Daniela Seixas

Resting-State Functional Magnetic Resonance Imaging for Language Preoperative Planning.

Functional magnetic resonance imaging (fMRI) is a well-known non-invasive technique for the study of brain function. One of its most common clinical applications is preoperative language mapping, essential for the preservation of function in neurosurgical patients. Typically, fMRI is used to track task-related activity, but poor task performance and movement artifacts can be critical limitations in clinical settings. Recent advances in resting-state protocols open new possibilities for pre-surgical mapping of language potentially overcoming these limitations. To test the feasibility of using resting-state fMRI instead of conventional active task-based protocols, we compared results from fifteen patients with brain lesions while performing a verb-to-noun generation task and while at rest. Task-activity was measured using a general linear model analysis and independent component analysis (ICA). Resting-state networks were extracted using ICA and further classified in two ways: manually by an expert and by using an automated template matching procedure. The results revealed that the automated classification procedure correctly identified language networks as compared to the expert manual classification. We found a good overlay between task-related activity and resting-state language maps, particularly within the language regions of interest. Furthermore, resting-state language maps were as sensitive as task-related maps, and had higher specificity. Our findings suggest that resting-state protocols may be suitable to map language networks in a quick and clinically efficient way.

Investigating the role of the ventromedial prefrontal cortex in the assessment of brands.

The ventromedial prefrontal cortex (vmPFC) is believed to be important in everyday preference judgments, processing emotions during decision-making. However, there is still controversy in the literature regarding the participation of the vmPFC. To further elucidate the contribution of the vmPFC in brand preference, we designed a functional magnetic resonance imaging (fMRI) study where 18 subjects assessed positive, indifferent, and fictitious brands. Also, both the period during and after the decision process were analyzed, hoping to unravel temporally the role of the vmPFC, using modeled and model-free fMRI analysis. Considering together the period before and after decision-making, there was activation of the vmPFC when comparing positive with indifferent or fictitious brands. However, when the decision-making period was separated from the moment after the response, and especially for positive brands, the vmPFC was more active after the choice than during the decision process itself, challenging some of the existing literature. The results of the present study support the notion that the vmPFC may be unimportant in the decision stage of brand preference, questioning theories that postulate that the vmPFC is in the origin of such a choice. Further studies are needed to investigate in detail why the vmPFC seems to be involved in brand preference only after the decision process.

Pain in multiple sclerosis: A systematic review of neuroimaging studies

Introduction While pain in multiple sclerosis (MS) is common, in many cases the precise mechanisms are unclear. Neuroimaging studies could have a valuable role in investigating the aetiology of pain syndromes. The aim of this review was to synthesise and appraise the current literature on neuroimaging studies of pain syndromes in MS. Methods We systematically searched PubMed and Scopus from their inception dates to the 2nd of April 2013. Studies were selected by predefined inclusion and exclusion criteria. Methodological quality was appraised. Descriptive statistical analysis was conducted. Results We identified 38 studies of variable methodology and quality. All studies but one used conventional structural magnetic resonance imaging, and the majority reported a positive association between location of demyelinating lesions and specific neuropathic pain syndromes. Most investigated headache and facial pain, with more common pain syndromes such as limb pain being relatively understudied. We identified a number of methodological concerns, which along with variable study design and reporting limit our ability to synthesise data. Higher quality studies were however less likely to report positive associations of lesion distribution to pain syndromes. Conclusions Further high quality hypothesis-driven neuroimaging studies of pain syndromes in MS are required to clarify pain mechanisms, particularly for the commonest pain syndromes.

Functional Transcranial Doppler: Presymptomatic Changes in Fabry Disease

Background and Aim: Cerebrovascular disease may progress asymptomatically in the early stages of Fabry disease (FD). Our aim was to test whether functional transcranial Doppler (fTCD) could provide useful data in the evaluation of these presymptomatic FD patients. Methods: A cohort of 12 adult FD patients from families with the classical phenotype of the disease was evaluated with fTCD in the posterior cerebral artery. Results: Compared to healthy controls, resting blood velocities were significantly lower in the FD cohort (p = 0.032 for systolic, p = 0.021 for diastolic). FTCD suggested a disturbed neurovascular coupling in the visual cortex of FD patients, with lower gain (p = 0.007) and rate time (p = 0.019). Men had a significantly higher attenuation (p = 0.013) and lower natural frequency (p = 0.046) than the heterozygous women. Conclusion: These data are the first to suggest that patients with FD may develop cortical vascular dysfunction in the territory of the posterior circulation, early in the natural history of the disease. If the present findings are confirmed in larger, prospective studies, fTCD will be useful for assessing stroke risk in as yet asymptomatic FD patients, improving preventive therapeutic management.

Ethics in fMRI Studies

Functional magnetic resonance imaging (fMRI) has surfaced as a powerful method to study brain function in humans. While the involvement of neuroradiologists in fMRI studies in the clinical setting is obvious, in neuroscience research most of the investigators are not specialists trained in reading brain images. Advances in neuroimaging are increasingly intersecting with issues of ethical, legal, and social interest. Debate on fMRI is starting, mainly under the impetus of a new interdisciplinary field, neuroethics. The objective of this review is to bring forth reflection and discussion about ethical issues regarding fMRI, with emphasis to the perspective of the neuroradiologist. EMBASE® and MEDLINE® were searched for articles pertaining to ethics in fMRI, between 1991 and 2007. A total of 42 articles were retrieved, 95% published in the last 6 years. Only 10% were published in radiology journals. The major potential ethical issues identified in the reviewed articles concerned recruitment of vulnerable groups; informed consent; incidental findings; limitations of the technique, interpretation and validity of results; risks and safety; confidentiality and privacy; fMRI applications outside the laboratory (presurgical planning; diagnostic and predictive potential; forensic, security, military and commercial use); and public communication of research results. Not all the identified issues in this review were directly relevant to neuroradiologists in particular, but for sure some did. Neuroradiologists must find the time and energy to have an important role in identifying and solving ethical (and related) issues in fMRI, working in collaboration with ethicists, social scientists, clinicians, neuroscience researchers, patients, healthy volunteers, journalists, marketers, lawyers, and policy makers.ZusammenfassungDie funktionale Magnetresonanztomographie (fMRT) hat sich als überzeugende Methode zum Studium der menschlichen Gehirnfunktion erwiesen. Während das Engagement der Neuroradiologen bei fMRI-Studien im klinischen Rahmen auf der Hand liegt, sind die meisten Forscher in der Neurowissenschaft keine Fachleute für die Auswertung der Bildgebung des Gehirns. Die Fortschritte in der Neuroradiologie tangieren zunehmend ethische, rechtliche und soziale Interessen. Es gibt bereits Diskussionen über fMRI, hauptsächlich vor dem Hintergrund eines neuen interdisziplinären Fachgebiets, der Neuroethik. Ziel dieser Übersicht ist es, Überlegungen und Diskussionen über ethische Fragen hinsichtlich der fMRT anzustellen, mit Betonung der Perspektive des Neuroradiologen. EMBASE® und MEDLINE® wurden nach Artikeln durchsucht, welche in der Zeit zwischen 1991 und 2007 erschienen sind und sich auf die Ethik in der fMRT beziehen. Insgesamt fanden sich 42 Artikel, von denen 95% in den letzten 6 Jahren publiziert wurden. Lediglich 10% der Artikel sind in radiologischen Fachzeitschriften erschienen. Die in den untersuchten Artikeln identifizierten wichtigsten, potentiell ethischen Fragen betrafen die Rekrutierung gefährdeter Gruppen, Patienteneinwilligung, zufällige Ergebnisse, Grenzen der Technik, Interpretation und Gültigkeit der Ergebnisse, Risiken und Sicherheit, Arztgeheimnis und Intimsphäre, fMRT-Anwendungen außerhalb des Labors (präoperative Planung, diagnostisches und prädiktives Potential, Forensik, Sicherheit, militärische und kommerzielle Nutzung) sowie die öffentliche Mitteilung der Forschungsergebnisse. Nicht alle in diesem Überblick identifizierten Fragen waren für Neuroradiologen unmittelbar relevant, einige allerdings schon. Neuroradiologen müssen die Zeit und Energie aufbringen, um eine wichtige Rolle bei der Identifikation und Lösung ethischer (und verwandter) Fragen der fMRT zu spielen, und mit Ethikern, Sozialwissenschaftlern, Klinikern, neurowissenschaftlichen Forschern, Patienten, gesunden Freiwilligen, Journalisten, Marketingplanern, Rechtsanwälten und Politikern zusammenarbeiten.

Pain in Portuguese patients with multiple sclerosis

Early reports often ignored pain as an important symptom in multiple sclerosis (MS). Pain prevalence figures in MS from European countries other than Portugal range between 40 and 65%. To our knowledge there is no published data in English on pain in MS in Portugal. We describe the demographic and clinical characteristics, with an emphasis on pain, of 85 MS patients followed-up in a Portuguese hospital, contributing to pain epidemiology in MS. Patients were interviewed sequentially after their regular appointments at the MS clinic; patients with pain completed The Brief Pain Inventory and The McGill Pain Questionnaire (MPQ). The prevalence of pain found was 34%. Headache and back pain were the most common anatomical sites described, followed by upper and lower limbs. Intensity of pain in an 11-point scale was, for the maximum pain intensity 6.7 ± 1.8, for the minimum pain intensity 2.2 ± 2.0, for the mean pain intensity 4.5 ± 1.5, and for the actual pain intensity 2.4 ± 2.9. Pain interfered significantly with general activity, mood, work, social relations, and enjoyment of life. All MS patients with pain employed words from both the sensory and affective categories of the MPQ to describe it. Patient pain descriptions’ included the word “hot-burning” in 59% of the cases, common in the report of central pain, but neuropathic pain medications were only used by 10% of them. Pain is an important symptom in Portuguese patients with MS, not only because of the high prevalence found, concordant with other European countries, but also because of its interference with quality-of-life.

Temporal reliability of ultra-high field resting-state MRI for single-subject sensorimotor and language mapping

ABSTRACT Resting‐state fMRI is a well‐suited technique to map functional networks in the brain because unlike task‐based approaches it requires little collaboration from subjects. This is especially relevant in clinical settings where a number of subjects cannot comply with task demands. Previous studies using conventional scanner fields have shown that resting‐state fMRI is able to map functional networks in single subjects, albeit with moderate temporal reliability. Ultra‐high resolution (7 T) imaging provides higher signal‐to‐noise ratio and better spatial resolution and is thus well suited to assess the temporal reliability of mapping results, and to determine if resting‐state fMRI can be applied in clinical decision making including preoperative planning. We used resting‐state fMRI at ultra‐high resolution to examine whether the sensorimotor and language networks are reliable over time — same session and one week after. Resting‐state networks were identified for all subjects and sessions with good accuracy. Both networks were well delimited within classical regions of interest. Mapping was temporally reliable at short and medium time‐scales as demonstrated by high values of overlap in the same session and one week after for both networks. Results were stable independently of data quality metrics and physiological variables. Taken together, these findings provide strong support for the suitability of ultra‐high field resting‐state fMRI mapping at the single‐subject level. HIGHLIGHTSTemporal reliability of single‐subject rs‐fMRI was examined at ultra‐high field imaging.Intrasession (same day) and intersession reliabilities (one week after) were tested.Language and sensorimotor networks were identified successfully in single subjects.Temporal reliability was high and did not differ across time points.Networks were stable with little impact from data‐quality and physiological confounds.

Neural imprints of national brands versus own-label brands

Purpose This paper aims to explore brain-based differences in national and own-label brands perceptions. Because price is a differentiating characteristic, able to discriminate between national and own-label brands, its influence is also studied. Design/methodology/approach The study uses the Save Holdings Or Purchase (SHOP) task with functional magnetic resonance imaging to explore the differences in brain functioning for national versus own-label branded products. Findings For the same product, the higher priced national brands and the lower priced own-label brands lead to more buying decisions. It is also found that there are brain structures that are more active/deactive for national than for own-label brands, both marked with real market prices. Price is a powerful driver of buying decisions and has its neural correlates. Parietal regions activate when brand information is subtracted from brand-plus-price information. The most surprising finding is that visual and visual associative areas are involved in the contrasts between branded products marked with switched prices and marked with real market prices. Originality/value The activation/deactivation brain patterns suggest that accepted models of brain functioning are not suitable for explaining brand decisions. Also, to our knowledge, this is the first time that a study directly addresses the brain’s functioning when subjects are stimulated with national versus own-label brands. It paves the way for a new approach to understanding how such brand categories are perceived, revealing the neural origins of the associated psychological processes.

Accuracy, reliability, validity and limitations of functional and structural magnetic resonance imaging data

Brain imaging applications are numerous, and no longer restricted to medicine or neuroscience: neuroimaging is already in use for example in marketing, economics and forensic science. While these other disciplines start to exploit brain imaging, concerns are raised, and even if somewhat behind the field, literature discussing imaging methodology, neuroethics or philosophy of science is also emerging (Seixas and Ayres Basto, 2008). Besides its complex nature, expensive hardware and difficult interpretation, neuroimaging is more and more available, and its potential uses are only limited by imagination. And although neuroimages represent brain data, they are also just pictures e that are worth a thousand words (Roskies, 2007). Structural neuroimaging, in general, deals with the structure of the central nervous system and is important for the diagnosis of focal lesions of the brain in the individual patient, as well as, for example, for the purpose of image registration. Functional neuroimaging, on the other hand, studies brain function, and the term characteristically applies to functional magnetic resonance imaging (fMRI). fMRI detects changes in blood oxygenation and flow that occur in response to neural activity, but there are other imaging techniques that can measure brain function, for example perfusion or neurotransmission.

Chronic pain disrupts the reward circuitry in multiple sclerosis.

Pain commonly affects multiple sclerosis (MS) patients, and has the potential to become chronic and burden an already damaged central nervous system. Imaging studies are providing insights into brain restructuring associated with chronic pain and different chronic pain conditions seem to evoke distinct plasticity patterns. Our objective was to study the structural and functional brain changes of chronic neuropathic pain of MS. Employing structural and resting functional magnetic resonance imaging we compared MS patients with chronic central pain with MS patients without pain matched with respect to age, gender, subtype and duration of MS and disability. Mean duration of pain was 7.6 years. Comparing the pain and no‐pain groups, brain functional default‐mode network differences were found. There was decreased coactivation in the caudate nucleus and nucleus accumbens bilaterally. Also, for the relapsing‐remitting subgroup of patients, grey matter thickness changes predominated in the pain group in the mesial region of the temporal lobes, caudate, putamen, thalami and the fronto‐parietal cortex; in the group without pain, changes predominated in the frontopolar and orbitofrontal cortices and in the occipital areas. A dysfunction in the reward system in chronic pain of MS was found, particularly in the brain areas involved in its motivational aspects, as such probably reflecting the maladaptive physiology of chronic pain, and possibly the signature of pain in MS, in a disease where reward impairment seems to be already one of its features.