[The differentiation of locus coeruleus neurons after their allotransplantation into the preliminarily denervated hippocampus of white rats]. / Differentsirovka neironov golubovatogo mesta posle ikh allotransplantatsii v predvaritel'no denervirovannyi gippokamp belykh krys.

The suspension of embryonic locus coeruleus (LC) was transplanted into outbred albino rat hippocampus after its preliminary 6-hydroxy-dopamine-induced denervation. Immunohistochemical and morphometric analysis revealed that 3 months after the transplantation, embryonic noradrenergic LC cells which have completed their histogenesis in recipient hippocampus, appear as differentiated multipolar and fusiform cells, typical to LC. Intrahippocampal allotransplants of rat embryonic LC were also demonstrated to normalize the level of orientation activity in an open area, that was significantly reduced after administration of 6-hydroxy-dopamine to the animals.

[Effect of artificial polarization of the membrane on IPSP of neurons in the cat sensorimotor cortex]. / Vliianie iskusstvennoi poliarizatsii membrany na TSPS neironov sensomotornoi kory koshki.

Inversion of the early component of IPSPs in neurons of the sensorimotor cortex by artificial hyperpolarization of the membrane was demonstrated in cats immobilized by myorelaxants in acute experiments. The late component of IPSP was not inverted. Amplitudes of the early component of IPSPs were decreased by the membrane depolarization while the late component was completely reduced. The input resistance of the membrane which decreased during the early component of IPSPs was restored to the initial level during the late component.

[Participation of calcium-dependent potassium conductance in the processes of membrane hyperpolarization of the pyramidal neurons in the sensorimotor cortex in the cat]. / Uchastie kal'tsiizavisimoi kalievoi provodimosti v protsessakh giperpoliarizatsii membran piramidnykh neironov sensomotornoi kory koshki.

In acute experiments on immobilized cats intracellular injection of Ca+ decreased of IPSP and postburst hyperpolarization amplitudes in pyramidal neurons of the sensorimotor cortex. Intracellular injection of ethylene glycol tetraacetic acid had almost the same effect. This substance also reduced the late part of spike afterhyperpolarization, while the early part remained practically unchanged. It is concluded that Ca2+-dependent K+-conductance might play an important role in the genesis of IPSP, postburst and spike afterhyperpolarization in the membrane of pyramidal neurons of the cat sensorimotor cortex.

[Postsynaptic reactions of neurons of the sensomotor cortex of the cat during evoked and self-sustained rhythmic activity of the "peak-wave" type]. / Postsinapticheskie reaktsii neironov sensomotornoi kory koshki vo vremia vyzvannoi i samopodderzhivaiushcheisia ritmicheskoi aktivnosti tipa "pik-volna".

Intracellular correlates of evoked rhythmic cortical "spike-and-wave" potentials produced in sensorimotor cortex during 3/s stimulation of the thalamic relay nucleus (VPL) and of self-sustained "spike-and-wave" afterdischarges following 8-14/s stimulation of the same nucleus were studied in acute experiments on cats immobilized by myorelaxants. Intracellular recordings of pyramidal tract neurons revealed that different components of evoked "spike-and-wave" potentials, i. e. the spike-like negative wave and the long lasting negative wave, are postsynaptic in origin: the first is due to EPSPs with spike discharges, and the latter--to IPSPs of cortical neurons. Components of "spike-and-wave" afterdischarge mostly reflect the paroxysmal depolarizing shifts of the membrane potential of cortical neurons. After cessation of sustained "spike-and-wave" activity the long-lasting hyperpolarization accompanied by inhibition of spike discharges and subsequent recovery was observed in cortical neurons. It is presumed that the negative wave of the evoked "spike-and-wave" potential as well as slow negative potentials of direct cortical and primary responses reflect IPSPs of deeper parts of pyramidal tract neurons, while the waves of the sustained "spike-and-wave" afterdischarges are due to paroxysmal depolarizing shifts in cortical neurons.

[Self-sustaining rhythmic activity of the "peak-wave" type and responses of neuronal and glial cells of the sensomotor cortex of the cat]. / Samopodderzhivaiushchaiasia ritmicheskaia aktivnost' tipa "pik-volna" i reaktsii nervnykh i glial'nykh kletok sensomotornoi kory koshki.

In acute unanesthetized immobilized cats a sequence of fast hyperpolarization and long-lasting depolarization was found in pyramidal tract neurons of the sensorimotor cortex during tetanic stimulation (8-14/s for 10 s) of the ventro-postero-lateral nucleus of the thalamus. During long-lasting depolarization after cessation of stimulation self-sustained rhythmic paroxysmal depolarizing membrane potential shifts appeared which were terminated by long-lasting hyperpolarization. In glial cells only depolarization was observed during stimulation as well as during self-sustained "spike-and-wave" rhythmic activity. Hyperpolarization in glial cells appeared only after its termination in neurons. It is suggested that the long-lasting changes in the membrane potential of cortical elements may play a particular role in formation and cessation of "spike-and-wave" rhythmical activity.

[Dendritic action potentials of pyramidal neurons of the sensomotor cortex of the cerebral cortex of the cat]. / Dendritnye potentsialy deistviia piramidnykh neironov sensomotornoi kory bol'shikh polusharii koshki.

The intracellular activity of pyramidal tract neurons during electrical stimulation of ventro-lateral and ventro-postero-lateral nuclei of thalamus was studied in acute experiments on cats immobilized by myorelaxants. Both somatic and presumably dendritic spikes (d-spikes) were observed. The latter were characterized by relatively low and variable (5-60 mV) amplitude; d-spikes occurred both spontaneously and in response to single shock and tetanic (8-14/s) stimulation of the thalamus. They were also induced by intracellular depolarizing current pulses and thalamic stimulation following iontophoretic application of strychnine. Simultaneously generated somatic and d-spikes revealed no collision between each other. Intracellular hyperpolarizing current pulses abolished only somatic spikes, while d-spikes were not affected. Dendritic origin with multiple generation zones of these variable spikes is suggested. Possible functional role of d-spike is discussed.

[Effect of intracellular injections of chloride ion on the inhibitory postsynaptic potential and post-burst hyperpolarization of sensomotor cortex neurons in the cat]. / Vliianie vnutrikletochnoi in"ektsii ionov khlora na tormoziashchii postsinapticheskii potentsial i postzalpovuiu giperpoliarizatsiiu neironov sensomotornoi kory koshki.

Inversion of the early component of IPSPs in pyramidal neurons of the sensorimotor cortex by intracellular injection of chloride ions was demonstrated in cats immobilized by myorelaxants in acute experiments under moderate composed anesthesia (40 mg/kg nembutal and 20 mg/kg chloralose intraperitoneally). The late component of IPSPs as well as the post-burst hyperpolarization in pyramidal neurons were not inverted. It is concluded that during the early component of IPSPs of both pyramidal and nonpyramidal neurons the membrane permeability is increased for chloride ions, while both the late component of IPSPs and the post-burst hyperpolarization in pyramidal neurons are less dependent on the chloride permeability.

[Prolonged negative potentials of the surface of the sensomotor cortex of the cat and responses of neural and glial cells]. / Dlitel'nye otritsatel'nye potentsialy poverkhnosti sensomotornoi kory koshki i reaktsii nervnykh i glial'nykh kletok.

In acute experiments on immobilized cats, potentials evoked by stimulation of the ventrolateral and intralaminar thalamic nuclei, of the surface of the sensorimotor cortex and pyramidal pathways as well as the corresponding postsynaptic responses of pyramidal neurons, were studied. A negative shift of potential in response to tetanic stimulation of the cortical surface or thalamic nucleus occurred on the cortical surface. Concominantly, intracellular recording of the glial-cell activity was performed. Superficial application of strychnine induced the suppression of the slow-negative potential arising during direct cortical and primary responses and the corresponding slow potentials of IPSP. The effects of iontophoretic application of strychnine on IPSP of pyramidal neurons and cortical glial-cell response were also studied. Both ways of application appeared to block mainly the early component of IPSP during which the input resistance was significantly lesser than that of the late component, pointing to the difference in their genesis. The findings indicate that slow-negative potentials reflect hyperpolarization of pyramidal neurons, while the separate components of responses have common genesis.

[Effect of strychnine on evoked potentials and postsynaptic responses of sensomotor cortex neurons in the cat]. / Deistvie strikhnina na vyzvannye potentsialy i postsinapticheskie reaktsii neironov sensomotornoi kory koshki.

In acute experiments on cats under light nembutal anaesthesia, immobilized by myorelaxants, superficial application of strychnine was shown to suppress the slow negative potentials (arising during direct and primary cortical responses) and IPSPs of the pyramidal neurons corresponding to the slow negative potentials. Iontophoretic application of strychnine blocks predominantly the early component of IPSP during which the input resistance is significantly less than that of the late component indicating their different genesis. It is concluded that individual components of evoked potentials have a common genesis, the slow negative potential is the reflection of the IPSP of pyramidal neurons whose early component seems to be generated by axo-somatic synapses while the late one by axo-dendritic inhibitory synapses. Neurotransmitters in these inhibitory synapses may be different.