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Brain architecture, neoclassical style.

Brain architecture, neoclassical style

Anatomical studies of sonar-using animals reveal a striking architecture in three brain areas, called nuclei, which are devoted to hearing. "Cells in these nuclei form orderly rows or columns that are more uniformly aligned than is found in most" non-sonar-sing mammals, reports John Zook of Ohio University in Athens. In addition, these auditory nuclei, which he and his colleagues examined in several bat and dolphin species, appear to be connected by bundles of parallel nerve fibers.

In relation to cells in the first nucleus, cells in the second nucleus were arranged in a "slanted-line pattern," Zook's group observed. Since these two nuclei are connected with parallel fibers of differing lengths, simultaneous impulses traveling from different cells in the first nucleus will arrive in a staggered fashion at the second nucleus. Such an arrangement could "preserve or analyze temporal patterns" in the signals being relayed through the auditory system, they report. For example, the many frequencies in a single sound could be separated if different cells of the first nucleus were frequency-specific.

Zook also found that a third auditory nucleus gets orderly input from both of the other nuclei -- a direct line from the first nucleus and an indirect or "delayed line" from the second. He speculates that such a structure could be the place where the brain compares sounds from sonar emissions with sounds from the returning echoes. Using such comparisons, he says, bats and dolphins could construct acoustic images of their environment.
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Title Annotation:anatomy of sonar-using animals
Publication:Science News
Date:Oct 11, 1986
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