Depression and Huntington's disease: prevalence, clinical manifestations, etiology, and treatment

In order to determine the extent to which depression complicates Huntington's disease (HD), we have analyzed the existing literature on depression in HD in order to report the prevalence, clinical manifestations, and treatment of HD depression. By means of MEDLINE literature searches and reviews of HD articles' bibliographies, we identified for our analysis 16 HD depression studies. Our results indicate that the prevalence of depression is 30% for all HD patients. Clinical manifestations of HD depression include a marked increased risk for suicide. The etiology of HD depression is unclear, but may be due to a number of factors, such as dysfunction in the caudate nucleus, dysfunction in the ventral striatum, and various genetic factors that are discussed in this review. Case reports and case series support the efficacy of standard antidepressant interventions in resolving symptoms of depression. Efficacious treatments reported in the literature include tricyclic antidepressants, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors, and electroconvulsive therapy. In this study, the successful anecdotal treatment of seven consecutive HD depressed patients with sertraline suggests that sertraline may be a safe and efficacious treatment of HD depression.     

Choice in transition: Replication and extension to preschool children in a naturalistic setting

This study replicated previous basic research into the dynamics of choice and extended this analysis to children's behavior in a naturalistic setting. Two preschoolers with disabilities were observed interacting with their teachers at baseline and during an experimental analysis involving four pairs of concurrent variable‐interval schedules of adult attention implemented by an experimenter. Each child was exposed to four experimental phases in which the relative reinforcer rates for on‐ and off‐task behavior were 10:1, 1:1, 1:10, and reversed back to 10:1. The 10:1 phase was designed to mimic the same schedules and types of adult attention observed at baseline. We used the generalized matching equation to model steady‐state behavior at the end of the transition phases and to evaluate changes in sensitivity at various points throughout the phases. Choice in transition was evaluated by plotting log behavior ratios by session, cumulated time on‐ and off‐task and cumulated attention for on‐ and off‐task behavior by session, and interreinforcer behavior ratios following different sequences of the first four reinforcer deliveries. The generalized matching equation accounted for a large proportion of variance in steady‐state responding, sensitivity values increased steadily throughout the phases, patterns of choice in transition were similar to those reported in basic research, and interreinforcer preference generally shifted toward the just‐reinforced alternative. These findings are consistent with previous basic research and support the generality of the dynamics of choice to children's on‐ and off‐task behavior reinforced by adult attention.     

Killing begets killing: evidence from a bug-killing paradigm that initial killing fuels subsequent killing

Killing appears to perpetuate itself even in the absence of retaliation. This phenomenon may occur in part as a means to justify prior killing and so ease the threat of prior killing. In addition, this effect should arise particularly when a killer perceives similarity to the victims because similarity should exacerbate threat from killing. To examine these ideas, the authors developed a bug-killing paradigm in which they manipulated the degree of initial bug killing in a "practice task" to observe the effects on subsequent self-paced killing during a timed "extermination task." In Studies 1 and 2, for participants reporting some similarity to bugs, inducing greater initial killing led to more subsequent self-paced killing. In Study 3, after greater initial killing, more subsequent self-paced killing led to more favorable affective change. Implications for understanding lethal human violence are discussed.     

The Instructional Hierarchy as a Model of Stimulus Control over Student <Emphasis Type="Italic">and</Emphasis> Teacher Behavior: We're Close but are We Close Enough?

As a stage-based model of learning, the Instructional Hierarchy offers a useful heuristic for organizing research on effective instructional strategies at different levels of skill proficiency. In this paper, we summarize and highlight the unique contributions of each empirical study presented in the special issue. We describe common methodological features across the studies that likely contributed to intervention effectiveness, and present several implications for research and practice.     

Free Will and Psychosis: Theoretical and Therapeutic Implications

In this article the determinants of psychotic disorder and correlated free will is examined. Althought there is empirical evidence for significant cognitive, emotional and neurobiological correlates of psychosis the precise impact of these abnornalities on free will is largely unclear. More research is needed into a) the role of free will into psychotic etiology and maintenance and b) the impact of different categories of psychotic disorder on free will of the patient. Director of “W. Kahn Institute of Theoretical Psychiatry and Neuroscience” and advisor Psychiatry appointed by the European Commision (Leonardo da Vinci).     

One-trial conditioning of aerial respiratory behaviour in Lymnaea stagnalis

Repeated spaced training sessions of contingent tactile stimulation to the pneumostome as it opens are required to cause long-term memory (LTM) formation of aerial respiratory behaviour making if difficult to determine exactly when memory forms. We have devised a single-trial aversive operant conditioning training procedure in Lymnaea to be better able to elucidate the causal mechanisms of LTM formation. Observations of baseline breathing behaviour in hypoxia were first made. Twenty-four hours later the snails were trained using the single trial procedure, by placing them in a small Petri dish containing 4 ml of 25 mM KCl for 30-35s as soon as the first pneumostome opening in hypoxia was attempted. LTM was present if (1) breathing behaviour following training was significantly less than before; and (2) breathing behaviour post-training was significantly less in experimental groups than in yoked control groups. LTM persisted for 24 h but not 48 h. Yoked controls that received an aversive stimulus not contingent with pneumostome opening had no evidence of memory. Cooling directly after, but not at any other time, blocks LTM formation. LTM formation was also prevented by removal of the cell body of the neuron RPeD1 before training.     

Do familiarity and expectations change perception? Drivers’ glances and response to changes

The present study shows that repeated exposure to a road environment changes eye movement behaviour. In addition, repeated exposure may result in inadequate responses to unexpected changes in the road environment. Participants drove a low-cost simulator while their eye movements were recorded. With repeated exposure participants’ glances at traffic signs along the route were shorter while having a better recollection of the traffic signs along the route. At the last drive, the priority situation at an intersection was changed (a priority road was changed into a yield situation). Even though drivers glanced at the sign that indicated the new priority situation, they did not sufficiently process the information to show an adequate response. Only two out of 12 drivers showed any response, being a response only after crossing the priority road markings. The current finding that unexpected but relevant information may be missed by drivers is relevant for other monitoring tasks.     

Disdain for anxious individuals as a function of mortality salience

Terror management theory research has shown that reminders of mortality tend to decrease liking for people who threaten one's worldview. In research, these worldview threats typically come from outgroup members, but they may also come from ingroup members who are negatively characterized. Presumably the negative characteristics of ingroup members threaten to diminish or undermine the worldview by their association with it. In this research we examine anxious individuals as potentially threatening ingroup members. We hypothesized that a brief contemplation of mortality would lead people to decrease their liking for anxious individuals associated with their ingroup. Study 1 showed that a mortality reminder led people to react more negatively to an anxious police liaison from their community, but not to a calm police liaison. Study 2 showed that a mortality reminder led people who strongly identified with university students to react more negatively to a fellow university student who was anxious, but not to a student who did not display anxiety. Copyright © 2009 John Wiley & Sons, Ltd.     

On the temporal organization of facial identity and expression analysis: Inferences from event-related brain potentials

In the present study, behavioral and electrophysiological markers of information processing—the lateralized readiness potential, the N170, and the P300—were recorded in order to assess the functional and temporal organization of facial identity and expression processing. A two-choice go/no-go task was used in which facial expression (happy vs. angry) determined response hand and response execution depended on facial familiarity (familiar vs. unfamiliar). The duration of facial identity and expression processing was manipulated in separate experiments. Together, the present findings in measures of overt and covert response activation indicate that facial identity is analyzed in parallel with, and typically somewhat faster than, facial expression. These data support a parallel model of face perception that assumes partial output from facial identity and expression processes to motor activation processes.