Skeletal muscle contains intramyocellular lipid droplets within the cytoplasm of myocytes as well as intermuscular adipocytes. These depots exhibit physiological and pathological variation which has been revealed with the advent of diagnostic imaging approaches: magnetic resonance (MR) imaging, MR spectroscopy and computed tomography (CT). CT uses computer-processed X-rays and is now being applied in muscle physiology research. The purpose of this review is to present CT methodologies and summarize factors that influence muscle radiation attenuation, a parameter which is inversely related to muscle fat content. Pre-defined radiation attenuation ranges are used to demarcate intermuscular adipose tissue [from −190 to −30 Hounsfield units (HU)] and muscle (−29 HU to +150 HU). Within the latter range, the mean muscle radiation attenuation [muscle (radio) density] is reported. Inconsistent criteria for the upper and lower HU cut-offs used to characterize muscle attenuation limit comparisons between investigations. This area of research would benefit from standardized criteria for reporting muscle attenuation. Available evidence suggests that muscle attenuation is plastic with physiological variation induced by the process of ageing, as well as by aerobic training, which probably reflects accumulation of lipids to fuel aerobic work. Pathological variation in muscle attenuation reflects excess fat deposition in the tissue and is observed in people with obesity, diabetes type II, myositis, osteoarthritis, spinal stenosis and cancer. A poor prognosis and different types of morbidity are predicted by the presence of reduced mean muscle attenuation values in patients with these conditions; however, the biological features of muscle with these characteristics require further investigation.

in some respect from the actual symptomatology, then that information might be useful in identifying fabrications. Second, and perhaps more importantly, the common knowledge about the sequalae of these injuries can be ofconsiderable utility in understanding attitudes of family, friends, juries and others to persons who are in no way malingering, but for whom the symptom complex has a real physical basis. MethodSubjects andprocedure Forty three university students participated as an option for an Introductory Psychology course requirement. Minor head injury was not a topic covered in the course and they were unaware of the goals of the research at the time they volunteered to participate. Twenty two subjects completed a likelihood judgement task and 21 subjects made speed judgements. Both groups read one short description of a car accident and made judgements about 50 symptoms and five outcomes that might have been experienced by the driver. Each group then read a second, different accident description and made judgements about the symptoms and outcomes for that situation. The two descriptions were given to about half ofeach group in one order (A followed by B) and presented in the other order (B followed by A) to the remaining subjects. Two random presentation orders of the symptom and outcome list were used.The symptom list included items from five categories: Physical symptoms (HiPhys) frequently reported in the literature as typical of the PTS, less frequently reported but none the less representative physical symptoms (LoPhys), 842 by copyright.

"You-Are-Here" (YAH) maps, common in shopping malls and office buildings, are difficult to interpret if not aligned with their surroundings. Younger and older adults made direction decisions after viewing simple maps representing a university campus. YAH arrows were either upright and coordinated with viewer position or contra-aligned 180 degrees. Contra-alignment caused subjects, especially older adults, to take more time and be less accurate. Women were slower on contra-aligned maps, although no less accurate, than men. The need to mentally realign such incongruent maps in order to make correct direction decisions can cause serious difficulty for older adults trying to navigate through large, complex environments.

An important issue in aging and memory research concerns whether there is an age-related decline in the encoding and use of semantic attributes. Presumably, impoverished encoding of the to-be-learned material may account in part for the poorer performance of older adults. Several studies have used the Wickens release from proactive inhibition (PI) task to investigate the semantic encoding of different age groups. The general consensus from these studies has been that there is no decline in the extent of semantic encoding with increases in age. In this review, the existing research is critiqued and methodological and measurement issues are discussed. The Wickens PI release measure was reported in only one study. The relevance of that measure of PI is discussed and it is calculated and presented for each experiment for which requisite data had been reported. In every study the Wickens measure of release was greater for the younger group, but statistical tests were not possible. Methodological concerns and evidence from the Wickens release measure provided the bases for suggesting that the existing evidence provides ambiguous support for the claim that the extent of semantic encoding is unchanged with advancing age.

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