ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<159::AID-MRDD1>3.0.CO;2-U

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractThe emergence of new technologies to study brain function in vivo has resulted in an explosion of interest in cognitive neuroscience within the last ten years. While most research in functional neuroimaging has been geared toward adult normal volunteers, the development of functional magnetic resonance imaging (fMRI) has made it possible to study neural development in normal children, as well as those with developmental disorders. This technology provides an unprecedented opportunity to expand our knowledge of brain function throughout childhood. A variety of technological, experimental, and practical difficulties are amplified when imaging children. This paper reviews some of the more challenging theoretical and practical concerns and provides suggestions for their management. MRDD Research Reviews 6:161–165, 2000. © 2000 Wiley‐Liss,

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<161::AID-MRDD2>3.0.CO;2-W

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractVirtually all developmental neuropsychiatric disorders involve some dysfunction or dysregulation of emotion. Moreover, many psychiatric disorders with adult onset have early subclinical manifestations in children. This essay selectively reviews the literature on the neuroimaging of affect and disorders of affect in children. Some critical definitional and conceptual issues are first addressed, including the distinctions between the perception and production of emotion and between emotional states and traits. Developmental changes in morphometric measures of brain structure are then discussed and the implications of such findings for studies of functional brain activity are considered. Data on functional neuroimaging and childhood depression are then reviewed. While the extant data in this area are meager, they are consistent with studies in adults that have observed decreased left‐sided anterolateral prefrontal cortex activation in depression. Studies in children on the recognition of emotion and affective intent in faces using functional magnetic resonance imaging are then reviewed. These findings indicate that the amygdala plays an important role in such affective face processing in children, similar to the patterns of activation observed in adults. Moreover, one study has reported abnormalities in amygdala activation during a task requiring the judgment of affective intent from the eye region of the face in subjects with autism. Some of the methodological complexities of developmental research in this area are discussed, and directions for future research are suggested. MRDD Research Reviews 6:166–170, 2000. © 2000 Wiley‐Lis

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<166::AID-MRDD3>3.0.CO;2-O

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractFunctional neuroimaging methods hold promise for elucidating the neurobiology of autistic disorders, yet they present difficult practical and scientific challenges when applied to these complex and heterogeneous syndromes. Single‐state studies of brain metabolism and blood flow thus far have failed to yield consistent findings, but suggest considerable variability in regional patterns of cerebral synaptic activity. Patients with idiopathic autism are less likely to show abnormalities than are patients with comorbid illness or epilepsy. Activation studies have begun to suggest alterations in brain organization for language and cognition. Neurotransmitter studies using positron emission tomography (PET) suggest abnormalities of serotonergic and dopaminergic function. Studies using magnetic resonance spectroscopy (MRS) have begun to document metabolic deficits in the frontal cortex and cerebellum. A single study using magnetoencephalography suggests a high incidence of epileptiform activity in children with autistic regression. Research needs include well‐controlled developmental studies, particularly of young subjects and relatively homogeneous subgroups, which balance scientific rigor with ethical constraints. Investigations of the serotonergic and dopaminergic systems, limbic‐based memory and emotional systems, and the role of epileptiform activity in autism represent priorities for future research. MRDD Research Reviews 6:171–179, 2000. Published 2000 Wiley‐

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<171::AID-MRDD4>3.0.CO;2-N

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractChildhood‐onset schizophrenia (COS) is a rare, severe form of schizophrenia in which there are structural brain abnormalities that may be related to the psychotic symptomatology and neurocognitive deficits found in these patients. While there are numerous structural imaging studies of the adult‐onset variant of schizophrenia (with many conflicting findings), relatively few brain imaging studies of COS have been conducted. This paper summarizes the extant literature of magnetic resonance imaging (MRI) studies of structural brain abnormalities in COS, and compares findings to similar studies of adult‐onset patients. Volumetric MRI studies of COS patients have consistently shown evidence for increased ventricular volume, reduced cerebral gray matter, and increased caudate volume, consistent with findings from adult‐onset studies. Other volumetric brain abnormalities are observed in COS patients, such as reduced total brain volume, but not consistently across all studies. Voxel‐based morphometric analyses have revealed abnormalities in the shape and spatial location of structures in COS such as the corpus callosum, caudate, and thalamus that could not be observed in the more traditional volumetric assessments. Similar findings also are observed in adult‐onset patients. Progressive degenerative changes, such as ventricular enlargement, appear to occur in COS only until young adulthood where there is an apparent asymptote with no further degenerative changes. This is consistent with the lack of progressive changes noted in most longitudinal studies of adult‐onset schizophrenia. MRDD Research Reviews 6:180–185, 2000. © 2000

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<180::AID-MRDD5>3.0.CO;2-I

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractBehavioral neurogenetics research is a new method of scientific inquiry that focuses on investigation of neurodevelopmental dysfunction associated with specific genetic conditions. This research method provides a powerful tool for scientific inquiry into human gene–brain–behavior linkages that complements more traditional research approaches. In particular, the use of specific genetic conditions as models of common behavioral and cognitive disorders occurring in the general population can reveal insights into neurodevelopmental pathways that might otherwise be obscured or diluted when investigating more heterogeneous, behaviorally defined subject groups. In this paper, we review five genetic conditions that commonly give rise to identifiable neurodevelopmental and neuropsychiatric disability in children: fragile X syndrome, velo‐cardio‐facial syndrome, Williams syndrome, Turner syndrome, and Klinefelter syndrome. While emphasis is placed on describing the brain morphology associated with these conditions as revealed by neuroimaging studies, we also include information pertaining to molecular genetic, postmortem, and neurobehavioral investigations to illustrate how behavioral neurogenetics research can contribute to an improved understanding of brain disorders in childhood. MRDD Research Reviews 6:186–197, 2000. © 2000 Wiley

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<186::AID-MRDD6>3.0.CO;2-9

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractThe search for a neurobiological substrate for dyslexia has focused on anomalous planum symmetry. The results of imaging studies of the planum have been inconsistent, perhaps due to diagnostic uncertainty, technical differences in measurement criteria, and inadequate control of handedness, sex, and cognitive ability. Although structural imaging studies have not clarified the neurobiology of reading disability, converging evidence suggests that variation in asymmetry of the planum temporale does have functional significance. Studies in a variety of populations have shown a significant association between planar asymmetry, the strength of hand preference, and general verbal skills such as vocabulary and comprehension. Future structural imaging studies of dyslexia should match participants on hand preference and general verbal ability in order to determine the relationship between brain structure and written and oral language. MRDD Research Reviews 6:198–206, 2000. © 2000 Wiley‐Liss,

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<198::AID-MRDD7>3.0.CO;2-1

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractConverging evidence from a number of neuroimaging studies, including our own, suggest that fluent word identification in reading is related to the functional integrity of two consolidated left hemisphere (LH) posterior systems: a dorsal (temporo‐parietal) circuit and a ventral (occipito‐temporal) circuit. This posterior system is functionally disrupted in developmental dyslexia. Reading disabled readers, relative to nonimpaired readers, demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers the dorsal circuit predominates at first, and is associated with analytic processing necessary for learning to integrate orthographic features with phonological and lexical‐semantic features of printed words. The ventral circuit constitutes a fast, late‐developing, word identification system which underlies fluent word recognition in skilled readers. MRDD Research Reviews 6:207–213, 2000. © 2000 Wiley

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<207::AID-MRDD8>3.0.CO;2-P

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractAttention‐deficit/hyperactivity disorder (ADHD) is a common childhood behavioral disorder most often characterized by inattentiveness, impulsivity, and hyperactivity. Current etiologic theories suggest that ADHD stems from abnormalities in dopaminergic and possibly noradrenergic brainstem nuclei that act to regulate a cortico‐striato‐thalamo‐cortical network, believed to be critical for executive functions and the regulation of behavioral responses such as arousal, attention, and inhibition. Noninvasive structural and functional neuroimaging techniques provide a new avenue for exploring the validity of these theories. Despite their limitations, neuroimaging studies have provided a unique and otherwise inaccessible, biological perspective of ADHD. Collectively, the studies reviewed here reveal that dysfunction in arousal, behavioral inhibition, and attention associated with ADHD may result from structural abnormalities in frontostriatal regions that in turn result in diminished activity essential for normal function. MRDD Research Reviews 6:214–219, 2000. © 2000 Wiley

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<214::AID-MRDD9>3.0.CO;2-M

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY

摘要:

AbstractImaging plays an increasingly important role in the evaluation of children with complex partial seizures. Most partial epilepsy, especially of temporal lobe origin, begins during childhood. Structural imaging with high‐resolution MRI can help identify the etiology of partial seizure disorders in many children. MRI studies also show the more widespread effect of seizures on brain structure. Progressive volume loss of the hippocampal formation in some patients with temporal lobe epilepsy provides evidence that continued seizures may be associated with progressive neuronal injury. FDG‐PET studies show regional decreases in glucose consumption in the cortical zone from which seizures arise. Functional abnormalities often are more extensive than the seizure focus. Studies in children with recent‐onset epilepsy show that metabolic abnormalities are considerably less common than in adults with partial epilepsy, supporting the notion that in some patients there may be progressive metabolic changes that occur with continued seizures. Functional MRI may be used to identify language areas in children with partial epilepsy. fMRI language tasks reliably identify the dominant hemisphere for language dominance when compared to the intracarotid amytal procedure. Tests of verbal fluency and semantic decision identify frontal lobe language areas, while reading text paradigms and auditory passage paradigms are better for identifying temporal language areas. A panel of paradigms is best used to identify language areas in children being considered for epilepsy surgery. fMRI is a valuable tool for elucidating the impact of chronic neurologic disease states on the functional organization of language networks during development. MRDD Research Reviews 6:220–226, 2000. Published 2000 Wiley‐

ISSN:1080-4013    

DOI:10.1002/1098-2779(2000)6:3<220::AID-MRDD10>3.0.CO;2-C

出版商:John Wiley&Sons, Inc.    

年代:2000

数据来源: WILEY