The disturbing influences of background gradient fields, eddy currents, and the finite mixing time can be minimized using 84 direction combinations based on nine directions and their antipodes. "But when you look at these new maps we have of what's happening in the fetal brain," Insel says, suddenly much of this begins to make sense.To demonstrate that rotationally invariant measures of the diffusion anisotropy on a microscopic scale can be mapped in human brain white matter in vivo.Įcho-planar imaging experiments (resolution 3.0 × 3.0 × 3.0 mm(3) ) involving two diffusion-weighting periods (δ = 22 ms, Δ = 25 ms) in the same acquisition, so-called double-wave-vector or double-pulsed-field-gradient diffusion-weighting experiments, were performed on a 3 T whole-body magnetic resonance system with a long mixing time ( τm=45 ms) between the two diffusion weightings. That realization is already helping to explain the complex role that genes often play in brain disorders, Insel says.įor example, researchers have been puzzled by some of the genes that appear to be involved in autism and schizophrenia because their function in the adult brain didn't seem to have anything to do with the disorders. "It's almost as if the fetal brain is a different organ altogether." "It's an enormous surprise to us that the genes that get expressed in the fetal brain don't look anything like what we would have expected from the adult brain," Insel says. The map also reveals just how little scientists had known about the brain of a fetus. These differences could explain why a number of brain drugs that work well in mice have failed badly in people. The second important finding from the mapping project, Lein says, is that the human brain is different from a mouse brain in ways researchers didn't know before.
Yet its basic architecture is created in just nine months, when it grows from a single cell to more than 80 billion cells organized in a way that will eventually let us think and feel and remember. The human brain is often called the most complex object in the universe. Thomas Insel, director of the National Institute of Mental Health. Having a map like this is important because many psychiatric and behavioral problems appear to begin before birth, "even though they may not manifest until teenage years or even the early 20s," says Dr. "Basically, there was no information of this sort prior to this project." "It's a pretty big leap," says Ed Lein, an investigator at the Allen Institute for Brain Science in Seattle who played a central role in creating the map. The map shows where genes are turned on and off throughout the entire brain at about the midpoint of pregnancy, a time when critical structures are taking shape, researchers reported Wednesday in the journal Nature. Images of the developing fetal brain show connections among brain regions.Īllen Institute for Brain Science Bruce Fischl, Martinos Center for Biomedical Imaging, Massachusetts General HospitalĪ high-resolution map of the human brain in utero is providing hints about the origins of brain disorders including schizophrenia and autism.
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