Differential prefrontal-temporal neural correlates of semantic processing in children

This study used functional magnetic resonance imaging (fMRI) to examine brain-behavior correlations in a group of 16 children (9- to 12-year-olds). Activation was measured during a semantic judgment task presented in either the visual or auditory modality that required the individual to determine whether a final word was related in meaning to one of two previous words (e.g., found-tank-lost). The main finding was that higher performers (i.e., accuracy) were associated with more activation in posterior representational systems including the inferior and middle temporal gyri, whereas lower performers were associated with more activation in anterior regions including the inferior and middle frontal gyri. This pattern of results was interpreted as reflecting an elaborated semantic representational system in temporal areas for the high accuracy performers that allowed them to efficiently and accurately make meaning based judgments. The low accuracy performers may have an inaccurate or weakly interconnected semantic system that results in greater use of frontal areas in a feature selection process.     

Large-scale neural network for sentence processing

Our model of sentence comprehension includes at least grammatical processes important for structure-building, and executive resources such as working memory that support these grammatical processes. We hypothesized that a core network of brain regions supports grammatical processes, and that additional brain regions are activated depending on the working memory demands associated with processing a particular grammatical feature. We used functional magnetic resonance imaging (fMRI) to test this hypothesis by comparing cortical activation patterns during coherence judgments of sentences with three different syntactic features. We found activation of the ventral portion of left inferior frontal cortex during judgments of violations of each grammatical feature. Increased recruitment of the dorsal portion of left inferior frontal cortex was seen during judgments of violations of specific grammatical features that appear to involve a more prominent working memory component. Left posterolateral temporal cortex and anterior cingulate were also implicated in judging some of the grammatical features. Our observations are consistent with a large-scale neural network for sentence processing that includes a core set of regions for detecting and repairing several different kinds of grammatical features, and additional regions that appear to participate depending on the working memory demands associated with processing a particular grammatical feature.     

Simulating single word processing in the classic aphasia syndromes based on the Wernicke-Lichtheim-Geschwind theory

The Wernicke-Lichtheim-Geschwind (WLG) theory of the neurobiological basis of language is of great historical importance, and it continues to exert a substantial influence on most contemporary theories of language in spite of its widely recognized limitations. Here, we suggest that neurobiologically grounded computational models based on the WLG theory can provide a deeper understanding of which of its features are plausible and where the theory fails. As a first step in this direction, we created a model of the interconnected left and right neocortical areas that are most relevant to the WLG theory, and used it to study visual-confrontation naming, auditory repetition, and auditory comprehension performance. No specific functionality is assigned a priori to model cortical regions, other than that implicitly present due to their locations in the cortical network and a higher learning rate in left hemisphere regions. Following learning, the model successfully simulates confrontation naming and word repetition, and acquires a unique internal representation in parietal regions for each named object. Simulated lesions to the language-dominant cortical regions produce patterns of single word processing impairment reminiscent of those postulated historically in the classic aphasia syndromes. These results indicate that WLG theory, instantiated as a simple interconnected network of model neocortical regions familiar to any neuropsychologist/neurologist, captures several fundamental "low-level" aspects of neurobiological word processing and their impairment in aphasia.     

Training to use voice onset time as a cue to talker identification induces a left-ear/right-hemisphere processing advantage

We examined the effect of perceptual training on a well-established hemispheric asymmetry in speech processing. Eighteen listeners were trained to use a within-category difference in voice onset time (VOT) to cue talker identity. Successful learners (n=8) showed faster response times for stimuli presented only to the left ear than for those presented only to the right. The development of a left-ear/right-hemisphere advantage for processing a prototypically phonetic cue supports a model of speech perception in which lateralization is driven by functional demands (talker identification vs. phonetic categorization) rather than by acoustic stimulus properties alone.     

Stronger Relationships, Stronger Communities: Lessons From a Regional Intergroup Grant Initiative

This paper tells the story of an intergroup grant initiative and the neighborhood projects it supported. It highlights the challenges of race and power, in conjunction with other overlapping identities and forms of discrimination. The demographics of the greater Goodland region have changed dramatically over the last few years and decades. The life for traditionally European American and African American communities is being altered by a steady influx of new immigrants from Africa, Asia, and Latin America. This paper discusses a philanthropic community's response to these changes and within this, two specific neighborhood-based responses. The lessons and insights described in this paper, told by the initiative's evaluator and advisory council co-chair, are drawn from five years' of systematic data collection and analysis, focused observations, and the reflections of other participants in the initiative.

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Strategy shifts in classification skill acquisition: Does memory retrieval dominate rule use?

In two experiments, we demonstrated two types of strategies (rule-based and memory-based) and strategy transitions within the same binary classification task. The strategy that dominated later in practice depended on the difficulty of the operative classification rule and on the salience of the cue for that rule. Accuracy increased over practice trials, and response times were faster for the dominant strategy, either rule or memory. Rule retention was superior to stimulus item retention, so that, even for participants who preferred a memory-based strategy, a rule-based strategy dominated at least temporarily after a 1-week interval. Strategy use over trials and the retention interval reflected a given task's affordance of a shift between rule- and memory-based processes.     

Previewing the neighborhood: the role of orthographic neighbors as parafoveal previews in reading

In 2 experiments, a boundary technique was used with parafoveal previews that were identical to a target (e.g., sleet), a word orthographic neighbor (sweet), or an orthographically matched nonword (speet). In Experiment 1, low-frequency words in orthographic pairs were targets, and high-frequency words were previews. In Experiment 2, the roles were reversed. In Experiment 1, neighbor words provided as much preview benefit as identical words and greater benefit than nonwords, whereas in Experiment 2, neighbor words provided no greater preview benefit than nonwords. These results indicate that the frequency of a preview influences the extraction of letter information without setting up appreciable competition between previews and targets. This is consistent with a model of word recognition in which early stages largely depend on excitation of letter information, and competition between lexical candidates becomes important only in later stages.     

The effect of word frequency, word predictability, and font difficulty on the eye movements of young and older readers

Young adult and older readers' eye movements were recorded as they read sentences containing target words that varied in frequency or predictability. In addition, half of the sentences were printed in a font that was easy to read (Times New Roman) and the other half were printed in a font that was more difficult to read (Old English). Word frequency, word predictability, and font difficulty effects were apparent in the eye movement data of both groups of readers. In the fixation time data, the pattern of results was the same, but the older readers had larger frequency and predictability effects than the younger readers. The older readers skipped words more often than the younger readers (as indicated by their skipping rate on selected target words), but they made more regressions back to the target words and more regressions overall. The E-Z Reader model was used as a platform to evaluate the results, and simulations using the model suggest that lexical processing is slowed in older readers and that, possibly as a result of this, they adopt a more risky reading strategy.     

Do Investment Risk Tolerance Attitudes Predict Portfolio Risk?

We investigated a new instrument designed to assess investment risk tolerance, the Risk Tolerance Questionnaire (RTQ). RTQ scores were positively correlated with scores on two other investment risk measures, but were not correlated with a measure of sensation-seeking (Zuckerman, 1994), suggesting that investment risk tolerance is not explainable by a general cross-domain appetite for risk. Importantly, RTQ scores were positively correlated with the riskiness of respondents’ actual investment portfolios, meaning that investors with high risk-tolerance score tend to have higher-risk portfolios. Finally, respondents with relatively more investment experience had more risk-tolerant responses and higher-risk portfolios than less experienced investors.