Integration and central processing in temperature regulation.

Our understanding of the neural control of body temperature has been clarified by research over the past ten years. Overall, ascending thermal inputs are integrated with other thermal and nonthermal inputs, which results in efferent signals with the spatial and temporal characteristics necessary for driving effector organs involved in thermal homeostasis. There is substantial support for the hypothesis that the afferent component of the thermoregulatory system integrates thermal stimuli into several neural patterns, the principal ones being a stepwise, switching response of neuron activity during scrotal thermal stimulation and a proportional response to other thermal inputs. Furthermore, some thermointegrative CNS neurons respond relatively rapidly or slowly during peripheral thermal stimulation, which may be critical in driving behavioral and autonomic motor outputs, respectively. The control of thermoregulatory motor outputs is multifaceted and exhibits proportional, rate-sensitive, and/or on-off regulatory patterns during thermal stimulation. These complex motor patterns indicate the presence of extensive temporal and spatial integration of ascending thermal information. This is supported by the fact that the pattern of efferent nerve activity in various motor systems (e.g. vasomotor) is vastly different from that produced by recordings of primary thermoreceptor activity. Understanding the nature and mechanisms of the CNS transduction of peripheral thermal stimuli to efferent command signals for driving thermoregulatory motor outputs will be a challenging endeavor in the future.