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Trends Neurosci. 1994 Sep;17(9):379-89.

Columnar organization in the midbrain periaqueductal gray: modules for emotional expression?

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Dept of Anatomy and Histology, University of Sydney, New South Wales, Australia.

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  • Trends Neurosci 1994 Nov;17(11):445.


Independent discoveries in several laboratories suggest that the midbrain periaqueductal gray (PAG), the cell-dense region surrounding the midbrain aqueduct, contains a previously unsuspected degree of anatomical and functional organization. This organization takes the form of longitudinal columns of afferent inputs, output neurons and intrinsic interneurons. Recent evidence suggests: that the important functions that are classically associated with the PAG--defensive reactions, analgesia and autonomic regulation--are integrated by overlapping longitudinal columns of neurons; and that different classes of threatening or nociceptive stimuli trigger distinct co-ordinated patterns of skeletal, autonomic and antinociceptive adjustments by selectively targeting specific PAG columnar circuits. These findings call for a fundamental revision in our concept of the organization of the PAG, and a recognition of the special roles played by different longitudinal PAG columns in co-ordinating distinct strategies for coping with different types of stress, threat and pain.

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[Indexed for MEDLINE]

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