Effect of Salivation by Facial Somatosensory Stimuli of Facial Massage and Vibrotactile Apparatus

We studied the effects of salivary promotion of fluid secretion after hand massage, and the apparatus of vibrotactile stimulation (89 Hz frequency, 15 min) in normal humans. Personal massage cannot be performed on handicap and stroke patients, and then giving hand massage to them for 5 min massage gives a tired feeling. So, we focused 3 min stranger massage. Salivary glands can discharge the accumulated saliva by extrusion from the acinus glands’ massages as described in the recent Japanese textbook. We think that this method may not produce realistic recovery. Our aim ideas are to relieve stress and increase temperature with lightly touch massage of the skin and for a 1 cycle of 1 s. We recorded RR interval of ECG, total salivation, facial skin temperature, OxyHb of fNIRS on the frontal cortex, and amylase activity for the autonomic changes. In increased 2°C of the facial skin temperature, the hand massage had a need for 3 min and the vibrotactile stimulation for 15 min. Increase from 700 to 1000 ms of RR intervals had a need for 3 min in the hand massage and had 15 min in the vibrotactile stimulation. Although vibrotactile stimulation needs long time of 4–7 years as effective recovery, hand massage may have more effect with a repetition of day after day

Method for Spatial Overlap Estimation of Electroencephalography and Functional Magnetic Resonance Imaging Responses

Background Simultaneous functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) measurements may represent activity from partially divergent neural sources, but this factor is seldom modeled in fMRI-EEG data integration. New method This paper proposes an approach to estimate the spatial overlap between sources of activity measured simultaneously with fMRI and EEG. Following the extraction of task-related activity, the key steps include, 1) distributed source reconstruction of the task-related ERP activity (ERP source model), 2) transformation of fMRI activity to the ERP spatial scale by forward modelling of the scalp potential field distribution and backward source reconstruction (fMRI source simulation), and 3) optimization of fMRI and ERP thresholds to maximize spatial overlap without a priori constraints of coupling (overlap calculation). Results FMRI and ERP responses were recorded simultaneously in 15 subjects performing an auditory oddball task. A high degree of spatial overlap between sources of fMRI and ERP responses (in 9 or more of 15 subjects) was found specifically within temporoparietal areas associated with the task. Areas of non-overlap in fMRI and ERP sources were relatively small and inconsistent across subjects. Comparison with existing method The ERP and fMRI sources estimated with solely jICA overlapped in just 4 of 15 subjects, and strictly in the parietal cortex. Conclusion The study demonstrates that the new fMRI-ERP spatial overlap estimation method provides greater spatiotemporal detail of the cortical dynamics than solely jICA. As such, we propose that it is a superior method for the integration of fMRI and EEG to study brain function

Magnetoencephalography in cognitive neuroscience: a primer

Magnetoencephalography (MEG) is an invaluable tool to study the dynamics and connectivity of large-scale brain activity and their interactions with the body and the environment in functional and dysfunctional body and brain states. This primer introduces the basic concepts of MEG, discusses its strengths and limitations in comparison to other brain imaging techniques, showcases interesting applications, and projects exciting current trends into the near future, in a way that might more fully exploit the unique capabilities of MEG

Integration of EEG-FMRI in an Auditory Oddball Paradigm Using Joint Independent Component Analysis

The integration of event-related potential (ERP) and functional magnetic resonance imaging (fMRI) can contribute to characterizing neural networks with high temporal and spatial resolution. The overall objective of this dissertation is to determine the sensitivity and limitations of joint independent component analysis (jICA) within-subject for integration of ERP and fMRI data collected simultaneously in a parametric auditory oddball paradigm. The main experimental finding in this work is that jICA revealed significantly stronger and more extensive activity in brain regions associated with the auditory P300 ERP than a P300 linear regression analysis, both at the group level and within-subject. The results suggest that, with the incorporation of spatial and temporal information from both imaging modalities, jICA is more sensitive to neural sources commonly observed with ERP and fMRI compared to a linear regression analysis. Furthermore, computational simulations suggest that jICA can extract linear and nonlinear relationships between ERP and fMRI signals, as well as uncoupled sources (i.e., sources with a signal in only one imaging modality). These features of jICA can be important for assessing disease states in which the relationship between the ERP and fMRI signals is unknown, as well as pathological conditions causing neurovascular uncoupling, such as stroke

Characterization of Neuroimage Coupling Between EEG and FMRI Using Within-Subject Joint Independent Component Analysis

The purpose of this dissertation was to apply joint independent component analysis (jICA) to electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to characterize the neuroimage coupling between the two modalities. EEG and fMRI are complimentary imaging techniques which have been used in conjunction to investigate neural activity. Understanding how these two imaging modalities relate to each other not only enables better multimodal analysis, but also has clinical implications as well. In particular, Alzheimer’s, Parkinson’s, hypertension, and ischemic stroke are all known to impact the cerebral blood flow, and by extension alter the relationship between EEG and fMRI. By characterizing the relationship between EEG and fMRI within healthy subjects, it allows for comparison with a diseased population, and may offer ways to detect some of these conditions earlier. The correspondence between fMRI and EEG was first examined, and a methodological approach which was capable of informing to what degree the fMRI and EEG sources corresponded to each other was developed. Once it was certain that the EEG activity observed corresponded to the fMRI activity collected a methodological approach was developed to characterize the coupling between fMRI and EEG. Finally, this dissertation addresses the question of whether the use of jICA to perform this analysis increases the sensitivity to subcortical sources to determine to what degree subcortical sources should be taken into consideration for future studies. This dissertation was the first to propose a way to characterize the relationship between fMRI and EEG signals using blind source separation. Additionally, it was the first to show that jICA significantly improves the detection of subcortical activity, particularly in the case when both physiological noise and a cortical source are present. This new knowledge can be used to design studies to investigate subcortical signals, as well as to begin characterizing the relationship between fMRI and EEG across various task conditions

FMRI identification of eloquent language brain areas

Функционална магнетна резонанца (фМР), у последњој деценији дала је значајан допринос у испитивању различитих аспеката можданих функција како код здравог мозга тако и у различитим патолошким стањима. Сврха ове дисертације била је да испита могућности фМР у детекцији елоквентних говорних можданих зона како код здравих волонтера тако и код пацијената са туморима мозга. У групи здравих волонтера било је 12 испитаника, 6 мушкараца и 6 жена. Групу пацијената чинило је 17 испитаника (9 мушкараца и 8 жена) са туморима мозга Код свих испитаника начињени су фМР снимци ендокранијума за два различита стимулуса бројање у напред и бројање у назад, а потом су начињене фМР мапе активираних можданих зона. Поред тога начињене су и групне анализе за здраве испитанике и испитанике са туморима мозга као и групне анализе према полу у овиру обе групе испитаника. За све испитанике и оба стимулуса израчунат је индекс латерализације говора. Код здравих испитаника на задате стимулусе активирана је дистрибуирана мрежа можданих зона која је осим канонских говорних зона у инфериорном фронталном гирусу (ИФГ) и супериорном темпоралном гирусу (СТГ) подразумевала и активност у примарним моторним зонама, суплементној моторној зони, префронталним регијама, церебелуму и медијалним аспектима темпоралног режња а уочене су одређене разлике у одговору на задате стимулусе између мушкараца и жена. Индекс латерализације био је у складу са проценом латерализације говора за све посматране здраве испитанике. Код испитаника са туморима мозга осим примарних говорних зона у ИФГ и СТГ идентификована је активност у примарним моторним зонама, префронталним регијама, церебелуму и у медијалним аспектима темпоралног режња...Functional magnetic resonance imaging (fMRI), in the last decade, has made significant contributions in the study of various brain functions in the healthy brain and in different pathological brain conditions as well. The purpose of this thesis was to explore the possibilities of fMRI in detection of eloquent language cortex in healthy volunteers and patients with brain tumors. In the group of healthy volunteers there were 12 subjects, 6 males and 6 females. In the patient group there were 17 patients, (9 males and 8 females) with brain tumors. For all participants fMR exam was made for two different stimuli, counting forward and counting backward. After that fMR maps of activated brain areas were made. In addition, group analysis for healthy individuals and patient with brain tumors were made, as well as group analysis according to gender for both groups. For all subjects and both stimulus laterality index was calculated. In healthy subject for both stimulus distributed network of cortical areas were detected. Besides of canonical language areas in inferior frontal gyrus (IFG) and superior temporal girus (STG), activation in primary motor areas, supplementary motor areas, prefrontal region, cerebellum and medial temporal region were detected. There were some differences in response to given stimuli between females and males. Laterality index was consistent with the assessment of speech lateralization in all observed healthy subjects. In patients with brain tumors besides the brain areas identified in healthy volunteers, additional activity was observed in sensory motor areas, the occipital and parietal region. There were certain differences in brain responses for given stimuli between females and males in this group as well. Laterality index in patients with brain tumors were only partially in line with the evaluation of language lateralization in this group..

Spatio-temporal analysis in functional brain imaging

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 119-137).Localizing sources of activity from electroencephalography (EEG) and magnetoencephalography (MEG) measurements involves solving an ill-posed inverse problem, where infinitely many source distribution patterns can give rise to identical measurements. This thesis aims to improve the accuracy of source localization by incorporating spatio-temporal models into the reconstruction procedure. First, we introduce a novel method for current source estimation, which we call the l₁l₂-norm source estimator. The underlying model captures the sparseness of the active areas in space while encouraging smooth temporal dynamics. We compute the current source estimates efficiently by solving a second-order cone programming problem. By considering all time points simultaneously, we achieve accurate and stable results as confirmed by the experiments using simulated and human MEG data. Although the l₁l₂-norm estimator enables accurate source estimation, it still faces challenges when the current sources are close to each other in space. To alleviate problems caused by the limited spatial resolution of EEG/MEG measurements, we introduce a new method to incorporate information from functional magnetic resonance imaging (fMRI) into the estimation algorithm.(cont.) Whereas EEG/MEG record neural activity, fMRI reflects hemodynamic activity in the brain with high spatial resolution. We examine empirically the neurovascular coupling in simultaneously recorded MEG and diffuse optical imaging (DOI) data, which also reflects hemodynamic activity and is compatible with MEG recordings. Our results suggest that the neural activity and hemodynamic responses are aligned in space. However, the relationship between the temporal dynamics of the two types of signals is non-linear and varies from region to region. Based on these findings, we develop the fMRI-informed regional EEG/MEG source estimator (FIRE). This method is based on a generative model that encourages similar spatial patterns but allows for differences in time courses across imaging modalities. Our experiments with both Monte Carlo simulation and human fMRI-EEG/MEG data demonstrate that FIRE significantly reduces ambiguities in source localization and accurately captures the timing of activation in adjacent functional regions.by Wanmei Ou.Ph.D

The role of the rostral prefrontal cortex in the context of the aesthetic experience

The evaluation of visual art involves sensory, emotional and cognitive processes that lead to an aesthetic judgement or an aesthetic emotion (e.g. beauty). Aesthetic experiences are multisensory processes that undergo a variety of stages. Early processes occur in the visual and sensory cortices, and are central to object identification that may be no different from visual experiences of everyday objects. Later processing stages are related to complex human thought consisting of emotion and cognition that involve areas such as the orbitofrontal cortex, hippocampus and prefrontal cortex (PFC). The later stages are concerned with the comprehension and meaningful analysis of the artwork that contribute to the formation of an aesthetic judgement or emotion.This thesis aims to investigate affective evaluations and their interactions with cognitive processes during the later processing stages of the aesthetic experience in the rostral prefrontal cortex (rPFC). The role of the rPFC will be explored using functional near-infrared spectroscopy (fNIRS) with reference to existing frameworks. Specifically: hemispheric asymmetry in the processing of emotional stimuli, the Gateway Hypothesis and the Default Mode Network will be explored.Experimental WorkA database of sixty images was created in an online survey (chapter 3) at the beginning of the experimental programme. Images were rated online (N = 1028) for complexity, comprehension, novelty, activation, attraction and valence providing stimuli that could be systematically manipulated according to their psychological properties in the experimental studies.The first hypothesis (is the rPFC involved in early perceptual processes such as complexity during aesthetic experience?) was addressed in a pilot study (chapter 4) and repeated in the first experimental study (chapter 5). Both cognitive (high/low complexity) and emotional (positive/negative valence) aspects of the images were manipulated. Images were shown for sixty second and analysed in three time periods (early, middle and late) each consisting of twenty seconds. The results showed an interaction between valence and time with positive images yielding greater activation in the early period and negative images in the late period. This highlighted the importance of long exposure times to capture the aesthetic experience.The second hypothesis (is the rPFC involved in implicit memory formation such as the comprehension of an image during aesthetic experience) was investigated in chapter 6 where the levels of comprehension (high/low) and postive/negative valence associated with the viewed image were manipulated. An interaction between comprehension and valence was found with respect to rPFC activity. Positive easy to comprehend images and negative difficult to comprehend images yielded greater rPFC oxygenation. These findings indicated that the experience of pleasure in positive artworks and increased cognitive effort during the resolution of uncertainty or threat in negative artworks is related to rPFC activation.The third hypothesis (is the rPFC involved in prospective memory during aesthetic experience?) was investigated in chapter 7 where positive and negative artworks were shown under two conditions. Condition one asked participants to introspect about their emotions and condition two to direct their attention to features in the image through a spot-the-difference task. A main effect of emotion was found, but no interaction or effect for condition. Greater rPFC activation was found during the contemplation of positive images. This may be attributed to pleasantness experienced in relation to these images.The last question (is the rPFC involved in self-referential processing and is this important to aesthetic experience?) was investigated in chapter 8 where participants viewed negative and positive images under two viewing conditions. Condition one asked participants to introspect about their own emotions (Self) and condition two about the artist’s emotions at the time of painting (Other). The other-condition resulted in overall greater rPFC activation indicating that participants found it more challenging to think of another’s emotions. An interaction showed greater rPFC activation for positive images in the self -condition and greater activation for negative images in the other-condition. This may have been the result of a positive bias and the detection of self-relevance in positive images and the analysis of threat or uncertainty in negative images.ConclusionsThis thesis used a cognitive model of the aesthetic experience as a framework to understand the interaction between emotional and cognitive processes in the formation of an aesthetic judgement or emotion. No evidence for asymmetrical processing of emotional stimuli, or the Gateway Hypothesis was found. The research reported here indicates that the rPFC has an important role during the later processing stages of the aesthetic experience. Viewing negative visual art activated rPFC when the images were difficult to comprehend and when participants thought about the artist’s feelings. Positive emotions, on the other hand, activated rPFC when the images were easy to comprehend and when participants thought about their own feelings. The contemplation of visual art was continuously associated with medial rPFC activation, indicating that the rPFC has a key role in self-relevant processing of visual art. The rPFC may aid personal value judgements of visual art (e.g. this artwork means xyz to me) because this area of the brain mediates the interaction between self-relevance, autobiographical memories and continuously changing emotional states

An assessment of cortical function in expert and novice surgeons

Imperial Users onl