Functional magnetic resonance imaging of cognitive processing in young adults with Down syndrome

The authors used functional magnetic resonance imaging (fMRI) to investigate neural activation during a semantic-classification/object-recognition task in 13 persons with Down syndrome and 12 typically developing control participants (age range = 12-26 years). A comparison between groups suggested atypical patterns of brain activation for the individuals with Down syndrome. Correlation analyses between an index of visual spatial ability and brain activation depicted a positive relationship between (a) this index and brain activation in regions of the occipital and parietal lobes for the typically developing individuals and (b) the middle and dorsal frontal gyri in the individuals with Down syndrome. These findings supported the authors' hypothesis that persons with Down syndrome demonstrate atypical neural activation compared with typically developing individuals matched for chronological age.     

Functional magnetic resonance imaging

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a powerful approach to defining activity in the healthy and diseased human brain. BOLD fMRI detects local increases in relative blood oxygenation that are most probably a direct consequence of neurotransmitter action and thus reflect local neuronal signalling. The method allows localisation to volumes of the order of a few to several cubic millimetres and can be used in serial studies of individual subjects. Basic approaches to experimental design and analysis are reviewed briefly, as well as potential clinical applications. The latter include three broad areas: anatomical characterisation of normal or pathological patterns of brain functioning; distinguishing pathological traits; and monitoring treatment responses. New research is emphasising the integration of fMRI with other techniques, particularly electrophysiological. In conjunction with MRI methods for characterising pathological load, fMRI promises a refined understanding of when disease processes begin and how they can be modified by new treatments.     

Co-registration of magnetoencephalography with magnetic resonance imaging using bite-bar-based fiducials and surface-matching.

OBJECTIVE: To introduce a new technique for co-registration of Magnetoencephalography (MEG) with magnetic resonance imaging (MRI). We compare the accuracy of a new bite-bar with fixed fiducials to a previous technique whereby fiducial coils were attached proximal to landmarks on the skull. METHODS: A bite-bar with fixed fiducial coils is used to determine the position of the head in the MEG co-ordinate system. Co-registration is performed by a surface-matching technique. The advantage of fixing the coils is that the co-ordinate system is not based upon arbitrary and operator dependent fiducial points that are attached to landmarks (e.g. nasion and the preauricular points), but rather on those that are permanently fixed in relation to the skull. RESULTS: As a consequence of minimizing coil movement during digitization, errors in localization of the coils are significantly reduced, as shown by a randomization test. Displacement of the bite-bar caused by removal and repositioning between MEG recordings is minimal ( approximately 0.5 mm), and dipole localization accuracy of a somatosensory mapping paradigm shows a repeatability of approximately 5 mm. The overall accuracy of the new procedure is greatly improved compared to the previous technique. CONCLUSIONS: The test-retest reliability and accuracy of target localization with the new design is superior to techniques that incorporate anatomical-based fiducial points or coils placed on the circumference of the head.     

Functional magnetic resonance imaging in schizophrenia

The integration of functional magnetic resonance imaging (fMRI) with cognitive and affective neuroscience paradigms enables examination of the brain systems underlying the behavioral deficits manifested in schizophrenia; there have been a remarkable increase in the number of studies that apply fMRI in neurobiological studies of this disease. This article summarizes features of fMRI methodology and highlights its application in neurobehavioral studies in schizophrenia. Such work has helped elucidate potential neural substrates of deficits in cognition and affect by providing measures of activation to neurobehavioral probes and connectivity among brain regions. Studies have demonstrated abnormalities at early stages of sensory processing that may influence downstream abnormalities in more complex evaluative processing. The methodology can help bridge integration with neuropharmacologic and genomic investigations.     

Functional magnetic resonance imaging in pediatrics

Functional magnetic resonance imaging (fMRI) allows non-invasive assessment of human brain function in vivo by detecting blood flow differences. In this review, we want to illustrate the background and different aspects of performing functional magnetic resonance imaging (fMRI) in the pediatric age group. An overview over current and future applications of fMRI will be given, and typical problems, pitfalls, and benefits of doing fMRI in the pediatric age group are discussed. We conclude that fMRI can successfully be applied in children and holds great promise for both research and clinical purposes.     

Functional magnetic resonance imaging in children

Functional magnetic resonance imaging (fMRI) allows for the noninvasive mapping of the anatomical location of disparate functional brain activities. The means for carrying out fMRI involves the use of existing MR technology coupled with a special software image acquisition program or the use of a specially designed head coil. Thus far in pediatric neurology, fMRI has assisted in the presurgical localization of critical functions and the investigation of various developmental activities. The technique of fMRI, its applications in pediatric neuroscience, and future potential are outlined in this article.     

Functional magnetic resonance imaging study comparing rhythmic finger tapping in children and adults

This study compared brain activation during unpaced rhythmic finger tapping in 12-year-old children with that of adults. Subjects pressed a button at a pace initially indicated by a metronome (12 consecutive tones), and then continued for 16 seconds of unpaced tapping to provide an assessment of their ability to maintain a steady rhythm. These analyses focused on the superior vermis of the cerebellum, which is known to play a key role in timing. Twelve adults and 12 children performed this rhythmic finger tapping task in a 3 T scanner. Whole-brain analyses were performed in Brain Voyager, with a random-effects analysis of variance using a general linear model. A dedicated cerebellar atlas was used to localize cerebellar activations. As in adults, unpaced rhythmic finger tapping in children demonstrated activations in the primary motor cortex, premotor cortex, and cerebellum. However, overall activation was different, in that adults demonstrated much more deactivation in response to the task, particularly in the occipital and frontal cortices. The other main differences involved the additional recruitment of motor and premotor areas in children compared with adults, and increased activity in the vermal region of the cerebellum. These findings suggest that the timing component of the unpaced rhythmic finger tapping task is less efficient and automatic in children, who need to recruit the superior vermis more intensively to maintain the rhythm, although they performed somewhat more poorly than adults.     

Refreshing one of several active representations: behavioral and functional magnetic resonance imaging differences between young and older adults

We explored age-related differences in executive function during selection of a target from among active representations. Refreshing (thinking briefly of a just-activated representation) is an executive process that foregrounds a target relative to other active representations. In a behavioral study, participants saw one or three words, then saw a cue to refresh one of the words, saw one word again and read it, or read a new word. Increasing the number of active representations increased response times (RTs) only in the refresh condition for young adults but increased RTs equally in all conditions for older adults, suggesting that they experienced interference from activated irrelevant information during perception and reflection. Consistent with this interpretation, in a functional magnetic resonance imaging study, young adults showed two areas of the left dorsolateral frontal cortex and a medial area of frontal cortex, including anterior cingulate, that were relatively more sensitive to number of active representations during refresh than read trials; for older adults these areas were equally sensitive to number of active items for refresh and read trials. Young and older adults showed activity associated with refreshing on trials requiring selection in left mid-ventral frontal cortex (an area associated with selection from active representations); older adults also showed activity in left anterior ventral frontal cortex (an area associated with controlled semantic activation). Our results support the hypothesis of an age-related decrease in ability to gate out activated but currently irrelevant information, and are consistent with a dissociation of function between left mid-ventral and left anterior ventral frontal cortex.     

Localizing the central sulcus by functional magnetic resonance imaging and magnetoencephalography

To further validate the potential of functional magnetic resonance imaging (fMRI) for localization of the sensorimotor cortex, fMRI was compared with somatosensory evoked fields (SEFs) in eight normal volunteers. A conventional 1.5 T MRI scanner and an MRI-linked 66-channel whole head magnetoencephalography system were used. fMRI activated by unilateral hand squeeze movement indicated the highest activation on the central sulci that were localized by SEFs in all 16 contralateral hemispheres. This indicates that although the fMRI signal activation may originate from a vein running along the central sulcus, fMRI is reliable to detect the central sulcus. The pre-central gyrus also indicated some signal activation on fMRI implying better visualization of spatial distribution of activation. fMRI and SEFs are complementary methods for localizing the central sulcus.     

Localization of auditory response sources using magnetoencephalography and magnetic resonance imaging

Magnetoencephalography offers the possibility of localizing accurately and noninvasively the source of intracranial currents associated with normal and abnormal brain activity. The purpose of this study was to assess the validity and across-subject reliability of localization of cortical sources responding to ipsilateral and contralateral auditory stimulation. Magnetic evoked fields to both stimulation conditions were measured in eight consecutive normal subjects, and the cortical sources of these fields were estimated on the basis of these measurements. Subsequent projection of the source location coordinates onto magnetic resonance images showed that in all subjects the sources were accurately estimated to fall in the vicinity of the auditory cortex and that two separate sources may account for the response to ipsilateral and contralateral stimulation.     

Incidental findings in magnetic resonance imaging of the brains of healthy young men

BACKGROUND AND PURPOSE: To determine the frequency of serious intracranial abnormalities in a healthy young male population. METHODS: Cranial MRI of 2,536 healthy young males, mean age 20.5 years, all applicants for military flying duties in the German Air Force. RESULTS: The authors report a variety of morphological abnormalities in the brains of a large population of healthy young males, providing data on disease prevalence. Arachnoid cysts were found in 1.7% (95% CI 1.2 to 2.3%), vascular abnormalities in 0.51% (95% CI 0.29 to 0.9%), and intracranial tumors in 0.47% (95% CI 0.26 to 0.85%) of the applicants. No cerebral aneurysms were found. CONCLUSION: The prevalence of primary brain tumors seems to be higher, whereas the prevalence of intracranial aneurysms is lower than expected. Only a small percentage of the detected abnormalities require urgent medical attention.     

Functional magnetic resonance imaging in children with Asperger's syndrome

Asperger's syndrome is a pervasive developmental disorder of unknown etiology. We evaluated children with this syndrome (n = 9) and control (n = 8) children by functional magnetic resonance imaging (MRI) during a task involving social judgment. All control and 5 of 9 subjects with Asperger's syndrome showed signal intensity changes in frontal regions. Four patients with Asperger's syndrome, including one case with right frontal dysplasia, had no signal intensity change during the task. In this first functional MRI study of childhood Asperger's syndrome, frontal activation patterns demonstrated some differences between patients and normal subjects. Further studies using other functions frequently impaired in Asperger's syndrome are warranted.     

Functional magnetic resonance imaging research in China

Functional magnetic resonance imaging (fMRI) non-invasively measures the activity of the human brain and provides a unique technological tool for investigating aspects of the human brain including cognition, development, and disorders. As one of the main funding agencies for basic research in China, the National Natural Scientific Foundation of China (NSFC) has initiated various research programs during the last two decades that are related to fMRI research. In this review, we collected and analyzed the metadata of the projects and published studies in research fields using fMRI that were funded by the NSFC. We observed a trend of increasing funding amounts from the NSFC for fMRI research, typically from the General Program and Key Program. Leading research institutes from economically developed municipalities and provinces received the most support and formed close collaboration relationships. Finally, we reviewed several representative achievements from research institutions in china, involving data analysis methods, brain connectomes, and computational platforms in addition to their applications in brain disorders.     

Functional magnetic resonance imaging in awake animals

Awake animal imaging is becoming an important tool in behavioral neuroscience and preclinical drug discovery. Non-invasive ultra-high-field, functional magnetic resonance imaging (fMRI) provides a window to the mind, making it possible to image changes in brain activity across distributed, integrated neural circuits with high temporal and spatial resolution. In theory, changes in brain function, anatomy, and chemistry can be recorded in the same animal from early life into old age under stable or changing environmental conditions. This prospective capability of animal imaging to follow changes in brain neurobiology after genetic or environmental insult has great value to the fields of psychiatry and neurology and probably stands as the key advantage of MRI over other methods in the neuroscience toolbox. In addition, awake animal imaging offers the ability to record signal changes across the entire brain in seconds. When combined with the use of 3D segmented, annotated, brain atlases, and computational analysis, it is possible to reconstruct distributed, integrated neural circuits or 'fingerprints' of brain activity. These fingerprints can be used to characterize the activity and function of new psychotherapeutics in preclinical development and to study the neurobiology of integrated neural circuits controlling cognition and emotion. In this review, we describe the methods used to image awake animals and the recent advances in the radiofrequency electronics, pulse sequences, and the development of 3D segmented atlases and software for image analysis. Results from pharmacological MRI studies and from studies using provocation paradigms to elicit emotional responses are provided as a small sample of the number of different applications possible with awake animal imaging.     

Functional magnetic resonance imaging research in psychiatry

Advanced functional imaging techniques now make it possible to study in vivo the relationship between altered cerebral activation patterns and the psychopathologic and cognitive features of psychiatric disorders. Functional MR imaging (fMRI) offers new approaches to research questions in psychiatry that could not have been addressed earlier by positron emission tomography and single photon emission CT. Basic features of the biology of psychiatric disorders now can be elucidated by means of fMRI. Study designs involving fMRI capitalize on the technique's enhanced spatial and temporal resolution, noninvasive nature, and absence of radiation exposure.     

Pediatric magnetoencephalography and magnetic source imaging

Magnetoencephalography (MEG) and magnetic source imaging (MSI) together represent a uniquely powerful functional imaging modality because of their capabilities of directly observing the electrophysiologic activity of neurons with exquisite temporal detail and accurately localizing corresponding neuromagnetic field sources onto high-resolution MR images. These features have and should continue to advance our understanding of the complex spatiotemporal basis of normal and abnormal brain function and development in children. By more clearly delineating and characterizing epileptogenic foci and their relation to eloquent cortex, MSI enables earlier and more effective neurosurgery to be performed, thus resulting in improved seizure outcomes. Although MEG and MSI cannot replace scalp electroencephalography, neuropsychologic testing, and the need for meticulous intraoperative cortical mapping in patients undergoing excision of epileptogenic lesions, their increasing availability should ultimately persuade many clinicians of their key, if not essential, role in the evaluation and treatment of children with epilepsy.     

Ethnic differences and responses to pain in healthy young adults

Ethnic disparities in pain have recently gained increasing attention; however, relatively few studies have examined ethnic differences in pain prevalence, and even fewer have addressed whether ethnic groups differ in their pain-reducing behaviors. Thus, this study investigated ethnic differences in pain prevalence and impact among healthy young African Americans, Hispanics, and non-Hispanic whites.(1) Also, ethnic differences in pain-reducing behaviors were explored. Undergraduate students (N = 1,037) from three ethnic groups completed a telephone survey of recent pain experiences. Groups did not differ in overall pain frequency or severity; however, more African Americans reported chest and stomach region pain, whereas more Hispanics reported pain in the legs/feet. Significant group differences regarding pain-reducing behaviors emerged. More whites utilized self-care behaviors, compared to Hispanics and African Americans. Conversely, greater numbers of African Americans and Hispanics than whites reported having prayed to relieve pain. The predictors of the total number of pain-reducing behaviors used differed across ethnic groups. For whites, pain intensity and interference were the strongest predictors of pain-reducing behaviors. For African Americans, total pain sites, as well as interference and frustration, were significantly associated with pain-reducing behaviors, while among Hispanics, worry and frustration were the strongest predictors for total pain-reducing behaviors. These results suggest potentially important ethnic differences in patterns and predictors of pain-reducing actions, and their emergence in a healthy sample suggest that ethnic differences in pain-related responses predate the development of chronic pain. These findings may have important implications for understanding ethnic differences in responses to clinical pain and for tailoring treatment approaches to eliminate disparities.