In vivo studies of brain development by magnetic resonance techniques

Understanding of the morphological development of the human brain has largely come from neuropathological studies obtained postmortem. Magnetic resonance (MR) techniques have recently allowed the provision of detailed structural, metabolic, and functional information in vivo on the human brain. These techniques have been utilized in studies from premature infants to adults and have provided invaluable data on the sequence of normal human brain development. This article will focus on MR techniques including conventional structural MR imaging techniques, quantitative morphometric MR techniques, diffusion weighted MR techniques, and MR spectroscopy. In order to understand the potential applications and limitations of MR techniques, relevant physical and biological principles for each of the MR techniques are first reviewed. This is followed by a review of the understanding of the sequence of normal brain development utilizing these techniques. MRDD Research Reviews 6:59-67, 2000.     

Developmental neuroimaging of the human ventral visual cortex

Here, we review recent results that investigate the development of the human ventral stream from childhood, through adolescence and into adulthood. Converging evidence suggests a differential developmental trajectory across ventral stream regions, in which face-selective regions show a particularly long developmental time course, taking more than a decade to become adult-like. We discuss the implications of these recent findings, how they relate to age-dependent improvements in recognition memory performance and propose possible neural mechanisms that might underlie this development. These results have important implications regarding the role of experience in shaping the ventral stream and the nature of the underlying representations.     

Operant-contingency-based preparation of children for functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI) is used to study brain function during behavioral tasks. The participation of pediatric subjects is problematic because reliable task performance and control of head movement are simultaneously required. Differential reinforcement decreased head motion and improved vigilance task performance in 4 children (2 with behavioral disorders) undergoing simulated fMRI scans. Results show that behavior analysis techniques can improve child cooperation during fMRI procedures.     

Reading and controlling human brain activation using real-time functional magnetic resonance imaging

Understanding how to control how the brain's functioning mediates mental experience and the brain's processing to alter cognition or disease are central projects of cognitive and neural science. The advent of real-time functional magnetic resonance imaging (rtfMRI) now makes it possible to observe the biology of one's own brain while thinking, feeling and acting. Recent evidence suggests that people can learn to control brain activation in localized regions, with corresponding changes in their mental operations, by observing information from their brain while inside an MRI scanner. For example, subjects can learn to deliberately control activation in brain regions involved in pain processing with corresponding changes in experienced pain. This may provide a novel, non-invasive means of observing and controlling brain function, potentially altering cognitive processes or disease.     

Forward inference using functional neuroimaging: dissociations versus associations

Many people are excited by functional neuroimaging as a new tool for cognitive science; many others are sceptical. In this opinion article, I describe a 'forward inference' that one can make from patterns of brain activity to distinguish between cognitive theories. I give an example of forward inferences in research on recognition memory, and outline some statistical criteria for a 'qualitative difference' in brain activity. Forward inferences resemble the dissociation logic long-used in behavioural studies of healthy and brain-damaged people, although I argue that dissociations in neuroimaging data can go beyond behavioural dissociations. Nonetheless, forward inferences are only as good as the cognitive theories to which they pertain, and are most valuable in conjunction with other types of inference.     

Magnetoencephalography and magnetic source imaging: technology overview and applications in psychiatric neuroimaging

Magnetoencephalography (MEG) is an electrophysiologic brain imaging technology that has been applied to the study of mental illness, particularly schizophrenia. Like electroencephalography, it provides excellent temporal resolution, and in combination with magnetic resonance imaging, can also provide good spatial resolution. Studies of the auditory system in schizophrenia using MEG have demonstrated an abnormality in functional cerebral asymmetry, in which persons with schizophrenia typically show reduced, or reversed, cerebral asymmetry compared with normal subjects. This abnormality is sex-specific; it is more pronounced in males with schizophrenia. These findings have not been demonstrated using other neuroimaging strategies. Thus, MEG appears to offer a unique and valuable contribution to psychiatric neuroimaging. Current research and clinical applications of MEG are limited, however, by the high cost of instrumentation. The cost of MEG systems should improve as more applications are developed, in schizophrenia as well as other neuropsychiatric conditions, and hospitals begin to invest in the technology.     

Fiber tracking using magnetic resonance diffusion tensor imaging and its applications to human brain development

Diffusion tensor imaging is unique in its ability to noninvasively visualize white matter fiber tracts in the human brain in vivo. Diffusion is the incoherent motion of water molecules on a microscopic scale. This motion is itself dependent on the micro-structural environment that restricts the movement of the water molecules. In white matter fibers there is a pronounced directional dependence on diffusion. With white matter fiber tracking or tractography, projections among brain regions can be detected in the three-dimensional diffusion tensor dataset according to the directionality of the fibers. Examples of developmental changes in diffusion, tracking of major fiber tracts, and examples of how diffusion tensor tractography and functional magnetic resonance imaging can be combined are provided. These techniques are complimentary and allow both the identification of the eloquent areas of the brain involved in specific functional tasks, and the connections between them. The noninvasive nature of magnetic resonance imaging will allow these techniques to be used in both longitudinal developmental and diagnostic studies. An overview of the technique and preliminary applications are presented, along with its current limitations.     

Cognitive-behavior therapy with children: Developmental reconsiderations

The present paper reconsiders the role of developmental theory in the use of cognitive-behavior therapy (CBT) with children. The implication of Piaget's theory of cognitive development and Selman's social perspectivetaking theory are reviewed briefly in regard to CBT. It is argued that the assessment of both logical/analytical thought structures and social perspective-taking abilities may be useful in planning a course of CBT with children.Andrew Kinney, Ph.D., is an Associate Fellow at the Institute for Rational-Emotive Therapy, New York City. He is an Assistant Professor of Psychology at Mohawk Valley Community College, Utica, NY, and an Adjunct Lecturer of psychology at the State University of New York Institute of Technology at Utica/Rome, NY.     

Developmental features of speech-sound production in language-impaired children

The speech-sound production of severely language-impaired children was monitored in a longitudinal study. In order to generalize findings, acoustical, phonemic, and clinical observation data were collected from 30 children. Results showed that speech-sound acquisition goes through a hierarchical sequence of development and that speech-sound production will deteriorate in a predictable manner depending on the pathology. The authors hypothesize a speech-sound acquisition model, SSAM, based on the development observed.This project was supported by the Swiss National Foundation for Scientific Research-Projects No. 3.237.69, 3.448.70, and 3.902.72-and by North Carolina State University Research and Development Grant 056.     

Functional magnetic resonance imaging study of Piaget's conservation-of-number task in preschool and school-age children: a neo-Piagetian approach

Jean Piaget’s theory is a central reference point in the study of logico-mathematical development in children. One of the most famous Piagetian tasks is number conservation. Failures and successes in this task reveal two fundamental stages in children’s thinking and judgment, shifting at approximately 7 years of age from visuospatial intuition to number conservation. In the current study, preschool children (nonconservers, 5-6 years of age) and school-age children (conservers, 9-10 years of age) were presented with Piaget’s conservation-of-number task and monitored by functional magnetic resonance imaging (fMRI). The cognitive change allowing children to access conservation was shown to be related to the neural contribution of a bilateral parietofrontal network involved in numerical and executive functions. These fMRI results highlight how the behavioral and cognitive stages Piaget formulated during the 20th century manifest in the brain with age.     

Multivariate strategies in functional magnetic resonance imaging

We discuss aspects of multivariate fMRI modeling, including the statistical evaluation of multivariate models and means for dimensional reduction. In a case study we analyze linear and non-linear dimensional reduction tools in the context of a 'mind reading' predictive multivariate fMRI model.     

Imaging intelligence with proton magnetic resonance spectroscopy

Proton magnetic resonance spectroscopy (¹H-MRS) is a technique for the assay of brain neurochemistry in vivo. N-acetylaspartate (NAA), the most prominent metabolite visible within the ¹H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA–cognition relationships, particularly whether such relationships are moderated by sex, or tissue type (gray or white matter). We administered standard measures of intelligence to 63 young, healthy subjects and obtained spectroscopic imaging data within a slab of tissue superior to the lateral ventricles. We found that lower NAA within right anterior gray matter predicted better performance VIQ (F = 6.83, p = .011, r² = .10), while higher NAA within the right posterior gray matter region predicted better PIQ (F = 8.175, p = .006, r² = .12). These findings add to the small but growing body of literature linking brain biochemistry to intelligence in normal healthy subjects using ¹H-MRSI.     

Functional magnetic resonance imaging of human cognitive processes

Functional magnetic resonance imaging (fMRI) is now widely accepted as a tool for analyzing human brain function. Since the realization of fMRI in the early 1990s, numerous reports have been published. In this paper, we present three studies. The first examined syntactic processing of Japanese sentences and the results prove that Broca's area is involved in the use of grammar. The second study compared binocular with monocular stereopsis. There were significant activations in the right inferior parietal lobe. The third study concerned the encoding and retrieval processes underlying face recognition. It revealed activations mainly in the right prefrontal areas, which is contrary to the hemispheric encoding and retrieval asymmetry (HERA) theory. fMRI will continue to play an important role in the analysis of human brain function.     

Multisensory integration in children with Developmental Coordination Disorder

This study examines how multisensory stimuli affect the performance of children with Developmental Coordination Disorder (DCD) on a choice reaction time (CRT) task. Ten children with DCD, identified using the Movement Assessment Battery for Children-2, aged 7–10 years (4F, M = 8 y 3 m, SD = 17 m) and 10 typically developing peers (TDC) (5F, M = 8 y 4 m, SD = 17 m) reached to unimodal (auditory (AO), visual (VO)) and bimodal (audiovisual (AV)) stimuli at one of three target locations. A multisensory (AV) stimulus reduced RTs for both groups (p < 0.001, η² = 0.36). While the children with DCD had a longer RT in all conditions, the AV stimulus produced RTs in children with DCD (494 ms) that were equivalent to those produced by the TDC to the VO stimulus (493 ms). Movement Time (DCD = 486 ms; TDC = 434 ms) and Path Length (DCD = 25.6 cm; TDC = 24.2 cm) were longer in children with DCD compared to TDC as expected (p < 0.05). Only the TDC benefited from the AV information for movement control, as deceleration time of the dominant hand was seen to decrease when moving to an AV stimulus (p < 0.05). Overall, data shows children with DCD do benefit from a bimodal stimulus to plan their movement, but do not for movement control. Further research is required to understand if this is a result of impaired multisensory integration.