Atypical brain responses to sounds in children with specific language and reading impairments

This study tested if children with specific language impairment (SLI) or children with specific reading disability (SRD) have abnormal brain responses to sounds. We tested 6‐ to 12‐year‐old children with SLI (N =19), children with SRD (N =55), and age‐matched controls (N =36) for their passive auditory event‐related potentials (ERPs) to tones, rapid tones, vowels and consonant‐vowels. Thirty‐eight percent of the children with SLI or SRD had less typical passive auditory ERPs in the N1–P2 window to sounds in general, rather than to tones, rapid tones, vowels or consonant‐vowels specifically. The ERPs of these children were significantly ‘flatter’ in the N1–P2 region than normal. All the children with flatter ERPs in the N1–P2 region had poor non‐word reading. A subgroup of these poor non‐word readers also had poor non‐word repetition. These findings support the hypothesis that impaired auditory processing is a causal risk factor for both SLI and SRD.     

A System for Relational Reasoning in Human Prefrontal Cortex

The integration of multiple relations between mental representations is critical for higher level cognition. For both deductive- and inductive-reasoning tasks, patients with prefrontal damage exhibited a selective and catastrophic deficit in the integration of relations, whereas patients with anterior temporal lobe damage, matched for overall IQ but with intact prefrontal cortex, exhibited normal relational integration. In contrast, prefrontal patients performed more accurately than temporal patients on tests of both episodic memory and semantic knowledge. These double dissociations suggest that integration of relations is a specific source of cognitive complexity for which intact prefrontal cortex is essential. The integration of relations may be the fundamental common factor linking the diverse abilities that depend on prefrontal function, such as planning, problem solving, and fluid intelligence.     

Signing an Organ Donation Letter: The Prediction of Behavior From Behavioral Intentions1

The signing of an organ donation letter was examined among 149 unmarried university students. The letter was developed for the purpose of conveying one's wishes regarding posthumous donation to one's next of kin. Predictors of letter signing were examined that explain hypothesized inconsistencies between the behavioral intention to sign and actual letter-signing behavior. Respondents were offered the opportunity to sign and send the donation letter to their parents. As predicted, reported willingness to sign the letter was only moderately related to actual behavior. Decision confidence, organ donation knowledge, and perceived decision importance positively influenced signing, independent of willingness. Unfavorability toward defending one's donation decision to one's parents inhibited signing, even among those expressing a high initial willingness to sign.     

Effects of the Acquisition of Prerequisite Behavior on the Learning of Nonvocal Verbal Behavior and Vocal Imitation in Children With Severe Retardation

The effects of acquisition and maintenance of prerequisite interactions, such as attending behavior, nonverbal imitative behavior, and disruptive behavior, on the learning of nonvocal verbal behavior and vocal imitation were evaluated. Four severely retarded children were selected on the basis of low level or absence of the target behaviors (nonvocal verbal behavior and vocal imitation) and failure to reach the acquisition criterion on prerequisite behavior. The results were evaluated visually and by time series analysis. Findings indicated that the acquisition of prerequisite interactions led to superior performance and fewer trials to reach criteria in this language intervention.

     

Effects of subchronic administration of gammahydroxybutyrate (GHB) on spatial working memory in rats

GHB, a popularly known drug as "liquid ecstasy", is a substance with abuse potential. Among the possible described side-effects after the continued consumption of GHB are amnesia and deterioration of memory. Likewise, recent studies indicate the existence of neurotoxicity in certain brain regions after its prolonged treatment. The aim of this study was to examine the effect of the subchronic administration of GHB (10 and 100 mg/kg) on spatial memory and sensoriomotor reflexes in male rats, using the Morris water maze and a battery of sensoriomotor tests, respectively. The results indicated that animals treated with GHB (10 mg/kg) showed a greater latency of escape during the phase of acquisition in the days first and third of tests, as compared with the control group (p<0.05), as well as a deterioration of grasping reflex with the two doses of GHB (p<0.01). Numerous studies indicated that the medial prefrontal cortex is a crucial neuronal substrate in the working memory and grasping reflex modulation. These results suggest that prolonged administration of GHB could alter structure and/or function of the medial prefrontal cortex, as well as its interconnections with other brain regions involved in the evaluated cognitive and neurological processes.     

Building Interdisciplinary/Intersectoral Research Partnerships for Community-Based Mental Health Research with Older Minority Adults

Community-based research often brings investigators from different disciplinary backgrounds together with community representatives to conduct research on topics of mutual concern. This paper describes a case example that illustrates an interdisciplinary/intersectoral study of depression and barriers to mental health care among older adults and illustrate the factors central to implementing a successful research partnership. It will address the following conditions that facilitate and challenge interdisciplinary/intersectoral research: (1) achieving commonality of purpose in study design and research and referral approaches; (2) ensuring the ability to develop, field-test and implement psychometrically rigorous and culturally and qualitatively appropriate instruments; (3) building effective management structures for interdisciplinary/intersectoral research partnerships; and (4) identifying, training and supporting qualified researchers to carry out a mental health study with older ethnically diverse adults. The paper concludes with strengths and limitations of the approach.     

Neuropsychological evidence for "word-meaning deafness" in a Spanish-speaking patient

In this paper we present a case of "word-meaning deafness," characterised by serious problems in the comprehension of spoken language, whilst repetition and writing words and non-words from dictation are preserved. This performance indicates the impossibility of correctly accessing phonological representation from the semantic representation of words. Neuropsychological evidence on specific alterations in word-meaning disorders is scarce, and this study contributes new findings with a Spanish-speaking patient. The nature of the processes involved in understanding language and the cerebral mechanisms that might be affected in each case were discussed, in accordance with current neuropsychological theories.     

Fragment difficulty in priming on word-completion tests

Word-fragment completion is a frequently used test in implicit memory research. In this test priming is the relevant variable. Priming is obtained by subtracting the proportion of nonstudied word fragments correctly completed (called "completion difficulty baseline") from the studied word fragments correctly completed. Since completion difficulty can spuriously vary greatly between experimental conditions, its effect on magnitude of priming is studied. Normative frequency of occurrence of target words was considered because their influence over performance is known. In an experiment using a word-fragment completion test, participants' completion of fragments at three levels of completion difficulty and two levels of frequency was tested. Analysis showed that completion difficulty had a significant effect on global priming. The priming magnitude was higher for Difficult and Moderately Difficult fragments than for Easy ones. An interaction between fragment difficulty and normative word frequency was observed. When the fragments were easy to complete, the expected effect of higher priming for low-frequency words than for high-frequency words was not observed.     

Optimization of sample size in controlled experiments: The CLAST rule

Sequential rules are explored in the context of null hypothesis significance testing. Several studies have demonstrated that the fixed-sample stopping rule, in which the sample size used by researchers is determined in advance, is less practical and less efficient than sequential stopping rules. It is proposed that a sequential stopping rule called CLAST (composite limited adaptive sequential test) is a superior variant of COAST (composite open adaptive sequential test), a sequential rule proposed by Frick (1998). Simulation studies are conducted to test the efficiency of the proposed rule in terms of sample size and power. Two statistical tests are used: the one-tailed t test of mean differences with two matched samples, and the chi-square independence test for twofold contingency tables. The results show that the CLAST rule is more efficient than the COAST rule and reflects more realistically the practice of experimental psychology researchers.