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A A Petrosian

Publications and source records attributed to A A Petrosian.

10 recordsLinked to original sources
PubMed2002

[Septal nuclei in the regulation of vago-sensitive neurons activity of the solitary nucleus in cats].

The descending influences of the septal nuclei (lateral nucleus--LSN and bed nucleus stria terminalis--BNST) on activity of viscero-sensory neurons of the nucleus of tractus solitarius (NTS) identified by stimulation of cervical part of the n. vagus were investigated in the cat anaesthetised by chloraloze-nembutal combination. It was found that out of 70 units recorded in the NTS area 50 were identified as those of primary and secondary input vagal neurons. Influence of single, paired and frequency stimulation on the septal structures was studied on these neurons. It was revealed that 30% (15 un) reacted by phase-specific response to the single stimulation of the septal nuclei. The latent period of initial excitation was in the range 5-25 ms. During the paired stimulation these neurons were not able to react to the second stimulus for the equal 10-300 ms. It was revealed that 34% (17 un) of the identified vagal neurons reacted by a tonic change of their spontaneous activity. The increase of frequency stimulation to 20 Hz evoked different changes of the rhythmical activity of the vagal neurons (increase, diminishing or inhibition). The study of interaction between central and peripheral signals in the solitary neurons induced blocking influence of descending septal discharge on the vagal test response. It is possible that the septal downward impulses reach the vago-sensitive solitary neurons indirectly through other structures of the limbic brain (amygdala, hypothalamus) and participate in modulation of the spontaneous activity of these neurons.

Animals↗
PubMed2001

Recurrent neural network-based approach for early recognition of Alzheimer's disease in EEG.

OBJECTIVE: We explored the ability of specifically designed and trained recurrent neural networks (RNNs), combined with wavelet preprocessing, to discriminate between the electroencephalograms (EEGs) of patients with mild Alzheimer's disease (AD) and their age-matched control subjects. METHODS: Twomin recordings of resting eyes-closed continuous EEGs (as well as their wavelet-filtered subbands) obtained from parieto-occipital channels of 10 early AD patients and 10 healthy controls were input into RNNs for training and testing purposes. The RNNs were chosen because they can implement extremely non-linear decision boundaries and possess memory of the state, which is crucial for the considered task. RESULTS: The best training/testing results were achieved using a 3-layer RNN on left parietal channel level 4 high-pass wavelet subbands. When trained on 3 AD and 3 control recordings, the resulting RNN tested well on all remaining controls and 5 out of 7 AD patients. This represented a significantly better than chance performance of about 80% sensitivity at 100% specificity. CONCLUSION: The suggested combined wavelet/RNN approach may be useful in analyzing long-term continuous EEGs for early recognition of AD. This approach should be extended on larger patient populations before its clinical diagnostic value can be established. Further lines of investigation might also require that EEGs be recorded from patients engaged in certain mental (cognitive) activities.

Aged↗
PubMed2000

Optimal zonal wavelet-based ECG data compression for a mobile telecardiology system.

A new integrated design approach for an optimal zonal wavelet-based ECG data compression (OZWC) method for a mobile telecardiology model is presented. The hybrid implementation issues of this wavelet method with a GSM-based mobile telecardiology system are also introduced. The performance of the mobile system with compressed ECG data segments selected from the MIT-BIH arrhythmia data base is evaluated in terms of bit error rate (BER), percent rms difference (PRD), and visual clinical inspection. The compression performance analysis of the OZWC is compared with another wavelet-based (Discrete Symmetric Wavelet Compression) approach. The optimal wavelet algorithm achieved a maximum compression ratio of 18: 1 with low PRD ratios. The mobile telemedical simulation results show the successful compressed ECG transmission at speeds of 100 (km/h) with BER rates of less than 10(-15), providing a 73% reduction in total mobile transmission time with clinically acceptable reconstruction of the received signals. This approach will provide a framework for the design and functionality issues of GSM-based wireless telemedicine systems with wavelet compression techniques and their future integration for the next generation of mobile telecardiology systems.

Cardiology↗
PubMed1998

[Neuron mechanisms of the regulation of bulbar vagosolitary activity by structures of basolateral amygdala nuclei in cats].

Neuronal reactivity to single stimuli applied to both the peripheral nerves and the cortex, was the same in the cat solitary tract nucleus. The 1-20 Hz stimulation frequency rendered the reactivity either tonic in character or with reduced firing rate. A high degree of convergence (80.2%) on baso-lateral nuclei neurons was established, as well as a significant cortico-fugal effect (71%) on the viscero-sensory units of these nuclei. Single shocks and tetanic stimulation of the baso-lateral amygdala evoked mostly phasic responses of the primary as well as secondary vagal neurons. Feed-back mechanisms of the amygdaloid control of the bulbar viscero-sensory units are discussed.

Amygdala↗
PubMedDate not supplied

[Effect of beditine on the cerebral circulation and various metabolic parameters].

Beditin, or 2-(2-amino-4-thiazolyl)-1,4-benzodioxane hydrochloride, is a new benzodioxane derivative possessing antihypoxant and alpha 2-adrenoreceptor blocker properties. In contrast to idazoxan, a well-known alpha 2-adrenoreceptor blocker, beditin (3 mg/kg) significantly increases the circulation rate and decreases the blood vessel resistance in various brain structures of rats and cats without considerably changing their systemic hemodynamic indices. Upon a one-side ligation of the common carotid artery in rats, beditin prevented a sharp increase in the lactate dehydrogenase activity and a growth in the content of free ammonia in the brain, which are characteristic of the ischemic states. The ammonia-eliminating effect of beditin is related to an increase in the glutamate dehydrogenase activity in the reductive amination reaction.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

[Effect of a postsynaptic alpha2-adrenoreceptor antagonist beditin on the rat resistance to seizure and Ca(+)-level in the brain tissue].

In rats with a hemodynamic disorder caused by acute myocardial ischemia, preliminary administration of beditin in a dose of 25 mg/kg fully prevents a manifold increase in the level of 45Ca2+ in the cytosol of brain cells and leads to enhanced trapping and accumulation of labeled calcium in endoplasmic reticulum. With respect to calcium binding in endoplasmic reticulum, the action of beditin substantially differs from that of verapamil.

Adrenergic alpha-2 Receptor Antagonists↗
PubMedDate not supplied

[Age-related changes in the serotonin content of the epiphysis of birds].

Serotonin content of the epiphysis has been studied in 1-day chicks, 1-, 5-5 1/2-, 8-12- and 24-month hens. It was found that this content undergoes significant changes during life cycle of hens, being dependent on physiological activity of the gonads. The highest level of serotonin (16 micrograms/g) was observed in 8-12 months old hens which corresponds to the period of the most intensive activity of the gonads.

Aging↗
PubMedDate not supplied

[Electron microscopic study of the epiphysis in the hen in different age periods].

Electron microscopic investigation of the epiphysis in 1 and 2 years old hens revealed that pineocytes are rich in mitochondria, ribosomes, granular endoplasmic network, Golgi apparatus, synapses. In contrast to 1-year hens, large amounts of lipofuscin granules and lysosomes were found in older animals. The data obtained reveal intensive hormone formation and oxidation-reduction processes in the epiphysis of birds.

Aging↗