Chronic jet-lag increases mortality in aged mice

already extensive evidence from fMRI and architectonic studies that the human brain contains many more cortical areas (possibly 150 or more) than the brains of macaque monkeys. One would also expect areas to be more frequently subdivided into sets of modules or columns of functionally related neurons, such as the three types of bands of neurons subdividing the second visual area, V2, of primates, but there is only limited evidence for this. However, the premise that hemispheric asymmetries increase with brain size in order to reduce the need for costly interhemispheric communication is well supported by the extensive evidence for hemispheric specializations in the human brain related to handedness, language, attention, memory and object recognition. In conclusion, an outline of the course of the evolution of the human brain is starting to emerge. Great progress in the gathering of relevant data has occurred over the last 20–30 years. A more complete description could easily occupy a series of volumes, and interested readers are invited to read further. Most importantly, there is much yet to be gained by applying current methods of investigation so that future reviews can be better informed and greatly enriched. Why is brain size so important: Design problems and solutions as neocortex gets bigger or smaller. Brain and Mind 1, 7–23. Despite the fact that trans-meridian travel and shift work are commonplace in our 24/7 society, few controlled studies have addressed the health effects of repeated phase shifts of the biological clock. Shift work [1] and chronic jet-lag [2] reduce mental acuity and increase the risk of a number of medical problems, including cancer, peptic ulcers and sleep disorders. Some of these problems become more severe with the number of years on the job, the result either of cumulative damage or the increased age of the subjects [3]. In general, morbidity associated with many organic disorders is increased in the aged; however, the role played by age-associated alterations in the circadian clock is poorly understood. In particular the effect of repeated schedule changes is largely unaddressed. Here we report evidence that chronic jeg-lag increases mortality rates in aged mice. We were led to the current experiment by an observation in an unrelated study where we found that three of eight aged transgenic rats exposed to a 6 hour advance of the light cycle died following the light schedule change. In contrast, no deaths were observed if the …