A new group-training procedure for habituation demonstrates that presynaptic glutamate release contributes to long-term memory in Caenorhabditis elegans

In the experiments reported here we have developed a new group-training protocol for assessing long-term memory for habituation in Caenorhabditis elegans. We have replicated all of the major findings of the original single-worm protocol using the new protocol: (1) distributed training produced long-term retention of training, massed training did not; (2) distributed training at long interstimulus intervals (ISIs) produced long-term retention, short ISIs did not; and (3) long-term memory for distributed training is protein synthesis-dependent as it could be blocked by heat shock during the inter-block interval. In addition, we have shown that long-term memory for habituation is graded, depending on the number of blocks of stimuli in training. The inter-block interval must be >40 min for long-term retention of training to occur. Finally, we have tested long-term memory for habituation training in a strain of worms with a mutation in a vesicular glutamate transporter in the sensory neurons that transduce tap (eat-4). The results from these eat-4 worms indicate that glutamate release from the sensory neurons has an important role in the formation of long-term memory for habituation.     

Effects of Stimulant Medication Treatment on Mothers' and Children's Attributions for the Behavior of Children with Attention Deficit Hyperactivity Disorder

Participants were 55 children with attention deficit hyperactivity disorder (ADHD) who were receiving ongoing treatment with stimulant medications and their mothers, and 31 children with ADHD who were beginning stimulant medication and their mothers. Mothers and children offered attributions for child behaviors that occurred when the child was medicated and not medicated. Mothers rated child compliance and prosocial behavior as more global and stable when the child was medicated and rated noncompliance, ADHD symptoms, and oppositional behavior as more externally caused, less global and stable, but more controllable by the child when the child was medicated. Children rated both their compliance and noncompliance as more controllable in the medicated condition. On a forced-choice measure, both mothers and children selected ability, effort, and task attributions for compliance more in the not-medicated condition, and pill-taking attributions more in the medicated condition. This was reversed for noncompliance, which was attributed more to effort, task, or ability in the medicated condition and more to not taking a pill in the not-medicated condition. The potential risks and benefits for parent–child interactions and children's self-perceptions of these medication-related differences in attributions are discussed.     

The problems of internal validation without a theoretical context: the different conceptual underpinnings of psychopathy and the disruptive behavior disorder criteria

G. L. Burns (2000) has concluded that the Psychopathy Screening Device's content is limited because it contains items that overlap with criteria for several disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM). The problem with G. L. Burns's analysis is that it was conducted without an adequate understanding or specification of the conceptual underpinnings of either the construct of psychopathy or the constructs assessed by the DSM criteria. This reply attempts to clarify these conceptual frameworks to illustrate that to judge the adequacy of the content of a measure of psychopathy by comparing it with DSM criteria is inconsistent with the differing theoretical frameworks underlying these classification systems. Forcing measures of psychopathy to be designed around DSM criteria leads to inadequate measures of psychopathy and can limit advances both in our understanding of developmental precursors to psychopathy and in the classification of DSM disorders.     

Psychopathy in Children and Adolescents: The Need for a Developmental Perspective

The current paper introduces the special issue on research attempting to extend the construct of psychopathy to child and adolescent samples. Past special sections and reviews have typically focused on the implications of this research for forensic research and practice. The current special issue focuses on topics relevant for integrating this research within the broader literature on childhood psychopathology. Papers included in this special issue focus on the structure of psychopathic traits in youth, the relation of these traits to other important psychopathological and personality constructs in children and adolescents, and the utility of these traits for identifying a distinct subgroup of antisocial youth who differ on important cognitive processes and on the severity and stability of their problem behavior. These empirical works are followed by commentary provided by two prominent scholars who outline the potential importance of the construct for advancing our understanding of childhood psychopathology. In addition, these scholars provide a discussion of important directions for future research.     

Reaction time and accuracy in individuals with aphasia during auditory vigilance tasks

Research indicates that attentional deficits exist in aphasic individuals. However, relatively little is known about auditory vigilance performance in individuals with aphasia. The current study explores reaction time (RT) and accuracy in 10 aphasic participants and 10 nonbrain-damaged controls during linguistic and nonlinguistic auditory vigilance tasks. Findings indicate that the aphasic group was less accurate during both tasks than the control group, but was not slower in their accurate responses. Further examination of the data revealed variability in the aphasic participants' RT contributing to the lower accuracy scores.     

Effects of environmental enrichment on spatial memory and neurochemistry in middle-aged mice

The present study compared the effects of environmental enrichment on spatial memory, glutamic acid decarboxylase (GAD) activity, and synaptophysin levels in middle-aged male and female mice. Prior to testing, a subset of 18-month-old male and female C57BL/6 mice was housed with two to three toys and a running wheel in the home cage for up to 29 d. Adult mice (7 mo) of both sexes and the remaining middle-aged mice were group (social) housed, but not exposed to enriching objects. After the enrichment period, all mice were tested in a 1-day version of the Morris water maze, in which both spatial and nonspatial memory were assessed. Immediately after testing, the hippocampus and frontoparietal cortex were dissected, and GAD activity and synaptophysin levels were measured. Environmental enrichment reduced the age-related impairment in spatial acquisition and retention; relative to adult social controls, middle-aged enriched mice were unimpaired, whereas middle-aged social controls were impaired. This reduction was similar in middle-aged males and females. Enrichment did not affect cued memory in either sex. Although hippocampal GAD activity was increased by enrichment in males, all other neurochemical measurements were unaffected by enrichment or aging in either sex. These data suggest that environmental enrichment initiated at middle age can reduce age-related impairments in spatial memory in males and females, although the underlying neurobiological mechanisms of this effect remain unknown.     

Callous-Unemotional Traits and Subtypes of Conduct Disorder

There has been growing consensus that children with conduct disorder (CD) constitute a very heterogeneous group containing children who vary substantially on the development, course, and causes of the disorder. While many have recognized the importance of this heterogeneity for developing better causal theories and for developing more effective treatments, there has been little consensus as to the best way to subtype children with CD. In this paper, we review a number of approaches to subtyping, each with some evidence for its validity for certain purposes. We focus on two recent approaches that have great potential for integrating past subtyping approaches and for advancing causal theory. The first approach is the division of children with CD into those with a childhood onset to their severe antisocial behavior and those with an adolescent onset to their behavior. The second approach is to designate children within the childhood-onset group who show callous and unemotional traits, which is analogous to adult conceptualizations of psychopathy. Both approaches help designate children who many show different causal processes underlying their severe aggressive and antisocial behavior, and who may warrant different approaches to treatment.     

Gender, Somatization, and Psychopathic Traits in a College Sample

The structure of psychopathic traits and their association with somatization symptoms were investigated in a sample of 199 undergraduate college students enrolled in introductory psychology classes. Using multiple measures of psychopathic traits, an iterated principal axis (IPA) analysis revealed two dimensions of psychopathy that were similar to ones typically found in forensic samples. One dimension focused on a cold, callous, and unemotional interpersonal style and the second dimension focused on an impulsive and antisocial lifestyle. These two dimensions emerged for both men and women, although the correlation between the two was somewhat higher for men than women. Also, the callous and unemotional dimension was negatively correlated with somatization symptoms, and the impulsive and antisocial dimension was positively associated with somatization symptoms. This pattern of associations was similar for both men and women and it suggests that somatization symptoms may be one aspect of the high rate of negative affectivity experienced by antisocial individuals.     

Developmental sequences in the age of onset of disruptive child behaviors

Retrospective and prospective reports of the onset of disruptive child behaviors were analyzed in a sample of clinic-referred boys. The younger boys (ages 7–9 years), compared with the older boys (ages 10–12 years), showed the highest level of disruptive behavior and, judging from mothers' reports, had the fastest progression of onsets from less serious to more serious problem behaviors. Despite some overlap, developmental sequences in problem behavior within the domains of hyperactivity/inattention, oppositional behavior, and conduct problems were similar across the two age groups. This was also the case for developmental sequences of overt or confrontive problem behaviors and covert or concealing conduct problems. Sequences of the onset of oppositional behavior and conduct problems were validated through prospective data, based on the information from mothers, teachers, and boys themselves. The implications of the findings are discussed for the formulation of developmental pathways of behavior and the analysis of causal factors.