[Show abstract][Hide abstract] ABSTRACT: There is a long-standing debate about the neurocognitive implementation of mental imagery. One form of mental imagery is the imagery of visual motion, which is of interest due to its naturalistic and dynamic character. However, so far only the mere occurrence rather than the specific content of motion imagery was shown to be detectable. In the current study, the application of multi-voxel pattern analysis to high-resolution functional data of 12 subjects acquired with ultra-high field 7 Tesla functional Magnetic Resonance Imaging allowed us to show that imagery of visual motion can indeed activate the earliest levels of the visual hierarchy, but the extent thereof varies highly between subjects. Our approach enabled classification not only of complex imagery, but also of its actual contents, in that the direction of imagined motion out of four options was successfully identified in two thirds of the subjects and with accuracies of up to 91.3% in individual subjects. A searchlight analysis confirmed the local origin of decodable information in striate and extra-striate cortex. These high-accuracy findings not only shed new light on a central question in vision science on the constituents of mental imagery, but also show for the first time that the specific sub-categorical content of visual motion imagery is reliably decodable from brain imaging data on a single-subject level.
[Show abstract][Hide abstract] ABSTRACT: Spider phobics show an exaggerated fear response when encountering spiders. This fear response is aggravated by negative and irrational beliefs about the feared object. Cognitive reappraisal can target these beliefs, and therefore has a fear regulating effect. The presented study investigated if neurofeedback derived from functional magnetic resonance imaging (fMRI) would facilitate anxiety regulation by cognitive reappraisal, using spider phobia as a model of anxiety disorders. Feedback was provided based on activation in left dorsolateral prefrontal cortex and right insula, as indicators of engagement and regulation success, respectively.
Eighteen female spider phobics participated in a randomized, controlled, single-blinded study. All participants completed a training session in the MRI scanner. Participants assigned to the neurofeedback condition were instructed to shape their regulatory strategy based on the provided feedback. Participants assigned to the control condition were asked to adapt their strategy intuitively.
Neurofeedback participants exhibited lower anxiety levels than the control group at the end of the training. In addition, only neurofeedback participants achieved down-regulation of insula activation levels by cognitive reappraisal. Group differences became more pronounced over time, supporting learning as a mechanism behind this effect. Importantly, within the neurofeedback group, achieved changes in insula activation levels during training predicted long-term anxiety reduction.
The conducted study provides first evidence that fMRI neurofeedback has a facilitating effect on anxiety regulation in spider phobia.
Full-text · Article · Jun 2015 · Frontiers in Behavioral Neuroscience
[Show abstract][Hide abstract] ABSTRACT: The goal of neurofeedback training is to provide participants with relevant information on their ongoing brain processes in order to enable them to change these processes in a meaningful way. Under the assumption of an intrinsic brain-behavior link, neurofeedback can be a tool to guide a participant towards a desired behavioral state, such as a healthier state in the case of patients. Current research in clinical neuroscience regarding the most robust indicators of pathological brain processes in psychiatric and neurological disorders indicates that fMRI-based functional connectivity measures may be among the most important biomarkers of disease. The present study therefore investigated the general potential of providing fMRI neurofeedback based on functional correlations, computed from short-window time course data at the level of single task periods. The ability to detect subtle changes in task performance with block-wise functional connectivity measures was evaluated based on imaging data from healthy participants performing a simple motor task, which was systematically varied along two task dimensions representing two different aspects of task difficulty. The results demonstrate that fMRI-based functional connectivity measures may provide a better indicator for an increase in overall (motor) task difficulty than activation level-based measures. Windowed functional correlations thus seem to provide relevant and unique information regarding ongoing brain processes, which is not captured equally well by standard activation level-based neurofeedback measures. Functional connectivity markers, therefore, may indeed provide a valuable tool to enhance and monitor learning within an fMRI neurofeedback setup.
[Show abstract][Hide abstract] ABSTRACT: Neuroimaging biomarkers of depression have potential to aid diagnosis, identify individuals at risk and predict treatment response or course of illness. Nevertheless none have been identified so far, potentially because no single brain parameter captures the complexity of the pathophysiology of depression. Multi-voxel pattern analysis (MVPA) may overcome this issue as it can identify patterns of voxels that are spatially distributed across the brain. Here we present the results of an MVPA to investigate the neuronal patterns underlying passive viewing of positive, negative and neutral pictures in depressed patients. A linear support vector machine (SVM) was trained to discriminate different valence conditions based on the functional magnetic resonance imaging (fMRI) data of nine unipolar depressed patients. A similar dataset obtained in nine healthy individuals was included to conduct a group classification analysis via linear discriminant analysis (LDA). Accuracy scores of 86% or higher were obtained for each valence contrast via patterns that included limbic areas such as the amygdala and frontal areas such as the ventrolateral prefrontal cortex. The LDA identified two areas (the dorsomedial prefrontal cortex and caudate nucleus) that allowed group classification with 72.2% accuracy. Our preliminary findings suggest that MVPA can identify stable valence patterns, with more sensitivity than univariate analysis, in depressed participants and that it may be possible to discriminate between healthy and depressed individuals based on differences in the brain's response to emotional cues.
Full-text · Article · May 2013 · Clinical neuroimaging
[Show abstract][Hide abstract] ABSTRACT: Many patients with Disorders of Consciousness (DOC) are misdiagnosed for a variety of reasons. These patients typically cannot communicate. Because such patients are not provided with the needed tools, one of their basic human needs remains unsatisfied, leaving them truly locked in to their bodies. This chapter first reviews current methods and problems of diagnoses and assistive technology for communication, supporting the view that advances in both respects are needed for patients with DOC. The authors also discuss possible solutions to these problems and introduce emerging developments based on EEG (Electroencephalography), fMRI (Functional Magnetic Resonance Imaging), and fNIRS (Functional Near-Infrared Spectroscopy) that have been validated with patients and healthy volunteers.
[Show abstract][Hide abstract] ABSTRACT: A substantial number of patients who survive severe brain injury progress to a nonresponsive state of wakeful unawareness, referred to as a vegetative state (VS). They appear to be awake, but show no signs of awareness of themselves, or of their environment in repeated clinical examinations. However, recent neuroimaging research demonstrates that some VS patients can respond to commands by willfully modulating their brain activity according to instruction. Brain-computer interfaces (BCIs) may allow such patients to circumvent the barriers imposed by their behavioral limitations and communicate with the outside world. However, although such devices would undoubtedly improve the quality of life for some patients and their families, developing BCI systems for behaviorally nonresponsive patients presents substantial technical and clinical challenges. Here we review the state of the art of BCI research across noninvasive neuroimaging technologies, and propose how such systems should be developed further to provide fully fledged communication systems for behaviorally nonresponsive populations. Ann Neurol 2012;72:312-323.
Full-text · Article · Sep 2012 · Annals of Neurology
[Show abstract][Hide abstract] ABSTRACT: Since the successful demonstration of “brain reading” of fMRI BOLD signals using multivoxel pattern classification (MVPA) techniques, the neuroimaging community has made vigorous attempts to exploit the technique in order to identify the signature patterns of brain activities associated with different cognitive processes or mental states. In the current study, we tested whether the valence and arousal dimensions of the affective information could be used to successfully predict individual’s active affective states. Using a whole-brain MVPA approach, together with feature elimination procedures, we are able to discriminate between brain activation patterns associated with the processing of positive or negative valence and cross validate the discriminant function with an independent data set. Arousal information, on the other hand, failed to provide such discriminating power. With an independent sample, we test further whether the MVPA identified brain network could be used for inter-individual classification. Although the inter-subject classification success was only marginal, we found correlations with individual differences in affective processing. We discuss the implications of our findings for future attempts to classify patients based on their responses to affective stimuli.
[Show abstract][Hide abstract] ABSTRACT: Human communication entirely depends on the functional integrity of the neuromuscular system. This is devastatingly illustrated in clinical conditions such as the so-called locked-in syndrome (LIS), in which severely motor-disabled patients become incapable to communicate naturally--while being fully conscious and awake. For the last 20 years, research on motor-independent communication has focused on developing brain-computer interfaces (BCIs) implementing neuroelectric signals for communication (e.g., [2-7]), and BCIs based on electroencephalography (EEG) have already been applied successfully to concerned patients. However, not all patients achieve proficiency in EEG-based BCI control. Thus, more recently, hemodynamic brain signals have also been explored for BCI purposes. Here, we introduce the first spelling device based on fMRI. By exploiting spatiotemporal characteristics of hemodynamic responses, evoked by performing differently timed mental imagery tasks, our novel letter encoding technique allows translating any freely chosen answer (letter-by-letter) into reliable and differentiable single-trial fMRI signals. Most importantly, automated letter decoding in real time enables back-and-forth communication within a single scanning session. Because the suggested spelling device requires only little effort and pretraining, it is immediately operational and possesses high potential for clinical applications, both in terms of diagnostics and establishing short-term communication with nonresponsive and severely motor-impaired patients.
No preview · Article · Jun 2012 · Current biology: CB
[Show abstract][Hide abstract] ABSTRACT: Many patients show no or incomplete responses to current pharmacological or psychological therapies for depression. Here we explored the feasibility of a new brain self-regulation technique that integrates psychological and neurobiological approaches through neurofeedback with functional magnetic resonance imaging (fMRI). In a proof-of-concept study, eight patients with depression learned to upregulate brain areas involved in the generation of positive emotions (such as the ventrolateral prefrontal cortex (VLPFC) and insula) during four neurofeedback sessions. Their clinical symptoms, as assessed with the 17-item Hamilton Rating Scale for Depression (HDRS), improved significantly. A control group that underwent a training procedure with the same cognitive strategies but without neurofeedback did not improve clinically. Randomised blinded clinical trials are now needed to exclude possible placebo effects and to determine whether fMRI-based neurofeedback might become a useful adjunct to current therapies for depression.
[Show abstract][Hide abstract] ABSTRACT: A brain-computer interface (BCI) is a system allowing for communication between the brain and the external environment. It is independent from any peripheral neural or muscular activity and it directly converts brain activity into a computerized command. In this chapter, we present the recent progress in the development of BCIs. Moreover, we discuss clinical applications in LIS patients and studies performed in patients recovering from coma.
[Show abstract][Hide abstract] ABSTRACT: Patients with striate cortex damage and clinical blindness retain the ability to process certain visual properties of stimuli that they are not aware of seeing. Here we investigated the neural correlates of residual visual perception for dynamic whole-body emotional actions. Angry and neutral emotional whole-body actions were presented in the intact and blind visual hemifield of a cortically blind patient with unilateral destruction of striate cortex. Comparisons of angry vs. neutral actions performed separately in the blind and intact visual hemifield showed in both cases increased activation in primary somatosensory, motor, and premotor cortices. Activations selective for intact hemifield presentation of angry compared with neutral actions were located subcortically in the right lateral geniculate nucleus and cortically in the superior temporal sulcus, prefrontal cortex, precuneus, and intraparietal sulcus. Activations specific for blind hemifield presentation of angry compared with neutral actions were found in the bilateral superior colliculus, pulvinar nucleus of the thalamus, amygdala, and right fusiform gyrus. Direct comparison of emotional modulation in the blind vs. intact visual hemifield revealed selective activity in the right superior colliculus and bilateral pulvinar for angry expressions, thereby showing a selective involvement of these subcortical structures in nonconscious visual emotion perception.
Full-text · Article · Sep 2011 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: To describe cortical reorganization after classic hypoglossal-facial nerve anastomosis (HFA) (four patients), hypoglossal-facial nerve jump anastomosis (HFJA) (three patients), and facial nerve interpositional graft (FNIG) (three patients).
Prospective case series.
Functional magnetic resonance imaging (fMRI) was performed during lip and tongue movement using a block or an event-related design.
Despite the presence of some intersubject variability, the following general brain activation patterns were revealed: As expected, lip movements after FNIG led to selective brain activation in the original facial motor cortex, and lip movements after HFA were associated with activation in the hypoglossal motor cortex. Following HFJA, lip movements resulted in overlapping activation encompassing both the original facial and the hypoglossal motor cortex, but tongue movements led solely to strong activation within the original hypoglossal motor cortex. In contrast, tongue movements after HFA were associated with strong activation in the original hypoglossal motor cortex and weaker activation in the facial motor cortex.
Direct facial nerve repair (FNIG) leads to restoration of the original cortical activation. A cross nerve suture (HFA or HFJA) changes cortical activation and leads to different patterns of cortical activation during lip and tongue movements.
[Show abstract][Hide abstract] ABSTRACT: In natural environments, a sound can be heard as stable despite the presence of other occasionally louder sounds. For example, when a portion in a voice is replaced by masking noise, the interrupted voice may still appear illusorily continuous. Previous research found that continuity illusions of simple interrupted sounds, such as tones, are accompanied by weaker activity in the primary auditory cortex (PAC) during the interruption than veridical discontinuity percepts of these sounds. Here, we studied whether continuity illusions of more natural and more complex sounds also emerge from this mechanism. We used psychophysics and functional magnetic resonance imaging in humans to measure simultaneously continuity ratings and blood oxygenation level-dependent activity to vowels that were partially replaced by masking noise. Consistent with previous results on tone continuity illusions, we found listeners' reports of more salient vowel continuity illusions associated with weaker activity in auditory cortex (compared with reports of veridical discontinuity percepts of physically identical stimuli). In contrast to the reduced activity to tone continuity illusions in PAC, this reduction was localized in the right anterolateral Heschl's gyrus, a region that corresponds more to the non-PAC. Our findings suggest that the ability to hear differently complex sounds as stable during other louder sounds may be attributable to a common suppressive mechanism that operates at different levels of sound representation in auditory cortex.
Preview · Article · Jan 2011 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience
[Show abstract][Hide abstract] ABSTRACT: Real-time functional MRI (rt-fMRI) allows for brain-computer interfaces based on hemodynamic brain signals and opens up various novel clinical applications. For example, rt-fMRI-based neurofeedback has been suggested as a novel tool for the treatment of neurological and psychopathological disorders. In contrast to conventional offline applications, neurofeedback requires the analysis of functional MRI signals online in order to provide participants with information about their brain activation during an ongoing MRI scan. Recent research supports the idea that an improvement of symptoms of diseases can be achieved if patients are trained with rt-fMRI-based neurofeedback to change their brain activation patterns. rt-fMRI also enables online 'brain-reading' applications that can be exploited to develop alternative communication and control devices for patients with severe motor impairments (e.g., 'locked-in patients). Although other methods, especially electroencephalography-based brain-computer interfacing, have been successfully used in this context, rt-fMRI-based methods may enable robust communication and control in cases where traditional approaches do not provide satisfactory results.
Full-text · Article · Aug 2010 · Imaging in medicine