Reduction of the postexcitatory cortical inhibition upon paired-click auditory stimulation in patients with Parkinson's disease.

Objectives: The aims of this study were: to investigate the postexcitatory inhibition of cortical evoked potentials on auditory paired-click stimulation in patients with Parkinson's disease (PD), to analyze the correlation of N1-P2 amplitude ratios (A2/A1) with latency of the P300 auditory event-related potential and to determine the influence of Levodopa intake on postexcitatory inhibition and P300 latency.

Methods: The central (Cz) auditory evoked potentials were recorded in 61 patients with PD and 21 age-matched healthy subjects.

Results: Postexcitatory inhibition in auditory cortex in PD was significantly reduced for interstimulus intervals 500, 700 and 900ms compared to control group.

Two phases of the contingent negative variation in humans: association with motor and mental functions.

The question of the relationship between contingent negative variation and the mechanisms controlling motor and mental functions has received inadequate study. The aims of the present work were to investigate the relationship between the early and late phases of contingent negative variation and the state of motor and mental functions in patients with Parkinson's disease and to study the effects of levodopa on contingent negative variation. Patients with Parkinson's disease showed significant decreases in the amplitudes and areas of both phases of contingent negative variation as compared with subjects of similar age.

[Two phases of the contingent negative variation in humans: connection with motor and mental functions].

The question of dependence of the contingent negative variation (CNV) on the regulating mechanisms of motor and mental functions is not sufficiently studied. The tasks of the present work were: to investigate the dependence of the CNV early and late phases on the state of motor and mental functions in patients with Parkinson's disease (PD), and to elucidate the levodopa influence on the CNV parameters. 18 healthy subjects and 56 patients with PD were studied.

[Effect of cerebrolysin on the electroencephalographic indices of brain activity in Parkinson's disease].

Cerebrolysin is a brain-derived peptide drug that increases the BBB-GLUT1 and MAP2 genes expression, thus exerting a neuroprotective effect. The present study aimed at investigating in patients with Parkinson's disease (PD) influence of Cerebrolysin infusions (intravenously, 10 ml during 10 days) combined with levodopa treatment on the electroencephalographic (EEG) indices of brain activity: P300 potential, contingent negative variation (CNV) and recovery functions of the cortical auditory evoked potentials, which reflect the postexcitatory inhibition at the paired stimulation. Nineteen PD patients, mean age 61.

Effect of stimulation of beta-adrenergic receptors on neuronal activity in primary motor cortex of the rat.

Modulatory influence of beta1- and beta2-subtypes of adrenergic receptors (ARs) on the background neuronal activity and cerebellocortical transmission was characterized in the rat primary motor cortex (M1). Microiontophoretic administration of non-selective beta-ARs agonist isoproterenol significantly decreased firing rate and responses to superior cerebellar peduncle stimulation in 82% of studied neurons in a dose-dependent manner. Similar changes were induced by ejection of selective beta1-ARs agonist dobutamine, while fenoterol (selective beta2-ARs agonist) increased or reduced firing rate in 32% and 19% of M1 neurons, respectively.

[The use of amantadine sulfate in combined therapy of Parkinson's disease].

The efficacy of PK-Merz medication has been studied in 17 patients with Parkinson's disease (PD), who have developed a resistance to levodopa as a result of a long-term treatment. The efficacy was evaluated according to clinical symptoms (UPDRS) and electromyography (EMG) indices. The summary motor score measured by UPDRS estimated as 49-79 (58.

A quantitative surface electromyogram analysis for diagnosis and therapy control in Parkinson's disease.

Computer analysis of EMG data on tonic and phasic activities of mm. biceps and triceps brahii was performed to evaluate objectively Parkinson's disease (PD) symptoms and to quantify levodopa therapy effects. Fifteen patients were evaluated in the OFF and eleven in the ON states.

[Regional distribution of the brain steady potential level in patients with Parkinson's disease].

Regional distribution of the brain steady potential level (SPL) was shown to depend on the predominant clinical symptom in parkinsonian patients. Those with prevailing bradykinesia revealed a statistically significant decrease in the SPL in the frontal area as compared with the healthy subjects or the patients with prevailing tremor.

Influence of the blockade of D2 dopamine receptors of the cat neostriatum on the baseline activity and saccadic eye movement-associated reactions of neurons of the reticular portion of the substantia nigra.

The activity of neurons of the reticular portion of the substantia nigra before and after the microinjection of haloperidol (25 micrograms/5 microliters) into the head of the caudate nucleus on the ipsilateral side was investigated under chronic experimental conditions in cats, using the extracellular microelectrode pickup technique. A significant (p < 0.05) increase, from 34 to 61%, of neurons with the burst type of spontaneous activity was established after the injection of haloperidol.

Electrophysiological investigation of thalamic neuronal mechanisms of motor disorders in parkinsonism: an influence of D2ergic transmission blockade on excitation and inhibition of relay neurons in motor thalamic nuclei of cat.

In acute experiments on cats anaesthetized with ketamine (25 mg/kg, i.m.) and immobilized with myorelaxine (2 mg/kg, i.

[The effect of a blockade of the dopamine D2 receptors in the cat neostriatum on the neuronal background activity and reactions of the reticular portion of the substantia nigra related to saccadic eye movements].

In cats, the activity of the substantia nigra reticular part's neurons was extracellularly recorded prior to and after haloperidol administration into the head of the caudate nucleus. The number of neurons with burst-type firing increased after the administration from 34 to 61 per cent. The excitatory/inhibitory responses ratio associated with saccadic eyes movements also increased from 0.

Participation of nucleus entopeduncularis in motor instrumental reflex and entopeduncular influences on motor thalamic nuclei in normal and MPTP-treated cats.

Activity of entopeduncular neurons was studied in chronic experiments on cats during performance of instrumental movement: pedal pressing and holding. One-hundred and twenty-four neurons were extracellularly investigated in intact animals and 81 neurons in cats treated with N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (5 mg/kg daily, intramuscularly for five days). The mean discharge frequency of nucleus entopeduncularis neurons recorded 48-72 h after the last MPTP injection increased from 12.

[Effect of nucleus entopeduncularis stimulation on thalamic nuclei motor neurons under normal conditions and after injury of the nigrostriatal dopaminergic system produced by the neurotoxin MPTP].

Two groups of acute experiments were performed on cats anesthetized by ketamine and immobilized by myorelaxine to study reactions of neurons in ventral anterior (VA) and ventral lateral (VL) thalamic nuclei to stimulation of nucleus entopeduncularis (nEp) in normal animals and in those treated with chronic injections of neurotoxin--N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 5 mg/kg, i.m., daily, for five days).

Influence of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced injury of dopaminergic nigrostriatal system on movement components of the instrumental reflex and motor thalamic neurons' reactions in the cat.

Peculiarities of excitation and inhibition in ventral lateral and ventral anterior thalamic neurons were studied in cats with movement disorders (bradykinesia and muscle rigidity) induced by injury of nigrostriatal dopaminergic neurons with neurotoxin N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (5 mg/kg daily, intramuscularly for five days). As was shown in chronic experiments, mean discharge frequency of neurons related to initiation of upper limb movements increased. Excitation of these neurons coincided with movement initiation, flexion and extension becoming more prominent and prolonged as compared with normal animals.

[Effect of catecholaminergic transmission deficiency on neuronal responses of the ventrolateral thalamic nucleus evoked by stimulation of the cerebellar and pallidal inputs].

Neuronal responses of the ventrolateral thalamic nucleus (VL) to the afferent stimulation were studied in chronic experiments on cats before and after injection of haloperidol and droperidol in cataleptic doses. As distinct from the reactions of intact animals, after injection of neuroleptics the initial excitative VL neuronal responses to the cerebellar stimulation were characterized by the irregularity of manifestation and the variability of the latent period, the responses in the form of burst discharges appeared. During pallidal stimulation a statistically significant increase in the number of initial inhibitory responses consisting of two periods of the background activity suppression with an excitation phase separating them was observed, while monophase inhibitory reactions prevailed (68%) in intact animals.

[The effect of the experimentally induced failure of catecholaminergic transmission on the neuronal activity of the thalamic ventrolateral nucleus].

In chronic experiments on cats the background activity of 272 neurons of the ventrolateral thalamic nucleus was registered extracellularly before and after the systemic injection of haloperidol and droperidol (neuroleptics) in cataleptic doses. Autocorrelation and spectral analyses have revealed rhythmic changes in the frequency of the background neuronal activity with periodicity measured by parts of seconds (0.2-0.

[The effect of the systemic administration of neuroleptics on the neuronal background activity of the ventrolateral thalamic nucleus in the cat].

The background activity of 272 neurons of the ventrolateral thalamic nucleus was registered extracellularly in chronic experiments on cats in drowsy state before and after systemic injection of haloperidol and droperidol in cataleptic doses. In intact animals the neuronal activity was characterized by the burst discharges with short duration (5-50 ms) and high intraburst frequency (200-450/s). In 15% of investigated cells the rhythmic sequences of burst discharges with frequency of 2-2.

[Excitation and inhibition processes in the neurons of the thalamic motor nuclei of normal cats and following an N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced lesion of the nigrostriatal dopaminergic system].

Peculiarities of excitation and inhibition evoked in motor thalamic nuclei (VA-VL) neurons by electrical stimulation of red nucleus were studied on intact cats and after injection of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 5 mg/kg i.m., p.

[Rhythmic background activity of the thalamic neurons of patients with extrapyramidal movement disorders].

When applying the microelectrode method in neurosurgical clinic to differentiate white matter and thalamic nuclei the background activity of 123 thalamic neurons has been registered in 30 patients with motor extrapyramidal disorders. The recordings were performed from ventral oral anterior, ventral oral posterior and adjacent reticular thalamic nuclei. Autocorrelation functions and spectral density functions for the activity of 44 cells were analyzed.

Spontaneous and evoked activity of neurons in deep structures of the brain during their anodal polarization.

The influence of anodal polarization on the spontaneous activity of neurons in the caudate nucleus, medial geniculate body, and the median center of the thalamus and on the evoked impulse activity of neurons in the medial geniculate body was investigated during auditory stimulation. The impulse activity was recorded extracellularly with glass and metallic microelectrodes. Nichrome polarizing electrodes of 0.

[Use of the microelectrode method for differentiation of white matter from thalamic nuclei during stereotaxic procedures].

Two hundred and three neurograms were recorded from the ventrolateral and reticular nuclei of the thalamus in 29 patients. Pulsed neuron activity was encountered in 116 cases. Reactions to motor tests were recorded from 26 neurons.

[Spontaneous and evoked activity of neurons of the deep structures of the brain in response to anodal polarization].

In cats, the effect of anodal polarization on the spontaneous unit activity of the caudate nucleus, MGB, center median and on the evoked unit activity of the MGB during sound stimulation, was studied. The polarization (300-500 microA for 1-3 min, at the distance up to 3 mm from the polarizing electrode) caused a reversible inhibition of the spontaneous and evoked unit activity followed by a prolonged aftereffect: inhibition of the spontaneous discharges for 4-10 min and disappearance of the evoked unit responses for 5-20 min.

[Reaction of caudate nucleus neurons to acoustic stimulation during functional exclusion of the medial geniculate body].

In chronic experiments, responses of the cat caudate nucleus neurons to sound clicks (0.2/s) were recorded extracellularly under conditions of functional blockade of the medial geniculate body (MGB). Analysis of the average poststimulus histograms showed that, under anodic polarization of the parvo- and magnocellular parts of the MGB, 39% of the caudate nucleus neurons responded to sound signals by a decrease of phasic activation and 30% of neurons--by its disappearance, 9%--by lengthening of latency of the responses.

[Short-latency responses of neurons of the striate system of the brain to sensory activation].

Experiments were carried out on awake cats to study responses of caudate neurons to different afferent stimuli (visual, auditory, somatic and direct electrical stimulation of medial geniculate body). Mean response latencies varied within 15-55 ms with the maximum value to 200 ms. At the same time 1-10% of cells responded with short latency to all applied stimuli.

[Activity of caudate nucleus neurons during purposeful and forced limb movements in the alert cat].

Experiments were carried out on freely moving cats in a screened chamber. Activity of 121 neurones of the caudate nucleus head was examined during various sensory stimulations and during realization of components of a behavioural act (natural food-procuring reflex). No prevailing was found of neuronal reactions to impulses from passively contracting muscle groups of the body and the limbs over responses of the same neurones to sensory stimuli or limb movements during food-procuring reflex.