Portable Neuroimaging Research Articles

Book Review: Cognitive Neuroscience of Natural Language Use

Book Review: Cognitive Neuroscience of Natural Language Use

Potential biomarker of subjective quality of life: Prefrontal activation measurement by near-infrared spectroscopy

Recently, there has been growing emphasis on enhancing subjective quality of life (QOL), in addition to treating symptoms or extending one’s life. However, the neurobiological basis of subjective QOL is unknown. To illuminate the neural substrates that inform subjective QOL, the association between prefrontal function and subjective QOL was explored in 72 healthy volunteers (40 women and 32 men; age, 45.1 ± 20.1 y), using 52-channel near-infrared spectroscopy (NIRS), a portable neuroimaging device that can measure brain function in a less-constrained condition. Results confirmed that subjective QOL was positively correlated with prefrontal hemodynamic response during a cognitive task and that subjective satisfaction regarding social relationships and in the physical domains were cardinal contributors to the association. These findings suggest that subjective QOL has possible involvement in prefrontal function and that NIRS potentially plays a role as a biological marker of subjective QOL.

Prefrontal activation during inhibitory control measured by near-infrared spectroscopy for differentiating between autism spectrum disorders and attention deficit hyperactivity disorder in adults

The differential diagnosis of autism spectrum disorders (ASDs) and attention deficit hyperactivity disorder (ADHD) based solely on symptomatic and behavioral assessments can be difficult, even for experts. Thus, the development of a neuroimaging marker that differentiates ASDs from ADHD would be an important contribution to this field. We assessed the differences in prefrontal activation between adults with ASDs and ADHD using an entirely non-invasive and portable neuroimaging tool, near-infrared spectroscopy. This study included 21 drug-naïve adults with ASDs, 19 drug-naïve adults with ADHD, and 21 healthy subjects matched for age, sex, and IQ. Oxygenated hemoglobin concentration changes in the prefrontal cortex were assessed during a stop signal task and a verbal fluency task. During the stop signal task, compared to the control group, the ASDs group exhibited lower activation in a broad prefrontal area, whereas the ADHD group showed underactivation of the right premotor area, right presupplementary motor area, and bilateral dorsolateral prefrontal cortices. Significant differences were observed in the left ventrolateral prefrontal cortex between the ASDs and ADHD groups during the stop signal task. The leave-one-out cross-validation method using mean oxygenated hemoglobin changes yielded a classification accuracy of 81.4% during inhibitory control. These results were task specific, as the brain activation pattern observed during the verbal fluency task did not differentiate the ASDs and ADHD groups significantly. This study therefore provides evidence of a difference in left ventrolateral prefrontal activation during inhibitory control between adults with ASDs and ADHD. Thus, near-infrared spectroscopy may be useful as an auxiliary tool for the differential diagnosis of such developmental disorders.

Prefrontal Cortex Activity During Walking While Multitasking

Previous work has demonstrated that walking while carrying out secondary cognitive tasks (e.g., talking on a cell phone) can lead to decrements in performance on both tasks. Studying these decrements in an ecologically valid setting has generally been limited to behavioral data (e.g., error rates, task completion times). Recently, the advent of portable neuroimaging technology – specifically, functional Near-Infrared spectroscopy (fNIR) – has made it possible to measure cortical activity while a participant is walking. We conducted an experiment using fNIR to measure cortical blood flow (in dorsolateral prefrontal cortex) while participants walked and carried out cognitive tasks of varying difficulty. Participants walked 25 feet on each trial, and performed either a low-load condition (counting backward by 1), or a high-load condition (counting backward by 7). Participants in the high load condition walked more slowly and performed the counting task more slowly and with more errors than those in the low load condition. fNIR results indicated a higher level of Prefrontal Cortex (PFC) activity during the high load condition. The difference in blood flow between load conditions was slightly more pronounced in the left hemisphere than in the right.

Neuroimaging-aided differential diagnosis of the depressive state

A serious problem in psychiatric practice is the lack of specific, objective biomarker-based assessments to guide diagnosis and treatment. The use of such biomarkers could assist clinicians in establishing differential diagnosis, which may improve specific individualised treatment. This multi-site study sought to develop a clinically suitable neuroimaging-guided diagnostic support system for differential diagnosis at the single-subject level among multiple psychiatric disorders with depressive symptoms using near-infrared spectroscopy, which is a compact and portable neuroimaging method. We conducted a multi-site, case–control replication study using two cohorts, which included seven hospitals in Japan. The study included 673 patients (women/men: 315/358) with psychiatric disorders (major depressive disorder, bipolar disorder, or schizophrenia) who manifested depressive symptoms, and 1007 healthy volunteers (530/477). We measured the accuracy of the single-subject classification in differential diagnosis among major psychiatric disorders, based on spatiotemporal characteristics of fronto-temporal cortical haemodynamic response patterns induced by a brief (<3min) verbal fluency task. Data from the initial site were used to determine an optimal threshold, based on receiver-operator characteristics analysis, and to generate the simplest and most significant algorithm, which was validated using data from the remaining six sites. The frontal haemodynamic patterns detected by the near-infrared spectroscopy method accurately distinguished between patients with major depressive disorder (74.6%) and those with the two other disorders (85.5%; bipolar disorder or schizophrenia) that presented with depressive symptoms. These results suggest that neuroimaging-guided differential diagnosis of major psychiatric disorders developed using the near-infrared spectroscopy method can be a promising biomarker that should aid in personalised care in real clinical settings. Potential confounding effects of clinical (e.g., age, sex) and systemic (e.g., autonomic nervous system indices) variables on brain signals will need to be clarified to improve classification accuracy.

Neuroimaging to detect cortical projection of vestibular response to caloric stimulation in young and older adults using functional near-infrared spectroscopy (fNIRS)

Functional near-infrared spectroscopy (fNIRS) is a non-invasive and portable neuroimaging technique. The method uses non-ionizing laser light in the range of red to near-infrared to detect changes in cerebral blood oxygenation. In this study, we used fNIRS to investigate cortical hemodynamic changes in the temporo-parietal and frontal regions during caloric vestibular stimulation. Caloric stimulation has previously been investigated using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), which serves as a validation of the fNIRS imaging modality toward the measurement of vestibular related brain regions. To date, only a single study has used fNIRS during caloric irrigations, which observed blood volume changes in the temporal-parietal area in healthy younger subjects. In this current study, fNIRS was used to measure cortical vestibular activation in 10 right-handed younger subjects (5 male and 5 female, age 25+/-6 years) and 10 right-handed older subjects (6 male and 4 female, age 74+/-5 years). We investigated both warm (44 °C) and cool (30 °C) unilateral caloric vestibular stimulation. Consistent with previous reports, we found that warm (44 °C) caloric irrigation caused a bilateral activation. In addition, we found that cool (30 °C) caloric irrigation caused contralateral activation of the temporo-parietal area. This study is the first to investigate age effects of the caloric stimulation on brain activity. We found that the older subjects had stronger bilateral effects than the younger subjects. Our results confirm previous fMRI and PET studies that showed cortical activation during caloric vestibular irrigation is dependent on side of irrigation, and temperature of irrigation. Furthermore, our results demonstrate that fNIRS is a viable technique in measuring cortical effects during vestibular tasks.

Communication, langage et cerveau : du passé antérieur au futur proche

The goal of this article is to share some reflection on the astonishing evolution of the ideas in communication neuroscience and neurolinguistics over the last 30 years, since the founding of the société de neuropsychologie de langue française. in particular, a number of conceptual and methodological advancements have characterized this period, many of which have been lead or heavily contributed by french-speaking research groups in that field. among the advances discussed, are (a) the widening to discourse and pragmatic components of the concept of language, as well as the theoretical and clinical implication of this conceptual extension, (b) the unique contribution of anatomical and functional neuroimaging, (c) the massive impact of the cognitive revolution on theoretical frameworks of language components, and its influence on therapy, (d) the disappearance and the re-appearance of the brain in the main stream research on language over this period, (e) the new perspectives offered though attention put on social aspects of language and the social participation of the individual with language disorders, (f) the emergence of a genuine science of aphasia rehabilitation, and (g) the rediscovery of inter-individual characteristics both genetically- and environmentally- determined. The authors then risk themselves in trying to envision what could characterize the evolution in the field for the next 30 years. Though perilous, this speculative exercise allowed to pinpoint to a number of anticipated advancements including (a) a probable reconciliation between cognitive and connectionist models to the benefit of both visions, (b) an increased contribution of social and emotional neurosciences, (c) some inescapable technological advancements, including light portable neuroimaging devices which will allow to study the neurobiological bases of communication in natural contexts, (d) the integration between communication and aging in cognitive neuroscience and (e) the development of new research fields at some unexpected cross-roads (e.g., physical activity and communication ?) as well as the description of new types of aphasia (e.g., towards a chat aphasia ǃ). Taken together, the advancements made over the 30 last years, and the perspective of future development, confirms the premier role of cognitive neuroscience of language and neurolinguistics in setting the pace through innovative approaches that allow unveiling the mysteries of the mutual relationships between brain and cognition.