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Search Results: 1 - 10 of 25 matches for " Wichian Sittiprapaporn "
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Preattentive Processing of Level to Contour Tone Changes
Wichian Sittiprapaporn
Research Journal of Applied Sciences , 2012, DOI: 10.3923/rjasci.2012.301.309
Abstract: The main objective of the research reported here is to investigate the preattentive processing of changing from level tone to contour tone and vice versa. The long to short duration change with level to falling/rising and falling/rising to level tone changes perception elicited MMN between 196-220 msec with reference to the standard-stimulus ERPs. The long to short duration and level to falling/rising tone changes elicited a strong MMN bilaterally for both native and nonnative speakers of Thai, unlike short to long duration and falling/rising to level tone changes. Source localization analyses performed using LORETA-Key demonstrates that sources were obtained in the Middle Temporal Gyrus (MTG) of the left hemisphere and in the Superior Temporal Gyrus (STG) of the right hemisphere for both groups. The present study demonstrated that the grand enterprise of mapping language onto the human brain can be vitally enhanced by MMN studies.
Preattentive Processing of Different Vowel Duration Changes with Level Tones in Monosyllabic Thai Words
Wichian Sittiprapaporn
Research Journal of Applied Sciences , 2012, DOI: 10.3923/rjasci.2012.310.315
Abstract: The main objective of this study is to use the Mismatch Negativity (MMN) to provide an index of experience-dependent and long-term memory traces for duration of vowel changes with level tone in monosyllabic Thai words. About twenty two healthy right-handed adults participated in this study. It was found that both long to short and short to long duration of vowels changes with level tone elicited MMN between 184-208 msec with reference to the standard-stimulus ERPs. The long to short duration changes with level tone elicited a strong MMN bilaterally for both native and nonnative speaker of Thai unlike short to long duration change with level tone. The source of long to short duration changes was estimated to be located in the middle temporal gyrus of each hemisphere for both groups.
Mismatch Negativity of the Contour Tone Changes in Monosyllabic Thai Words
Wichian Sittiprapaporn
Research Journal of Applied Sciences , 2012, DOI: 10.3923/rjasci.2012.316.321
Abstract: As both hemispheres are lateralized for speech and language, the objective of this study is to extend the investigation of how the preattentive processing of contour tone changes in Thai monosyllabic words. Twenty two healthy right handed adults participated in this study. This study found that both rising to falling and falling to rising tone changes perception elicited MMN between 212-244 msec with reference to the standard-stimulus ERPs. The rising to falling and falling to rising tone changes elicited a strong MMN bilaterally for native and nonnative speakers of Thai. Source localization was obtained in the Middle Temporal Gyrus (MTG) of the left hemisphere and in the Superior Temporal Gyrus (STG) of the right hemisphere for both groups. Automatic detection of changes in contour tones is a useful index of language universal auditory memory traces.
Auditory P300 Late Positive Complex Peaking-Picking Procedure
Wichian Sittiprapaporn
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2012.387.388
Abstract: Latency and amplitude figures for waveforms were picked at their point of maximal deflection as seen at their electrode site of maximal voltage distribution. The foregoing procedure for peak-picking was usually rather simple and straightforward for the early peaks. However for the Late Positive Complex (LPC) components due to their inherent but limited morphological identification had to be used in order not to confuse and admix together different LPC components from different subjects. Basically it is assumed that there are a maximum of three components in a person s LPC which we call P3a, P300 and P3b. P3a is the earliest and P3b the latest such component while P300 falls somewhere in the middle usually assumed as the waveform s center of gravity where a distinct peak cannot be ascertained. The range of LPC morphological variability which is seen in a general population including both healthy and sick people is then considered to represent a kind of gradient of LPC degeneration or deterioration and can be classified as such.
Electroencephalogram Technology Synopsis
Wichian Sittiprapaporn
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2012.395.398
Abstract: Electroencephalogram (EEG) source is within the cerebral cortex, large neural populations, all synchronized together to summate at the scalp surface. EEG signal recorded is the summation of the various neuronal populations beneath it and is a composite of various frequencies, designed Δ (0-3.5 Hz), θ (4-7 Hz), α (8-13 Hz) and β (13+ Hz). EEG is analyzed according to voltage, frequency, location, degree of symmetry and coherence between left and right hemispheres and specific waveform morphology and patterns. The International 10-20 System of Electrode Placement was introduced by Herbert Jasper in 1958 and adopted by the International Federation of EEG Societies and is currently in widespread use. Evoked Potentials (EP) are time-locked to the stimulus. Testing modalities and EP test types include: Auditory (BAER and AER), Visual (VER), Somatosensory (SER) and Cognitive (ERP). Quantified EEG includes Topographic Brain Mapping (TBM, BEAM) and Fast Fourier Transform (FFT) to analyze both EEG and EP data.
The Design and Interpretation of EEGs, FFTs, Visual EPs, Auditory EPs and Auditory P300 ERPs Studies with Topographic Brain Mapping
Wichian Sittiprapaporn
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2012.399.404
Abstract: This study discusses some of the central issues in the design and interpretation of Electroencephalograms (EEGs), Fast Fourier Transforms (FFTs), Visual Evoked Potentials (Visual EPs), Auditory Evoked Potentials (Auditory EPs) and Auditory P300 Event-Related Potentials (Auditory P300 ERPs) tests. Many design and interpretation issues are unique to a given content area but many principles apply to virtually all EEGs, EPs and ERPs studies and these common principles are the focus of this study. The study begins with a discussion of the file numbering system for all topographic brain mapping tests assigned by the Brain Atlas III (BA-III). It then discusses the principles of design and interpretation. Throughout the study, the most significant points are distilled into a set of paradigms for designing and interpreting EEGs, FFTs, EPs and ERPs tests.
An Effect of Attention on Mismatch Negativity in Audiovisual Visual Modalities
Wichian Sittiprapaporn
Pakistan Journal of Biological Sciences , 2012,
Abstract: It remains unclear whether there is an analogous automatic deviant-related negativity elicited outside the auditory modality even though the MMN can be elicited in auditory modality. The present study employed simultaneous audio-visual stimulus in the oddball paradigm to re-examine the effects of attention on visual mismatch negativity in audiovisual perception. The electrical brain activities were recorded from normal, from normal participants subjects. Stimuli consisted of a set of four audio-visual stimuli that are distinguished by frequencies (Hz) for audio and features for visual appearing on the computer screen. ANOVA showed statistically significant of the interaction between electrode site and modality. The difference waves with 100-200 msec latency at the anterior sites were markedly different to the posterior sites. The emergence of posterior negativity in the audio-visual modality might not be attributed to visual discrimination process as it did not appear in the visual modality.
Music Sound and Picture Perception: Topography of the Human Brain Electrical Activity
Wichian Sittiprapaporn
International Journal of Computer Science Issues , 2010,
Abstract: The functional properties and topographic distribution of eventrelated potential (ERP) components elicited by simultaneously music sound and picture discrimination were investigated. Simultaneous audio-visual stimulus in the oddball paradigm was used to re-examine the MMN occurrence in auditory, visual and audiovisual modalities. This study was designed to investigate whether task-related processing of visual and auditory features was independent or task-related processing in one modality might influence the processing of the other. The grand-average deviant-related components producing deviant-related negativities (DRNs) divided into and early DRN1 around 100- 200 ms and late DRN2 around 200-300 ms. Two ERP components were found: MMN associated with DRN1, and N2b associated with DRN2. MMN and N2b were more negative when a stimulus was a target, showing the selection negativity effect. Feature-specific effects on component amplitude or topography varied by component. ANOVA shows that the interaction between electrode site and modality of MMN amplitudes at 100- 200 ms was statistically significant. The difference waves with 100-200 ms latency at the anterior sites were markedly different to the posterior sites. In visual modality, there was no MMN elicitation in the posterior sites compared to the auditory and audiovisual modalities. The emergence of posterior negativity (MMN) in the present study is thus not to be attributed to visual discrimination process. These data provide topographic evidence that ERP components in the 100-300 ms time domain can be differentiated on the basis to proceeding of specific stimuli features, and reflect neurophysiologically distinct auditory and visual pathways in the human cortex.
Evoked Potentials: Electrical Events Specific to Brain’s Receiving Sensory Input
Wichian Sittiprapaporn
Journal of Artificial Intelligence , 2012,
Abstract: This study aims to review the fundamental concept of the clinical testing modalities in Evoked Potentials (EPs) recording strategies. The article starts from the terminology of EPs which means the electrical events specific to the brain’s receiving sensory input from the outside e.g., visual, auditory, somatosensory. EPs is a method to tune-in to one specific part of the sensory neuraxis from a primary sensory receptor. There are basically two distinct approaches or strategies to recording EPs, depending on the focus of interest in nervous system malfunctioning. Basic characteristics of EPs include, (1) they are time-locked to the stimulus, (2) short-latency EPs especially are deterministic, stereotyped or characterized by having the same latency, amplitude, polarity and waveform every time and (3) longer-latency EPs are somewhat less deterministic especially as regards displaying more latency jitter or variability, as well as being more subject to state variations e.g., drowsiness, sleep or coma. This article then concludes the usual clinical testing modalities in EPs.
Cortical Activation of Level-to-Contour Tone Changes in Different Vowel Duration Indexed by Mismatch Negativity
Wichian Sittiprapaporn
Journal of Applied Sciences , 2012,
Abstract: Mismatch Negativity (MMN) generally increased as a function of the degree of discrepancy from the standard-stimulus duration. The MMN generator is indeed sensitive to even very small amounts of stimulus energy. The main objective of this study was to investigate the cortical activation of level-to-contour tone changes in different vowel duration indexed by mismatch negativity. Twenty-two healthy right-handed adults participated in this study. It was found that the long-to-short vowel duration changes with level-to-falling/rising and falling/rising-to-level tone changes perception elicited MMN between 196-220 msec with reference to the standard-stimulus Event-related Potentials (ERPs). The long-to-short vowel duration and level-to-falling/rising tone changes elicited a strong MMN bilaterally for both native and nonnative speakers of Thai, unlike short-to-long vowel duration and falling/rising-to-level tone changes. Source localization analyses performed using Low Resolution Electromagnetic Tomography (LORETA) demonstrated that sources were obtained in the Middle Temporal Gyrus (MTG) of the left hemisphere and in the Superior Temporal Gyrus (STG) of the right hemisphere for both subject groups.
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