[THE INFLUENCE OF LOCUS COERULEUS ON DIFFERENT ACTIVITIES OF THE THALAMO-CORTICAL SYSTEMS].

As revealed from our experiments, in facilitation of passage of the thalamo-cortical visual signals a key role is attributed to variability of activity of visual neurons in reticular nucleus of the thalamus. It was demonstrated that a facilitatory action of locus coeruleus gets augmented following functional exclusion of the thalamic reticular nucleus. Nevertheless, stimulation of locus coeruleus stipulated facilitation of neuronal activity in the anterior part of thalamic reticular nucleus. Emerging from this data one may assume that in the inhibition of evoked responses from a sensorimotor area of the neocortex in response to stimulation of locus coeruleus a certain role is played by reticular nucleus of the thalamus. Namely, augmentation of neurons activity in the anterior part of the thalamic reticular nucleus must condition inhibition of neuronal activity in the ventral nuclei. In spite of the stated, it is not excluded locus coeruleus ha-ving an immediate, direct inhibitory action on the neuron activity within the sensorimotor cortex and thalamic ventral nucleus.

INTERACTION BETWEEN THE THALAMIC NUCLEUS AND PREOPTIC AREA NEURONS.

The thalamic reticular nucleus which is known to delineate the dorsal thalamus stipulates development of inhibitory processes in the thalamo-cortical neurons that is necessary for generating slow (8-12 Hz), high-amplitude electric activity in this system. It was demonstrated that majority of preoptic area neurons get activated during slow-wave sleep. Activation of neurons in the anterior hypothalamus and preoptic area during slow-wave sleep and synchronization of the brain electric activity was demonstrated. The study was aimed at clarifying the relationship between the thalamic reticular nucleus and the preoptic area neurons. Under acute conditions experiments were carried out on mature cats. It was shown that blockade of preoptic area neuron activity during mesencephalic reticular formation stimulation and the fact that on the background of mesencephalic reticular formation stimulation thalamic reticular nucleus stimulation elicited preoptic area neurons activation must be in part stipulated by the fact that thalamic reticular nucleus activation leads to suppression of mesencephalic reticular formation neuron activity.

NEOCORTICAL IMPACT ON THE AUDIOGENIC SEIZURE ACTIVITY DEVELOPMENT.

Out of genetically determined epilepsy models a special interest draws the model of audiogenic seizures, which does not require whatever additional intervention (e.g. pharmacological or/and electric stimulation), because epileptic responses are elicited by specific sensory stimulation only. Notwithstanding the fact that different formations of the central nervous system are recruited in audiogenic seizure reactions, critical importance for the manifestation of this type epilepsy is attributed to the inferior colliculus and brainstem reticular nuclei. Significance of the diencephalic structures and the thalamic reticular nucleus, in particular for development and/or modulation of audiogenic seizures is ambiguous. Total of eight Krushinsky- Molodkina (KM) strain rats, weighting 250-300 g, served as the subjects of chronic experiments. The neocortex was bilaterally activated by way of administration of 1 µl strychnine (0.1% solutipon) with a microsyringe through a metal capillary prefixed on the cortical surface. Metal electrodes for recording electrical activity were implanted into the neocortex and brainstem reticular formation. Experiments have shown that against strychnine discharges in the neocortex there occurred an increase in the latency of wild runs and the pause between the first and second wild runs in response to a sound stimulus. Proceeding from the above-said, it can be assumed that activation of the neocortex must stipulate intensification of the thalamic reticular nucleus neuronal activity that, in turn, should have a modulating effect on the audiogenically induced seizure reactions.

UNUSUAL MANIFESTATION OF NEUROBORELIOSIS (CASE REPORT).

The paper reported the verified case of neuroboreliosis with unusual clinical presentation of Parkinsonism. Study aimed at establishing the significance of a precise differential diagnosis with substantial analysis of the symptoms of several diseases to avoid the false diagnosis and to conduct the opportune and adequate therapeutic management. We described the case of the diagnosed neuroboreliosis with clinical expression of Multiple Sclerosis (MS) and Parkinsonism. A 44 years old man was diagnosed as MS according to the McDonald's Criteria, who within two years developed typical clinical signs of Parkinsonism. Patient investigated neurologically, Brain contrast MRI (1.5 Tesla) was performed; Cerebrospinal fluid was researched for oligoclonal bands. Blood IgM and IgG were researched against Chlamidia pneumonie, Micoplasma pneumonie, Borrelia Burgdorferi, Herpes simplex 1/2, Cytomegalovirus by ELISA method. Clinically the patient expressed amimic face, oligobradikinesia, extrapiramidal rigidity in all limbs, resting tremor in upper limb fingers, horizontal nystagmus. Brain MRI showed multiple gadolinium enhanced demyelization lesions in periventricular and sub-cortical white matter. CSF oligoclonal bands were positive without dysfunction of blood-brain barrier. Blood IgM, IgG detected to be negative against Chlamidia pneumonie, Micoplasma pneumonie, cytomegalovirus, Herpes simplex ½, while the blood IgG was strongly positive against Borrelia burgdorferi, confirmed by followed Western blot test. Patient was stabilized by puls-therapy with 1 gr/intravenous Solumedrol (5 days) along with Rocephin treatment (2 gr /iv) for 21 days followed by long term treatment with Antiparkin (Carbidopa 250 mg, Levodopa 25 mg). MS and even Parkinsonism in suspicious cases should thoroughly be investigated for differentiation from chronic Neuroboreliosis.

[DIAGNOSTIC VARIATIONS OF X-LINKED MUSCULAR DYSTROPHY WITH CONTRACTURES].

Case report with review describes X-linked muscular dystrophy with contractures in 28 years old man and his cousin. The disease revealed itself in an early stage (age 5-10), the process was progressing with apparent tendons retraction and contraction, limited movement in the areas of the neck and back of spine, atrophy of shoulder and pelvic yard and back muscles. Intellect was intact. Cardyomyopathy was exhibited. CK was normal. EMG showed classic myopathic features. Muscle biopsy showed different caliber groups of muscle fibers, growth of endo-perimesial connective tissue. Clinical manifestations together with electrophysiological and histological data suggest consistency with Rotthauwe-Mortier-Bayer X-linked muscular dystrophy.

[The impact of pregnancy and postnatal period on the development of generalized convulsive activity in experiment].

Interrelation between pregnancy and epilepsy is one of the pressing problems of current neurology. Those mechanisms, which suppress or amplify the seizure reactions in pregnancy, have not been yet determined experimentally. The goal of present work was investigation of impact of gestation and the postpartum period on initiation and development of convulsive reactions in the experimental animal model. Epileptic reactions were significantly suppressed during gestation (2 and 3 weeks). The data showed changes in behavioral reactions and EEG seizure activity. In the period of gestation the development of audiogenic kindling in response to repetitive acoustic stimulation is markedly reduced. This indicates the strengthening of inhibitory processes in the brain. It is supposed that in the period of gestation in rats with genetically determined audiogenic seizures excess of sexual hormones and enhancement of GABA-ergic transmission causes marked reduction of development of audiogenic kindling.

Influence of carbamazepine on kindling grades in depressive and non-depressive rats.

It has been clinically established that epilepsy and depression frequently represent a comorbid pair. Most of investigators consider that epilepsy is a cause of emotional disorders such as anxiety and depression. On the other hand, some anti-epileptic drugs were found to aggravate depressive state, even to a suicide outcome. Bearing in mind these findings, we endeavored an experimental study in the laboratory rats, 25% of which display an inborn depressive behavior. An anti-epileptic drug to be tested was carbamazepine, while epileptic state was elicited by means of the kindling method. Selection of animals was made with the Porsolt's forced swimming test. Seven rats possessed clear depression-like traits; similar number of the non-depressive animals served as controls. Along with the inherently depressive rats, the third group of animals was used, in which depression was elicited with the immobilization stress procedure (exogenous depression). Epileptization of the rats was performed with sub-threshold electrical stimulation of the ventral hippocampus. The rapid kindling paradigm has been implemented in these experiments (40 stimulations in one day). Following development of epileptic state up to the grades 4-5 according to the Racine scale, the animals were intraperitoneally administered carbamazepine, once a day, for three consecutive days. On the fourth day the animals were tested again in order to assess their epileptic state; after this procedure, depressiveness of the animals was reevaluated. It was found that: a) the fastest and most vigorous kindling developed in the endogenously depressive rats; b) carbamazepine almost completely abolished the highest grades of convulsions; and c) kindling procedure did not alter initial emotional status of the animals and carbamazepine administration also did not change their behavior. The latter observation allows concluding that in our model depression and epilepsy interact insignificantly.

Noradrenergic modulation of seizure activity.

The mechanisms underlying pathogenesis of epileptic rections have been studied insufficiently as yet. Therefore, it is considered that determining the structures, transmitters, and receptors of the brain, which putatively produce development and intensity modulation of the convulsions, is highly important. The locus coeruleus is a norepinephrinic structure and an endogenous modulator of epilepsy, determining a role of which in a course of seizure reactions is an important problem of epileptology. The goal of the study was assessment of importance of the norepinephrine synapses in development of the local hippocampal seizure activity. The studies were carried out in adult rats, in conditions of chronic experiments. Influences of microinjections of agonist (clonidine) and antagonist (yohimbine) of the alpha-2 norepinephrine receptors on a course of local hippocampal seizure reactions (without behavioral manifestation), have been evaluated. It was found that microinjection of alpha-2 norepinephrine receptors' agonist determined a blockage of the local hippocampal seizures, while alpha-2 norepinephrine receptors' antagonist increased the seizures' power. It is suggested that the effects of locus coeruleus are determined by activation of the alpha-2 norepinephrine receptors.

[Influence of solitary tract nucleus stimulation on activity of thalamic reticular nucleus and mesencephalic reticular formation of the brain].

Elucidation of interrelations between the brainstem (BSN) and diencephalic structures of the brain is an important problem of neurophysiology, solution of which might allow revealing mechanisms of the workings of certain structures of the brain, on the one hand, and an overall activity of the central nervous system, on the other. The goal of present investigation was examination of the mechanism of interrelations between the mesencephalic reticular formation (MRF), solitary tract nucleus (STN), and the thalamic reticular nucleus (TRN). Activity of the TRN and MRF neurons was recorded with the tungsten microelectrodes, with tip diameter of 4-8 microm and a resistance of 4-15 MOhm. In some experiments a simultaneous (coupled) recording of the TRN and MRF neurons was made with an aid of two separate microelectrodes. Our experiments have shown that threshold stimulation of the MRF exerted an inhibitory influence on activity of the TRN neurons, while supra-threshold stimulation induced their activation. Stimulation of the STN induced inhibition of the MRF neurons and activation of the TRN. Meanwhile, during activation of the TRN neurons, in the MRF neurons inhibitory postsynaptic potentials did occur. Whatever mechanisms may underlie inhibition of the TRN neurons in response to the STN stimulation, it seems an important fact that synchronizing structure of the brainstem, which exerted a blocking impact on the MRF, facilitated activity of the TNR neurons. This is even more important because for revealing the neurophysiologic mechanisms of activity of the whole central nervous system in both norm and disorder.

Influence of hypothalamic stimulation on the development of status epilepticus in rats.

The main objectives of the present study were to explore whether emotional behavior, elicited by stimulation of the dorso-medial hypothalamus, can influence seizure development during self-sustained status epilepticus (SSSE). The study was conducted on animal models. The results suggest that increased inhibition in the hippocampal neurons during dorsomedial hypothalamic stimulation may trigger the mechanisms preventing the epileptiform activity and that hippocampal theta rhythm is a physiological state, which opposes its involvement into seizures. It was concluded that activation of the dorsomedial hypothalamus, as well as emotional behavior (anxiety/fear) retard development of the seizures experimentally induced SSSE by limbic stimulation.

Interictal emotional state and epilepsy.

The main objectives of the present study were twofold: to explore whether emotional behavior, elicited by stimulation of the hypothalamus, can influence seizure development during kindling epileptogenesis; to determine whether such stimulation can alter the expression of generalized convulsions when the fully epileptic syndrome has been established beforehand.The kindling process has been used as an animal model for studies of epilepsy. The findings indicate that stimulation in the hypothalamus, which determines fear, anxiety, and escape responses, with concomitant hippocampal theta, can significantly dampen the course of epileptogenesis. The emotional behaviors elicited by stimulation of the dorsomedial hypothalamus can suppress the development of generalized motor limbic convulsions during epileptogenesis, as well as dampen seizure expression in already established limbic epilepsy. It is assumed that the emotional disturbances can be considered as the emergence of instinctive behavior with an adaptive significance of defense and as a by-product of the inhibitory processes that build up to protect the occurrence of future seizures.

[Effect of stimulation of the thalamic reticular nucleus on spino-bulbo-spinal reflex activity]. / Vliianie stimuliatsii retikuliarnogo iadra talamusa na spino-bul'bo-spinal'nuiu reflektornuiu aktivnost'.

The effect of the thalamic reticular nucleus (RN) stimulation on the spino-bulbo-spinal reflex was studied in chloralose-anesthetized cats. RN stimulation was found to exert an inhibitory influence on this reflex. The same stimulation has also exerted an inhibitory influence on the spinal units activated during the spino-bulbo-spinal reflexes.

[The effect of adrenaline and adrenal desympathization on cerebral convulsive activity]. / Vliianie adrenalina i desimpatizatsii nadpochechnikov na sudorozhnuiu aktivnost' golovnogo mozga

The influence of adrenalin and bilateral adrenal desympathization on the seizure activity of the brain caused by dorsal hippocampal electric stimulation was studied in adult cats. It is shown that within some days of adrenal bilateral desympathization the threshold of hippocampal epileptogenic stimulation fells and the duration of the seizure action grows. Intravenous injection of adrenalin causes an increase in the effectiveness of the hippocampal epileptogenic stimulation. Injection of small doses of adrenalin into the mesencephalic reticular formation causes suppression of the evoked seizure activity: the threshold of hippocampal epileptogenic stimulation increases and duration of seizure discharges reduces. It is assumed that one of the main factors limiting the seizure activity of the brain is the enrichment of the circulating blood with adrenalin.