this is a crucial oversight because continual depletion promotes the searching efficiencies of some Levy walks above that of ballistic motion. the continual depletion effect is not so important for two- and three-dimensional searches. Nevertheless, we show that Levy walks and ballistic movements can be equally or almost equally effective when searching within two- and three-dimensional environments for randomly and sparsely distributed targets or when searching for targets that are occasionally concealed. We also show that Levy walks are advantageous when searching for targets that can occasionally evade capture. These situations represent common predator-prey interactions in which

predators are involved in ‘imperfect destructive’ searches. Our model suggests that accounting for coevolutionary arms races at the predator-prey detection/reaction scales can explain to some extent Levy walk searching patterns of predators at larger find more scales. This result provides new insights into the Levy walk movement patterns of some destructive for agers. (C) 2009 Elsevier

Ltd. All rights reserved.”
“Evidence of prefrontal cortex decline among healthy older adults has been widely reported, although many questions remain regarding the functional heterogeneity of the prefrontal lobes and the uniformity (or lack thereof) with which discrete regions decline with age. MacPherson, Phillips, and Della Sala (2002) AP24534 in vitro previously reported age differences in tasks associated with dorsolateral prefrontal cortex (DLPFC) function (executive control), but not for tasks associated with ventromedial prefrontal cortex VE-822 chemical structure (VMPFC) function (emotional/cognitive integration).

The present study, conducted using 39 younger adults and 39 older adults, replicates the MacPherson et al. findings regarding DLPFC functioning. However, and perhaps due to the use of more sensitive tasks, we also find age differences in tasks associated with VMPFC function. Specifically, both univariate and multivariate analyses indicated older adults showed deficits across the DLPFC and VMPFC tasks. Exploratory factor analysis of the task performance scores indicated four underlying dimensions, two related to DLPFC functioning and two related to VMPFC functioning. A set of structural equation models specifying age effects on the four task performance factors was tested, in order to contrast models of process-specific vs. common age effects. Our results suggest that older adults show deficits in emotional/cognitive integration as well as in executive function, and that those effects do include process-specific age deficits. (C) 2009 Elsevier Ltd. All rights reserved.”
“Body parts are represented in the brain in a very specific fashion, as compared to other three-dimensional objects, with reference to their prototypic shape and multisensory coding.