The functions of the resting state networks (RSNs) revealed by functional MRI remain unclear, but it has seemed possible that networks emerge in parallel with the development of related cognitive functions. We tested the alternative hypothesis: that the full repertoire of resting state dynamics emerges during the period of rapid neural growth before the normal time of birth at term (around 40 wk of gestation). We used a series of independent analytical techniques to map in detail the development of different networks in 70 infants born between 29 and 43 wk of postmenstrual age (PMA). We characterized and charted the development of RSNs from recognizable but often fragmentary elements at 30 wk of PMA to full facsimiles of adult patterns at term. Visual, auditory, somatosensory, motor, default mode, frontoparietal, and executive control networks developed at different rates; however, by term, complete networks were present, several of which were integrated with thalamic activity. These results place the emergence of RSNs largely during the period of rapid neural growth in the third trimester of gestation, suggesting that they are formed before the acquisition of cognitive competencies in later childhood.blood oxygen level-dependent | functional MRI | neurodevelopment | intrinsic brain activity | newborn T he detection of spontaneous spatially coherent fluctuations of the blood oxygen level-dependent (BOLD) signal by functional MRI (fMRI) (1) offers potential insights into the largescale organization of neural function at the system levels (comprehensive review presented in 2). These resting state networks (RSNs) replicate the set of functional networks exhibited by the brain over its range of possible tasks (3), encompassing various spatially distinct neural systems, including the medial visual and lateral visual, auditory, somatosensory, motor, cerebellum, executive control, and frontoparietal or dorsal visual stream networks as well as the default mode network (DMN) (2-4). However, although the configurations and consistency of these networks are established, their functions are still not fully understood.Elucidating the ontogeny of RSNs could clarify the role of this large-scale neural organization. Previous studies at the time of normal birth [term, around 40 wk of postmenstrual age (PMA)] have detected RSNs in the primary visual areas, somatosensory and motor cortices, temporal cortex, cerebellum, prefrontal cortex (5, 6), and incomplete DMN (7) but did not find the complete DMN, executive control network, or dorsal visual network. This led to the suggestion that the full architecture emerges during later childhood in parallel with the development of corresponding cognitive functions.Here, we test the alternative hypothesis: that the full adult repertoire of resting state dynamics emerges during the period of rapid neural growth before the normal time of birth at 38-43 postconceptional weeks (term).We used a series of independent analytical techniques to map in detail the development of different networks in ...

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Motion of an object degrades MR images, as the acquisition is time-dependent, and thus k-space is inconsistently sampled. This causes ghosts. Current motion correction methods make restrictive assumptions on the type of motions, for example, that it is a translation or rotation, and use special properties of k-space for these transformations. Such methods, however, cannot be generalized easily to nonrigid types of motions, and even rotations in multiple shots can be a problem. Here, a method is presented that can handle general nonrigid motion models. A general matrix equation gives the corrupted image from the ideal object. Thus, inversion of this system allows us to get the ideal image from the corrupted one. This inversion is possible by efficient methods mixing Fourier transforms with the conjugate gradient method. A faster but empirical inversion is discussed as well as methods to determine the motion. Simulated three-dimensional affine data and two-dimensional pulsation data and in vivo nonrigid data are used for demonstra- Motion of an object can degrade MR images and imposes constraints on scan parameters that can in turn compromise image quality. The cause of the degradation is that the acquisition is time-dependent, and the Fourier transform of the image seen during acquisition changes due to the deformation of the object. This causes inconsistencies in k-space and hence ghosts in the image.Standard motion correction methods make assumptions on the type of motions, for example, that it is a translation or a rotation, and use formulas on Fourier transforms to correct the data (1-3). We assume here that these data are acquired in shots. When the data positions at each shot are known, an empirical motion correction method could be used to spatially transform the ghosted image by the transformation corresponding to a shot, pick the k-space lines corresponding to that shot, and repeat this operation for all shots (this is a version of the method used in (1)). We could then rebuild an image by inverse Fourier transform. This method is in general incorrect, as shown by the difference between translations and rotations. Correcting translation requires only pointwise phase changes in k-space. On the other hand, correcting rotations requires knowledge of the data at neighboring k-space positions and these are acquired at different times. Before applying the Fourier rotation theorem, we would need to "synchronize" neighboring values. Furthermore, complicated motions such as nonrigid deformations cannot have a simple description in Fourier space. Here, however, we show that it is possible to correct complicated motions, including nonrigid motions. We give a full mathematical description of the problems involved; the motion corruption is entirely described by a large matrix acting on the space of images. Thus, inversion of this matrix should correct the motion's effects. This approach is of theoretical interest, but its practical value depends on how easily we can find a solution of the linear system. It turns out ...

Magnetic resonance imaging and spectroscopy systems use coils, either singly or as arrays, to intercept radio-frequency (RF) magnetic flux from regions of interest, often deep within the body. Here, we show that a new magnetic material offers novel possibilities for guiding RF flux to the receiver coil, permitting a clear image to be obtained where none might otherwise be detectable. The new material contains microstructure designed according to concepts taken from the field of photonic band gap materials. In the RF range, it has a magnetic permeability that can be produced to specification while exhibiting negligible direct-current magnetism. The latter property is vital to avoid perturbing the static and audio-frequency magnetic fields needed to obtain image and spectral data. The concept offers a new paradigm for the manipulation of RF flux in all nuclear magnetic resonance systems.

This study provides objective evidence that DEHSI represents diffuse white matter abnormality.