With 100 billion neurons and 1,000 trillion synapses, the human brain is beyond complex. While the field of neuroscience is devoted to studying the brain and the nervous system, we know incredibly little about how the mind actually works. What is personality? Consciousness? Many believe synapses, the connections made between neurons, are the key. Subtle differences in brain connections may be the explanation behind the difference between the brains of a mathematical genius and a star quarterback.
In investigating such differences, neuroscientists have begun a huge undertaking they have dubbed “the connectome”, which gets its name from the genome. This project has a relatively straightforward goal: to map the brain on both macro and micro scales, from the largest lobes of the neocortex down to every last neuron and the connections between them. While some doubt this can be completed, scientists are mounting efforts to achieve this goal by means of several new technologies, including brainbow, Brain Navigator, and the Allen Brain Atlas.
Neurons are tightly intertwined and extremely tiny. Two new technologies, “brainbow” and diffusion tensor imaging (DTI), have helped neuroscientists to identify these cells. Brainbow technology causes individual neurons to fluoresce with one of a hundred colors, enabling researchers to identify individual neurons and trace their axons and dendrites under a confocal microscope with relative ease. The identification and quantification of cells and their synapses becomes a more feasible task. How this technology will be used in the future has yet to be seen; it has a great deal of potential. Brainbow may one day be able to indicate specific types of neurons, not just random cells.
White matter in the brain is made of myelin, a sheathing substance that wraps around the axons of neurons. Most technologies show white matter as a mass, with no detail, even though it is made of billions of fibers running in many directions. Diffusion tensor imaging uses the vibration of water molecules in the brain to indicate the orientation and direction of these fibers. This is the only technology currently available that can show this level of white matter structure.
One technology contributing to efforts to map the connectome are computerized brain atlases. These bring the ability to visualize the brain to a new level, allowing the user to rotate, slice, and identify and remove structures. They also show patterns of expression for genes and neurostransmitter receptors in brain sections. These digital images help neuroscientists locate structures and their surroundings, leading to more accurate and efficient research. Any person with access to the internet can experience these accomplishments firsthand, giving him or her a more complete and thorough understanding of the position of any brain structure. Brain Navigator and the Allen Brain Atlas are two of the most well-developed resources available; be sure to check them out by clicking the links above! Such databases may someday include detail on the cellular level, showing every neuron and every synapse each cell makes, exposing pathways of neurons and synapses throughout the brain, helping to achieve the goal of the connectome.
Standard maps of the brain have also been developed in 4D, the fourth dimension being time. The brain changes during fetal life, childhood, and adolescence development and in the adult brain through changes caused by diseases such as Alzheimer’s or schizophrenia. Being able to document and view a full representation of the brain over time is a very valuable resource that will help solve some of the most important questions surrounding human diseases and the changes that cause neurological disorders. Brain atlases in 4D are still in their beginning stages; a great deal of data needs to be documented and compiled from many disease sufferers to establish such a resource.
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