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

Trends Neurosci. 1994 Sep;17(9):379-89. doi: 10.1016/0166-2236(94)90047-7.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Emotions / physiology*
  • Humans
  • Mesencephalon / anatomy & histology
  • Mesencephalon / physiology*
  • Neural Pathways / anatomy & histology
  • Neural Pathways / physiology
  • Periaqueductal Gray / anatomy & histology
  • Periaqueductal Gray / physiology*