all of which need to be stored, catalogued, and integrated if they are to be of general use.

Some of the data come from the imaging techniques that help neuroscientists peer into the brain and observe its structure and function. Magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) each offer a unique way of seeing the brain and its components. Functional magnetic resonance imaging (fMRI) reveals which parts of a brain are working hardest during a mental activity, electroencephalography (EEG) tracks electric activity on the surface of the brain, and magnetoencephalography (MEG) traces deep electric activity. Cryosectioning creates two-dimensional images from a brain that has been frozen and carved into thin slices, and histology produces magnified images of a brain's microscopic structure. All of those different sorts of images are useful to scientists studying the brain and should be available in databases, Koslow said.

Furthermore, many of the images are most useful not as single shots but as series taken over some period. “The image data are dynamic data,” Koslow said. “They change from day to day, from moment to moment. Many events occur in a millisecond, others in minutes, hours, days, weeks, or longer.”

Besides images, neuroscientists need detailed information about the function of the brain. Each individual section of the brain, from the cerebral cortex to the hippocampus, has its own body of knowledge that researchers have accumulated over decades, Koslow noted. “And if you go into each of these specific regions, you will find even more specialization and detail—cells or groupings of cells that have specific functions. We have to understand each of these cell types and how they function and how they interact with other nerve cells. ”

“In addition to knowing how these cells interact with each other at a local level, we need to know the composition of the cells. Technology that has recently become available allows us to study individual cells or individual clusters of similar cells to look at either the genes that are being expressed in the cells or the gene products. If you do this in any one cell, you can easily come up with thousands of data points.” A single brain cell, Koslow noted, may contain as many as 10,000 different proteins, and the concentration of each is a potentially valuable bit of information.

The brain's 100 billion cells include many types, each of which constitutes a separate area of study; and the cells are hooked together in a network of a million billion connections. “We don't really understand the mechanisms that regulate these cells or their total connectivity, ” Koslow said; “this is what we are collecting data on at this moment.”

Neuroscientists describe their findings about the brain in thousands



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