Activity Of Nerve Cells Research Articles

Histophysiological characteristics of the subcommissural organ of the brain during isolated inhibition of the adrenal zona glomerulosa

cally from nonspecific changes described during seizures induced by toxic substances such as cobalt, aluminum, and strychnine [2, 5]. These substances have a harmful effect mainly on the rough endoplasmic reticulum of the neurons, i.e., on the apparatus for protein synthesis. The changes now discovered, however, point to activation of synapses, postsynaptic dendrites, and nerve cells. Each change is nonspecifJc, but it may be part of a combination of changes characteristic for thisparticular type of experimental epilepsy.

Bradykinin as an algesic (pain producing) substance in the pulp : R. Inoki, K. Matsumoto, T. Kudo, Y. Kotani and M. Oka, Naunyn-Schmiedeberg's Arch. exp. Path. Pharmak., 306 (1979) 29–36

A rat uterine smooth muscle contracting substance was released into the superfusate of the dog's exposed canine pulp after noxious stimulation of the pulp by pricking, heat and electrical stimulation. This active substance was acid- and heat-resistant and was decomposed by carboxypeptidase B and α-chymotrypsin, but not by carboxypeptidase A and trypsin. This substance was also tested on several types of smooth muscle. Electrical activity of nerve cells in the reticular formation, which were sensitive to stimulation of the instep of the foot by pinching, was activated by the intrafemoral administration of the active substance. The algesic activity of this substance was examined in cantharidin blister base in man. This study conclusively demonstrated that the active substance of the pulp released by noxious stimulation produced pain and it was identified as bradykinin.

Histochemical and cytochemical observations on the acetylcholinesterase (AChE) localization in the superior cervical ganglion (SCG) after preganglionic sympathectomy of the neonatal rat.

Results of histochemical and cytochemical reactions show that after the section of preganglionic nerve trunk performed in newborn animals, the appearance and the individual increase in AChE activity in non-innervated nerve cells follow the pattern of normally innervated ganglion cell.

Construction of an inexpensive hydraulic microdrive for recording single nerve cell activity

A hydraulic microdrive that can be constructed for less than thirty dollars is described. The microdrive is assembled from stock hardware and two glass syringes. It consists of three sections: (1) a base section, (2) a driver section, and (3) a carriage section. The master cylinder is a 5 cm3 syringe, while the slave cylinder is a 50 cm3 syringe. The piston of the slave cylinder moves 10 μm for each 10° arc through which the drive wheel passes. The microdrive is effective in that it serves as the vehicle by which metal or glass electrodes are brought next to single nerve cells in order to record the electrical activity of the cells.

Interferon enhances the excitability of cultured neurones

INTERFERON has varied biological effects on cells1,2 and induces modifications of the cell surface both in vitro3–6 and in vivo7. The particular capacity of the neuronal membrane to generate propagated action potentials (well retained in culture8) makes neurones excellent material for the study of substances that affect the cell surface. We have therefore determined the effect of interferon on the electrical activity of nerve cells. Most of the experiments reported here were carried out on the cat cerebral and cerebellar cortex, because the electrical patterns of these structures have been well defined in vitro8,9. Furthermore, as human leukocyte interferon exhibits a high degree of antiviral activity on cat cells10, we were able to study the effect of highly purified interferon preparations on the spontaneous and evoked electrical activity of these neurones. In other experiments, we studied the effect of rat interferon on rat neurones in culture. Our results, which show that human and rat interferon specifically enhance the excitability of cat and rat nerve cells, respectively, may have implications for the therapeutic use of interferon as well as for the understanding of some of the manifestations of viral diseases.

Bradykinin as an algesic (pain producing) substance in the pulp

A rat uterine smooth muscle contracting substance was released into the superfusate of the dog's exposed canine pulp after noxious stimulation of the pulp by pricking, heat and electrical stimulation. This active substance was acid- and heat-resistant and was decomposed by carboxypeptidase B and alpha-chymotrypsin, but not by carboxypeptidase A and trypsin. This substance was also tested on several types of smooth muscle. Electrical activity of nerve cells in the reticular formation, which were sensitive to stimulation of the instep of the foot by pinching, was activated by the intrafemoral administration of the active substance. The algesic activity of this substance was examined in cantharidin blister base in man. This study conclusively demonstrated that the active substance of the pulp released by noxious stimulation produced pain and it was identified as bradykinin.

Neurones with synchronous bursting discharges in organ cultures of the hypothalamic supraoptic nucleus area

Explants of the hypothalamic supraoptic nucleus area from newborn rats were cultured. Ultrastructural studies revealed the existence of typical neurosecretory granules in neuronal perikarya as well as in axons. Large nerve cells that were spontaneously active discharged at an average firing rate of 7.2 +/- 4.4 (S.D., n = 98) spikes/sec and 42% of these neurones displayed a phasic firing pattern as shown by the existence of peaks in their autocorrelograms. The firing of 59% of the neurones was synchronous with the activity of other nerve cells. In some neurones, only the onsets of bursts were correlated, whereas in others periods of high correlation alternated with periods of no correlation. The relative proportion of rhythmically or synchronously firing hypothalamic neurones was not altered when a neurohypophysial explant was co-cultured. Field stimulation in the cultures resulted in a short-latency excitation followed by an inhibition which was found to be bicuculline-sensitive. The existence of functional synapses was furthermore demonstrated by intracellular recordings of postsynaptic potentials.

Drinking behaviour induced by intracranial injections of eledoisin and substance P in the pigeon.

THE only peptide known which rapidly and consistently elicits a specific behavioural response when injected into the brain is angiotensin II, which in picomole doses causes reptiles, birds and mammals to seek out and drink water1. But, there is evidence to suggest that other peptides such as substance P may also participate in the control of brain function and behaviour. Substance P is distributed throughout the mammalian peripheral and central nervous system, particularly in myenteric plexus, sensory afferent pathways, hypothalamus and substantia nigra2. In the human brain regional concentrations as high as 0.5 × 10−9 mol per g wet tissue have been reported3. Substance P is a member of a family of peptides with similar pharmacological properties and which also includes eledoisin, an undecapeptide obtained from the salivary glands of certain Mediterranean cephalopods4. These peptides share a similar amino acid sequence at the C-terminal end (Fig. 1). Both eledoisin and substance P stimulate nerve cell activity in vertebrates and invertebrates and may act as regulators of neural activity5, but no specific behavioural effect of these peptides has yet been reported. We report here that eledoisin and substance P elicit vigorous drinking when injected into the brain of conscious pigeons.

Direct and indirect activation of nerve cells by electrical pulses applied extracellularly.

1. The mode of activation of nerve cells by extracellular stimuli was investigated while recording from a selected cell with one electrode, and applying current pulses around this cell with another electrode. The analysis was done on motoneurones and on spinal border cells from lower lumbar segments in the cat. 2. Directly evoked action potentials were defined by their appearance in an all-or-none fashion with stable latencies of less than 0-5 ms. The lowest thresholds for their generation were 0-15-0-20 muA in the spinal border cells and 0-35-0-40 muA in the motoneurones. In the main series on motoneurones a correlation has been established between different positions of the extracellular stimulating electrode in relation to the cells and the thresholds for the direct excitation of these cells. The position of the electrode were defined on the basis of an analysis of the IS and SD components of the action potentials recorded extracellularly around the cell when evoked by current pulses applied through the intracellular electrode; both the amplitudes of these IS and SD components and their timing with the IS and SD spikes, which were simultaneously recorded with the intracellular electrode, were then taken into account. The lowest thresholds (less than 2 muA) for the direct activation of cells were found nearest the initial segment of the axon. Their values increased to about 5 mu A at near-soma positions and to greater than 10 muA at near-dendrites positions about 150 mum away. 3. Transsynaptically evoked action potentials which were clearly set up by the preceding e.p.s.p.s appeared with latencies greater than 0-7 ms. When single current pulses were used, the lowest thresholds for transsynaptic spike activation were usually greater than 5-10 muA but they considerably decreased with repetitive stimuli. These thresholds were higher than the thresholds for the direct activation of cells within the region of the initial segment, of the same order of magnitude near the soma, and lower when the stimulating electrode was nearer the dendrites than the soma and generally at all larger distances from the cells. 4. All the observations on direct excitation of cells by extracellular stimuli (generation of the IS spike before the SD spike, lowest thresholds near the region of the initial segment of the axon, similar rates of increase in these thresholds with distance as for fibres) lead to the conclusion that the effects of the extracellular stimuli are exerted primarily via spread of current to the initial segment of the axon and its depolarization. 5. Late extracellular negativities presumably related to dendritic activation were observed in a few cells. These negativities were synchronous with late components of the intracellulary recorded action potentials.

The use of amine fluorescence histochemistry in the study of drugs, especially morphine, on the CNS

This chapter discusses the use of amine fluorescence histochemistry in the study of drugs, especially morphine, on the central nervous system. With the introduction of the Falck-Hillarp technique, it became possible to demonstrate dopamine (DA), noradrenaline (NA), and 5-hydroxytryptamine (5-HT) in nerve cell bodies, axons, and terminals of the central nervous system. The method is based on the conversion of DA, NA, and 5-HT into intensely fluorescent compounds in situ . Thus, these amines can be localized by fluorescence microscopy. Very early, it became evident that with this method it might be possible to study the action of drugs on discrete monoamine cell body and terminal systems in the central and peripheral nervous system. Recently, quantitative microfluorimetric studies have been performed on DA fluorescence in the nucleus caudatus, tuberculum olfactorium, and nucleus accumbens. A significant increase of DA turnover is observed in all these three areas, whereas no clear effect is seen in the DA nerve terminals of the median eminence. Also it has been found that morphine can block adrenaline receptors in a high dose and stimulate adrenaline receptors in a low dose. Thus, morphine can be described as a partial adrenaline agonist. In agreement with this hypothesis, morphine has been found to block Clonidine-induced hypotension and bradycardia and in this dose, it will itself cause hypotension and bradycardia just as clondine does. An adrenaline receptor stimulation in these doses of morphine could also explain why morphine in doses of 2–4 mg/kg causes an inhibition of spontaneous activity in the NA nerve cells of the locus coeruleus.

Neuronal control of swimming in the medicinal leech

Leeches swim by undulating their extended and flattened body in the dorsoventral direction, to form a wave that travels backwards along the animal. The troughs and crests of this body wave are produced by a metachronal rhythm of antiphasic contractions of the dorsal and ventral longitudinal musculature of the body wall of successive segments. Cinematographic records of swimming leeches show that over a range of cycle periods from 390 to 1100 msec the animal maintains one full wave along the length of its body. This constant wave form is achieved by compensating for the increase in the cycle period by an increase in the intersegmental travel time of the wave from 19 to 77 msec per segment. Direct muscle tension measurements of the segmental body wall during the swimming movement of a restrained, brainless and partially denervated leech lead to values for the dynamic parameters of the body wave which are in agreement with those abstracted from cinematographic records. In order to study the neuronal control of the swimming movement, a semi-intact leech preparation was developed. This preparation carries out movements that are clearly vestiges of the swimming rhythm while allowing the taking of electrophysiological records from exposed and immobilized parts of its peripheral and central nervous systems. The records reveal a nerve cell activity rhythm whose period matches that of the swimming rhythm. The swimming rhythm and its body wave must be generated by a system of distributed, phase-locked segmental oscillators that cause an antiphasic activity of the motor neurons innervating the segmental dorsal and ventral longitudinal muscles. The cycle of these oscillators can be inferred to consist of a variable time sector whose changes in length are responsible for changes in the cycle period, and of a constant time sector whose length is independent of the cycle period.

Spontaneous whole brain slow potential changes during recovery from experimental neurosurgery.

Prolonged, nonlocalized brain slow potential changes, frequently associated with cortical spreading depression, occur spontaneously during 5 days following brain implant surgery in rats. These potentials are accompanied by reductions in multiple nerve cell activity and reductions in behavioral motility. The method used in this study provides a tool for evaluating recovery from neurosurgical trauma or other brain injuries, and for testing procedures that facilitate or impede this process.

Histometric observations on the metabolism of tangle-bearing neurons

The diameter of the nucleolus in neurons containing neurofibrillary tangles is smaller than in adjacent, normal-appearing neurons. This suggests that the metabolic activity of tangle-bearing nerve cells is diminished.

Evoked Potentials in Psychology, Sensory Physiology and Clinical Medicine

Only quite recently has it become technically possible to record, from elec trodes attached to the scalp, the human brain's electrical responses to sensory stimulation. The core of this book is a critical survey of endeavours to use these electrical responses (called evoked potentials) as tools in attempts to discover the ways in which the brain first processes incoming sensory information and then forms internal representations of features ofthe external world. Buttressed by quantities of undeniably sloppy evoked potential research there are some who would dismiss out of hand the recording of evoked potentials as being comparable to 'holding an oscilloscope probe 6 feet in diameter up to a computer and pronouncing from the resultant waveform on the underlying structure and function'; many would contrast the scientific value of recording the activities of single nerve cells with microelectrodes. However, although it is certainly true that the brain may indeed function in a way which would not be susceptible to the approaches of the evoked potential researcher it might equally well resist the stratagems of the single-cell man. If, for example, the neural correlate of some sensation were the state of some large population of nerve cells, then the present-day researcher who records in great detail the activity of one single cell or of a very few cells would be faced with a major problem in trying to see the forest for the trees.

A Plasma Model of Brain Dynamics

A plasma model of the brain is proposed to explain the long range correlations observed in the nervous system of the living brain and to understand such mental functions of the brain as the remembering (as well as forgetting) and the recalling of information received from the external world. In this model a waking but inattentive state of the brain is repre­ sented by a single-humped distribution function for the nerve cell activity (measured by the firing rate of bioelectrical impulses), and an attentive excited state brought about by an ex­ ternal stimulation by a distribution function with a small second hump on the tail. The quasi-linear approximation to the Liouville equation for the activity distribution function in the neural phase space predicts the flattening of the small hump and the formation of a plateau persisting for indefinitely long time, which is interpreted as the . memory process of the brain. The model is compared with the model of Ricciardi and Umezawa, in which the stable memory of the brain is related to the Bose condensation into the ground state of the qnan­ tum many-body system of Goldstone particles which are associated with the spontaneous breakdown of various symmetries in the brain.

The Genesis of the Eeg

EEG is derived from wave activity of nerve cells in the cerebral cortex. The elementary generators of the EEG are relatively small patches of the cell membrane, including several synapses and some passive membrane through which the synaptic current returns into the cell. However, there is still no definitive evidence as to the approximate size of such unitary generators and their relative distribution on the cell body and dendrites. An analysis of the relationships between the gross EEG and the wave activity of individual nerve cells is presented in the chapter. The analysis indicates that the gross activity is produced through summation of the synchronized activity of a comparatively small fraction of the cerebral neuronal population. Although the rest of the population also is active, their contributions are not synchronized and summate much less effectively, not reaching the limit of resolution of EEG recorders. Implications for computer analysis of EEG data are presented in the chapter.

Interrelation and dynamic activity of visceral muscle and nerve cells from insect embryos in long-term cultures.

AbstractMultiple segments of esophagus dissected out from 16‐day cockroach embryos were cultured in vitro in a chemically defined medium in the presence of dissociated nerve cells from the same donors. A first migratory wave of cells took place from the explants between the first and fourth week of culture. The morphological characteristics of these cells suggest that they originate from tracheolar cells. Between the second and fifth month of culture, a second migratory wave of a different cell type replaces the first wave of short‐living cells. These cells migrate out only after nerve fibers from the ingluvial ganglion have branched into the medium. They form long cellular ribbons and exhibit spontaneous contractility. The characteristics of the contractile cycles were examined at the inverted microscope, with Nomarski optics, and in time‐lapse cinematography. The cells were identified as myocytes and their origin traced to the longitudinal and circular muscle layer of the explants. The contratile cell ribbons establish firm contact with nerve fibers from the ingluvial ganglion, which in turn exhibit a vibratory motion identical to that of the cells. The most plausible interpretation is that nerve fibers are pushed and pulled by contractile myocytes. The results of these in vitro experiments show a strong affinity of myocytes for nerve fibers and bring to light a new aspect of the relationship between these cells and the visceral fibers which provide for their innervation.

Electrophysiological Equipment for Measuring the Activity of Single Olfactory Nerve Cells on the Antennae of Mosquitoes13

Electrophysiological Equipment for Measuring the Activity of Single Olfactory Nerve Cells on the Antennae of Mosquitoes13

Influence of lithium ions on the electrical activity of nerve cells of the leech

The influence of lithium ions on the electrical activity of the nerve cells of the leech,Hirudo medicinalis, was investigated by the method of microelectrode recording. It was discovered that the electrical activity of the giant nerve cells disappears rapidly in a solution with lithium ions. In such a solution, the membrane of these cells is depolarized by 5–7 mV; however, polarization of the cells with direct current does not lead to a restoration of their activity. Possible mechanisms of the inability of lithium ions to replace sodium ions in the generation of the action potentials of leech nerve cells are discussed.

Electrical activity of neurons in the cat cortex during cooling

Changes of the activity of cortical neurons were studied in the posterior crucial gyrus and in the middle parts of the suprasylvian and ectosylvian gyri on cooling the brain to 18°C and below. In exact experiments it was noted that cooling the cortex to 18.8–21.8° causes a complete cessation of neuron activity. The kinetics of the change of activity under these conditions follows a definite order: first an increase of the frequency of spike discharges is observed (31–27°), then a decrease of their amplitude (at 25–22°), and finally a complete disappearance of neuron activity (at 21.8–18.8°). Discontinuation of the cooling leads to restoration of the activity of the nerve cells in inverse order: low-amplitude high-frequency discharges manifest (at 23–26°), the amplitude of the spikes increases (at 29–31°) and then the initial activity is restored (at 31–32°). The decrease of neuron activity depends on the rate of temperature drop in the cortex. The faster the cortex is cooled, the lower is the temperature at which the neurons cease to function. And conversely, slow cooling of the cortex causes an inactivation of the spike potentials at a higher temperature.