Category deficits and paradoxical dissociations in Alzheimer's disease and Herpes Simplex Hencephalitis

Most studies examining category specificity are single-case studies of patients with living or non living deficits. Nevertheless, no explicit or agreed criteria exist for establishing category-specific deficits in single-cases regarding the type of analyses, whether to compare with healthy controls, the number of tasks, or the type of tasks. We examined to groups of patients with neurological pathology frequently accompained with impaired semantic memory (19 patients with Alzheimer disease and 15 with Herpes Simplex Encephalitis). Category knowledge was examined using three tasks (picture naming, naming-to-description and features verification). Both patients groups were compared with aged- and education- matched healthy controls. The profile of each patients was examined for consistency across tasks and across different analyses; however both prove to be inconsistent. One striking findings was the presence of a paradoxical dissociation ( i.e., patients who were impaired on living things on one task and non living things on another task). The findings have significant implication for how we determine category effects and, more generall for the methods use to document double dissociation across individual cases in this literature

Shifting trends: detecting environmentally mediated regulation in long-lived marine vertebrates using time-series data

© Springer-Verlag 2008Assessing the status and trends in animal populations is essential for effective species conservation and management practices. However, unless time-series abundance data demonstrate rapid and reliable fluctuations, objective appraisal of directionality of trends is problematic. We adopted a multiple-working hypotheses approach based on information-theoretic and Bayesian multi-model inference to examine the population trends and form of intrinsic regulation demonstrated by a long-lived species, the southern elephant seal. We also determined the evidence for density dependence in 11 other well-studied marine mammal species. (1) We tested the type of population regulation for elephant seals from Marion Island (1986–2004) and from 11 other marine mammal species, and (2) we described the trends and behavior of the 19-year population time series at Marion Island to identify changes in population trends. We contrasted five plausible trend models using information-theoretic and Bayesian-inference estimates of model parsimony. Our analyses identified two distinct phases of population growth for this population with the inflexion occurring in 1998. Thus, the population decreased between 1986 and 1997 (−3.7% per annum) and increased between 1997 and 2004 (1.9% per annum). An index of environmental stochasticity, the Southern Oscillation Index, explained some of the variance in r and N. We determined analytically that there was good evidence for density dependence in the Marion Island population and that density dependence was widespread among marine mammal species (67% of species showed evidence for population regulation). This approach demonstrates the potential functionality of a relatively simple technique that can be applied to short time series to identify the type of regulation, and the uncertainty associated with the phenomenon, operating in populations of large mammals.Clive R. McMahon, Marthan N. Bester, Mark A. Hindell, Barry W. Brook and Corey J. A. Bradsha