Distinct Patterns Of Brain Activity Research Articles

Neural Correlates of Maladaptive Pain Behavior in Chronic Neck Pain – A Single Case Control fMRI Study

Chronic neck pain patients display functional impairments like decreased range of motion, decreased strength, and reduced sensorimotor function. In patients without structural damage, the reason for the persistence of pain is not well understood. Therefore, it is assumed that in chronic pain states, memory processes play an important role. We have now detected and tested a patient that might help us to better understand the neural correlates of maladaptive pain expectation/memory. This patient displays chronic neck pain and restricted unilateral motion of the cervical spine to the left. However, when the patient is distracted, she can perform head rotations without experiencing pain and without restricting her range of movement. Based on this observation, we asked her to imagine movements shown in a video: conscious, non-distracted head rotations (pain-provoking) versus distracted head rotations (pain-free) and compared these results with an age and gender matched control volunteer. Functional magnetic resonance imaging (fMRI) showed distinct brain activation patterns that depended on the side of rotation (pain-free versus painful side) and the kind of movement (distracted versus non-distracted head rotation). Interestingly, brain areas related to the processing of pain such as primary somatosensory cortex, thalamus, insula, anterior cingulate cortex, primary motor cortex, supplementary motor area, prefrontal cortex, and posterior cingulate cortex were always more strongly activated in the non-distracted condition and when turning to the left. The age and gender matched control volunteer displayed no comparable activation of pain centers. In the patient, maladaptive pain behavior and the activity of pain-related brain areas during imagined head rotations were task-specific, indicating that the activation and/or recall of pain memories were context-dependent. These findings are important not only to improve the understanding of the neural organization of maladaptive pain behavior but also to reconsider clinical evaluation and treatment strategies. The current results therefore suggest that treatment strategies have to take into account and exploit the context in which the movement is performed.Key words: Maladaptive pain behavior, pain memory, brain plasticity, motor control, neck pain, fMRI, action observation, motor imagery.

Facial emotion processing in patients with social anxiety disorder and Williams-Beuren syndrome: an fMRI study.

Social anxiety disorder (SAD) and Williams-Beuren syndrome (WBS) are 2 conditions with major differences in terms of genetics, development and cognitive profiles. Both conditions are associated with compromised abilities in overlapping areas, including social approach, processing of social emotional cues and gaze behaviour, and to some extent they are associated with opposite behaviours in these domains. We examined common and distinct patterns of brain activation during a facial emotion processing paradigm in patients with SAD and WBS. We examined patients with SAD and WBS and healthy controls matched by age and laterality using functional MRI during the processing of happy, fearful and angry faces. We included 20 patients with SAD and 20 with WBS as well as 20 matched controls in our study. Patients with SAD and WBS did not differ in the pattern of limbic activation. We observed differences in early visual areas of the face processing network in patients with WBS and differences in the cortical prefrontal regions involved in the top-down regulation of anxiety and in the fusiform gyrus for patients with SAD. Compared with those in the SAD and control groups, participants in the WBS group did not activate the right lateral inferior occipital cortex. In addition, compared with controls, patients with WBS hypoactivated the posterior primary visual cortex and showed significantly less deactivation in the right temporal operculum. Participants in the SAD group showed decreased prefrontal activation compared with those in the WBS and control groups. In addition, compared with controls, participants with SAD showed decreased fusiform activation. Participants with SAD and WBS also differed in the pattern of activation in the superior temporal gyrus, a region that has been linked to gaze processing. The results observed in the WBS group are limited by the IQ of the WBS sample; however, the specificity of findings suggests that the pattern of brain activation observed for WBS is more likely to reflect a neurobiological substrate rather than intellectual impairment per se. Patients with SAD and WBS showed common and specific patterns of brain activation. Our results highlight the role of cortical regions during facial emotion processing in individuals with SAD and WBS.

Intuitive decision making as a gradual process: investigating semantic intuition-based and priming-based decisions with fMRI.

IntroductionIntuition has been defined as the instantaneous, experience‐based impression of coherence elicited by cues in the environment. In a context of discovery, intuitive decision‐making processes can be conceptualized as occurring within two stages, the first of which comprises an implicit perception of coherence that is not (yet) verbalizable. Through a process of spreading activation, this initially non‐conscious perception gradually crosses over a threshold of awareness and thereby becomes explicable. Because of its experiential basis, intuition shares conceptual similarities with implicit memory processes. Based on these, the study addresses two research questions: (1) Is the gradual nature of intuitive processes reflected on a neural level? (2) Do intuition‐based decisions differ neurally from priming‐based decisions?MethodsTo answer these questions, we conducted an fMRI study using the triads task and presented participants with coherent word triads that converge on a common fourth concept, and incoherent word triads that do not converge on a common fourth concept. Participants had to perform semantic coherence judgments as well as to indicate whether they immediately knew the fourth concept. To enable investigating intuition‐based and priming‐based decisions within the same task and with the same participants, we implemented a conceptual priming procedure into the coherence judgment task. We realized this by priming participants with concepts associated with incoherent triads in separate priming blocks prior to the coherence judgments.ResultsFor intuition‐based decisions, imaging results mainly revealed activity within the orbitofrontal cortex, within the inferior frontal gyrus and the middle temporal gyrus. Activity suppression in the right temporo‐occipital complex was observed for priming‐based decisions.ConclusionsWith respect to research question 1, our data support a continuity model of intuition because the two intuitive stages show quantitatively distinct brain activation patterns. Regarding research question 2, we can draw the preliminary conclusion of a qualitative difference between intuition‐based and priming‐based decisions.

Aging and sequential modulations of poorer strategy effects: An EEG study in arithmetic problem solving

This study investigated age-related differences in electrophysiological signatures of sequential modulations of poorer strategy effects. Sequential modulations of poorer strategy effects refer to decreased poorer strategy effects (i.e., poorer performance when the cued strategy is not the best) on current problem following poorer strategy problems compared to after better strategy problems. Analyses on electrophysiological (EEG) data revealed important age-related changes in time, frequency, and coherence of brain activities underlying sequential modulations of poorer strategy effects. More specifically, sequential modulations of poorer strategy effects were associated with earlier and later time windows (i.e., between 200- and 550ms and between 850- and 1250ms). Event-related potentials (ERPs) also revealed an earlier onset in older adults, together with more anterior and less lateralized activations. Furthermore, sequential modulations of poorer strategy effects were associated with theta and alpha frequencies in young adults while these modulations were found in delta frequency and theta inter-hemispheric coherence in older adults, consistent with qualitatively distinct patterns of brain activity. These findings have important implications to further our understanding of age-related differences and similarities in sequential modulations of cognitive control processes during arithmetic strategy execution.

Brain basis of communicative actions in language

Although language is a key tool for communication in social interaction, most studies in the neuroscience of language have focused on language structures such as words and sentences. Here, the neural correlates of speech acts, that is, the actions performed by using language, were investigated with functional magnetic resonance imaging (fMRI). Participants were shown videos, in which the same critical utterances were used in different communicative contexts, to Name objects, or to Request them from communication partners. Understanding of critical utterances as Requests was accompanied by activation in bilateral premotor, left inferior frontal and temporo-parietal cortical areas known to support action-related and social interactive knowledge. Naming, however, activated the left angular gyrus implicated in linking information about word forms and related reference objects mentioned in critical utterances. These findings show that understanding of utterances as different communicative actions is reflected in distinct brain activation patterns, and thus suggest different neural substrates for different speech act types.

Distinct patterns of spontaneous brain activity between children and adults with anisometropic amblyopia: a resting-state fMRI study.

To detect the altered spontaneous brain activity patterns in children and adults with anisometropic amblyopia using resting-state functional magnetic resonance imaging (rs-fMRI) technique combined with the amplitude of low-frequency fluctuation (ALFF) method. Thirty-two monocular anisometropic amblyopia and 34 normal-sight controls were divided into child group and adult group. Rs-fMRI was performed in all participants and analysis of ALFF value within the whole brain was conducted in each subject. ALFF value differences between the patients and controls in the two groups were compared via an independent two-sample t test. The amblyopic children mainly exhibited increased ALFF in part of the bilateral calcarine (BA17), the left middle occipital gyrus (BA18/19), and the left postcentral gyrus (BA2). By contrast, the amblyopic adults showed decreased ALFF in the bilateral precuneus cortex (part of BA7), and the standardized ALFF value of bilateral precuneus were correlated with the amount of anisometropia of the amblyopic adults. Rs-fMRI is an effective noninvasive technique for exploring brain activity of the anisometropic amblyopia. Our findings demonstrated that brain activity changed both in amblyopic children and adults under the resting state, and revealed the differences in spontaneous activity patterns between the amblyopic children and adults.

Distinct patterns of brain activity in progressive supranuclear palsy and Parkinson's disease.

The basal ganglia-thalamo-cortical and cerebello-thalamo-cortical circuits are important for motor control. Whether their functioning is affected in a similar or different way by progressive supranuclear palsy (PSP) and Parkinson's disease (PD) is not clear. A functional magnetic resonance imaging (fMRI) force production paradigm and voxel-based morphometry were used to assess differences in brain activity and macrostructural volumes between PSP, PD, and healthy age-matched controls. We found that PSP and PD share reduced functional activity of the basal ganglia and cortical motor areas, but this is more pronounced in PSP than in PD. In PSP the frontal regions are underactive, whereas the posterior parietal and occipital regions are overactive as compared with controls and PD. Furthermore, lobules I through IV, V, and VI of the cerebellum are hypoactive in PSP and PD, whereas Crus I and lobule IX are hyperactive in PSP only. Reductions in gray and white matter volume are specific to PSP. Finally, the functional status of the caudate as well as the volume of the superior frontal gyrus predict clinical gait and posture measures in PSP. PSP and PD share hypoactivity of the basal ganglia, motor cortex, and anterior cerebellum. These patients also display a unique pattern, such that anterior regions of the cortex are hypoactive and posterior regions of the cortex and cerebellum are hyperactive. Together, these findings suggest that specific structures within the basal ganglia, cortex, and cerebellum are affected differently in PSP relative to PD.

Soldiers With Posttraumatic Stress Disorder See a World Full of Threat: Magnetoencephalography Reveals Enhanced Tuning to Combat-Related Cues

BackgroundPosttraumatic stress disorder (PTSD) is linked to elevated arousal and alterations in cognitive processes. Yet, whether a traumatic experience is linked to neural and behavioral differences in selective attentional tuning to traumatic stimuli is not known. The present study examined selective awareness of threat stimuli and underlying temporal-spatial patterns of brain activation associated with PTSD. MethodsParticipants were 44 soldiers from the Canadian Armed Forces, 22 with PTSD and 22 without. All completed neuropsychological tests and clinical assessments. Magnetoencephalography data were collected while participants identified two targets in a rapidly presented stream of words. The first target was a number and the second target was either a combat-related or neutral word. The difference in accuracy for combat-related versus neutral words was used as a measure of attentional bias. ResultsAll soldiers showed a bias for combat-related words. This bias was enhanced in the PTSD group, and behavioral differences were associated with distinct patterns of brain activity. At early latencies, non-PTSD soldiers showed activation of midline frontal regions associated with fear regulation (90–340 ms after the second target presentation), whereas those with PTSD showed greater visual cortex activation linked to enhanced visual processing of trauma stimuli (200–300 ms). ConclusionsThese findings suggest that attentional biases in PTSD are linked to deficits in very rapid regulatory activation observed in healthy control subjects. Thus, sufferers with PTSD may literally see a world more populated by traumatic cues, contributing to a positive feedback loop that perpetuates the effects of trauma.

La lésion fonctionnelle dans la conversion hystérique : des aliénistes à l’imagerie cérébrale

Recent progress in functional imagery confirmed the intuition of the 19th century French alienists who introduced, before Charcot, the concept of “functional lesion” applied to hysterical conversion. Neural mechanism underlying conversion paralysis has been more particularly studied in recent years using these new tools. Distinct patterns of brain activation have been elicited in healthy subjects simulating weakness and conversion paralysis. Several brain areas are over-activated in conversion paralysis when compared to healthy subjects: prefrontal cortex, precuneus, anterior cingulate cortex, amygdala. These results, not only confirm that conversion must be distinguished from malingering, they also provide new insights on the neural mechanisms of conversion paralysis. The activation of regions associated to the default mode network such as the precuneus and the ventral prefrontal cortex could reflect an increase in self-monitoring or motor imagery. The involvement of limbic regions like the anterior cingulate cortex and the amygdala suggest disturbed influence of emotional processes over motor execution. In the second part of this study, we report the results of brain structural and functional explorations performed in a case of chronic left conversion paralysis. The abnormal involvement of the precuneus is discussed together with the possible transition from functional to organic lesion in chronic paralysis. Simultaneous presence of sensory impairment and more remarkably left spatial neglect emphasize the singularity of each case and the necessary caution that should be taken for the interpretation of brain images. From a therapeutic point of view, these data could provide some new theoretical basis for rehabilitation and the use of brain stimulation techniques.

Functional brain imaging in survivors of critical illness: A prospective feasibility study and exploration of the association between delirium and brain activation patterns

PurposeWe undertook this pilot prospective cohort investigation to examine the feasibility of functional magnetic resonance imaging (fMRI) assessments in survivors of critical illness and to analyze potential associations between delirium and brain activation patterns observed during a working memory task (N-back) at hospital discharge and 3-month follow-up. Materials and MethodsAt hospital discharge and 3 months later, fMRI assessed subjects' functional activity during an N-back task. Multiple linear regression was used to examine associations between duration of delirium and brain activity, and elastic net regression was used to assess the relationship between brain activation patterns at 3 months and cognitive outcomes at 12 months. ResultsOf 47 patients who underwent fMRI at discharge, 38 (80%) completed the protocol; of 37 who underwent fMRI at 3 months, 34 (91%) completed the protocol. At discharge, the mean (SD) percentage of correct responses on the most challenging version (the N2 version) of the N-back task was 70.4 (23.2; range of 20-100) compared with 76 (23.4; range of 33-100) at 3 months. No association was observed between delirium duration in the hospital and brain region activity in any brain region at discharge or 3 months after adjusting for relevant covariates (P values across all 11 brain regions of interest were >.25). ConclusionsOur data support the feasibility of using fMRI in survivors of critical illness at 3-month follow-up but not at discharge. In this small study, delirium was not associated with distinct or abnormal brain activation patterns, although overall performance on a cognitive task of working memory was poorer than observed in other cohorts of individuals with medically related executive dysfunction, mild cognitive impairment, and mild traumatic brain injury.

The granularity of grasping: Comment on “Grasping synergies: A motor-control approach to the mirror neuron mechanism” by A. D'Ausilio et al.

The idea that mirror neuron systems in the human and the macaque monkey could provide a link between perceiving an action and performing it has spurred intense research [1,2]. Hundreds of papers now examine if this link exists and what it might contribute to human behaviour. The review article from D’Ausilio et al. [3] highlights how relatively few papers have considered the granularity of coding with mirror neuron systems, and even fewer have directly tested different possibilities. Granularity refers to the critical question of what actually is encoded within the mirror system – are neurons selective for low level kinematic features such as joint angle, or for postural synergies, or for action goals? Focusing on studies of single neurons in macaques and on studies measuring the excitability of primary motor cortex with TMS, the review suggests that it is very hard to distinguish low-level kinematic from goal representations. Furthermore, these two levels are often highly correlated in real-life contexts – the kinematics needed to grasp an apple are defined by the shape of the goal (an apple tends to be a large sphere) and these kinematics differ for other possible goals (a pencil which is a narrow cylinder). In some cases, kinematics may be enough to define a goal [4]. The review suggests that it is therefore arbitrary to distinguish these levels, and that a synergy level might be a better way to understand the mirror system. Synergies are a form of coding based on commonly used hand-shapes or hand postures, which take into account the fact that some joint angles are more likely to co-occur than others. Evidence that different grasp shapes are represented separately in premotor cortex has been found [5]. These could provide an intermediate level of representation between muscle activity and goals. The review proposes that a synergy level of granularity provides the best way to consider both the motor system and the role of the mirror system in understanding actions. This is a useful proposal, but has some limitations. The proposed synergies seem much closer to a kinematic representation than to goals, and do not necessarily resolve the problem of if/how the mirror neuron system could contribute to understanding goals. Just because it is not easy to separate cognitive concepts such as kinematics and goals, does not mean it should not be done. A small number of carefully designed fMRI experiments have been able to show distinct patterns of brain activity for goals and kinematics. For example, grasping a tennis ball and grasping an apple both involve the same hand kinematics and the same hand synergies, but quite different goals. Anterior intraparietal sulcus can distinguish these actions [6] and shows cross-modal sensitivity to other action goals too [7].

Priming and competition of associated memory representations: A comparison between response times and event-related potentials following lesions to left temporal cortex

Priming and competition of associated memory representations: A comparison between response times and event-related potentials following lesions to left temporal cortex

Type 1 Diabetes Modifies Brain Activation in Young Patients While Performing Visuospatial Working Memory Tasks.

In recent years, increasing attention has been paid to the effects of Type 1 Diabetes (T1D) on cognitive functions. T1D onset usually occurs during childhood, so it is possible that the brain could be affected during neurodevelopment. We selected young patients of normal intelligence with T1D onset during neurodevelopment, no complications from diabetes, and adequate glycemic control. The purpose of this study was to compare the neural BOLD activation pattern in a group of patients with T1D versus healthy control subjects while performing a visuospatial working memory task. Sixteen patients and 16 matched healthy control subjects participated. There was no significant statistical difference in behavioral performance between the groups, but, in accordance with our hypothesis, results showed distinct brain activation patterns. Control subjects presented the expected activations related to the task, whereas the patients had greater activation in the prefrontal inferior cortex, basal ganglia, posterior cerebellum, and substantia nigra. These different patterns could be due to compensation mechanisms that allow them to maintain a behavioral performance similar to that of control subjects.

Neural systems for cognitive reappraisal in children and adolescents with autism spectrum disorder

Despite substantial clinical and anecdotal evidence for emotion dysregulation in individuals with autism spectrum disorder (ASD), little is known about the neural substrates underlying this phenomenon. We sought to explore neural mechanisms for cognitive reappraisal in children and adolescents with ASD using functional magnetic resonance imaging (fMRI). We studied 16 youth with ASD and 15 age- and IQ-matched typically developing (TD) comparison youth. Participants were instructed in the use of cognitive reappraisal strategies to increase and decrease their emotional responses to disgusting images. Participants in both groups displayed distinct patterns of brain activity for increasing versus decreasing their emotions. TD participants showed downregulation of bilateral insula and left amygdala on decrease trials, whereas ASD participants showed no modulation of insula and upregulation of left amygdala. Furthermore, TD youth exhibited increased functional connectivity between amygdala and ventrolateral prefrontal cortex compared to ASD participants when downregulating disgust, as well as decreased functional connectivity between amygdala and orbitofrontal cortex. These findings have important implications for our understanding of emotion dysregulation and its treatment in ASD. In particular, the relative lack of prefrontal-amygdala connectivity provides a potential target for treatment-related outcome measurements.

Phasic dopamine release in the nucleus accumbens in response to pro-social 50 kHz ultrasonic vocalizations in rats.

Rats emit ultrasonic vocalizations (USVs) that are thought to serve as situation-dependent affective signals and accomplish important communicative functions. In appetitive situations, rats produce 50 kHz USVs, whereas 22 kHz USVs occur in aversive situations. Reception of 50 kHz USVs induces social approach behavior, while 22 kHz USVs lead to freezing behavior. These opposite behavioral responses are paralleled by distinct brain activation patterns, with 50 kHz USVs, but not 22 kHz USVs, activating neurons in the nucleus accumbens (NAcc). The NAcc mediates appetitive behavior and is critically modulated by dopaminergic afferents that are known to encode the value of reward. Therefore, we hypothesized that 50 kHz USVs, but not 22 kHz USVs, elicit NAcc dopamine release. While recording dopamine signaling with fast-scan cyclic voltammetry, freely moving rats were exposed to playback of four acoustic stimuli via an ultrasonic speaker in random order: (1) 50 kHz USVs, (2) 22 kHz USVs, (3) time- and amplitude-matched white noise, and (4) background noise. Only presentation of 50 kHz USVs induced phasic dopamine release and elicited approach behavior toward the speaker. Both of these effects, neurochemical and behavioral, were most pronounced during initial playback, but then declined rapidly with subsequent presentations, indicating a close temporal relationship between the two measures. Moreover, the magnitudes of these effects during initial playback were significantly correlated. Collectively, our findings show that NAcc dopamine release encodes pro-social 50 kHz USVs, but not alarming 22 kHz USVs. Thus, our results support the hypothesis that these call types are processed in distinct neuroanatomical regions and establish a functional link between pro-social communicative signals and reward-related neurotransmission.

Reward sensitivity modulation of brain activity during response inhibition

This work investigated the relationship between individual differences in reward sensitivity and the activity of brain regions involved in response inhibition. Participants (n = 51, 20 females) performed a stop-signal task while undergoing fMRI scanning. Inhibition of dominant responses during the task was associated to activation of bilateral anterior insula. Parameter estimates from these activation clusters were extracted to run an ROI analysis. Reward sensitivity, as measured by the Sensitivity to Reward (SR) scale from the SPSRQ (Torrubia et al., 2001), was negatively correlated with activity in right anterior insula. A whole-brain correlation analysis was also conducted, in which SR scores were negatively correlated with activity in the anterior cingulate cortex and the left supramarginal gyrus. These results suggest that individual differences in reward sensitivity may involve differences in cognitive processing that are manifested as distinct patterns of brain activation, even in the absence of explicit reward contingencies.

Distinct Patterns of Brain Activity Characterise Lexical Activation and Competition in Spoken Word Production

According to a prominent theory of language production, concepts activate multiple associated words in memory, which enter into competition for selection. However, only a few electrophysiological studies have identified brain responses reflecting competition. Here, we report a magnetoencephalography study in which the activation of competing words was manipulated by presenting pictures (e.g., dog) with distractor words. The distractor and picture name were semantically related (cat), unrelated (pin), or identical (dog). Related distractors are stronger competitors to the picture name because they receive additional activation from the picture relative to other distractors. Picture naming times were longer with related than unrelated and identical distractors. Phase-locked and non-phase-locked activity were distinct but temporally related. Phase-locked activity in left temporal cortex, peaking at 400 ms, was larger on unrelated than related and identical trials, suggesting differential activation of alternative words by the picture-word stimuli. Non-phase-locked activity between roughly 350–650 ms (4–10 Hz) in left superior frontal gyrus was larger on related than unrelated and identical trials, suggesting differential resolution of the competition among the alternatives, as reflected in the naming times. These findings characterise distinct patterns of activity associated with lexical activation and competition, supporting the theory that words are selected by competition.

Fusion analysis of functional MRI data for classification of individuals based on patterns of activation

Classification of individuals based on patterns of brain activity observed in functional MRI contrasts may be helpful for diagnosis of neurological disorders. Prior work for classification based on these patterns have primarily focused on using a single contrast, which does not take advantage of complementary information that may be available in multiple contrasts. Where multiple contrasts are used, the objective has been only to identify the joint, distinct brain activity patterns that differ between groups of subjects; not to use the information to classify individuals. Here, we use joint Independent Component Analysis (jICA) within a Support Vector Machine (SVM) classification method, and take advantage of the relative contribution of activation patterns generated from multiple fMRI contrasts to improve classification accuracy. Young (age: 19-26) and older (age: 57-73) adults (16 each) were scanned while listening to noise alone and to speech degraded with noise, half of which contained meaningful context that could be used to enhance intelligibility. Functional contrasts based on these conditions (and a silent baseline condition) were used within jICA to generate spatially independent joint activation sources and their corresponding modulation profiles. Modulation profiles were used within a non-linear SVM framework to classify individuals as young or older. Results demonstrate that a combination of activation maps across the multiple contrasts yielded an area under ROC curve of 0.86, superior to classification resulting from individual contrasts. Moreover, class separability, measured by a divergence criterion, was substantially higher when using the combination of activation maps.

Two Distinct Dynamic Modes Subtend the Detection of Unexpected Sounds

The brain response to auditory novelty comprises two main EEG components: an early mismatch negativity and a late P300. Whereas the former has been proposed to reflect a prediction error, the latter is often associated with working memory updating. Interestingly, these two proposals predict fundamentally different dynamics: prediction errors are thought to propagate serially through several distinct brain areas, while working memory supposes that activity is sustained over time within a stable set of brain areas. Here we test this temporal dissociation by showing how the generalization of brain activity patterns across time can characterize the dynamics of the underlying neural processes. This method is applied to magnetoencephalography (MEG) recordings acquired from healthy participants who were presented with two types of auditory novelty. Following our predictions, the results show that the mismatch evoked by a local novelty leads to the sequential recruitment of distinct and short-lived patterns of brain activity. In sharp contrast, the global novelty evoked by an unexpected sequence of five sounds elicits a sustained state of brain activity that lasts for several hundreds of milliseconds. The present results highlight how MEG combined with multivariate pattern analyses can characterize the dynamics of human cortical processes.

Spatiotemporal and time-frequency analysis of functional near infrared spectroscopy brain signals using independent component analysis

Functional near infrared spectroscopy (fNIRS) is a noninvasive method to capture brain activities according to the measurements of changes in both oxyhemoglobin and deoxyhemoglobin concentrations. However, fNIRS recordings are the hemodynamic signals that come from the latent neural sources that are spatially and temporally mixed across the brain. The purpose of this work is to extract the temporal and frequency characteristics as well as the spatial activation patterns in the brains using independent component analysis (ICA). In this study, the filtered fNIRS recordings were processed and the time-frequency and spatiotemporal domain independent components (ICs) were identified by ICA. We found that multiple task-related components can be separated by ICA in time-frequency domain, and distinct spatial patterns of brain activity can be derived from ICs that are well correlated with the specific neural events, such as finger tapping tasks.