In This Issue

A test requiring judgments about size differences between objects represented by their names revealed that patients meeting criteria for amnestic mild cognitive impairment had problems in semantic memory that were independent of the ability to retrieve the words themselves. The problems were more pronounced for objects with small size differences. When the objects were represented by drawings, incongruity in the size of the objects (figure) had an undue influence on patients’ judgments. Kirchberg et al. (p. 1275) suggest that the findings indicate a degraded store of semantic knowledge, their general store of knowledge about the world. The semantic memory deficit was associated with functional impairment, and in an editorial Salmon (p. 1226) considers how a loss of semantic knowledge could contribute to a decline in judgment about financial and other important matters.

Brain locations showing disrupted white matter, or “potholes,” were more numerous in war veterans with mild traumatic brain injury (TBI) than in veterans without TBI, even though the groups did not differ significantly when they were compared across each brain region. Jorge et al. (CME, p. 1284) conclude that the brain damage due to TBI is diffuse and does not target specific brain regions. A higher number of potholes was associated with greater TBI severity and loss of ability to execute mental tasks. Civilians with TBI had even higher numbers of potholes than the veterans with TBI, but as Silver notes in an editorial (p. 1230), the civilians’ injuries were much more recent and abnormalities vary over time.