Frequency specific impairment of automatic pitch change detection by fMRI acoustic noise: An MEG study
The loud acoustic noise produced by the magnetic resonance scanner is a major source of interference in auditory fMRI research. Whole-head magnetoencephalography (MEG) was used to investigate the interaction between the frequency range of auditory stimulation and fMRI acoustic noise. Pure tones and 3-harmonic complexes varying between 240 and 1240 Hz in frequency were presented while participants attended to a silent subtitled film. Continuous fMRI acoustic noise was presented during half of the blocks. The activity in six regions of interest was analyzed in 100–200 and 200–300 ms time windows to evaluate the magnetic counterparts of the mismatch negativity (MMN) and P3a brain responses. The results suggested that fMRI noise significantly reduced the amplitude of these responses. The effect of the noise on the automatic processing of the tones was more prominent for the tones with frequencies higher than 500 Hz. It is recommended that in the MMN protocols using continuous fMRI acquisition the sound stimuli should be spectrally separated from the fMRI scanner noise spectrum.
The principal possibility of creating optically pumped compact magnetic sensor for MEG operating in a wide magnetic field range is experimentally proved.
The spatiotemporal coupling of brainwaves is commonly quantified using the amplitude or phase of signals measured by electro- or magnetoencephalography (EEG/MEG). To enhance the temporal resolution for coupling delays down to millisecond level, a new power correlation (PC) method is proposed and tested.
The cross-correlations of any two brainwave powers at two locations are calculated sequentially through a measurement using the convolution theorem. For noise suppression, the cross-correlation series is moving-average filtered, preserving the millisecond resolution in the cross-correlations, but with reduced noise. The coupling delays are determined from the delays of the cross-correlation peaks.
Simulations showed that the new method detects reliably power cross-correlations with millisecond accuracy. Moreover, in MEG measurements on three healthy volunteers, the method showed average alpha–alpha coupling delays of around 0–20 ms between the occipital areas of two hemispheres. Lower-frequency brainwaves vs. alpha waves tended to have a larger lag; higher-frequency waves vs. alpha waves showed delays with large deviations.
Comparison with existing methods
The use of signal power instead of its square root (amplitude) in the cross-correlations improves noise cancellation. Compared to signal phase, the signal power analysis time delays do not have periodic ambiguity. In addition, the novel method allows fast calculation of cross-correlations.
The PC method conveys novel information about brainwave dynamics. The method may be extended from sensor-space to source-space analysis, and can be applied also for electroencephalography (EEG) and local field potentials (LFP).
The monograph presents results by professor Dr. A. Shalumov’s Research School of Modeling, Information Technology and Automated Systems (Russia). The program, ASONIKA, developed by the school is reviewed here regarding reliability and quality of devices for simulation of electronics and chips during harmonic and random vibration, single and multiple impacts, linear acceleration and acoustic noise, and steady-state and transient thermal effects. Calculations are done for thermal stress during changes in temperature and power in time. Calculations are done for number of cycles to fatigue failure under mechanical loads as well as under cyclic thermal effects. Simulation results for reliability analysis are taken into account. Models, software interface, and simulation examples are presented.
For engineers and scientists involved in design automation of electronics.
The effects of functional magnetic resonance imaging (fMRI) acoustic noise were investigated on the parameters of event-related responses (ERPs) elicited during auditory matching-to-sample location and pitch working memory tasks. Stimuli were tones with varying location (left or right) and frequency (high or low). Subjects were instructed to memorize and compare either the locations or frequencies of the stimuli with each other. Tape-recorded fMRI acoustic noise was presented in half of the experimental blocks. The fMRI noise considerably enhanced the P1 component, reduced the amplitude and increased the latency of the N1, shortened the latency of the N2, and enhanced the amplitude of the P3 in both tasks. The N1 amplitude was higher in the location than pitch task in both noise and no-noise blocks, whereas the task-related N1 latency difference was present in the no-noise blocks only. Although the task-related differences between spatial and nonspatial auditory responses were partially preserved in noise, the finding that the acoustic gradient noise accompanying functional MR imaging modulated the auditory ERPs implies that the noise may confound the results of auditory fMRI experiments especially when studying higher cognitive processing
The neurobiological basis and temporal dynamics of communicative language processing pose important yet unresolved questions. It has previously been suggested that comprehension of the communicative function of an utterance, i.e. the so-called speech act, is supported by an ensemble of neural networks, comprising lexico-semantic, action and mirror neuron as well as theory of mind circuits, all activated in concert. It has also been demonstrated that recognition of the speech act type occurs extremely rapidly. These findings however, were obtained in experiments with insufficient spatio-temporal resolution, thus possibly concealing important facets of the neural dynamics of the speech act comprehension process. Here, we used magnetoencephalography to investigate the comprehension of Naming and Request actions performed with utterances controlled for physical features, psycholinguistic properties and the probability of occurrence in variable contexts. The results show that different communicative actions are underpinned by a dynamic neural network, which differentiates between speech act types very early after the speech act onset. Within 50-90 ms, Requests engaged mirror-neuron action-comprehension systems in sensorimotor cortex, possibly for processing action knowledge and intentions. Still, within the first 200 ms of stimulus onset (100-150 ms), Naming activated brain areas involved in referential semantic retrieval. Subsequently (200-300 ms), theory of mind and mentalising circuits were activated in medial prefrontal and temporo-parietal areas, possibly indexing processing of intentions and assumptions of both communication partners. This cascade of stages of processing information about actions and intentions, referential semantics, and theory of mind may underlie dynamic and interactive speech act comprehension.
This article describes the expierence of studying factors influencing the social well-being of educational migrants as mesured by means of a psychological well-being scale (A. Perrudet-Badoux, G.A. Mendelsohn, J.Chiche, 1988) previously adapted for Russian by M.V. Sokolova. A statistical analysis of the scale's reliability is performed. Trends in dynamics of subjective well-being are indentified on the basis the correlations analysis between the condbtbions of adaptation and its success rate, and potential mechanisms for developing subjective well-being among student migrants living in student hostels are described. Particular attention is paid to commuting as a factor of adaptation.
The general aim of this thesis is to explore the gendered and classed nature of social work and social welfare in Russia to show how social policy can be a part of and reinforce marginalisation. The overall research question is in what ways class and gender are constructed in Russian social work practice and welfare rhetoric through Soviet legacies and contemporary challenges? In addition, which actors contribute to the constitution of social work values and how this value system affects the agency of the clients? This study focuses on contradictory ideologies that are shaped in discursive formations of social policy, social work training and practice. It is a qualitative study, containing fi ve papers looking at this issue from three different perspectives: policy and institutions, culture and discourse, actors and identity. The data collection was arranged as a purposive–iterative process. The empirical material consists of qualitative interviews with social work practitioners, administrators and clients, participant observations in social services and analysis of documents of various kinds.
The distractive effects on attentional task performance in different paradigms are analyzed in this paper. I demonstrate how distractors may negatively affect (interference effect), positively (redundancy effect) or neutrally (null effect). Distractor effects described in literature are classified in accordance with their hypothetical source. The general rule of the theory is also introduced. It contains the formal prediction of the particular distractor effect, based on entropy and redundancy measures from the mathematical theory of communication (Shannon, 1948). Single- vs dual-process frameworks are considered for hypothetical mechanisms which underpin the distractor effects. Distractor profiles (DPs) are also introduced for the formalization and simple visualization of experimental data concerning the distractor effects. Typical shapes of DPs and their interpretations are discussed with examples from three frequently cited experiments. Finally, the paper introduces hierarchical hypothesis that states the level-fashion modulating interrelations between distractor effects of different classes.
In the internal medicine wide spectrum the gastroenterology is one of the chapters, less enlightened by the scientific evidence. It does not mean that the practice of the grasntroenterology may ot be improved by the systematic use of the approaches of the evidence based medicine