Implications and Speculations
Hibernation is a highly specialized adaptive ability that has evolved relatively recently in various separate lineages of mammals (Chapter 1). Many aspects of hibernation involve changes in functions that a’e controlled in other mammals by hypothalamic areas (Chapter 2). Relatively little is known about the external or internal factors that in the hibernators initiate and moderate activity in this part of the brain (Chapters 4 and 6), however, rebalancing and extreme adjustments of normal mammalian systems provide a plausible framework for an array of phenomena of the prehibernation phase and also for thermoregulatory changes during hibernation (Chapters 3 and 5)- Moreover, such an account is consistent with what is known about the hypothalamus of hiberna-tors, and in the annual changes of the supraoptic nucleus there is already some evidence for special hypothalamic plasticity in hibernators (Chapters 2 and 7). Nevertheless, some minds may be exasperated by the lack of attempts to check directly whether hypothalamic systems concerned with obesity and temperature are actually changing in hibernators. Would it not be better to establish through biochemical, histological, or ultrastruc-tural investigations that there are indeed seasonal changes in the medial hypothalamus rather than marshaling a mass of indirect evidence which, however plausible it may be, proves nothing?
KeywordsLateral Hypothalamus Obese People Meal Size Medial Stimulation Medial Hypothalamus
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