Test-retest reliability of fMRI during nonverbal semantic decisions in moderate-severe nonfluent aphasia patients

Cortical reorganization in poststroke aphasia is not well understood. Few studies have investigated neural mechanisms underlying language recovery in severe aphasia patients, who are typically viewed as having a poor prognosis for language recovery. Although test-retest reliability is routinely demonstrated during collection of language data in single-subject aphasia research, this is rarely examined in fMRI studies investigating the underlying neural mechanisms in aphasia recovery. The purpose of this study was to acquire fMRI test-retest data examining semantic decisions both within and between two aphasia patients. Functional MRI was utilized to image individuals with chronic, moderate-severe nonfluent aphasia during nonverbal, yes/no button-box semantic judgments of iconic sentences presented in the Computer-assisted Visual Communication (C-ViC) program. We investigated the critical issue of intra-subject reliability by exploring similarities and differences in regions of activation during participants' performance of identical tasks twice on the same day. Each participant demonstrated high intra-subject reliability, with response decrements typical of task familiarity. Differences between participants included greater left hemisphere perilesional activation in the individual with better response to C-ViC training. This study provides fMRI reliability in chronic nonfluent aphasia, and adds to evidence supporting differences in individual cortical reorganization in aphasia recovery.     

Actor-observer differences in realism in confidence and frequency judgments

Taking a social psychological approach to metacognitive judgments, this study analyzed the difference in realism (validity) in confidence and frequency judgments (i.e., estimates of overall accuracy) between one's own and another person's answers to general knowledge questions. Experiment 1 showed that when judging their own answers, compared with another's answers, the participants exhibited higher overconfidence, better ability to discriminate correct from incorrect answers, lower accuracy, and lower confidence. However, the overconfidence effect could be attributable to the lowest level of confidence. Furthermore, when heeding additional information about another's answers the participants showed higher confidence and better discrimination ability. The overconfidence effect of Experiment 1 was not found in Experiment 2. However, the results of Experiment 2 were consistent with Experiment 1 in terms of discrimination ability, confidence, and accuracy. Finally, in both experiments the participants gave lower frequency judgments of their own overall accuracy compared with their frequency judgments of another person's overall accuracy.     

Orientational manoeuvres in the dark: dissociating allocentric and egocentric influences on spatial memory

Subjects in a darkroom saw an array of five phosphorescent objects on a circular table and, after a short delay, indicated which object had been moved. During the delay the subject, the table or a phosphorescent landmark external to the array was moved (a rotation about the centre of the table) either alone or together. The subject then had to indicate which one of the five objects had been moved. A fully factorial design was used to detect the use of three types of representations of object location: (i) visual snapshots; (ii) egocentric representations updated by self-motion; and (iii) representations relative to the external cue. Improved performance was seen whenever the test array was oriented consistently with any of these stored representations. The influence of representations (i) and (ii) replicates previous work. The influence of representation (iii) is a novel finding which implies that allocentric representations play a role in spatial memory, even over short distances and times. The effect of the external cue was greater when initially experienced as stable. Females out-performed males except when the array was consistent with self-motion but not visual snapshots. These results enable a simple egocentric model of spatial memory to be extended to address large-scale navigation, including the effects of allocentric knowledge, landmark stability and gender.     

Space- and object-based attention depend on motor intention

The authors investigated the impact of different motor demands on space- and object-based attention allocation. Responses to targets were either lifting a finger, or pointing to the target, or grasping a clay object placed on the target location. Reaction times and movement times were recorded to assess covert and overt attention, respectively. Both reaction times and movement times showed more space-based attention for pointing than for finger lifting and more object-based attention for grasping than for pointing. That result supports the view that visual selectivity is tuned to specific motor intentions (H. Bekkering & F. W. Neggers, 2002) and illustrates the tight coupling of perception and action.     

Illicit drug use and risky sexual behavior among African American and Puerto Rican urban adolescents: the longitudinal links

The authors assessed whether (a) early illicit drug use predicted later risky sexual activity, (b) early risky sex predicted later illicit drug use, and (c) common factors affected both risky sexual behavior and illicit drug use. African American and Puerto Rican youth completed questionnaires in their classrooms at Time 1 (T1) and face-to-face interviews with the authors in their homes 5 years later at Time 2 (T2). Logistic regression analyses showed the association between T1 illicit drug use and T2 risky sexual activity and between T1 risky sexual behavior and T2 illicit drug use. With few exceptions, T1 illicit drug use was associated with all of the T2 risky sexual behaviors. After controlling for demographic factors, the authors found that multiple sex partners at T1 was not related to illicit drug use at T2. Condom use at T1 was related to illicit drug use at T2, whereas sexually transmitted diseases and adolescent pregnancy were not related to this drug use. The findings indicated that assessments of and treatments for substance use should focus on the risky sexual behaviors that seem to accompany illicit drug use.     

Learning new names for new objects: cortical effects as measured by magnetoencephalography

We tracked the evolvement of naming-related cortical dynamics with magnetoencephalography when five normal adults successfully learned names and/or meanings of unfamiliar objects. In all subjects, the learning of new names was associated with pronounced cortical effects. The learning effect was of long latency and emerged as a change of activation in the same cortical network that was active during naming of familiar items. In four out of five subjects, the cortical learning effect occurred in the inferior parietal lobe. In three of these subjects, the cortical effect was left-sided. These results suggest that the inferior parietal lobe plays an important role in the acquisition of novel words, presumably as a part of working memory systems.     

Measurements of auditory-verbal STM span in aphasia: effects of item, task, and lexical impairment

In the first part of this study, we investigated effects of item and task type on span performance in a group of aphasic individuals with word processing and STM deficits. Group analyses revealed significant effects of item on span performance with span being greater for digits than for words. We also investigated associations between subjects' lexical-semantic and phonological processing abilities and performance on four measures of verbal span (digit and word span, each varied for type of response, verbal vs. pointing) as well as one measure of nonverbal span. We predicted and found that the patterns of association between verbal span tasks and lexical abilities reflected the integrity of language processes and representations deployed in each paradigm used to assess span. Performance on the pointing span task, which engages both lexical-semantic and phonological processes, correlated with measures of both lexical-semantic and phonological abilities. Performance on repetition span, which engages primarily input and output phonological processes, correlated with measures of phonological abilities but not measures of lexical-semantic abilities. However, when partial correlations were performed for two subject groups based on their relative preservation of lexical-semantic ability (less or more than phonological ability), repetition span correlated with lexical-semantic measures only in the subgroup with relatively impaired lexical-semantics. Additionally, performance on the nonverbal span task correlated with measures of phonological abilities, suggesting either a general cognitive deficit affecting verbal and nonverbal STM or possibly, the use of a verbal strategy to perform this task. Our discussion focuses on the interpretation of span measurements in clinical practice and research, as well as the implications of these data for theories of short-term memory and word processing.     

Inhibition and attention deficit hyperactivity disorder in adults

The inhibitory account of attention deficit hyperactivity disorder (ADHD) was tested by examining the performance of college-aged adults on a variety of inhibitory tasks. The poorer performance of adults with ADHD compared with controls on negative priming, stopping, and continuous performance tasks, combined with similar group performances on a test of working memory capacity, indicates a specific inhibitory deficit as opposed to a general limitation in attentional capacity. Overall results provide evidence for extending the inhibitory deficit hypothesis to adult ADHD, not only for mechanisms of response (or motor) inhibition but also for mechanisms of cognitive inhibition.     

Maternal correlates of toddler insecure and dependent behavior

The present study was designed to examine the relationship between characteristics of mothers and their toddler's insecure and dependent behavior. The authors studied 254 2-year-old toddlers and their mothers via a structured questionnaire administered to the mothers in their homes. The extent to which insecure and dependent behavior is related to the domains of maternal child rearing, maternal personality traits, parental marital relations, and maternal drug use was assessed. Using Pearson correlations and hierarchical multiple regression analyses, the authors found that the maternal child-rearing and maternal personality domains have a direct effect on the toddlers' insecure and dependent behavior. The maternal child-rearing domain also served as a mediator for the domains of the maternal personality attributes, parents' marital relations, and maternal drug use. There also was evidence suggesting an indirect effect of maternal personality attributes on the toddlers' insecure and dependent behavior, which is mediated by the domain of maternal child-rearing practices. Implications for the prevention of insecure and dependent behavior in toddlers are discussed.     

How lonely are gay and lesbian youth?

UCLA Loneliness Scale (8-item version) scores in a sample of 384 gay and lesbian adolescents support the hypothesis that such youths are especially vulnerable to loneliness.