The use of rhythm in attending to speech.

Three experiments examined attentional allocation during speech processing to determine whether listeners capitalize on the rhythmic nature of speech and attend more closely to stressed than to unstressed syllables. Ss performed a phoneme monitoring task in which the target phoneme occurred on a syllable that was either predicted to be stressed or unstressed by the context preceding the target word. Stimuli were digitally edited to eliminate the local acoustic correlates of stress. A sentential context and a context composed of word lists, in which all the words had the same stress pattern, were used. In both cases, the results suggest that attention may be preferentially allocated to stressed syllables during speech processing. However, a normal sentence context may not provide strong predictive cues to lexical stress, limiting the use of the attentional focus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dysfunctional attitudes and attribution style in healthy controls and patients with schizophrenia, psychotic depression, and nonpsychotic depression.

Compared the scores of 242 psychiatric inpatients with schizophrenia, psychotic depression, or nonpsychotic depression and 53 healthy controls on the Attribution Style Questionnaire (ASQ) and the Dysfunctional Attitude Scale (DAS). Results provide mixed support for the cognitive and learned helplessness models of depression. Depressed Ss scored significantly higher than healthy controls on the DAS and ASQ, but there were no differences between depressed and schizophrenic Ss. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emergent epileptiform activity in neural networks with weak excitatory synapses.

Brain electrical activity recorded during an epileptic seizure is frequently associated with rhythmic discharges in cortical networks. Current opinion in clinical neurophysiology is that strongly coupled networks and cellular bursting are prerequisites for the generation of epileptiform activity. Contrary to expectations, we found that weakly coupled cortical networks can create synchronized cellular activity and seizure-like bursting. Evaluation of a range of synaptic parameters in a detailed computational model revealed that seizure-like activity occurs when the excitatory synapses are weakened. Guided by this observation, we confirmed experimentally that, in mouse neocortical slices, a pharmacological reduction of excitatory synaptic transmission elicited sudden onset of repetitive network bursting. Our finding provides powerful evidence that onset of seizures can be associated with a reduction in synaptic transmission. These results open a new avenue to explore network synchrony and may ultimately lead to a rational approach to treatment of network pathology in epilepsy.     

Sample size and error in the determination of mode shapes by principal components analysis

Principal components analysis (PCA) is a multivariate statistical technique that transforms a data set having a large number of inter-related variables to a new set of uncorrelated variables called the principal components, determined to allow the dimensionality of the data set to be reduced while retaining as much of the variation present as possible. PCA can be applied to dynamic structural response data to identify the predominant modes of vibration of the structure. Because PCA is a statistical technique, there are errors in the computed modes due to the use of a sample of finite size. The aim of this paper is to study the effect of sample size on the accuracy with which the modes of vibration can be computed. The paper focuses predominantly on elastic response data and examines the potential influence of various parameters such as the period of the structure, the input excitation, and the spatial distribution of mass over the structure. Issues relating to errors in the modes of nonlinear structures are also discussed.     

A statnet Tutorial

The statnet suite of R packages contains a wide range of functionality for the statistical analysis of social networks, including the implementation of exponential-family random graph (ERG) models. In this paper we illustrate some of the functionality of statnet through a tutorial analysis of a friendship network of 1,461 adolescents.     

Validation of language subtypes in learning disabled children.

Hypothesized that children characterized by deficits in narrative skills, relative to other language skills (e.g., syntactic and semantic), would be most at risk for general academic problems, especially in reading comprehension. Using data from a previous longitudinal study by the 1st author and J. D. McKinney (see record 1985-02522-001), different subtypes of language disability were identified in 63 6- and 7-yr-old learning disabled (LD) children. Comparison data had been obtained from 66 non-LD children matched to the LD sample on age, race, and sex. Results, obtained with hierarchical cluster analysis, indicate that 6 language subtypes were derived and that these were both internally consistent and externally valid, being differentially linked to reading and math achievement over a 3-yr period. Narrative ability was shown to be relatively important in predicting academic outcomes. The 3 subtypes showing the poorest academic outcomes had the highest relative scores in syntax and semantics. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensitivity to the locomotor stimulant effects of ethanol and allopregnanolone is influenced by common genes.

Allopregnanolone is a neuroactive steroid that, like ethanol (EtOH), has stimulant, anxiolytic, ataxic, and depressant effects. Two experiments tested the hypothesis that sensitivity to the locomotor stimulant effects of these drugs is influenced by a common set of genes. Sensitivity to the locomotor stimulant effects of allopregnanolone was determined in 24 BXD recombinant inbred (RI) strains. Strain means were positively correlated with extant means for EtOH stimulation in 20 of the same strains. Quantitative trait locus (QTL) analysis provisionally identified many loci, including several known to influence sensitivity to EtOH. Sensitivity to allopregnanolone was also measured in FAST and SLOW mice, which were selectively bred for differential locomotor response to EtOH, to determine whether selection has also altered allopregnanolone sensitivity. FAST mice were more sensitive to the stimulant effects of allopregnanolone compared with SLOW mice. These data suggest that sensitivity to the locomotor stimulant effects of these drugs is influenced by common genes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)