Understanding the genetic and environmental contributions to measures of brain structure such as surface area and cortical thickness is important for a better understanding of the nature of brain-behavior relationships and changes due to development or disease. Continuous spatial maps of genetic influences on these structural features can contribute to our understanding of regional patterns of heritability, since it remains to be seen whether genetic contributions to brain structure respect the boundaries of any traditional parcellation approaches. Using data from magnetic resonance imaging scans collected on a large sample of monozygotic and dizygotic twins in the Vietnam Era Twin Study of Aging, we created maps of the heritability of areal expansion (a vertex-based area measure) and cortical thickness and examined the degree to which these maps were affected by adjustment for total surface area and mean cortical thickness. We also compared the approach of estimating regional heritability based on the average heritability of vertices within the region to the more traditional region-of-interest (ROI)-based approach. The results suggested high heritability across the cortex for areal expansion and, to a slightly lesser degree, for cortical thickness. There was a great deal of genetic overlap between global and regional measures for surface area, so maps of region-specific genetic influences on surface area revealed more modest heritabilities. There was greater inter-regional variability in heritabilities when calculated using the traditional ROI-based approach compared to summarizing vertex-by-vertex heritabilities within regions. Discrepancies between the approaches were greatest in small regions and tended to be larger for surface area than for cortical thickness measures. Implications regarding brain phenotypes for future genetic association studies are discussed.

The present study aimed to determine how older bilingual subjects' naming performance is affected by their knowledge of two languages. Twenty-nine aging (mean age = 74.0; SD = 7.1) Spanish–English bilinguals were asked to name all pictures in the Boston Naming Test (BNT) first in their dominant language and then in their less-dominant language. Bilinguals with similar naming scores in each language, or relatively balanced bilinguals, named more pictures correctly when credited for producing a correct name in either language. Balanced bilinguals also named fewer pictures in their dominant language than unbalanced bilinguals, and named more pictures correctly in both languages if the pictures had cognate names (e.g., dart is dardo in Spanish). Unbalanced bilinguals did not benefit from the alternative (either-language) scoring procedure and showed cognate effects only in their nondominant language. These findings may help to guide the interpretation of neuropsychological data for the purpose of determining cognitive status in older bilinguals and can be used to develop models of bilingual language processing. Bilinguals' ability to name pictures reflects their experience with word forms in both languages. (JINS, 2007, 13, 197–208.)

We reported that bilingualism affects BNT performance, and that people who are “more bilingual” show larger “bilingual effects” on naming. The commentators suggested the interesting possibilities that degree of bilingualism may not be as critical as immersion in two different language environments over the course of a lifetime (Bialystok & Craik, this issue), and that proficiency in Spanish (or lack thereof in English-dominant speakers; Acevedo & Lowenstein, this issue) may be more powerful predictors of the effects we reported. In our response, we use the literature on bilingualism, and additional exploratory analyses of the data we published in this issue to predict that our findings will generalize (a) to bilinguals who speak languages other than Spanish and English, and perhaps even to (b) English-dominant bilinguals who were educated in an English speaking environment. (JINS, 2007, 13, 215–218.)

The very high sensitivity and specificity of odor identification tasks in discriminating between Alzheimer's patients and normals suggests that they reflect the presence of underlying neuropathology. Significant neuropathological changes are seen in areas critical to processing olfactory information, even in the early stages of Alzheimer's disease (AD). The current study was designed to investigate whether performance on olfactory tasks (odor threshold and odor identification) was related to volumetric MRI measures of mesial temporal areas central to olfactory information processing and important in the neuropathology of AD. Participants were 8 male and 5 female patients with probable AD, and 10 male and 12 female normal age-matched controls, diagnosed at the UCSD Alzheimer's Disease Research Center. The study investigated correlations between volumetric measures of hippocampus, the parahippocampal gyrus and the amygdala, and the psychophysical measures of olfactory function. Robust relationships were observed between mesial temporal lobe volumes and olfactory functional measures. The finding of a strong relationship between left hippocampal volume and performance on the odor identification task (r = .85) is compatible with a left-hemisphere superiority for verbally mediated olfactory tasks. The findings suggest a neural substrate for the breakdown in functional performance on verbally mediated odor identification tasks in Alzheimer's disease and suggest the utility of quantitative MRI measures and psychophysical performance in the assessment of AD. These results support the potential clinical utility of inclusion of odor identification tests in diagnostic batteries for detecting AD. (JINS, 2003, 9, 459–471.)

This article presents a new method that can compare lexical priming (word–word) and sentential priming (sentence–word) directly within a single paradigm. We show that it can be used to address modular theories of word comprehension, which propose that the effects of sentence context occur after lexical access has taken place. Although lexical priming and sentential priming each occur very quickly in time, there should be a brief time window in which the former is present but the latter is absent. Lexical and sentential priming of unambiguous words were evaluated together, in competing and converging combinations, using time windows designed to detect an early stage where lexical priming is observed but sentential priming is not. Related and unrelated word pairs were presented visually, in rapid succession, within auditory sentence contexts that were either compatible or incompatible with the target (the second word in each pair). In lexical decision, the additive effects of lexical priming and sentential priming were present under all temporal conditions, although the latter was always substantially larger. In cross-modal naming, sentential priming was present in all temporal conditions; lexical priming was more fragile, interacting with timing and sentential congruence. No evidence was found for a stage in which lexical priming is present but sentential priming is absent – a finding that is difficult to reconcile with two-stage models of lexical versus sentential priming. We conclude that sentential context operates very early in the process of word recognition, and that it can interact with lexical priming at the earliest time window.

Fifty-three volunteer participants were studied with the fade-in task (Ostergaard, 1998) to measure naming latency, word priming, and recognition-memory performance, and with morphometric magnetic resonance imaging (MRI) techniques to measure volumes of mesial temporal lobe, diencephalic, striatal, and neocortical structures. The relationship between measures of cerebral volume loss and performance deficits was modeled using simultaneous regression analyses in which the behavioral measures were dependent variables. The results suggested that damage in both hippocampal and amygdala/entorhinal areas as well as damage in the diencephalon and the nucleus accumbens all contributed independently to the severity of recognition-memory deficits. Both caudate nucleus damage and hippocampal damage contributed independently to increased naming latency (slowed single-word reading). Finally, only damage in the hippocampus appeared to result in decreased word priming. These results provide further evidence against the assertion that word priming represents a form of memory unaffected by damage to the mesial temporal lobes. (JINS, 2001, 7, 63–78.)