[Basis for the use of enclosed 125I sources for interstitial radiation therapy].

Experimental models of closed sources of 125I low energy photon radiation in the titanium capsules sealed by means of pulsed laser welding were designed. Doses in the tissue equivalent medium from a single 125I point source were calculated using ES-1022 computer, tables for calculating dose fields in different layouts of sources were drawn, and layout parameters in preset doses calculated. Using the 125I source in interstitial irradiation of murine breast tumors one managed to establish the local nature of tissues corresponding to the calculated dose distribution for photon radiation with the energy of 27-35 keV.

[Experimental evaluation of Bengal rose labeled with 123I].

Experimental evaluation of Bengal rose labeled with short-lived 123I was performed. The best diagnostic feature in 123I-Bengal rose were shown during a scintigraphic study of the rabbit liver and biliferous tract conducted in simultaneous experiments with the use of the agent labeled with 131I and 99mTc-HIDA. These were a high quality of the image of the organs, a low radiation exposure and the absence of extrahepatic uptake of the agent, particularly under conditions of the ligament of the common bile duct.

[Plastic changes in responses of chemo- and electro-excitable membranes of a cortical neurons following orthodromal tetanization].

Orthodromic tetanization produces in the turtle visual cortex two types of reversible plastic changes of electrical responses: facilitation and depression. Posttetanic facilitation is attended with reversible enhancement of evoked postsynaptic potentials and APs; the excitability of the electroexcitable membrane increases: the critical level of depolarization of the evoked spike shifts in the negative direction and its threshold potential decreases. Posttetanic depression is accompanied by a reversible decrease of the amplitude of evoked postsynaptic and spike potentials; the excitability of the electroexcitable membrane decreases: the critical level of depolarization of the evoked spike shifts in the positive direction, and its threshold potential increases.

[Electrophysiologic analysis of the representation of the somatosensory system in the dogfish midbrain tectum].

Evoked responses in the dogfish tectum opticum were studied during electrical stimulation of the spinal cord, its dorsal roots and ramus ophthalmicus of the facial nerve. Recordings were obtained from different depth as well as from different points on the tectum surface. Evoked responses could be detected mainly on the contralateral side of the tectum opticum either as slow positive (spinal cord stimulation) or negative-positive (facial stimulation) waves which were preceeded by one or two fast, probably, presynaptic deflections and followed by a very slow low-amplitude negative wave.

[Changes in cortical neuron input resistance and the stimulation threshold of its electroexcitable membrane by a depolarizing current during the habituation process].

The habituation of neurones in the turtle visual cortex is accompanied by changes in their input resistance and in the threshold of stimulation of their electro-excitable membrane by depolarizing current. Input resistance of the neurone during monotoneous stimulation decreases throughout habituation and increases following an alien stimulus. The threshold becomes higher if the current acts as a monotoneous stimulus and gets lower if it acts as an alien stimulus.

[Mechanisms of habituation of the electroexcitable membranes of cortical neurons].

Habituation of the cortical neurone response is attended with change in the membrane excitability generating peak potentials. Excitability of spontaneous AP trigger zones increases non-specifically. This is due to a non-specific depolarization shift of the membrane potential during habituation.

[On--off impulse activity of carp retina amacrine cells].

Properties of spontaneous and light-evoked spikes of the "on--off" amacrine cells of the carp retina were studied. It was assumed that the dendrites of amacrine cells generated spike potentials and conducted them to the cell body. The data obtained suggest that the dendrites of amacrine cells have many spike-generation zones and that the transient depolarization component of the amacrine response to light is the compound spike consisting of many separate spikes generated in different parts of the dendritic arborization of cells.

[Rhythmic activity of central portions of the cat visual analyzer during different forms of behavior].

Synchronized EEG activity of visual cortex and some other parts of the brain was recorded in cats during milk licking. The frequency range, cortico-subcortical topography and some conditions of its appearance and blockade were analyzed. It was found, that this activity consisted of two rhythms with frequencies of 6--9 and 9--15 c/s and was strongly influenced by visual conditions.

Responses and properties of receptive fields of neurons in the visual projection zone of the pigeon hyperstriatum.

Unit responses in the hyperstriatal region of the pigeon forebrain to the action of various visual stimuli were investigated. Particular attention was paid to the discovery of retinotopic projection in the Wulst region. It was shown that as the electrode was advanced in the caudal direction in the zone of visual projection of the hyperstriatum the receptive fields of the neurons recorded shifted in the opposite direction in the visual field.

[Postsynaptic excitation and inhibition in neurons of the general cortex of turtles during presentation of moving stimuli].

Reactions to moving stimuli were studied in the turtle general cortex. The evoked potentials, synaptic nature of their components and mechanism of their generation were analysed. The evoked potentials was negative-positive.

[Postsynaptic mechanism of habituation of turtle cortical neurons to moving stimuli].

An investigation was made into the change in the amplitude of evoked potentials and intracellular slow potentials of the turtle general cortex units in response to a periodic movement of a monotonous stimulus, a black band, across the visual field. The recorded depression of responses possesses all the properties of habituation. The first presentations of the monotonous stimulus produce a generalized habituation, gradually replaced by a selective habituation to the monotonous stimulus, as the number of stimulations increases.

[Reactions and properties of the receptive fields of neurons in the visual projection zone of the pigeon hyperstriatum].

Impulse responses of neurons of the pigeon forebrain hyperstriatal part to stationary and moving visual stimuli were investigated. Particular attention was given to revealing a retinotopic projection in the region of visual representation in Wulst. It is shown that as the electrode moved gradually in the caudal direction in the region of visual projection of the hyperstriatum, the receptive fields of the neurons under observation displaced in the visual field in the opposite direction.

[Intracellular on--off responses of carp retina amacrine cells adapted to the dark].

Dependence of the amplitude and latency of on and off responses of amacrine cells in the isolated dark-adapted carp retina upon the light spot intensity and diameter was studied by intracellular recordings. It is shown that the responses of amacrine cells to onset and offset of light consist of trasient depolarizations with oscillatory potentials and impulses. The latency of the on response decreases and the latency of the off response increases when the light spot intensity and diameter are increased.

[Reactions of frog retinal rods to light].

The amplitude and shape of the rod photoresponses were investigated at different intensity, duration, wavelength and diameter of the light spot. Intracellular recordings were performed from the green and red rod outer sigments. An increase in the light intensity produced an increase in the amplitude and a decrease in the time rise of the response.