bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypothalamic control of thyrotrophin secretion*
Authors: Panda J. N. , Turner C. W. 
Published: December 2014

1. By means of the haemagglutination‐inhibition technique, it has been possible to measure the plasma and pituitary levels of thyroid‐stimulating hormone (TSH) following unilateral and bilateral electrolytic lesions placed in the supraoptic area of the hypothalamus of female rats.2. Unilateral lesions after 8 and 48 hr caused a temporary decrease in the percentage of circulating TSH followed by a return to normal.3. Bilateral lesions caused a fall in plasma TSH to a level 41% below normal at 10 days whereas the pituitary level increased 70%.4. Rats with bilateral symmetrical supraoptic lesions, kept for 3 days at 4° C, had a lower plasma TSH content (23%) and a higher pituitary TSH content (16%) than the sham operated control animals but the levels of pituitary TSH did not show any significant difference (0·100 > P > 0·050).5. Thyroidectomized rats with bilateral lesions kept at 26° C for 3 days had a much lower plasma TSH (39%) and a slightly higher pituitary TSH as compared to the normal intact animals, suggesting that the hypothalamus also influences the synthesis of TSH in the pituitary.6. Thyroidectomized rats with bilateral lesions kept at 4° C for 3 days showed both a plasma and pituitary TSH increase compared to controls at 26° C, suggesting that when a higher demand for thyroid function is present the pituitary gland has some autonomy for both secretion and release of TSH. This autonomy appears to be slight, as there was no statistically significant difference between the pituitary TSH levels of the thyroidectomized animals bearing similar supraoptic lesions and exposed to 4 and 26° C.
The relation between neural and perceptual intensity: a comparative study on the neural and psychophysical response to taste stimuli
Authors: Borg G. , Diamant H. , Ström L. , Zotterman Y. 
Published: December 2014

1. Recording the summated electrical response from the human chorda tympani in the middle ear provides data for a quantitative study of the relation between the neural activity and the strength of the stimulus applied to the tongue which can be compared with the relation between the subjective estimation and the stimulus strength.2. Full comparative data obtained from two patients showed a very high correlation between the functions describing the subjective and the neural response in relation to the strength of citric acid and sucrose solutions applied to the tongue. In a third patient the same high correlation was obtained for NaCl and citric acid.3. The good agreement between the individual neurophysiological experiments and the psychophysical group experiment favours the view that a fundamental congruity is found between neural activity and perceptual intensity.
The topology of dermatomal projection in the medial lemniscal system
Authors: Werner Gerhard , Whitsel Barry L. 
Published: December 2014

1. The topographic organization of first order afferent fibres in the lumbar, sacral and coccygeal dorsal roots, and in the fasciculus gracilis was studied in squirrel monkeys.2. At the entry zone, progressing from caudal to rostral, dorsal root filaments receive fibres from tail and hind‐limb receptive fields which serially overlap and describe a spiral‐shaped trajectory. The latter starts with tail, progresses post‐axially towards the foot, crosses the foot from lateral to medial, and ascends the preaxial leg.3. In the fasciculus gracilis, this arrangement of fibres at the dorsal root entry zone is preserved in its entirety. It assumes the form of a fibre lamination, with the most caudal dorsal root fibres occupying a dorso‐medial location; further rostral dorsal root fibres come to lie more ventrolaterally.4. Dorsum and sole of foot project in an overlapping and interdigitating manner to the fibre lamina of the 7th lumber dermatome in the fasciculus gracilis. Thereby, dorsum and sole of foot behave in the projection as if they were one and the same surface.5. The argument is presented that the foot and its projection on to the cross‐sectional plane of the dorsal funiculus are topologically equivalent and that the hind‐limb as a whole and its projection are not. On the other hand, homotopic mapping of the foot together with the sequential fibre organization in the dorsal funiculus enable many more types of closed curves on the body surface to remain arc‐wise connected in the projection than would otherwise be possible.
The calcium content of the smooth muscle of the guinea‐pig taenia coli
Authors: Goodford P. J. 
Published: December 2014

1. The in vitro calcium content of the smooth muscle of the guinea‐pig taenia coli was 3·0 m‐mole Ca/kg wet wt. when phosphate was omitted from the bathing medium, and was almost independent of pH changes in the range 6·7‐7·6.2. The calcium content was not changed when 1 m
M phosphate was included in the medium, if the pH was 6·7 or 7·0. However, when the pH was 7·6, the calcium content increased by 1·5 m‐mole Ca/kg wet wt. in the presence of phosphate.3. The calcium content rose by 1·1 m‐mole Ca/kg wet wt. when NaCl in the bathing medium was replaced by isotonic sucrose, and rose by 0·7 m‐mole Ca/kg wet wt. when MgCl2 in the bathing medium was replaced. These increases may reflect a competition between Ca2+ and other cations for fixed negative sites in the tissue.4. The initial rapid phase of 42K exchange corresponded to an ‘extra‐cellular 42K‐space’ of 470 ml./kg fresh wt. in normal solution, rising to 560 ml./kg. fresh wt. in low‐sodium solution and to 760 ml./kg fresh wt. in calcium‐free low‐sodium solution. In this last medium the extra‐cellular [14C]sorbitol space was only 390 ml./kg fresh wt., so that there was a large excess of rapidly‐exchanging potassium which may have been competing at fixed negative sites.
Factors affecting the relative magnitudes of the sodium: potassium and sodium: sodium exchanges catalysed by the sodium pump
Authors: Garrahan P. J. , Glynn I. M. 
Published: December 2014

1. The effects of external potassium on sodium: potassium exchange and sodium: sodium exchange in human red cells have been estimated from measurements of ouabain‐sensitive potassium influx and ouabain‐sensitive sodium influx in media containing different concentrations of potassium.2. As the external potassium concentration is increased from zero to 5 m
M, sodium:sodium exchange—as judged by ouabain‐sensitive sodium influx—is progressively suppressed, and sodium:potassium exchange—as judged by ouabain‐sensitive potassium influx—is progressively increased. Both exchanges are half‐maximal between 1 and 2 m
M‐K, and at 5 m
M‐K sodium: sodium exchange becomes very small as sodium: potassium exchange approaches a maximum.3. Experiments have been carried out, mainly on resealed ghosts, to determine what factors affect the magnitude of the sodium:sodium exchange in potassium‐free solutions.4. Sodium:sodium exchange does not occur in the absence of adenosine triphosphate (ATP).5. Ghosts containing high concentrations of sodium, no potassium and high concentrations of ATP show no ouabain‐sensitive loss of sodium into potassium‐free solutions. The ability to carry out sodium:sodium exchange can be restored by replacing most of the internal sodium with potassium or by preparing the cells so that they contain much more orthophosphate (Pi) than ATP.6. Ghosts containing sodium in low concentration, potassium in high concentration and with a low [ATP]/([ADP].[Pi]) ratio show a greater ouabain‐sensitive loss of sodium into potassium‐free media than into media containing potassium; i.e. external potassium reduces ouabain‐sensitive sodium efflux.7. The effect of Pi is not the result of competitive inhibition of the transport ATPase since Pi at the concentrations used does not inhibit ATPase activity in fragmented ghosts.
Some factors involved in the thalamic control of spontaneous barbiturate spindles
Authors: Andersen P. , Andersson S. A. , Lømo T. 
Published: December 2014

1. The origin of thalamic and cortical spontaneous spindles was studied in cats anaesthetized with sodium pentobarbital.2. Complete removal of all cortical grey matter left the thalamic rhythmic spindle activity unchanged.3. Removal of the entire thalamus or pronounced oedema in the thalamus abolished completely the spindle activity in the corresponding hemisphere.4. In a neuronally isolated cortical area, a fast, low voltage background activity appeared, interrupted by occasional irregular rapid potential changes (sharp waves) of high voltage. Regular spindle rhythms were seldom observed unless excited by a depolarizing drug. Spontaneous spindles did not invade the isolated cortex via a bridge of intact cortical tissue.5. With increasingly larger destruction of the thalamus in a rostro‐caudal direction, the activity in the post‐cruciate cortex did not change until the anterior third of the thalamus was encroached upon. A transverse section in front of the thalamus nearly eliminated the cortical spindles.6. Complete removal of the mid line and intralaminar nuclei left the spontaneous rhythmic activity of the lateral thalamic nuclei and of the frontal cortex principally unchanged.7. Removal of the laterally located thalamic nuclei, including the n. ventralis posterolateralis (VPL), abolished virtually all spontaneous spindle activity of the frontal cortex, including the post‐cruciate area.8. Local cortical cooling reduced the amplitude but not the frequency of the cortical spindles.9. Cooling of the whole brain reduced both the amplitude and the frequency of the spindles. At low temperatures, all spindle activity in the cortex disappeared, and occasional sharp waves occurred, as with de‐afferentation.10. It is concluded that the rhythm of the cortical spontaneous barbiturate spindles is generated exclusively by thalamic neurones. The electromotive force of the corticographic waves, however, has a cortical origin.
Dependence of the magnitude of the Stiles—Crawford effect on retinal location
Authors: Westheimer Gerald 
Published: December 2014

1. The directional sensitivity (Stiles—Crawford effect) of retinal cones is supposed to be associated with their shape, but only extrafoveal cones have a cone‐like shape; cones in the central fovea are elongated and look like rods.2. To determine whether the directional sensitivity of cones depends on their shape, the Stiles—Crawford effect was measured both in the central fovea and in the parafovea of the human eye.2. To ensure that the cone population tested was homogeneous, a small brief test flash, brought into the eye through the centre of the pupil, was placed at threshold by varying the intensity of a large adapting field. The directional sensitivity of the cones was determined by finding the efficiency of light to act as an adapting background as a function of position of entry in the pupil.4. Central foveal cones have a less pronounced directional sensitivity than parafoveal cones and this lends support to the conclusion that the Stiles—Crawford effect is connected with the shape of the retinal receptors.
Cortical acetylcholine release and electroencephalographic arousal
Authors: Szerb J. C. 
Published: December 2014

1. In cats anaesthetized with N2O‐halothane acetylcholine (ACh) release from the parietal cortex was measured. In addition, low and high‐frequency electroencephalographic (e.e.g.) activity was recorded quantitatively.2. Stimulation of the mesencephalic reticular formation at 30, 60 and 100/sec produced an identical increase in cortical ACh output, while 300/sec stimulation was about ⅓ as effective and 10/sec stimulation failed to increase ACh output.3. Reticular formation stimulation at 60 and 100/sec reduced the low‐frequency and increased the high‐frequency e.e.g. activity. Stimulation at 30 and 300/sec was less effective, while 10/sec stimulation had no effect on e.e.g.4. Acute undercutting of the cortex did not affect the resting output of ACh but greatly reduced the increase due to reticular formation stimulation as compared to the contralateral intact side. Cutting the cortex around the collection area did not affect the increase in ACh output due to reticular formation stimulation.5. Stimulation of the hypothalamus, medial thalamus and septum at 100/sec also increased cortical ACh output while stimulation of the dorsal hippocampus and caudate nucleus failed to do so.6. Low frequency cortical e.e.g. activity was reduced by stimulating the reticular formation, the hypothalamus, the medial thalamus and slightly by septum stimulation. High‐frequency e.e.g. activity was increased by stimulating the reticular formation and the hypothalamus.7. It is concluded that the ACh measured originates from the neural tissue underlying the collection area. The increased release is concomitant to e.e.g. activation but the pathways involved in cortical e.e.g. activation and increased ACh release are distinct, since the two phenomena do not vary in a parallel fashion when the reticular formation is stimulated at different frequencies or when different subcortical areas are stimulated.8. The effectiveness of septal stimulation in increasing ACh release indicates that at least part of the cortical cholinergic fibres traverse this area on their way to the cortex.
The innervation of the vas deferens of the guinea‐pig
Authors: Ferry C. B. 
Published: December 2014

1. The compound action potential of the hypogastric nerve of the guinea‐pig contained two main elevations. The low‐threshold fibres had a range of conduction velocities from 1·5 to 10 m/sec. The high threshold fibres conducted action potentials at less than 1 m/sec. The hypogastric nerve contained small myelinated fibres and non‐myelinated fibres.2. In the preparation in vitro, junctional potentials and contractions were elicited by stimulation of the rapidly conducting fibres alone. Trains of C fibre volleys were ineffective.3. In the preparation in vivo, conduction from the hypogastric nerve to the vas deferens nerve was unidirectional and abolished by hexamethonium. After the administration of hexamethonium, the contraction produced by stimulation of the vas deferens nerve was unaffected.4. The close arterial injection of acetylcholine (ACh) into the pelvic viscera caused centrifugal activity in the motor fibres of the vas deferens nerve, but no impulses were detected in the hypogastric nerve.5. Ganglion cells are present in the last 2 cm of the hypogastric nerve.6. It is concluded that there is a ganglionic relay between the hypogastric and vas deferens nerves.
Local and central circulatory responses to sustained contractions and the effect of free or restricted arterial inflow on post‐exercise hyperaemia
Authors: Lind A. R. , McNicol G. W. 
Published: December 2014

1. The cardiovascular responses to sustained contractions at tensions from 5 to 30% maximal voluntary contraction (MVC) have been examined. At 5 and 10% MVC blood pressure, heart rate and forearm blood flow all reached a steady state during the contraction; post‐exercise hyperaemia did not show peak flows higher than those found during exercise. At tensions of 20 and 30% MVC, none of the measurements showed a steady state during the contractions, but increased steadily throughout the contraction; post‐exercise hyperaemia characteristically showed peak flows in excess of any flow measured during contractions. The results obtained at a tension of 15% MVC did not show a steady‐state during the contraction but the following hyperaemia showed a similar pattern to that seen at the lower tensions.2. Digital compression of the brachial artery after sustained handgrip contractions for periods of 3 or 6 min after the contraction ended resulted in only a small reduction, on average by 5‐15%, of the post‐exercise hyperaemia.3. Consideration of the evidence leads to the view that in physiological circumstances the post‐exercise hyperaemia following sustained contractions bears a close relationship to the metabolism of the active muscles.
Circulatory responses to sustained hand‐grip contractions performed during other exercise, both rhythmic and static
Authors: Lind A. R. , McNicol G. W. 
Published: December 2014

1. The cardiovascular responses to sustained hand‐grip contractions at 20, 30 and 50% maximal voluntary contraction (MVC) were measured in subjects who were engaged in treadmill walking at three different rates with oxygen intakes of 1·1, 1·7 and 2·8l./min. The increments in heart rate and blood pressure at tensions of 20 and 30% MVC were similar at all rates of walking, but the response to a contraction at 50% MVC was lower at the hardest work rate than at the two easier rates.2. When two or more muscle groups contracted at the same relative tension, the increments in heart rate and blood pressure were the same, whether they contracted separately or together.3. When two or more muscle groups contracted simultaneously at different relative tensions, the increments in heart rate and blood pressure were the same as when the muscle group, at the higher relative tension, contracted separately at that tension.4. The blood flow to a muscle engaged in sustained contraction was increased when a second muscle group contracted at a higher relative tension.
Athletes at altitude
Authors: Pugh L. G. C. E. 
Published: December 2014

1. Six international middle‐distance runners were investigated during 4 weeks in England and during a similar period in Mexico City (2270 m (7450 ft.))2. In 3‐mile (4828 m) time trials at 2270 m the increase in time taken by four subjects compared with sea level was 8·5% on the 4th day and 5·7% on the 29th day. There was thus a gain of 2·8% or 20 sec in time associated with acclimatization.3. In 1‐mile (1609 m) time trials the times were increased by 3·6% in the first week at altitude and by 1·5% in the 4th week. The improvement amounted to 2·1%, or 4·9 sec.4. In 5 min maximum exercise on the ergometer maximum O2 intake for six subjects at altitude was reduced by 14·6% on the 2nd day and 9·5% on the 27th. Only one subject showed no change in maximum oxygen intake (V̇O2, max) with time spent at altitude.5. Although V̇O2, max was persistently reduced at altitude work rates finally exceeded sea‐level values, owing to increased over‐all efficiency.6. Forty‐minute recovery O2 intakes after 5 min maximum exercise averaged 17·35 l. at sea level and 17·53 l. at altitude. Mean values from 40th to 50th min were within ± 7% of pre‐exercise values.7. Serial tests at increasing loads yielded a straight‐line relation between O2 intake and work rate over a wide range of work rates at sea level and at altitude. Heart rate and ventilation for given work intensity were maximal in the first 2‐10 days at altitude and thereafter declined.8. Capillary HbO2 saturation fell from 93% at rest to 87% in maximum exercise. The corresponding alveolar gas tensions were PA, O2 89 mm Hg, PA, CO2 24 mm Hg. About half the total unsaturation in maximum exercise was explained by the Bohr effect.9. In six of eight pairs of determinations V̇O2, max measured on the ergometer was within ± 0·15 l./min of V̇O2, max measured on the running track. Nevertheless, it was not possible to predict running performance from ergometer measurements.
Ca‐coupling in the anterior byssal retractor muscle of Mytilus edulis L
Authors: Leenders H. J. 
Published: December 2014

1. Experiments designed to elucidate the role of Ca in the excitation—contraction coupling of the anterior byssus retractor muscle (ABRM) were carried out. Ca influences membrane depolarization and provides for coupling of the contraction in response to repetitive electrical stimulation as well as of ACh and KCl contracture. Depriving ABRM of Ca results in two closely correlated events: disappearance of action potential and of the contraction in response to repetitive electrical stimulation.2. A sigmoid increase in tension with the log‐Ca concentration in artificial medium was observed whereas, over the same range of concentrations, the tension remnant decreased.3. Induction of relaxation by 5‐HT is Ca dependent. Either thiourea inactivation or Ca deprivation results in failure to relax. Low concentrations of 5‐HT (10−7 g/ml.) bring about increase in peak tension of the contraction in response to repetitive electrical stimulation, whereas higher concentrations (10−5 g/ml.) undermine peak tension.4. Frequencies exceeding 40 cycles evoke a contraction accompanied by tension remnant, which is eliminated with 5‐HT.5. Dropwise addition of Ca on a trypsin window in the muscle induces a latency relaxation before onset of Ca‐contracture.
A study of cholinoceptive cells in the lateral geniculate nucleus
Authors: Phillis J. W. , Tebēcis A. K. , York D. H. 
Published: December 2014

1. The dorsal lateral geniculate nucleus (LGN) of the cat stains densely for acetylcholinesterase, which is present in intra‐axonal and extracellular locations.2. Acetylcholine (ACh), cholinomimetic drugs, anticholinesterases and ACh antagonists were administered iontophoretically to neurones in the LGN.3. ACh excited eighty‐six of 184 (46·7%) geniculate neurones and depressed seven (3·8%).4. The excitatory response to ACh was frequently larger than that to
L‐glutamate and had a comparable time course.5. There was a considerable variation in the proportion of ACh sensitive cells in different animals. ACh firing was facilitated by optic nerve or visual stimulation.6. Carbamylcholine was the most active of the choline esters tested, frequently exceeding ACh in potency. The other choline esters and nicotine were consistently less active than ACh.7. Anticholinesterases, eserine, neostigmine and edrophonium potentiated the action of ACh, and often caused excitation. Eserine caused an initial small enhancement in the amplitude of the focal potential evoked by optic nerve stimulation followed by a reduction in amplitude and prolongation of duration of the potential.8. Atropine and benzoquinonium effectively prevented the ACh excitation of many cells. Dihydro‐β‐erythroidine failed to cause a significant reduction in the magnitude of the ACh response. All three ACh antagonists failed to reduce the excitant effects of optic nerve or visual stimulation.9. Stimulation of the mesencephalic reticular formation caused either an enhancement or a reduction in the excitability of ACh sensitive neurones in the LGN. Benzoquinonium abolished the excitatory effects of reticular formation stimulation.10. The findings presented in this paper suggest that ACh is the transmitter released by terminals of nerves of the reticular formation projection to the LGN.
The effects of light‐adaptation on rod and cone receptive field organization of monkey ganglion cells
Authors: Gouras Peter 
Published: December 2014

1. Receptive fields of perifoveal ganglion cells have been measured by determining threshold for eliciting a just detectable response using either concentric spot stimuli centred on the receptive field or small spot stimuli in different parts of the receptive field at various states of retinal adaptation and with stimuli selected to separate rod from cone function.2. Light‐adaptation decreases the sensitivity, latency and duration of threshold responses throughout the receptive field of a ganglion cell.3. With all patterns of retinal stimulation and states of adaptation, threshold signals of the rods reach a ganglion cell later and those of the cones earlier than approximately 50 msec after a light stimulus.4. In the more dark‐adapted retina threshold rod and cone signals can be transmitted to the brain by the same or by neighbouring ganglion cells but not simultaneously; in the light‐adapted state only the cone signal is transmitted.