassium uptake across the peritubular cell membrane. Sodium deprivation stimulates active reabsorptive transfer of potassium from the tubular lumen.
Analysis of Mauthner cell responses to iontophoretically delivered pulses of GABA, glycine and L‐glutamate
Authors: Diamond J. , Roper S.
Published: December 2014

1. The intracellularly recorded responses of goldfish Mauthner neurones to iontophoretically applied pulses of amino acids have been analysed: their time courses have been compared with each other, and with those predicted from diffusion theory.

2. The rise time of the response to GABA is slower than that to glycine or
L‐glutamate. The response curves of the latter substances were very similar, and unlike that of GABA were markedly affected by increasing the distance of pipette‐tip from the membrane. The results suggest that the time course of the responses to glycine and
L‐glutamate are determined mainly by free diffusion in the brain tissue (at least within about 200 μm of the cell), while that to GABA must be rate‐limited by other factors, e.g. drug‐receptor activation time.

3. The possibility that the responses are influenced by some desensitizing process was investigated by applying a second (test) drug pulse during the response to a prior conditioning one. In the case of glycine and of
L‐glutamate there was no attenuation of the response to a second pulse at any time. With GABA, however, the second response was reduced during the period of the conditioning response; the reduction was progressively less marked the later the test pulse occurred. A similar effect with GABA was seen when glycine was used as the test pulse. The responses to long‐maintained drug pulses also indicated that for GABA, but not for glycine or glutamate, there seems to be some desensitizing process present.

4. Calculated time courses of responses to brief pulses of glycine and of
L‐glutamate (based upon diffusion theory) differed somewhat from the observed curves, largely during the falling phase. However, when the calculations were based upon second‐order reactions (two molecules of drug per receptor) the diffusion model gave results very like the observed ones.

5. Possible implications of these results for the role these three amino acids may have as neuro‐transmitters are mentioned.
Prostaglandin E1 fever induced in rabbits
Authors: Stitt J. T.
Published: December 2014

1. Micro‐injections of prostaglandin E1 (PGE1) into the anterior hypothalamus of the rabbit produced fever which was nearly immediate in onset. The prostaglandin sensitive region appears to be identical to that described as being fever sensitive to leucocytic pyrogen.

2. Micro‐injections of PGE1 into the posterior hypothalamus and midbrain reticular formation of the rabbit did not produce fever.

3. The febrile response to PGE1 injected into the anterior hypothalamus was dose dependent over a range of 20–1000 ng.

4. Ambient temperature influenced the thermoregulatory mechanism by which PGE1 fever evolved. In the cold, PGE1 fever was due to increased heat production while during heat exposure both evaporative and dry heat losses were reduced without significant changes in heat production. Vasoconstriction, confined mainly to the ears, was effective in producing fever in standard room environments (24–25° C) along with a small increase in heat production.

5. The preoptic anterior hypothalamic area retained its thermosensitivity during PGE1 fever; heating this area attenuated, while cooling augmented the fever.

6. The results support the view that PGE1 is a mediator of pyrogen induced fever.
Extra‐segmental reflexes derived from intercostal afferents: phrenic and laryngeal responses
Authors: Remmers John E.
Published: December 2014

1. Phrenic and recurrent laryngeal efferent responses were evoked by brief tetani or single shocks to the cut external intercostal nerves of anaesthetized cats. The reflexes derived from middle thoracic segments (T5 and 6) were compared with those emanating from caudal thoracic segments (T9 and 10).

2. During inspiration, middle intercostal nerve stimulation transiently inhibited the spontaneous discharge in both efferent neurograms, whereas stimulation of caudal intercostal nerves facilitated phrenic discharge and usually inhibited recurrent laryngeal activity.

3. During expiration, stimulation at either thoracic level enhanced recurrent laryngeal discharge while provoking little or no phrenic response.

4. Superficial lesions of the lateral cervical cord, ipsilateral to the stimulus sites, above or below the phrenic outflow, eliminated all reflex responses except the phrenic response to caudal thoracic stimuli. Similarly, in the spinal animal, middle intercostal afferents could not be shown to decrease phrenic excitability. Caudal intercostal afferents cause phrenic excitation by a spinal reflex.

5. Group I afferents of the mid‐thoracic segments and group II afferents of the caudal thoracic segments initiate these extra‐segmental reflexes.

6. The recurrent laryngeal responses manifest, for the most part, changes in the discharge of fibres innervating the posterior cricoarytenoid muscle. The responses fit the overall pattern of response to middle intercostal nerve stimulation, namely, inhibition of inspiratory muscles and excitation of expiratory muscles. Intercostal afferent stimulation also activated the laryngeal adductor muscles.

7. The results support the view that intercostal mechanoreceptors initiate an array of extra‐segmental respiratory reflexes, including spinal and supraspinal arcs. The simplest way to account for the various responses to stimulation of middle intercostal afferents is to postulate a reflex involving supraspinal respiratory neurones.

8. The observed reflexogenic differences correlate with anatomical differences between the middle and caudal ribs. Possible functional implications of this relationship are discussed.
Rubidium influx into rat skeletal muscles in relation to electrical activity
Authors: Kernan R. P. , McDermott Mary
Published: December 2014

1. Rates of 86Rb influx were compared in vivo over 2, 4 and 6 hr periods in various tonic and phasic muscles of rat following its
I.P. injection.

During the 2 hr period its influx rate into soleus was about 4 times that of the vastus with the EDL muscles at an intermediate rate. Uptake by diaphragm was fastest reaching equilibrium within 2 hr.

2. Unilateral section of the sciatic nerve 48 hr before 86Rb injection reduced isotope uptake into soleus to about 50% of its contralateral control muscle over a 4 hr period. In EDL muscles on the other hand nerve section increased influx by about 75% of control in conscious rats and more than doubled influx in anaesthetized rats.

3. Tenotomy of soleus reduced 86Rb influx to 40% of control, but tenotomy in EDL was without effect in influx.

4. Uptake of urea into muscles within 5 min of its
I.V. injection was used to determine the possibility of muscle blood flow determining 86Rb influx. Accumulation of urea was not significantly different in control and denervated EDL muscles nor between soleus and vastus muscles in anaesthetized rats, so it seems unlikely that blood flow is important here.

5. Membrane depolarization in response to addition of 30 m
M rubidium to external bathing fluid was greater in the case of denervated than in control EDL muscles which was in keeping with the greater 86Rb influx seen in the former muscles. The ouabain sensitivity of rubidium‐induced depolarization in the denervated EDL muscles would suggest, however, that rubidium enters the fibres actively.
The respiratory effects in man of altering the time profile of alveolar carbon dioxide and oxygen within each respiratory cycle
Authors: Cunningham D. J. C. , Howson M. G. , Pearson S. B.
Published: December 2014

1. Breathing hypoxic gas through an external dead space (ca. 1200 c.c.) stimulated ventilation disproportionately. A loop (ca. 250 c.c.) in the inspiratory pathway reduced the effect.

2. The alveolar time patterns of PCO2 and PO2 characteristic of tube breathing with or without the loop have been simulated in moderate hypoxia by changing the composition of inspired gas at selected intervals after the beginning of inspiration.

3. Supplying CO2‐free gas in late inspiration usually stimulated ventilation, but less than did real tube breathing. Supplying CO2‐free gas early in inspiration usually depressed ventilation. The difference between the ‘CO2‐free late’ and ‘CO2‐free early’ effects was 20% of the control ventilation (P < 0·001), i.e. was nearly the same as between the effects of real tube breathing without and with the loop.

4. Tube‐like PA, O2 time patterns had no effects.

5. A—a PCO2 and PO2 gradients remained constant throughout.

6. The V̇E, f and VT relations were unaltered in tube breathing.

7. The respiratory system can discriminate between small differences in time patterns of PA, CO2 but not of PA, O2; the signal is amplified by steady hypoxia. The arterial chemoreceptors are probably responsible for these effects.
Analysis of unitary spikes recorded extracellularly from frog olfactory receptor cells and axons
Authors: Getchell Thomas V.
Published: December 2014

1. Differences in unitary spike conformation were systematically investigated with extracellular recordings at different depths in the frog's olfactory epithelium. Platinum‐black metal‐filled micro‐electrodes were used in the unit recordings. Their properties were carefully investigated and compared with those of micropipettes.

2. Three basic types of spikes were recorded: a diphasic spike with a positive—negative voltage sequence, a diphasic spike with a negative—positive voltage sequence and a triphasic spike with a positive—negative—positive voltage sequence.

3. The triphasic spike was correlated with the action potential in the axon. The initially negative diphasic spike was correlated with the action potential initiated in the cell body region. The initially positive diphasic spike was correlated with the spread of the impulse into the receptor cell dendrite.

4. A model is discussed which accounts for the differences in spike conformations and provides a basis for analysing impulse activity in spontaneously active and stimulus‐driven olfactory receptor cells.
Ionic properties of the neuromuscular junction of the frog: effects of denervation and pH
Authors: Mallart A. , Trautmann A.
Published: December 2014

1. The effects of denervation, reinnervation and pH on the ionic permeability changes mediated by junctional receptors have been studied in muscle fibres of the frog sartorius.

2. The reversal potential of acetylcholine responses in denervated junctions was about 25 mV more negative than in normal junctions.

3. The delay of the change in the ionic properties of junctional receptors was proportional to the nerve stump length: 10 and 14 days for lengths of 12 and 33 mm, respectively.

4. When the motor nerve reinnervates the junction, the reversal potential of the acetylcholine responses comes back to the normal value before the neuromuscular transmission is restored.

5. The Na/K conductance change decreases in high pH solutions. After denervation, the pH profile of this ratio is shifted to the acid values by about two pH units.

6. These observations can be explained by assuming that the Na and K channels differ by the pK of their anionic groups and that the denervation induces an alteration of the sites that bear the charges.
The regional distribution of emotional sweating in man
Authors: Allen Judith A. , Armstrong Janet E. , Roddie I. C.
Published: December 2014

1. Emotional sweating was induced in normal subjects by mental arithmetic at environmental temperatures of 29 and 26° C and estimated from continuous records of body weight loss.

2. The sweat output from four independent regions of the body — (a) the head and neck, (b) the arms and legs, (c) the trunk, and (d) the hands and feet — was studied separately, the remainder of the body being covered in each case by plastic bags. The evaporative water loss from each skin region increased markedly during mental arithmetic.

3. The sweat contribution from each region was a substantial fraction of the total body sweat response and appeared to be roughly proportional to the calculated number of sweat glands in each region.

4. There is no evidence from these experiments to indicate that the sweat glands of the skin of the hands and feet behave differently to those of the skin of the rest of the body in response to emotional stress.
Patterning in the regeneration of type I cutaneous receptors
Authors: Burgess P. R. , English Kathleen B. , Horch K. W. , Stensaas L. J.
Published: December 2014

1. Type I sensory fibres in cat hairy skin innervate structures characterized by twenty to fifty specialized epithelial (Merkel) cells aggregated in a small dome‐shaped elevation. Only one fibre enters each dome and it branches repeatedly to supply at least one terminal to each Merkel cell. After the nerve is cut, the Merkel cells and the dome ultimately disappear.

2. The distribution of domes on the posterior thigh was mapped before interruption of the femoral cutaneous nerve and after its regeneration. Regeneration after nerve crush was apparently complete, producing a coincidence pattern similar to those seen in control studies where the nerve was not damaged. After cutting the nerve fewer domes returned, but coincidence of regenerated femoral cutaneous domes with old sites generally was significantly greater than would be expected by chance alone. Non‐femoral cutaneous fibres sprouting into the denervated femoral cutaneous field tended to form domes at old sites. Domes were also reformed on scars where domes had been excised.

3. Domes appearing at new locations and on excision scars were often small and close together (clustered). Individual domes in a cluster could be innervated by different Type I fibres.

4. Type I fibres are directed by some mechanism to sites formerly occupied by domes and to sites where domes are being induced.
Mechanisms for differential block among single myelinated and non‐myelinated axons by procaine
Authors: Franz Donald N. , Perry Roger S.
Published: December 2014

1. The differential sensitivity of saphenous nerve fibres in the cat to block by procaine HCl was re‐examined by recording identifiable unit action potentials from small nerve filaments.

2. Small myelinated axons were blocked more quickly than large myelinated axons, but this differential effect could not be accounted for by differences in anaesthetic concentration requirements.

3. The onset of block in non‐myelinated axons was slower than or equal to that of small myelinated axons depending on anaesthetic concentration.

4. Absolute differential block of non‐myelinated and small myelinated axons was obtained by limiting the length of axons exposed to procaine to 2 mm.

5. Differential rates of blocking among myelinated axons appear to depend on differences in the length of axons that must be exposed to blocking concentrations of procaine and to arise from the irregular distribution of such concentrations within an exposed nerve.
The effect of antidiuretic hormone on human sweating
Authors: Allen Judith A. , Roddie I. C.
Published: December 2014

1. Changes in insensible perspiration and sweating were followed in normal subjects by continuously monitoring total body weight loss in environmental temperatures of 18, 29 and 37° C.

2. Pharmacological doses of ADH had no effect on cutaneous water loss at 18° C.

3. Pharmacological doses of ADH are capable of increasing the rate of cutaneous water loss in human subjects who are close to or above the thermal sweating threshold.

4. Physiological doses of ADH had no effect on cutaneous water loss in either cool or hot environments.

5. At normal rates of secretion in the body, ADH probably does not influence human sweat secretion.
Anode break excitation in denervated rat skeletal muscle fibres
Authors: Marshall M. W. , Ward M. R.
Published: December 2014

1. Anodal break action potentials were found to be a feature of denervated rat skeletal muscle fibres.

2. Depolarized innervated fibres failed to respond to anodal break stimulation in the same way as denervated fibres.

3. The critical level for action potential generation is related to membrane polarization in denervated fibres but not in innervated fibres. This relationship is inhibited by the
I.P. administration of actinomycin D, which also prevents the onset of anodal break action potentials in 3‐day denervated fibres.
The effect of lowering the 5‐hydroxytryptamine content of the rat spinal cord on analgesia produced by morphine
Authors: Vogt Marthe
Published: December 2014

1. Injection of 5,6‐dihydroxytryptamine (5,6‐DHT, 50 μg) into a lateral cerebral ventricle of male rats lowered the 5‐hydroxytryptamine (5‐HT) content of the lumbar cord to 12·8% and reduced the analgesic effect of low doses of morphine (0·64‐1·63 mg/kg), tested by exerting pressure on the foot; after doses of morphine of 1·33‐1·63 mg/kg, the analgesic response was reduced or abolished in 33% of the rats, and after 0·64 mg/kg, 58% of the animals failed to respond normally.

2. Two days after an
I.P. injection of p‐chlorophenylalanine (pCPA, 320 mg/kg), the loss of analgesic potency of morphine was more pronounced than after intraventricular 5,6‐HDT. The 5‐HT content was lowered to about 8% in the lumbar cord, and to 20% or less in pons and medulla.

3. The experiments show that interference with the descending tryptaminergic axons innervating the cord is by itself sufficient to reduce analgesia due to morphine, but they do not exclude the possibility that other tryptaminergic neurones take part in the effect of pCPA. The contribution to the analgesic effect of morphine made by the interaction of tryptaminergic axons with the interneurones ‘gating’ the afferent impulses in the posterior columns is discussed.
The sensitivity of Helix aspersa neurones to injected calcium ions
Authors: Meech R. W.
Published: December 2014

1. When calcium chloride was injected into Helix aspersa neurones there was a fall in membrane resistance and the membrane potential became hyperpolarized.

2. The reversal potential of the response was dependent on the concentration of potassium in the external solution.

3. Injection of a calcium—EGTA buffer containing 9 × 10−7
M free calcium reduced the membrane resistance by 25%. When calcium chloride was injected it was necessary to increase the total intracellular calcium concentration by about 10−3
M to produce similar change of resistance.

4. In sodium‐free (Tris) solution there was a slow fall of membrane resistance as if the intracellular calcium concentration had increased. There was a similar resistance change in the presence of 2,4‐dinitrophenol and iodoacetate.

5. A series of repetitive depolarizing pulses produced a long lasting reduction in membrane resistance which was enhanced by 2,4‐dinitrophenol and iodoacetate.

6. It is concluded that (a) injection of calcium causes an increase in potassium permeability, (b) the injected calcium is rapidly pumped from the cytoplasm by a sodium‐dependent mechanism and by mitochondria, and (c) 1–2 msec depolarizing pulses stimulate an influx of calcium. This influx is rapid enough to trigger potassium activation during an action potential.
The role of the carotid body chemoreceptors and carotid sinus baroreceptors in the control of cerebral blood vessels
Authors: Ponte J. , Purves M. J.
Published: December 2014

1. Cerebral blood flow was measured in 17 baboons, anaesthetized with pentobarbitone, paralysed with gallamine and mechanically ventilated and in which the right sinus and both aortic nerves had been cut and the left carotid sinus vascularly isolated. Later in each experiment, the head was artificially perfused with femoral arterial blood via the innominate artery.

2. Stimulation of the carotid body chemoreceptors with venous blood invariably caused a rise in regional cerebral blood flow whether the head was naturally or artificially perfused. This response was almost completely abolished if the VIIth cranial nerves were cut intracranially.

3. Regional cerebral blood flow varied inversely with carotid sinus pressure.

4. After the remaining (left) sinus nerve had been cut, the cerebral vascular response to hypoxia was negligible and the response to hypercapnia was markedly reduced. Blood flow then varied with perfusion pressure.

5. These results provide further evidence that cerebral blood vessels are reflexly controlled and that the peripheral arterial receptors are involved. Their action is most conspicuous in the vascular response to hypoxia and together with intrinsic factors in the cerebral vascular bed, they determine the size of the vascular response to changes in CO2 and pressure.
Effects of vagotomy, atropine, hexamethonium and adrenaline on the destination in the stomach of liquids sucked by milk‐fed lambs and calves
Authors: Newhook J. C. , Titchen D. A.
Published: December 2014

1. The normal passage to the abomasum of liquid sucked by lambs and calves was confirmed in radiographic studies to be changed to passage of liquid to the reticulum and rumen after cervical or abdominal vagotomy.

2. The effects of hexamethonium (8–10 mg kg−1 I.V.) were similar to those of vagotomy.

3. Atropine (200–800 μg kg−1 I.V.) had either no detectable effect on the destination in the stomach of liquid sucked by lambs or caused a partial failure of the reticular groove mechanism.

4. Fluid sucked by lambs passed wholly to the abomasum after adrenaline (5–40 μg kg−1 I.V.).

5. Atropine and adrenaline caused a greater dysfunction of the reticular groove mechanisms in calves than in lambs.

6. Contraction of the reticular groove was observed via rumen fistulae in three lambs. Eversion of the caudal oesophagus into the reticulum which occurred when saliva was swallowed into the reticulum and rumen was not observed when liquids were sucked from a bottle.

7. The continued passage to the abomasum of sucked liquid in atropinized lambs has been taken as an indication of the importance of caudal oesophageal reactions, tonic activity of the reticular groove and the atropine‐resistant vagally induced opening of the reticulo‐omasal orifice in the reticular groove mechanism.
Electrically induced release of acetylcholine from denervated Schwann cells
Authors: Dennis M. J. , Miledi R.
Published: December 2014

1. Focal electrical stimulation of Schwann cells at the end‐plates of denervated frog muscles elicited slow depolarizations of up to 30 mV in the muscle fibres. This response is referred to as a Schwann‐cell end‐plate potential (Schwann‐e.p.p.).

2. Repeated stimulation sometimes evoked further Schwann‐e.p.p.s, but they were never sustained for more than 30 pulses. Successive e.p.p.s varied in amplitude and time course independently of the stimulus.

3. The Schwann‐e.p.p.s were reversibly blocked by curare, suggesting that they result from a release of acetylcholine (ACh) by the Schwann cells.

4. ACh release by electrical stimulation did not seem to occur in quantal form and was not dependent on the presence of calcium ions in the external medium; nor was it blocked by tetrodotoxin.

5. Stimulation which caused release of ACh also resulted in extensive morphological disruption of the Schwann cells, as seen with both light and electron microscopy.

6. It is concluded that electrical stimulation of denervated Schwann cells causes break‐down of the cell membrane and releases ACh, presumably in molecular form.
The hippocampal control of neuronal discharges in the septum of the rat
Authors: McLennan H. , Miller J. J.
Published: December 2014

1. Records of field potentials and of the firing patterns of single neurones evoked by stimulation of the fimbria and fornix have been obtained from the septal nuclei of the rat.

2. Fimbrial stimulation caused orthodromic activation of lateral septal neurones which was followed by a lengthy inhibition. In the medial septum such stimulation could elicit an antidromic response; but inhibition whose duration depended upon whether the neurones were firing irregularly or in synchronized bursts was obtained without prior activation.

3. Stimulation of the medial septum evoked an antidromic response in the lateral septal neurones, which was followed by inhibition.

4. For all of these inhibitory phenomena, bursts of action potentials of small amplitude and correlated with the start of the inhibitory periods were observed, and are believed to indicate the firing of inhibitory interneurones.

5. Stimulation of the fornix caused excitation of medial septal neurones but was without effect on those in the lateral septum.

6. A scheme is proposed in which the direct inhibition of medial septal neurones from the fimbria is suggested to act as a ‘reset’ mechanism, while the phasic input from lateral septum resulting from the recurrent inhibitory pathways regulates the frequency of bursting in the medial septum.
Left atrial receptors and the antidiuretic hormone
Authors: Kappagoda C. T. , Linden R. J. , Snow H. M. , Whitaker Elaine M.
Published: December 2014

1. Stimulation of left atrial receptors by distending balloons located at the junction between the pulmonary veins and the left atrium and in the body of the left atrium resulted in a diuresis in anaesthetized dogs.

2. In the same dogs the diuresis was not consistently associated with a reduction in the antidiuretic activity of plasma as compared with that during the initial control period. The antidiuretic activity of dog plasma was assayed in water‐loaded rats anaesthetized with ethanol.

3. Intravenous injections of vasopressin suppressed a water diuresis in water‐loaded dogs anaesthetized with chloralose. The changes in antidiuretic activity of dog plasma which resulted from these injections were reliably detected by the bio‐assay in the rat.

4. It is concluded that the diuretic response to the stimulation of left atrial receptors is not accompanied by a reduction in the plasma antidiuretic hormone level.
Carviobascular alterations associated with bursts of panting in the exercising dog
Authors: Dampney R. A. L.
Published: December 2014

1. In conscious dogs exercising on a treadmill variations in arterial blood pressure and heart rate which were correlated with bursts of panting were observed. The blood pressure variations reflected similar variations in the total peripheral vascular resistance.

2. During exercise a change in respiration from slow breathing to panting was followed by a systemic vasodilatation and fall in blood pressure, but a rise in heart rate. Analysis of the time course of these effects demonstrated that the heart rate increase occurred later than the blood pressure fall.

3. The correlation between panting and blood pressure changes was not abolished by either of the receptor‐blocking drugs atropine sulphate or propranolol, nor by either of the following surgical procedures: acute bilateral cervical vagotomy, and denervation of the carotid sinus baroreceptors and carotid body chemoreceptors.

4. The vasodilatation which followed a burst of panting appeared to be due to a decrease in adrenergic vasoconstrictor sympathetic nerve activity, and not to a change in the chemical composition of the arterial blood.

5. It is concluded that the vascular changes are not reflex responses to stimulation of peripheral receptors by the bursts of panting. Instead, it is suggested that both the bursts of panting and associated falls in blood pressure are parallel effects resulting from activation at a suprabulbar level of the central nervous system. It is also concluded that the variations in heart rate are mediated by the baroreceptor reflex mechanism, activated by the changes in mean blood pressure.
Influence of temperature on retinal ganglion cell response and e.r.g. of goldfish
Authors: Schellart N. A. M. , Spekreijse H. , van den Berg T. J. T. P.
Published: December 2014

1. Extracellular recordings were made from the colour and spatial coded ganglion cells in the isolated goldfish retina.

2. Electroretinograms (e.r.g.s) were obtained from unanaesthetized goldfish.

3. For both types of responses the amplitude and phase characteristics were determined at various temperatures by means of Gaussian noise modulated light.

4. The shape of these characteristics, depicted as Bode plots, is invariant with temperature. For the ganglion cell responses this holds from 7 to 19° C, whereas for the e.r.g.s invariance is found over the entire range of temperatures used (6–30° C).

5. To obtain overlapping Bode plots shifts along the frequency axis are needed that are in accordance with the Arrhenius relation. The Q10 of the e.r.g. is about 1·9 and of the spike response about 2·7.

6. These relatively low values of Q10 indicate that the dynamics of retinal signal transformations are dominated by diffusion controlled reactions. This implies that real transport delays can be neglected in retinal input—output relations.

7. To verify whether a relationship exists between temperature and spectral coding, as has been suggested on the basis of behavioural studies, photopic e.r.g. action spectra were recorded and the spectral coding of ganglion cells were determined as a function of temperature.

8. The results point to a temperature invariance of both the photopic e.r.g. action spectra and the colour coding of ganglion cell responses.

9. The general conclusion of this study is that ‘rules’ found in the poikilothermic goldfish are not bound by temperature.