Endogenous oscillatory activity and TTX-sensitive spikes of the heart muscle in early juveniles of the isopod crustaceanLigia exotica

The heart beat of early juveniles of the littoral isopodLigia exotica occurred at a frequency of 250 to 350/min, associated with rhythmic activity of the heart muscle. Each burst was composed of a slow depolarizing potential with superimposed spike potentials. The spike potential was eliminated by perfusion with TTX-containing or Na⁺-free saline. In TTX-saline, the slow potential was unchanged in frequency and amplitude. By current injection into the heart muscle, the rhythm of the slow potential was phase-shifted and its frequency was changed in a membrane potential-dependent manner. These results show that the heart ofLigia early juveniles acts as an endogenous muscle oscillator generating oscillatory slow potentials and Na⁺-dependent spikes.     

Non-uniformity of regional vasomotor activity indicating the existence of 2 different systems in the sympathetic cardiovascular outflow

Summary In rabbits, 2 populations of sympathetic postganlionic fibres innervating the skin, heart, muscle and kidney could be classified by their different spike heights and their different susceptibility to noradrenaline and angiotensin amide. The ability of the 2 populations to respond to physiological stimuli in a highly differentiated manner leads to the assumption that 2 different systems in the cardiovascular sympathetic outflow exist.     

A cholinergic modulator.

Soluble proteins obtained from presynaptic cholinergic vesicles have been tested regarding their effects to modify postsynaptic spike generation. The results suggest that these proteins (or derivatives, incl. glycopeptides) may act as modulators in increasing the effectiveness and duration of postsynaptic spike generation. They may partake in generation of homosynaptic (posttetanic) potentiation.     

The effect of stimulus frequency on transmission in ganglia of Remak's nerve in the chicken

Summary Electrical stimulation of side branches of Remak's nerve evoked a synaptically-mediated spike discharge at the oral end of the nerve which increased in amplitude in response to successive stimuli. The maximum amplitude of the synaptic component was attained at a frequency of about 3 Hz but was almost completely absent at 31 Hz.     

Paroxysmal discharges in the electroencephalogram of the El mouse

Summary The spike discharges in the EEG of the El mouse, a seizure-susceptible strain, were recorded during convulsive seizures. This fact provides evidence that those seizures are really epileptic convulsions.I thank Dr.K. Imaizumi and Dr.K. Nakano of National Institute of Health for their sharing the strain of El mouse to us and MissY. Nakamoto and Mr.N. Ozawa for their technical assistance and Mr.K. Moriyama for his care for the mice, and also thank Dr. H.Narabayashi for his criticism on this paper.     

Pheromone behavioral responses in unusual male European corn borer hybrid progeny not correlated to electrophysiological phenotypes of their pheromone-specific antennal neurons

In genetic studies on the sex pheromone communication system of two races of European corn borer, which use opposite pheromone blends of the E and Z compounds, it was found that antennal olfactory cell response amplitudes to the two compounds were controlled by an autosomal factor, whereas behavioral responses to the blends were controlled by a sex-linked locus. Because of the difference in genetic controls, it was postulated that some unusual males would be produced in F₂ crosses between these two races. These unusual males would have antennal olfactory cells that respond as the Z-race males, but would respond behaviorally to the E blend. The present studies combined behavioral studies in a flight tunnel and single cell electrophysiological studies to show that these unusual males do indeed exist. These findings show that the spike amplitude of peripheral olfactory cells is not important in regulating species- or race-specific pheromone responses, as compared to some central nervous system factor assesses the spike frequencies from different pheromone-component-specific cells on the antenna. This factor seems to be essential in governing the pheromone-blend specific behavioral responses of male moths.     

On a relation of low phosphoglucomutase activity to starch accumulation in spiked sandal

Summary A considerable decline in the activity of phosphoglucomutase appeared to be a cause for the starch accumulation in the leaves of sandal affected by spike disease.     

Methylation of hippocampal phosphatidylethanolamine and proteins during long-lasting potentiation

Whereas the monomethylation of hippocampal phosphatidylethanolamine is decreased following the induction of long-lasting potentiation of the CA1 population spike, carboxymethylation of proteins is unaffected.     

Time course of excitatory and inhibitory states of bulbar respiratory modulated neurons

Summary In respiratory modulated neurons of rabbits, vagally mediated inhibition is not bound to resting membrane potential oscillations. Latency of spinally evoked antidromical spike invasion, however, is shorter and threshold voltage is lower during the shift of membrane potential towards depolarization accompanying burst discharge.     

A simple interspike interval analyzer for study of neuronal spike trains.

A simple, low cost interspike interval analyzer for the analysis of trains of nerve impulses is described. The analyzer is built with readily available integrated circuits and has been used to analyze spike trains in the lateral vestibular nucleus of cats.     

Is there a functional large intestine in the ferret?

Summary The intestine of the ferret (Putorius furo) is unusual in that there is no external anatomical division between ileum and colon. Up to 8–10 cm from the anus the electrical activity was organized into migrating myoelectric complexes typical of the small intestine. At this point the pattern of electrical activity changed abruptly to that characteristic of the colon, namely short and long spike burst activity. Histological examination showed that at this point the muscular layers were interupted by a band of connective tissue sufficient to permit the functional autonomy of the last part of the intestine.Acknowledgments. The authors are grateful to V. Rayner for helpful discussion and criticism. They acknowledge financial support received from INRA (Department of Veterinary Research).     

Methylation of hippocampal phosphatidylethanolamine and proteins during long-lasting potentiation

Summary Whereas the monomethylation of hippocampal phosphatidylethanolamine is decreased following the induction of long-lasting potentiation of the CA₁ population spike, carboxymethylation of proteins is unaffected.This work was supported by The University of British Columbia.     

Postsynaptic long-term potentiation follows coupling of dendritic glutamate application and synaptic activation

Dendritic depolarization, which seems to be involved in the induction of long-term potentiation (LTP), was elicited by localized glutamate application. When paired to low frequency synaptic activation in the same area, the subsequent changes had features in common with LTP, expressed as an increased probability of firing and shorter spike latency. The EPSP was not significantly increased.     

Postsynaptic long-term potentiation follows coupling of dendritic glutamate application and synaptic activation

Summary Dendritic depolarization, which seems to be involved in the induction of long-term potentiation (LTP), was elicited by localized glutamate application. When paired to low frequency synaptic activation in the same area, the subsequent changes had features in common with LTP, expressed as an increased probability of firing and shorter spike latency. The EPSP was not significantly increased.     

The influence of GABA on discharges of cortical epileptogenic focus

Summary GABA, when applied locally, acted similarly on both primary and mirror cortical focus: the negative component of the spike discharge was suppressed or inverted in polarity, whereas the late slow negative wave was strongly potentiated. Recordings from deep cortical layers suggested a different origin of these 2 surface-negative components of focal discharges.     

Multiplicity of beta lactamases: a problem of isoenzymes]

Analytical isoelectric focusing of beta lactamases is a very sensitive and powerful technique which generally shows a number of satellites near the main enzymatic spike. By this technique we studied two bacterial groups known to produce different beta lactamases, but only one by germ. Analytical isoelectric focusing showed that all bacteria from the same group produce the same satellite system which differs only in relative activity.     

A simple interspike interval analyzer for study of neuronal spike trains

Summary A simple, low cost interspike interval analyzer for the analysis of trains of nerve impulses is described. The analyzer is built with readily available integrated circuits and has been used to analyze spike trains in the lateral vestibular nucleus of cats.Acknowledgment. This research is supported in part by Higher Degrees and Research Grant No. 158/363 to J.C.H. from the University of Hong Kong.     

Effect of spike disease on the 5′-and 3′-nucleotidase activities in sandal plants

Summary In the sandal plant affected by spike disease, caused by mycoplasma-like organisms, the changes occurring in the 5-and 3-nucleotidase activities were studied and their possible significance discussed.     

Wellenlängen-Diskriminatoren im intrakranialen Pinealorgan vonRana catesbyana

Summary The photosensitivity of the epiphysis cerebri of bullfrogs (Rana catesbyana) was investigated by recording with 3 M-KC1 glasscapillary microelectrodes. Of 65 units isolated from the tractus pinealis 21 were inhibited by short wave lengths and excited by longer wave lengths (chromatic response), 44 units were inhibited by all wave lengths (achromatic responses). Most effective for the excitatory component of the chromatic response was green. The spike amplitude of the chromatic response was 5–15 mV, that of the achromatic response 30–40 mV.     

Veränderungen der elektrischen Hirntätigkeit bei Katzen nach Röntgentotalbestrahlung

Summary In cats with chronically implanted electrodes, hippocampus and amygdala consistently showed spike discharges immediately after relatively low doses of total body x-irradiation (400 r) and reticular arousal thresholds were transitorily decreased. Thalamic recruiting thresholds increased later, while hippocampal seizure thresholds remained practically unaltered. Experiments with lower doses are in progress.

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This article is based on work performed under Contract No. AT-(04-1)-GEN-12 between the Atomic Energy Commission and the University of California at Los Angeles.