Behavioral analysis of NR2C knockout mouse reveals deficit in acquisition of conditioned fear and working memory

N-methyl-D-aspartate (NMDA) receptors play an important role in excitatory neurotransmission and mediate synaptic plasticity associated with learning and memory. NMDA receptors are composed of two NR1 and two NR2 subunits and the identity of the NR2 subunit confers unique electrophysiologic and pharmacologic properties to the receptor. The precise role of NR2C-containing receptors in vivo is poorly understood. We have performed a battery of behavioral tests on NR2C knockout/nβ-galactosidase knock-in mice and found no difference in spontaneous activity, basal anxiety, forced-swim immobility, novel object recognition, pain sensitivity and reference memory in comparison to wildtype counterparts. However, NR2C knockout mice were found to exhibit deficits in fear acquisition and working memory compared to wildtype mice. Deficit in fear acquisition correlated with lack of fear conditioning-induced plasticity at the thalamo-amygdala synapse. These findings suggest a unique role of NR2C-containing receptors in associative and executive learning representing a novel therapeutic target for deficits in cognition.     

Peers increase adolescent risk taking by enhancing activity in the brain's reward circuitry

The presence of peers increases risk taking among adolescents but not adults. We posited that the presence of peers may promote adolescent risk taking by sensitizing brain regions associated with the anticipation of potential rewards. Using fMRI, we measured brain activity in adolescents, young adults, and adults as they made decisions in a simulated driving task. Participants completed one task block while alone, and one block while their performance was observed by peers in an adjacent room. During peer observation blocks, adolescents selectively demonstrated greater activation in reward-related brain regions, including the ventral striatum and orbitofrontal cortex, and activity in these regions predicted subsequent risk taking. Brain areas associated with cognitive control were less strongly recruited by adolescents than adults, but activity in the cognitive control system did not vary with social context. Results suggest that the presence of peers increases adolescent risk taking by heightening sensitivity to the potential reward value of risky decisions.     

Computerized assessment of syntactic complexity in Alzheimer’s disease: a case study of Iris Murdoch’s writing

Currently, the majority of investigations of linguistic manifestations of neurodegenerative disorders such as Alzheimer’s disease are conducted based on manual linguistic analysis. Grammatical complexity is one of the language use characteristics sensitive to the effects of Alzheimer’s disease and is difficult to operationalize and measure using manual approaches. In the current study, we demonstrate the application of computational linguistic methods to automate the analysis of grammatical complexity. We implemented the Computerized Linguistic Analysis System (CLAS) based on the Stanford syntactic parser (Klein and Manning, Pattern Recognition, 38(9), 1407–1419, 2005) for longitudinal analysis of changes in syntactic complexity in language affected by neurodegenerative disorders. We manually validated CLAS scoring and used it to analyze writings of Iris Murdoch, a renowned Irish author diagnosed with Alzheimer’s disease. We found clear patterns of decline in grammatical complexity consistent with previous analyses of Murdoch’s writing conducted by Garrard, Maloney, Hodges, and Patterson (Brain, 128(250–260, 2005). CLAS is a fully automated system that may be used to derive objective and reproducible measures of syntactic complexity in language production and can be particularly useful in longitudinal studies with large volumes of language samples.     

Expression and Indication in Ethics and Political Philosophy

We sometimes have reasons to perform actions due to what they would communicate. Those who have discussed such reasons have understood what an action ‘communicates’ as what it conventionally expresses. Brennan and Jaworski argue that when a convention ensures that expressing the appropriate thing would be costly, we should change or flout the convention. I argue that what really matters is often what attitudes we indicate rather than conventionally express, using social science to show that indicating our attitudes is often unavoidably costly, and sometimes worth the cost. I use this account to defend communicative arguments for egalitarian distributive policies.

     

Inattention as a key predictor of tobacco use in adolescence

The authors examined the prediction from inattention to tobacco use among 2 cohorts (ages 7 and 13) of a community sample followed to young adulthood. Changes in self-reported tobacco use were tested with marginal transitional regression models, using parent and teacher ratings of inattention, hyperactivity-impulsivity, and other psychopathology, along with other factors, as predictors. Inattention, but not hyperactivity-impulsivity, significantly predicted adolescent tobacco use and young adult daily tobacco use. Peer substance use, parental substance use, and conduct disorder also predicted increases in tobacco use. African American ethnicity was strongly protective against later tobacco use.     

Talking about interest: exploring the role of social interaction for regulating motivation and the interest experience

The Self-Regulation of Motivation Model suggests that the experience of interest is an important source of human motivation and that people often strategically regulate the experience of interest. Previous work based on this model suggests that the social context may influence this process at multiple points. The present research focuses on whether talking to others about an activity experience is one means by which individuals evaluate how interesting that activity is. In Study 1 college students completed questionnaires that asked about real life experiences where working on an activity was more interesting because they worked with others. They described experiences that occurred first in any domain, and then that occurred specifically in the school domain. Results suggested that the more students talked with others about the activity after it happened the more they reported greater interest in the activity after the conversations. In the school domain, this was especially true for Latinos and for individuals who scored higher on the Relational Self-Construal scale. Study 2 employed a lab paradigm to control for the task that individuals talked to others about and to examine whether the nature of listeners’ reactions influenced the speaker’s interest even after the study was ostensibly over. First, replicating Pasupathi and Rich (2005, ‘Inattentive listening undermines self-verification in personal storytelling’, Journal of Personality 73, pp. 1051–1086) college students who talked to a distracted friend about a computer game during the lab session reported a significant drop in interest relative to those who talked to attentive friends, regardless of whether the attentive listeners agreed or disagreed with participants. Importantly, interest ratings at a 4–6 week follow-up were affected by the perceived responsiveness of listeners during spontaneous conversational retellings outside the lab, controlling for interest levels at the end of the lab session. Taken together, results suggest that social interaction plays an important role in regulating activity interest even beyond the immediate activity experience.     

Inference Patterns in Theoretical Social Psychology: Looking Back as We Move Forward

An important hallmark of modern social psychology is the central importance of theory and hypothesis testing. The inference structure, however, underlying such tests are rarely acknowledged and may have important implications for the field. In this study, we examine the inference patterns utilized over 20 years of published work in a leading journal of social psychology. We found that verification, in contrast to falsification and crucial tests of alternative hypotheses, was the dominant inference structure utilized. Crucial tests were conducted least of all. These trends were discussed in light of larger issues from the philosophy of science, as well as its potential implications for the field.     

Competing Core Processes in Attention-Deficit/Hyperactivity Disorder (ADHD): Do Working Memory Deficiencies Underlie Behavioral Inhibition Deficits?

The current study examined competing predictions of the working memory and behavioral inhibition models of ADHD. Behavioral inhibition was measured using a conventional stop-signal task, and central executive, phonological, and visuospatial working memory components (Baddeley 2007) were assessed in 14 children with ADHD and 13 typically developing (TD) children. Bootstrapped mediation analyses revealed that the visuospatial working memory system and central executive both mediated the relationship between group membership (ADHD, TD) and stop-signal task performance. Conversely, stop-signal task performance mediated the relationship between group membership and central executive processes, but was unable to account for the phonological and visuospatial storage/rehearsal deficits consistently found in children with ADHD. Comparison of effect size estimates for both models suggested that working memory deficits may underlie impaired stop-signal task performance in children with ADHD. The current findings therefore challenge existing models of ADHD that describe behavioral inhibition as a core deficit of the disorder.