Tympanic temperature asymmetry and stress behavior in rhesus macaques and children
W. T. Boyce, J. D. Higley, J. J. Jemerin, M. Champoux and S. J. Suomi
Institute of Human Development, University of California, Berkeley, USA.
OBJECTIVES: To examine left-to-right tympanic membrane temperature
asymmetries and their possible association with biobehavioral stress
responses in rhesus macaques and children. SUBJECTS AND DESIGN: Infrared
tympanic membrane thermometry was completed bilaterally in 19 two-year-old
rhesus macaques and 18 eight-year-old children in a cross-sectional,
laboratory-based study. Unidirectional temperature gradients were
calculated as the mean of two left-sided measurements minus the mean of two
right-sided measurements. Biobehavioral stress responses were assessed in
monkeys as agitated motor activity and adrenocortical activation after
separation from the social group, and in children as parent-reported
resilience to psychological stress and child behavior problems. RESULTS:
Significant asymmetry was detected in tympanic membrane temperatures in
both monkey and child samples, with left-sided temperatures measuring
slightly but significantly higher than those from the right tympanic
membrane. Higher-magnitude left-to-right temperature gradients were
associated with stress-related locomotion in macaques and with lower
resilience and more behavior problems in children. CONCLUSIONS: There are
small but reliable asymmetries in the tympanic membrane temperatures of
young human and nonhuman primates. Tympanic membrane temperature gradients
reflect important individual differences in biologically derived responses
to psychological stressors.