Biomedical subjects

Denis Artchakov

Publications and source records attributed to Denis Artchakov.

4 recordsLinked to original sources

PubMed2005

Cortical generators of slow evoked responses elicited by spatial and nonspatial auditory working memory tasks.

OBJECTIVE: Slow evoked responses have been extensively studied using electrophysiological and neuroimaging methods, but there is no consensus regarding their generators. We investigated the generators of the P3 and positive slow wave (PSW) in the evoked responses to probes recorded during auditory working memory tasks to find out whether there is dissociation between functional networks involved in the generation of the P3 and PSW and between spatial and nonspatial auditory processing within this time window. METHODS: Whole-head magneto-(MEG) and electroencephalography (EEG); analysis of MEG data using minimum-norm current estimates. RESULTS: The associative temporal, occipito-temporal and parietal areas contributed to the generation of the slow evoked responses. The temporal source increased while the occipito-temporal source diminished activity during transition from the P3 to PSW. The occipito-temporal generator of the P3 was activated more during the spatial than nonspatial task, and the left temporal generator of the PSW tended to be more strongly activated during the nonspatial task. CONCLUSIONS: These findings indicate that partially distinct functional networks generate the P3 and PSW and provide evidence for segregation of spatial and nonspatial auditory information processing in associative areas beyond the supratemporal auditory cortex. SIGNIFICANCE: The present results support the dual-stream model for auditory information processing.

Acoustic Stimulation↗

PubMed2004

A potential aphrodisiac for female macaques.

Earlier studies suggest that alpha2-adrenoceptor antagonists and dopamine receptor agonists may enhance sexual activity in human and nonhuman male primates. It is not known whether these compounds influence the sexual behavior of female primates. We determined whether the administration of a selective alpha2-adrenoceptor antagonist (atipamezole), a dopamine receptor agonist (apomorphine), or their combination to female Macaca arctoides (stumptail macaque) monkeys produces changes in sexual behavior of the female with a male. Following the administration of drugs to the female, the behavior of the female with a male stumptail was observed for 30 min. Atipamezole dose dependently (0.03-0.3 mg/kg im) increased short-time mounting behavior of the male and the total number of copulations. Apomorphine alone (0.125-0.25 mg/kg) or in combination with atipamezole had no significant effects on sexual behavior. The result indicates that a selective alpha2-adrenoceptor antagonist administered in the female stumptail increases sexual behavior of the male with the female. A plausible explanation for this finding is that a selective alpha2-adrenoceptor antagonist increases sexual arousal in female stumptails and this, possibly due to a change in psychosocial behavior of the female, triggers increased sexual activity in males.

Adrenergic alpha-2 Receptor Agonists↗

PubMed2004

The effect of interstimulus interval on somatosensory point localization.

Somatosensory point localization is a clinical test evaluating spatial accuracy of the somatosensory system. Possible effects of the interstimulus interval (ISI) on point localization threshold have not been previously examined. In the present set of experiments the effect of time delay on somatosensory point localization was studied using ISIs of 1, 3, 5, 7, and 9 s, and applying a newly developed computer-controlled application method of a Semmes-Weinstein monofilament. It was found that the point localization threshold was not significantly affected by the ISI length. However, the response time was shorter and response accuracy better at the shorter (1 and 3 s) than at the longer (5, 7, and 9 s) ISIs, suggesting a change in the mechanism underlying point localization decision criteria in ISIs longer than 3 s.

Adult↗

PubMed2003

Differences between auditory evoked responses recorded during spatial and nonspatial working memory tasks.

Results from several recent studies suggest that neuronal processing of sound content and its spatial location may be dissociated. The use of modern neuroimaging techniques has allowed for the determination that different brain structures may be specifically activated during working memory processing of pitch and location of sound. The time course of these task-related differences, however, remains uncertain. In the present study, we performed simultaneous whole-head electroencephalogram and magnetoencephalogram recordings, using a new behavioral paradigm, to investigate the dynamics of differences between "what" and "where" evoked responses in the auditory system as a function of memory load. In the location task the latency of the N1m was shorter and its generator was situated more inferiorly than in the pitch task. Working memory processing of the tonal frequency enhanced the amplitude of the N2 component, as well as the negative-going deflection at a latency around 400 ms. A memory-load-dependent task-related difference was found in the positive slow wave which was higher during the location than pitch task at the low load. Late slow waves were affected by memory load but not type of task. These results suggest that separate neuronal networks are involved in the attribute-specific analysis of auditory stimuli and their encoding into working memory, whereas the maintenance of auditory information is accomplished by a common, nonspecific neuronal network.

Acoustic Stimulation↗