The genetic and environmental architecture to the stability of IQ: Results from two independent samples of kinship pairs

Existing research has revealed that IQ remains relatively stable over the life course, though questions remain about how stable IQ is and whether the stability of IQ varies across different developmental periods of the life course. Despite this stability, there are also questions surrounding the factors that might explain the stability of IQ. Against this backdrop, we conduct bivariate genetic models to estimate genetic, shared environmental, and nonshared environmental influences on the stability of IQ. To do so, we analyze kinship pairs drawn from two separate longitudinal samples: The National Collaborative Perinatal Project (CPP) and the National Longitudinal Study of Adolescent Health (Add Health). Across both samples, IQ was found to be relatively stable. Moreover, the genetic analyses revealed that between 66% and 83% of the stability in IQ was due to genetic factors and between 43% and 69% of the change in IQ was due to genetic factors. The remainder of the stability and change in IQ was the result of a combination of shared and nonshared environmental influences. Importantly, some substantive race differences emerged in respect to genetic and environmental influences on the stability of IQ. We conclude with a discussion of the limitations of the study and avenues for future research.     

The Visibility and Invisibility of Arab Americans and Implications for Psychological Treatment: A Comment on Cho

The following is a commentary on “Ethical Considerations for Psychologists Providing Treatment for Arab Americans” (Cho, this issue). Cho (this issue) brings to light important issues on providing ethical treatment with the Arab American community. However, there is currently no formal mechanism to identify the number of Americans of Arab descent, thus impacting the ability of researchers to study psychological treatment with Arab Americans. In addition, many Arab Americans are refugees with exposure to trauma, highlighting the need for understanding the role of culture in trauma when working with this community. Implications of these issues pertinent to the Arab American community and the need for psychologists to act in advocacy roles are discussed.     

Continuing Medical Education: A Cross Sectional Study on a Developing Country’s Perspective

To determine the attitude of general practitioners towards continuing medical education (CME) and reasons motivating or hindering them from attending CME procedures, we conducted a cross-sectional survey from November 2013 to April 2014 in Karachi. Three hundred general practitioners who possessed a medical license for practice in Pakistan filled a pre-designed questionnaire consisting of questions pertaining to attitudes towards CME. Data was entered and analyzed using SPSS v16.0. 70.3% (n = 211) of the participants were males. Mean age was 47.75 ± 9.47 years. Only 67.33% knew about CME and only 52% had attended a CME session. Reasons for attending CME procedures reported were: need for updating knowledge, skills and competencies (67.30%), opportunity to meet colleagues (18.58%) and presenting scientific papers (8.97%). Mean Likert score was 1.67 (±0.667) for those who thought CME is worthwhile and 1.44 (±0.686) for those who consider their clinical duties as the major hurdle in attending CME procedures. Most common cause for not attending CME was lack of knowledge (32.66%) followed by time constraint (24%). Most physicians were not sufficiently informed about the potential benefits of CME and had never attended a CME session. Most common reason for attending CME procedures reported was need for updating knowledge, skills and competencies while reasons hindering physicians from attending CME were lack of knowledge and time constraint.     

A model of amygdala–hippocampal–prefrontal interaction in fear conditioning and extinction in animals

Empirical research has shown that the amygdala, hippocampus, and ventromedial prefrontal cortex (vmPFC) are involved in fear conditioning. However, the functional contribution of each brain area and the nature of their interactions are not clearly understood. Here, we extend existing neural network models of the functional roles of the hippocampus in classical conditioning to include interactions with the amygdala and prefrontal cortex. We apply the model to fear conditioning, in which animals learn physiological (e.g. heart rate) and behavioral (e.g. freezing) responses to stimuli that have been paired with a highly aversive event (e.g. electrical shock). The key feature of our model is that learning of these conditioned responses in the central nucleus of the amygdala is modulated by two separate processes, one from basolateral amygdala and signaling a positive prediction error, and one from the vmPFC, via the intercalated cells of the amygdala, and signaling a negative prediction error. In addition, we propose that hippocampal input to both vmPFC and basolateral amygdala is essential for contextual modulation of fear acquisition and extinction. The model is sufficient to account for a body of data from various animal fear conditioning paradigms, including acquisition, extinction, reacquisition, and context specificity effects. Consistent with studies on lesioned animals, our model shows that damage to the vmPFC impairs extinction, while damage to the hippocampus impairs extinction in a different context (e.g., a different conditioning chamber from that used in initial training in animal experiments). We also discuss model limitations and predictions, including the effects of number of training trials on fear conditioning.