[Effective methods for shaping the recording tips of carbon microelectrodes].
Explore the source record for details and available documents.
Carbon↗
Biomedical subjects
N P Khusainovene
Publications and source records attributed to N P Khusainovene.
[The effect of cadmium ions on synaptic transmission in the tectum of the frog].
The effect of cadmium ions on the synaptic transmission in the frog tectum was analyzed in acute experiments by the method of recording of the quantum of EEG (the extracellular monosynaptic potential of synapses of a single axon) [1]. It was shown that perfusion of the tectum with CdCl2 in the concentration of 10-200 mumol/l reversibly inhibited the quanta of EEG, decreased their duration and increased the synaptic delay. Consequently, cadmium in industrial waste may be dangerous regarding the harm to the CNS, too. The results of the presented work correspond to the supposition based on experiments in vitro that presynaptic potential-dependent calcium channels prove to be one of the areas of synaptic action of Cd++ ions.
Action Potentials↗
[Paired facilitation of the summated extracellular synaptic potentials of individual retino-tectal fibers in the frog].
The paired-pulse facilitation of the EEG quanta (the extracellular monosynaptic PSPS of all synapses of one axon) was examined in layer F of the frog tectum at normal and at increased concentrations of external Ca or Mg ions. The maximum values of facilitation were observed with intervals between stimuli of about 5 ms. Under normal conditions the amount of maximal facilitation was different for separate EEG quanta and varied from 1.4 to 2.4. Distribution of the EEG quanta by the amount of maximal facilitation had two modes at the values fmax = 1.65 and 1.95. The time course of facilitation could be approximated by two exponential components with the time constants of decays tau 1 = 5-6 ms and tau 2 = 140-150 ms for more facilitated EEG quanta, and tau 1 = 6-8 ms and tau 2 = 60-70 ms for the others. Nonequal degree of facilitation of separate EEG quanta and experiments with increased external Ca2+ and Mg2+ concentrations have suggested the dependence of paired-pulse facilitation on the quantum content of the transmitter released in retinotectal synapses. Two types of terminal arbors of axons whose synapses differ in quantum content are supposed to exist in the tectum layer F.
Animals↗
[2-channel carbon-fiber microelectrode].
Explore the source record for details and available documents.
Carbon↗
[Mass extracellular monosynaptic potential of synapses of a single axon in the optic thalamus of frogs upon electric stimulation of the retina].
Mass extracellular monosynaptic PSP of one axon synapses ("EEG quantum") were reliable recorded in the frog thalamus as "all-or-none" potentials up to 250 muV at threshold electrical stimulation of the retina. The degree of facilitation of the second response was measured during paired-pulse stimulation. The ratio of the testing PSP amplitude to the conditioning one dependent on the signal amplitude. The ratio reached 250% at interstimulus interval of 5 ms with amplitude of conditioning PSP being about 50 muV.
Animals↗
[Properties of extracellular monosynaptic potential of a single afferent in the light of the theory of dendrites with N-shaped volt-ampere characteristics].
In the frog tectum mass extracellular monosynaptic PSP of the set of synapses of one individual afferent--the quantum of EEG--was registered. Using the electrical threshold stimulation of the retina we noticed a large pair facilitation. The radial decline of the facilitated quantum of EEG was measured in order to check the conclusions of the dendritic theory which postulates the N-shaped current-voltage characteristic of the membrane. Therefore, we synchronously derived conditional and test quanta of EEG in the centre and 40-60 microns peripherally of terminal axonal arborization. In a half of the experiments the test quantum of EEG twice as large as the conditional one radially declined 25% less. The half-width and rise-time of the test quantum of EEG were longer as compared with the conditional one, especially in the peripheric derivation, the difference being about 1 ms. The totality of our results agrees with the concept of electrically excitable inward current in non-synaptic membrane of the apical dendrites in the tectum. The current is predicted by the theory of the N-shaped current-voltage characteristic of dendrites.
Action Potentials↗