One-trial visual recognition in cats: the role of the rhinal cortex.

Memory for visual recognition in primates is at least partially mediated by the peripheral and entorhinal (i.e., rhinal) areas of the cerebral cortex. The roles of these structures in visual recognition in cats was studied by producing electrolytic combined lesions of the rhinal (perirhinal + entorhinal) areas in a group of cats trained in a modified Wisconsin test apparatus to delayed selection of an object on the basis of its image on presentation of a new object in every trial in the test. Control groups consisted of intact and sham-operated cats. Animals with rhinal lesions were no different from sham-operated and intact animals in the initial training to the rules for correct responding to the objects presented; they also showed no difference at the minimum delay period of 5 sec used in these experiments. However, a statistically significant difference was seen on testing with a delay of 10 sec, demonstrating impairment of intrinsic visual recognition memory.

[Spatial recognition in cats: effects of parahippocampal lesions].

To determine the contribution of the posterior parahippocampal region to spatial form of one-trial memory in cats, we trained 8 cats to remember the spatial positions of either two different trial-unique objects overlying two of three feeders in a feeder test tray (object-place trials) or simply two of the three feeders (place trials). Four cats then received electrolytic lesions restricted to the posterior parahippocampal region (experimental group) including mainly parahippocampal cortex, parasubiculum and presubiculum. Four other cats comprised sham-operated control group. This group was found to be completely unaffected postoperatively in both types of trials, whereas experimental group showed impaired performance in both types of trials equally. Thus, one-trial memory for object-place association and one-trial memory for two different places in cats appear to be critically dependent on the posterior parahippocampal region.

[One-trial visual recognition in cats: the role of the rhinal cortex].

Visual recognition memory in primates is mediated at least in part by the perirhinal and entorhinal (i.e., rhinal) cortices. To examine the role of these structures in cats' visual recognition memory, we performed combined electrolytic rhinal (perirhinal and entorhinal) lesions in a group of cats trained in visual delayed matching-to-sample with trial-unique objects in the modified Wisconsin General Testing Apparatus. Sham-operated and intact cats were used as control groups. Cats with rhinal lesions did not differ from the control sham-operated and unoperated groups in initial learning of the rules of the task; difference between experimental and control groups under conditions of minimum 5-sec delay was nonsignificant as well. However, significant difference between experimental and control groups was revealed under conditions of testing with 10-sec delay. This finding suggests a disorder in the visual recognition memory.

Prolonged negative surface potentials of the cat sensomotor cortex and responses of neurons and glial cells.

Evoked potentials to stimulation of the ventrolateral and intralaminar thalamic nuclei, the surface of the sensomotor cortex, and the pyramidal pathways, derived from the same point, and also corresponding postsynaptic responses of pyramidal neurons were studied in acute experiments on cats anesthetized with ether or superficially with pentobarbital (25-30 mg/kg, intraperitoneally), and immobilized with muscle relaxants. Surface application of strychnine inhibits the slow negative potential arising in response to direct and primary responses, and the corresponding slow potentials of the IPSP. The action of iontophoretic application of strychnine on IPSP of pyramidal neurons and responses of cortical glial cells also were studied. Both methods of application of strychnine block mainly the early component of the IPSP, during which the input resistance is significantly lower than that during the late component, evidence of their different genesis. The results of the investigation show that slow negative potentials are a reflection of hyperpolarization of pyramidal neurons, and that the separate components of the responses have a common genesis.

[Interaction of reticular structures in the brain of the cat]. / O vzaimodeistvii retikuliarnykh struktur golovnogo mozga koshek.

In acute and chronic experiments on 35 cats an inhibitory influence was found of the caudal reticular nucleus of pons Varolii on unit activity of the sensorimotor cortex and dorsal part of the midbrain reticular formation. The influence of this structure on unit activity of the ventral part of the midbrain reticular formation was mainly of a facilitatory character. Activation of the ventral part inhibited the unit activity of the dorsal part of the same structure. Consequently, the caudal reticular nucleus of pons Varolii elicits inhibition at the level not only of the cerebral cortex but also of the midbrain reticular formation (of its dorsal part). The character of these influences coincides with that of unit activity changes of these two areas of the midbrain reticular formation during the development of the paradoxical phase of sleep. The obtained facts must underlie the stopping of convulsive activity in this phase of sleep.

[Hypothalamic epileptogenesis]. / K épileptogenezu v gipotalamuse.

In cats the hypothalamus proved capable of the primary epileptogenesis. It suggests the principal feasibility of diencephalic (hypothalamic) epilepsy.

[Several electrophysiologic variants of temporal lobe epilepsy]. / O nekotorykh élektrofiziologicheskikh variantakh visochnoi épilepsii

The study discusses the diagnostic value of some electrophysiological methods of investigating patients with temporal lobe epilepsy. It is emphasized that routine EEG, basal and tympanic leads are not informative enough. Special attention is paid to the study of stereoelectroencephalographic activity of deep epileptic foci and "secondary" synchronization phenomena. It is suggested that SEEG is a necessary component of preoperative study. It is also pointed out that a bitemporal pathological activity should not be considered a contraindication to a surgical treatment of epilepsy.

[Concentration of phenobarbital in biological fluids during the treatment of epilepsy patients]. / O kontsentratsii fenobarbitala v biologicheskikh zhidkostiakh pri lechenii bol'nykh épilepsiei.

Using gas liquid chromatography, the authors studied phenobarbital levels in the blood and cerebrospinal fluid of 41 epileptic patients following the administration of this anticonvulsant alone. The data obtained showed variations in the concentration of blood phenobarbital at various time intervals after the intake of the drug and a certain correlation between its level and the therapeutic effect. The ratio of phenobarbital level in the cerebrospinal fluid to that in the blood indicates that phenobarbital penetrates the blood-brain barrier. Fluctuations in the blood phenobarbital content from one administration to another is important for selecting its optimal dosage and the interval between intakes.

[Metabolism of an antiepileptic drug halonal in experimental studies]. / Metabolizm protivoépilepticheskogo preparata galonala v éksperimente.

A study was made of metabolism of the new antiepileptic drug halonal in guinea-pigs. It was established that on oral administration halonal was not absorbed from the intestinal tract and only its metabolite, phenobarbital, was detectable in blood serum. It is assumed that halonal produces a therapeutic action only thanks to phenobarbital, its pharmacologically active metabolite.

[Role of the pharmacokinetic parameters of carbamazepine in optimizing epilepsy treatment]. / Rol' nekotorykh farmakokineticheskikh parametrov karbamazepina v optimizatsii antiépilepticheskogo lecheniia.

In 14 epileptic patients the authors determined concentrations of carbamazepine, its total and relative clearance, the period of half-elimination and the elimination constant. Blood levels of carbamazepine were assayed by gas liquid chromatography. The pharmacokinetic parameters have been found to be important for specifying the causes of dissociation between the level of blood anticonvulsant and the therapeutic effect when the attacks cannot be controlled or there were signs of intoxication. The mean diagrams of fluctuations of blood concentrations of the drug in the interval between single doses indicate the dependence of the clinical effect on the amplitude of fluctuations and create the prerequisites for the optimization of anticonvulsive therapy.

[Pharmacokinetic aspects of anticonvulsant therapy with benzonal]. / Nekotorye farmakokineticheskie aspekty protivosudorozhnoi terapii benzonalom.

Major pharmacokinetic parameters of the Soviet anticonvulsive drug benzobarbital used with different regimens of administration (single and prolonged) are described. The authors have studied the interrelationship between benzobarbital and carbamazepine when these drugs are used in combination and drawn a conclusion as to their weak pharmacokinetic synergism. On the basis of the established pharmacokinetic parameters a number of practical inferences pertaining to the mode of benzobarbital administration have been made.

[Metabolism of the anticonvulsant preparation Benzonal in the human body]. / O metabolizme protivosudorozhnogo preparata benzonala v organizme cheloveka.

One of the metabolites of the anticonvulsant drug Benzonal (BZL) has been isolated and its chemical structure studied. High-performance liquid chromatography (HPLC) was utilized for isolation of the metabolite from the blood plasma in patients after a single oral BZL dose of 100 mg. Using this technique and ultraviolet, infrared and mass spectrometries BZL was found to be partially metabolized into phenobarbital by human organism.

[Influence of the brain stem reticular formation on seizure activity in the cerebral cortex]. / Vliianie retikuliarnoi formatsii stvola golovnogo mozga na sudorozhnuiu aktivnost' kory bol'shikh polusharii.

Activation of the mesencephalic RF facilitates triggering of paroxysmal potentials and augments existing epileptic activity. Stimulation of nucleus reticularis pontis caudalis inhibits triggering of epileptic discharges. The microelectrode studies corroborated these data. The desynchronization elicited by the mesencephalic RF seems to be mostly activating, whereas desynchronization elicited by the nucleus reticularis pontis caudalis--mostly inhibitory.

[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.