Infant mammals devote considerable resources to thermal, fluid, and cardiovascular homeostasis. Recent work in the PI's laboratory has shown that infant rats, long considered poor thermoregulators because of their high rates of heat loss during cold exposure, actually exhibit many signs of successful thermoregulation when tested under appropriate conditions. Their success depends on the ability to produce heat internally using brown adipose tissue (BAT), as well as the delivery of this heat to the heart and other temperature-sensitive organs. We have learned that infants that possess endothermic capabilities (i.e., rats) exhibit significantly different behavioral and physiological responses to cold than infants that do not (i.e., hamsters). We still do not understand, however, how infants of either species orient and locomote toward warmth and whether the ability to produce heat internally interferes with the expression of thermoregulatory behavior. Therefore, this proposal represents the logical next step in a research program that addresses basic issues in biobehavioral research and aims to develop a better understanding of the myriad physiological and behavioral mechanisms by which infants regulate their internal thermal environment and select their external thermal environment. This work has important implications for the thermal management of preterm and full-term human infants, sick or healthy, who differ in their abilities to produce heat endogenously and about whose thermoregulatory behavior we know very little. First, with our new appreciation of the thermoregulatory capabilities of individual infant rats, the behavioral and physiological responses of huddling rat pups during cold exposure are examined. Group regulatory behavior is examined in infant rats after ganglionic blockade, after selective activation of BAT thermogenesis in ganglionically blocked pups, and in mixed huddles comprised of infant rats and hamsters. These experiments will reveal how endothermy contributes to the expression and effectiveness of huddling behavior. Second, thermoregulatory behaviors in isolated individuals are examined using a newly- developed, novel apparatus - a multi-tiled """"""""checkerboard"""""""" apparatus composed of peltier diodes - that provides fine control over the thermal environment. In addition, the use of infrared thermography provides essential thermal data without interfering with behavioral expression. The combination of these approaches places us in an ideal position to critically examine behavioral arousal, locomotion, orientation, and thermal preference in infant rats and hamsters during cold exposure, as well as the contributions of endothermy to each of these behavioral processes. Finally, subsequent experiments will address the sensory and neural mechanisms that mediate behavioral responses to cold.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH050701-07
Application #
6392058
Study Section
Special Emphasis Panel (ZRG1-BBBP-1 (01))
Program Officer
Oliveri, Mary Ellen
Project Start
1994-05-01
Project End
2004-03-31
Budget Start
2001-04-01
Budget End
2002-03-31
Support Year
7
Fiscal Year
2001
Total Cost
$220,500
Indirect Cost
Name
University of Iowa
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Blumberg, Mark S (2017) Development evolving: the origins and meanings of instinct. Wiley Interdiscip Rev Cogn Sci 8:
Gall, Andrew J; Todd, William D; Blumberg, Mark S (2012) Development of SCN connectivity and the circadian control of arousal: a diminishing role for humoral factors? PLoS One 7:e45338
Karlsson, K A E; Arnardóttir, H; Robinson, S R et al. (2011) Dynamics of sleep-wake cyclicity across the fetal period in sheep (Ovis aries). Dev Psychobiol 53:89-95
Mohns, Ethan J; Blumberg, Mark S (2010) Neocortical activation of the hippocampus during sleep in infant rats. J Neurosci 30:3438-49
Seelke, Adele M H; Blumberg, Mark S (2010) Developmental appearance and disappearance of cortical events and oscillations in infant rats. Brain Res 1324:34-42
Marcano-Reik, Amy Jo; Prasad, Tuhina; Weiner, Joshua A et al. (2010) An abrupt developmental shift in callosal modulation of sleep-related spindle bursts coincides with the emergence of excitatory-inhibitory balance and a reduction of somatosensory cortical plasticity. Behav Neurosci 124:600-11
Todd, William D; Gibson, James L; Shaw, Cynthia S et al. (2010) Brainstem and hypothalamic regulation of sleep pressure and rebound in newborn rats. Behav Neurosci 124:69-78
Gall, Andrew J; Joshi, Badal; Best, Janet et al. (2009) Developmental emergence of power-law wake behavior depends upon the functional integrity of the locus coeruleus. Sleep 32:920-6
Marcano-Reik, Amy Jo; Blumberg, Mark S (2008) The corpus callosum modulates spindle-burst activity within homotopic regions of somatosensory cortex in newborn rats. Eur J Neurosci 28:1457-66
Mohns, Ethan J; Blumberg, Mark S (2008) Synchronous bursts of neuronal activity in the developing hippocampus: modulation by active sleep and association with emerging gamma and theta rhythms. J Neurosci 28:10134-44

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