Tag Archives: Brain thermoregulation

Selective brain cooling in modern humans

The human brain is the most expensive and costly organ in terms of energetic resources and management. However, the current understanding of its sophisticated thermal control mechanisms remains insufficient. Wang et al., 2016, have reviewed the most recent studies on brain thermoregulation and examined the anatomical and physiological elements associated with selective brain cooling. Modern humans have a brain that is approximately three times larger than a primate with a similar body size, which uses 20%– 25% of the total body energy compared with a maximum of 10% in other primates and 5% in other mammals. The evolution of a large and expensive brain in modern humans effectively influences critical factors such as temperature, and functional limits can affect cerebral complexity and neural processes. Brain thermoregulation depends on many anatomical components and physiological processes, and it is sensitive to various behavioral and pathological factors, which have specific relevance for clinical applications and human evolution. The anatomical structures protecting the brain, such as the human calvaria, the scalp, and the endocranial vascular system, act as a thermal interface, which collectively maintains and shield the brain from heat challenges, and preserves a stable equilibrium between heat production and dissipation. Future advances in biomedical imaging techniques would allow a better understanding of the physiological and anatomical responses related to the cerebral heat management and brain temperature in modern humans.

Gizéh Rangel de Lázaro

 

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Craniovascular traits

This month we have published a review on craniovascular traits and anthropology, freely available to download from the Journal of Anthropological Sciences. The article describes many vascular traits that can be analyzed on skulls, through the traces they leave on the bone surface or within the bone itself. The traces of the middle meningeal vessels, the traces of the venous sinuses, the diploic channels, and the endocranial foramina, can provide information on the vascular networks and, indirectly, on the physiological processes associated with their growth and development. The functional information available from these imprints is partial and incomplete, but it is the only one we have on blood flow when dealing with fossils, archaeological remains, or forensic cases. Methods are an issue, because of the difficulties with small samples, scoring procedure, statistics of ordinal and nominal variables, and with an intrinsic limitation in current anatomy: we still ignore the variations and processes behind many macroanatomical features, even in our own species. Previous articles on this topic deal with middle meningeal artery, vessels and thermoregulation, diploic channels, and parietal bone vascularization. Most of these papers are part of a project funded by the Wenner-Gren Foundation through an International Collaborative Research Grant, entitled “Cranial anatomy, anthropology, and the vascular system”. This beautiful drawing of a sectioned skull is by Eduardo Saiz.