Developmental Changes in the Responsivity of the Brain to Endogenous and Exogenous Factors

  • Paola S. Timiras
Part of the Advances in Behavioral Biology book series (ABBI, volume 8)


Those of us working in the area of CNS development have become increasingly aware that the effects of drugs on this system, and especially on the brain, vary with age, the specific brain structure studied, and the selected neurologic parameter tested. The significance of such variables has been well demonstrated by the presentations delivered at this conference. Equally important in studies of the neurologic effects of drugs is the physiological state of the organism as a whole, and of the brain in particular at the time of drug administration, inasmuch as functional equilibrium is intrinsically related to neurologic competence. This consideration is crucial during development when the requirements for differentiation and growth impose an additional burden on the homeostatic capability of the organism (Timiras, 1972). Consequently, the role of internal factors (for example, the hormonal milieu) and external factors (represented by a variety of stressful environmental conditions) on the developing brain must be carefully evaluated in terms of possible synergisms or antagonisms with the effects of drugs. Additionally, it must be recognized that at no other time during the lifespan can drugs exert such dramatic effects as during development; indeed, the administration of drugs at selected critical periods in brain maturation, whether prenatally, neonatally or at puberty, is capable not only of immediately modifying the functional state of the brain but also of altering the normal timetable of development.


High Altitude Brain Development Brain Maturation Myelin Formation Testosterone Propionate 
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Copyright information

© Plenum Press, New York 1974

Authors and Affiliations

  • Paola S. Timiras
    • 1
  1. 1.Department of Physiology-AnatomyUniversity of CaliforniaBerkeleyUSA

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