Inhibition of the LH Surge by Restraint Stress in Cyclic Rats: Studies on the Role of GABAA and GABAB Receptors

There is evidence that stress can alter the activity in the brain of gamma-aminobutyricacid (GABA), a neurotransmitter that has been implicated in the regulation of LH secretion. In the present study the role of GABA in the restraint stress-induced inhibition of the LH surge was investigated in the intact cyclic rat. Intracerebroventricular (icv) administration of the GABAA receptor agonist muscimol (0.1, 0.5 or 1 μg) 5 min before the presumed onset of the pro-oestrous LH surge (at 0900 h) caused a dose dependent suppression of the surge. A single dose of the GABAB receptor agonist baclofen (1 μg; icv) injected at 0855 h postponed the onset of the LH surge, and repeated injections at 0855 and 1130 h suppressed the surge. These data indicate that GABA-ergic activity in the brain can inhibit the LH surge in the cyclic rat via GABAA and GABAB receptors. Pro-oestrous rats were subjected to 5 hrs of restraint starting at 0855 h. Pretreatment with the GABAA receptor antagonist bicuculine (1 μg; icv) at 0840, 0940 and 1040 h or pretreatment with the GABAB receptor antagonist phaclofen (10 μg; icv) at 0840 h were ineffective in preventing the restraint-induced inhibition of the LH surge. The results suggest that GABAA and GABAB receptors are not involved in the inhibitory effect of restraint stress on the LH surge.     

Liquid zinc embrittlement of a high-manganese-content TWIP steel

The cracking resistance of a twinning induced plasticity (TWIP) steel with high-manganese content has been studied in relation to the liquid metal embrittlement phenomenon. This phenomenon was investigated by hot tensile tests carried out on electrogalvanised specimens using a Gleeble® simulator at temperatures ranging from 600°C to 1000°C. The results show that this steel can be embrittled by liquid zinc within a limited range of temperature depending on strain rate.     

Suspicious Minds at Risk? The Role of Meaning in Processing War and Peacekeeping Experiences

The purpose of this study was to examine meaning as a mediator between perceived threat and posttraumatic stress responses among a sample of 1,561 veterans who participated in war or peacekeeping operations. Data were collected by questionnaire. Path analysis was performed to assess the expected relationships between the observed variables. Meaning in terms of distrust and personal benefits partially mediated the relation between perceived threat and posttraumatic stress responses. Distrustful beliefs about others and the world were strongly associated with perceived threat, as well as intrusive and avoidant thoughts. Creating meaning in terms of a positive worldview appears to be an important mission after military deployment.     

Direct brain communication: neuroelectric and metabolic approaches at Tübingen

The brain–computer interface (BCI) provides users with the possibility of sending messages and commands to the external world without using their muscles, thus enabling communication to occur independent of movement. Such a possibility is of utmost importance for paralyzed patients who may otherwise lose their ability to communicate. Enhanced methodology and the development of faster computers have substantially improved applications and offer new possibilities in this field. To date, there have been over 20 BCI research groups working on different approaches. In this paper, we review our studies of BCI based on electric and metabolic activity of the brain.     

Towards a mathematical model of within-session operant responding

Operant response rate changes within the course of a typical free-operant experimental session. These changes are orderly, and reliably demonstrated with subjects from different species, responding under different experimental conditions. Killeen (1995) postulated that the response rate changes are a function of the interplay between arousal and satiation and offered a mathematical model for this hypothesis. Here we analyze Killeen's model, demonstrating that, although solid in its principles, it presents some flaws in its implementation. Then, based on the same principles, we build and test a new model of within-session motivation dynamics. We also demonstrate that, by representing arousal as a variable that ranges between 0 and 1, we can obtain a surprisingly simple model of free-operant response rate.     

War trauma lingers on: Associations between maternal posttraumatic stress disorder,parent–child interaction,and child development

Maternal traumatization has been proposed as a risk factor for child development, but the mechanisms involved are poorly understood. This study analyzed the interrelations among maternal posttraumatic stress symptoms, parent–child interaction (emotional availability), and infants' psychosocial functioning and development among 49 asylum‐seeker and refugee mothers and their children (18–42 months). Measures included assessment of mothers' trauma and comorbid symptoms (Harvard Trauma Questionnaire: R.F. Mollica et al., 1992 ; Hopkins Symptom Checklist: L. Derogatis, R. Lipman, K. Rickels, E. Uhlenhuth, & L. Covi, 1974 ), emotional availability within parent–child interaction (Emotional Availability Scales: Z. Biringen, 2008 ), and infants' psychosocial functioning (Child Behavior Checklist: T.M. Achenbach & L.A. Rescorla, 2000 ) and development (Bayley Scales of Infant Development: B.F. van der Meulen, S.A.J. Ruiter, H.C. Spelberg, & M. Smrkovsky, 2000 ). The results show that higher levels of maternal posttraumatic stress symptoms are associated with a higher level of psychosocial problems of infants, but not with delays in their mental or psychomotor development. The results also show that higher levels of maternal posttraumatic stress symptoms are associated with higher levels of insensitive, unstructuring, or hostile, but not intrusive, parent–child interactions. Infants show lower levels of responsiveness and involvement to their traumatized mothers. Parent–child interaction did not function as a mediator between maternal trauma symptoms and infants' psychosocial functioning. Results are discussed in relation to the dyad's regulation of emotions. Results implicate a need to reestablish attunement between traumatized mothers and their nontraumatized children.     

Less may be more when choosing is difficult: Choice complexity and too much choice

Although consumers readily seek choice and abundance, the so-called too-much-choice effect suggests that having many alternatives to choose from eventually leads to negative consequences, such as decreased post-choice satisfaction. The present research extends this research by highlighting the role of choice complexity. It is argued that too-much-choice effects are associated with choice complexity, which is influenced not only by the number of alternatives, but also by other features of the choice set, such as the number of attributes that alternatives are differentiated upon. These other influences of choice complexity may propel or hinder the emergence of too-much-choice effects. Two experiments tested this hypothesis by orthogonally manipulating the number of alternatives and the number of attributes. Results revealed a too-much-choice effect when alternatives were differentiated on many attributes, but not when alternatives were differentiated on few attributes. Implications for theory and practice are discussed.     

Construct validation of the Dutch version of the impact of event scale

The Impact of Event Scale (ES; M. J. Horowitz, N. Wilner, & W. Alvarez, 1979) is a worldwide-used self-report measure to assess the frequency of intrusive and avoidant phenomena after a variety of traumatic experiences. The purpose of this article is to assess the psychometric value of the Dutch version of the IES (D. Brom & R. J. Kleber, 1985) in several samples of individuals who had experienced various traumatic stressors. The reliability and structure of the IES were evaluated in 3 different samples (total N = 1.588). The reliability of the Dutch version of the IES was adequate across the various stressors. The construct validity was assessed by using confirmatory factor analyses. Outcomes revealed a robust structure over the various samples, generally supporting the composition of the original IES.