fMRI Investigation Research Articles

On the difficulty to communicate with fMRI-based protocols used to identify covert awareness

Assessment of awareness in patients with disorders of consciousness such as patients in a vegetative state (unresponsive wakefulness syndrome, UWS) and patients in a minimally conscious state (MCS) remains difficult, with a high rate of misdiagnosis (around 40%). While patients with UWS have no awareness, patients with MCS have partial preservation of conscious awareness. To improve the assessment of awareness in these patients, recent functional neuroimaging protocols have been developed. However, does the complexity of realizing and interpreting these functional magnetic resonance imaging (fMRI) investigation protocols, which are currently carried out by only a few specialist teams, permit generalizable use in clinical routine?In this study, 32 healthy volunteers, by definition perfectly conscious and able to efficiently communicate, performed the protocol proposed by Monti et al. in 2010. Four methods (comprising the method proposed by Monti et al., a mean squared error-based method, a correlation-based method, and a support vector machine-based method) were tested for correctly and accurately interpreting the communication task.Firstly, the different instructions for the localizer and the communication tasks had no effect on activations. Secondly, 25% of participants (8/32) did not provide the expected patterns of activations during fMRI tasks (four for each imagery task). However, this did not necessarily prevent the classification methods from correctly guessing the answers during the communication task. Conversely, these classification methods may fail to detect the correct answers even though participants activated the expected brain areas. None of the four methods produced 100% correct detection during the communication phases. The correlation-based method obtained the best results with an error rate of 4.2%.The results of this study demonstrate that fMRI-based communication paradigms may not be robust enough to reliably detect awareness in all aware patients. There is still a need to develop new statistical and analytical methods before considering their generalization in clinical routine.

An fMRI investigation into the effect of preceding stimuli during visual oddball tasks

BackgroundThis study investigates the modulatory effect of stimulus sequence on neural responses to novel stimuli. A group of 34 healthy volunteers underwent event-related functional magnetic resonance imaging while performing a three-stimulus visual oddball task, involving randomly presented frequent stimuli and two types of infrequent stimuli – targets and distractors. New methodWe developed a modified categorization of rare stimuli that incorporated the type of preceding rare stimulus, and analyzed the event-related functional data according to this sequence categorization; specifically, we explored hemodynamic response modulation associated with increasing rare-to-rare stimulus interval. ResultsFor two consecutive targets, a modulation of brain function was evident throughout posterior midline and lateral temporal cortex, while responses to targets preceded by distractors were modulated in a widely distributed fronto-parietal system. As for distractors that follow targets, brain function was modulated throughout a set of posterior brain structures. For two successive distractors, however, no significant modulation was observed, which is consistent with previous studies and our primary hypothesis. Comparison with existing methodsThe addition of the aforementioned technique extends the possibilities of conventional oddball task analysis, enabling researchers to explore the effects of the whole range of rare stimuli intervals. ConclusionThis methodology can be applied to study a wide range of associated cognitive mechanisms, such as decision making, expectancy and attention.

Case-Based fMRI Analysis after Cognitive Rehabilitation in MS: A Novel Approach

Cognitive decline in multiple sclerosis (MS) negatively impacts patients' everyday functioning and quality of life. Since symptomatic pharmacological treatment is not yet available alternative treatment strategies such as cognitive rehabilitation are of particular interest. To analyse the ways in which MS patients respond to cognitive training, by combining behavioral and fMRI data in a case-based triangulation approach. Ten relapsing-remitting (RR) MS patients aged between 39 and 58 years and between 1 and 8 years post MS diagnosis were included. EDSS ranged from 1 to 3.5. Participants had normal to high intelligence levels. Six patients were assigned to the training group (TG) and four to the control group (CG) without intervention. The TG received a 4-week computerized working memory (WM) training, consisting of 16 training sessions of 45 min duration each. Before and after the training a neuropsychological examination and fMRI investigation by using an N-back task of different complexity was applied. Patients in the TG responded differently to cognitive training. Four participants did not meet the triangulation criteria for being treatment responders. The two responders showed two distinct changes regarding activation patterns after training: (I) decreased brain activation associated with increased processing speed and (II) increased brain activation associated with higher processing speed and WM performance. The occurrence of different and opposed response patterns after the same training indicates a risk in applying classical group statistics. Different and especially opposed patterns within the same sample may distort results of classical statistical comparisons. Thus, underlying processes may not be discovered and lead to misinterpretation of results.

Altered hemodynamic activity in conduct disorder: a resting-state FMRI investigation.

BackgroundYouth with conduct disorder (CD) not only inflict serious physical and psychological harm on others, but are also at greatly increased risk of sustaining injuries, developing depression or substance abuse, and engaging in criminal behaviors. The underlying neurobiological basis of CD remains unclear.ObjectiveThe present study investigated whether participants with CD have altered hemodynamic activity under resting-state conditions.MethodsEighteen medication-naïve boys with CD and 18 age- and sex- matched typically developing (TD) controls underwent functional magnetic resonance imaging (MRI) scans in the resting state. The amplitude of low-frequency fluctuations (ALFF) was measured and compared between the CD and TD groups.ResultsCompared with the TD participants, the CD participants showed lower ALFF in the bilateral amygdala/parahippocampus, right lingual gyrus, left cuneus and right insula. Higher ALFF was observed in the right fusiform gyrus and right thalamus in the CD participants compared to the TD group.ConclusionsYouth with CD displayed widespread functional abnormalities in emotion-related and visual cortical regions in the resting state. These results suggest that deficits in the intrinsic activity of resting state networks may contribute to the etiology of CD.

Effects of personal space intrusion in affective contexts: an fMRI investigation with women suffering from borderline personality disorder.

The amygdala and the parietal cortex play a key role in the neural representation of personal space. Although the concept of personal space is clinically very relevant for borderline personality disorder (BPD), especially in affective contexts, it has not been investigated thus far with functional magnetic resonance imaging (fMRI). In this fMRI study, 25 female BPD patients and 25 healthy women were exposed to photos of angry, disgusted and neutral facial expressions. All stimuli were once shown as still photos, and once were zoomed-in in order to simulate intrusion into one's own personal space. Approaching faces generally provoked activation of the amygdala and the somatosensory cortex. BPD patients showed an increased activation within both regions, but only toward approaching disgusted faces. Their amygdala activation in this specific condition positively correlated with self-disgust scores. Moreover, the clinical group indicated an enhanced personal distance preference, which was associated with parietal activation. The present study revealed altered personal space processing of BPD patients, especially in situations that relate to social contexts involving disgust. Future studies should focus on the temporal stability of personal space processing during the natural course of BPD as well as during therapy.

Journal Digest

Journal Digest

Resting State fMRI Investigation of ECT-Mediated Neurocognitive Effects

Resting State fMRI Investigation of ECT-Mediated Neurocognitive Effects

Domain-independent neural underpinning of task-switching: An fMRI investigation

The ability to shift between different tasks according to internal or external demands, which is at the core of our behavioral flexibility, has been generally linked to the functionality of left fronto-parietal regions. Traditionally, the left and right hemispheres have also been associated with verbal and spatial processing, respectively. We therefore investigated with functional MRI whether the processes engaged during task-switching interact in the brain with the domain of the tasks to be switched, that is, verbal or spatial. Importantly, physical stimuli were exactly the same and participants' performance was matched between the two domains. The fMRI results showed a clearly left-lateralized involvement of fronto-parietal regions when contrasting task-switching versus single task blocks in the context of verbal rules. A more bilateral pattern, especially in the prefrontal cortex, was instead observed for switching between spatial tasks. Moreover, while a conjunction analysis showed that the core regions involved in task-switching, independently of the switching context, were localized both in left inferior prefrontal and parietal cortices and in bilateral supplementary motor area, a direct analysis of functional lateralization revealed that hemispheric asymmetries in the frontal lobes were more biased toward the left side for the verbal domain than for the spatial one and vice versa. Overall, these findings highlight the role of left fronto-parietal regions in task-switching, above and beyond the specific task requirements, but also show that hemispheric asymmetries may be modulated by the more specific nature of the tasks to be performed during task-switching.

An fMRI investigation of expectation violation in magic tricks.

Magic tricks violate the expected causal relationships that form an implicit belief system about what is possible in the world around us. Observing a magic effect seemingly invalidates our implicit assumptions about what action causes which outcome. We aimed at identifying the neural correlates of such expectation violations by contrasting 24 video clips of magic tricks with 24 control clips in which the expected action-outcome relationship is upheld. Using fMRI, we measured the brain activity of 25 normal volunteers while they watched the clips in the scanner. Additionally, we measured the professional magician who had performed the magic tricks under the assumption that, in contrast to naïve observers, the magician himself would not perceive his own magic tricks as an expectation violation. As the main effect of magic – control clips in the normal sample, we found higher activity for magic in the head of the caudate nucleus (CN) bilaterally, the left inferior frontal gyrus and the left anterior insula. As expected, the magician’s brain activity substantially differed from these results, with mainly parietal areas (supramarginal gyrus bilaterally) activated, supporting our hypothesis that he did not experience any expectation violation. These findings are in accordance with previous research that has implicated the head of the CN in processing changes in the contingency between action and outcome, even in the absence of reward or feedback.

Reasoning with linear orders: differential parietal cortex activation in sub-clinical depression. An FMRI investigation in sub-clinical depression and controls.

The capacity to learn new information and manipulate it for efficient retrieval has long been studied through reasoning paradigms, which also has applicability to the study of social behavior. Humans can learn about the linear order within groups using reasoning, and the success of such reasoning may vary according to affective state, such as depression. We investigated the neural basis of these latter findings using functional neuroimaging. Using BDI-II criteria, 14 non-depressed (ND) and 12 mildly depressed volunteers took part in a linear-order reasoning task during functional magnetic resonance imaging. The hippocampus, parietal, and prefrontal cortices were activated during the task, in accordance with previous studies. In the learning phase and in the test phase, greater activation of the parietal cortex was found in the depressed group, which may be a compensatory mechanism in order to reach the same behavioral performance as the ND group, or evidence for a different reasoning strategy in the depressed group.

An fMRI Investigation into Facial Affect Perception in Body Dysmorphic Disorder

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Preserved cumulative semantic interference despite amnesia

Preserved cumulative semantic interference despite amnesia

Relationship between chronic pain and brain reorganization after deafferentation: A systematic review of functional MRI findings.

BackgroundMechanisms underlying the development of phantom limb pain and neuropathic pain after limb amputation and spinal cord injury, respectively, are poorly understood. The goal of this systematic review was to assess the robustness of evidence in support of “maladaptive plasticity” emerging from applications of advanced functional magnetic resonance imaging (MRI).MethodsUsing MeSH heading search terms in PubMed and SCOPUS, a systematic review was performed querying published manuscripts.ResultsFrom 146 candidate publications, 10 were identified as meeting the inclusion criteria. Results from fMRI investigations provided some level of support for maladaptive cortical plasticity, including longitudinal studies that demonstrated a change in functional organization related to decreases in pain. However, a number of studies have reported no relationship between reorganization, pain and deafferentation, and emerging evidence has also suggested the opposite — that is, chronic pain is associated with preserved cortical function.ConclusionBased solely on advanced functional neuroimaging results, there is only limited evidence for a relationship between chronic pain intensity and reorganization after deafferentation. The review demonstrates the need for additional neuroimaging studies to clarify the relationship between chronic pain and reorganization.

Functional Brain Connectivity During Fear of Pain: A Comparison Between Dental Phobics and Controls

Fear of pain is the most common reason for avoiding the dentist by patients suffering from dental phobia. Previous functional magnetic resonance imaging investigations demonstrated that already thinking about pain during the viewing of images depicting dental treatment provoked enhanced orbitofrontal cortex (OFC) activation in the clinical group. In the present study, the authors investigated whether this differential activation can be explained by differential connectivity patterns between patients and controls. They found that the control subjects displayed a stronger and more widespread connectivity compared to patients. This connectivity pattern comprised prefrontal seeds (e.g., the anterior cingulate cortex), which were coupled with limbic structures (e.g., the amygdala) and the basal ganglia (putamen, pallidum, caudate nucleus). This pattern might reflect successful emotion regulation, which was absent in the clinical group. The patients showed coupling of the OFC and the caudate nucleus, which may be the neural correlate of associating pain with dental treatment.

An fMRI investigation of consumer choice regarding controversial food technologies

Consumers must routinely decide whether to pay more for a perceived higher quality good or pay less for lower perceived quality. This study examined brain activations when consumers considered such a tradeoff in the context of food choice involving lower-priced options produced with controversial modern agricultural technologies. Functional magnetic resonance imaging (fMRI) data were obtained while consumers (n=47) made choices between two milk options which varied in price and/or use of technology (growth hormones and cloning). Results revealed both deliberative and affective processes were involved when deciding whether to choose a higher-price, more “natural” food. Brain activations in the dorsolateral prefrontal cortex and insula predicted the choice of higher-priced but more “natural” foods produced without the use of controversial technology. Brain activations in price-alone or technology-alone decisions predicted behavior in choice tasks involving price-technology tradeoffs, revealing cross-task predictive power. One of the key issues this study addresses is which type of data (e.g., behavioral, neuroimaging, or self-report) best predicts choice between a higher priced option that avoids technologies and a lower price option that uses modern food technologies. Estimates indicate that the best fitting model is one that included all types of data considered: demographics, psychometric scales, product attributes, and neural activations observed via fMRI. Overall, neuroimaging data adds significant predictive and explanatory power beyond the measures typically used in consumer research.

Is Motor Inhibition Mediated by Cerebello-cortical Interactions?

Motor inhibition is an essential skill for fully adapted behavior requiring motor control and higher-order functions of motor cognition. A wide set of cortical and subcortical areas, including the right inferior frontal gyrus, the pre-supplementary motor area, and the subthalamic nucleus in the basal ganglia, contribute to convey the inhibitory command to the motor cortex. In the present review, we discuss how recent evidence supports the idea that the cerebellum may also have a relevant contribution in certain aspects of motor inhibition. This evidence were provided by behavioral data collected in patients with cerebellar lesions, functional magnetic resonance (fMRI) investigations conducted in clinical samples and in healthy participants, and by transcranial magnetic stimulation (TMS) techniques used to non-invasively test cerebello-motor functional connectivity. The application of these methods, combined with the execution of inhibitory tasks, could provide new evidence for a causal role of the effective cerebello-cortical connectivity in motor inhibition. Understanding the neurophysiological mechanisms that mediate motor inhibition through the cerebellum could be essential to design new rehabilitative protocols for treating several neurological and psychiatric disorders characterized by disinhibited behavior such as addiction, schizophrenia, attention deficit hyperactivity disorder (ADHD) and Parkinson's disease.

A-06 * An fMRI Investigation of Visual Judgment in Older Adults and its Relationship with a Measure of Lutein and Zeaxanthin

A-06 * An fMRI Investigation of Visual Judgment in Older Adults and its Relationship with a Measure of Lutein and Zeaxanthin

Brain correlates of response inhibition in Internet gaming disorder.

The present study aimed to evaluate the brain correlates of response inhibition among subjects with Internet gaming disorder (IGD). For this purpose, 15 men with IGD for at least 1 year, and 15 controls with no history of IGD were recruited to perform the Go/Nogo task under functional magnetic resonance imaging investigation. Prior to scanning, the subjects were assessed using the Chen Internet Addiction Scale and the Barrett Impulsivity Scale. The control group exhibited activation of the right supplement motor area (SMA), dorsolateral prefrontal cortex, and caudate for response inhibition. However, the IGD group had a higher impulsivity and lower activity of the right SMA/pre-SMA in comparison to the control group. The results obtained suggest that dysfunctional activation of the SMA for response inhibition is one of the candidate mechanisms of IGD.

Neuromarkers of fatigue and cognitive complaints following chemotherapy for breast cancer: a prospective fMRI investigation.

The aim of this study is to use functional magnetic resonance imaging (fMRI) to prospectively examine pre-treatment predictors of post-treatment fatigue and cognitive dysfunction in women treated with adjuvant chemotherapy for breast cancer. Fatigue and cognitive dysfunction often co-occur in women treated for breast cancer. We hypothesized that pre-treatment factors, unrelated to chemotherapy per se, might increase vulnerability to post-treatment fatigue and cognitive dysfunction. Patients treated with (n=28) or without chemotherapy (n=37) and healthy controls (n=32) were scanned coincident with pre- and one-month post-chemotherapy during a verbal working memory task (VWMT) and assessed for fatigue, worry, and cognitive dysfunction. fMRI activity measures in the frontoparietal executive network were used in multiple linear regression to predict post-treatment fatigue and cognitive function. The chemotherapy group reported greater pre-treatment fatigue than controls and showed compromised neural response, characterized by higher spatial variance in executive network activity, than the non-chemotherapy group. Also, the chemotherapy group reported greater post-treatment fatigue than the other groups. Linear regression indicated that pre-treatment spatial variance in executive network activation predicted post-treatment fatigue severity and cognitive complaints, while treatment group, age, hemoglobin, worry, and mean executive network activity levels did not predict these outcomes. Pre-treatment neural inefficiency (indexed by high spatial variance) in the executive network, which supports attention and working memory, was a better predictor of post-treatment cognitive and fatigue complaints than exposure to chemotherapy per se. This executive network compromise could be a pre-treatment neuromarker of risk, indicating patients most likely to benefit from early intervention for fatigue and cognitive dysfunction.

An anatomical and functional topography of human auditory cortical areas.

While advances in magnetic resonance imaging (MRI) throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla). Importantly, we illustrate that—whereas a group-based approach to analyze functional (tonotopic) maps is appropriate to highlight the main tonotopic axis—the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e., myelination) as well as of functional properties (e.g., broadness of frequency tuning) is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post-mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions.