How the body controls brain temperature: the temperature shielding effect of cerebral blood flow

• Published in: Journal of applied physiology (1985) Vol. 101; no. 5; pp. 1481 - 1488
• Main Authors: Zhu, Mingming, Ackerman, Joseph J. H, Sukstanskii, Alexander L, Yablonskiy, Dmitriy A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-11-2006; American Physiological Society
• Subjects: Adaptation, Physiological - physiology; Adult; Animals; Biological and medical sciences; Blood Flow Velocity - physiology; Body Temperature Regulation - physiology; Brain; Brain - blood supply; Cerebrovascular Circulation - physiology; Cold Temperature; Fundamental and applied biological sciences. Psychology; Human body; Humans; Hypothermia; Infant, Newborn; Male; Models, Biological; Protection; Rats; Rats, Sprague-Dawley; Temperature; Regional blood flow; Body temperature; bio- heat equation; Central nervous system; Environmental factor; Metabolism; Encephalon; brain temperature regulation; Vertebrata; Heat; Mammalia; Hemodynamics; Hypothermia; cerebral metabolism
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00319.2006

Departments of 1 Chemistry, 2 Radiology, 3 Physics, and 4 Internal Medicine, Washington University, St. Louis, Missouri
Submitted 14 March 2006
; accepted in final form 6 July 2006
ABSTRACT
Normal brain functioning largely depends on maintaining brain temperature. However, the mechanisms protecting brain against a cooler environment are poorly understood. Reported herein is the first detailed measurement of the brain-temperature profile. It is found to be exponential, defined by a characteristic temperature shielding length, with cooler peripheral areas and a warmer brain core approaching body temperature. Direct cerebral blood flow (CBF) measurements with microspheres show that the characteristic temperature shielding length is inversely proportional to the square root of CBF in excellent agreement with a theoretical model. This "temperature shielding effect" quantifies the means by which CBF prevents "extracranial cold" from penetrating deep brain structures. The effect is crucial for research and clinical applications; the relationship between brain, body, and extracranial temperatures can now be quantitatively predicted.
brain temperature regulation; cerebral metabolism; hypothermia; bioheat equation
Address for reprint requests and other correspondence: D. A. Yablonskiy, Mallinckrodt Institute of Radiology, CB 8227, 4525 Scott Ave., St. Louis, MO 63110 (e-mail: YablonskiyD{at}wustl.edu )