Firearms Matter: The Moderating Role of Firearm Storage in the Association Between Current Suicidal Ideation and Likelihood of Future Suicide Attempts Among United States Military Personnel

The relationship between firearm ownership and suicide is well documented. This study hypothesized that how soldiers store their firearms would moderate the relationship between suicidal ideation and the self-reported likelihood of engaging in a future suicide attempt, and that this relationship would be explained by fearlessness about death. There were 432 military personnel (91.3% men, 74.2% White, M_age = 27.60) who endorsed current ownership of a private firearm and who were recruited from a military base in the southeastern United States (94.5% National Guard). Firearm storage moderated the relationship between suicidal ideation and the self-reported likelihood of engaging in a future suicide attempt, but this relationship was not explained by fearlessness about death. Individuals who reported keeping their firearms loaded and stored in an unsecure location exhibited higher mean levels of fearlessness about death. Findings highlight the need for research examining contributors to suicide risk in the context of firearm storage, and provide support for suicide prevention efforts involving restricting means.     

Stress risk factors and stress-related pathology: neuroplasticity, epigenetics and endophenotypes

This paper highlights a symposium on stress risk factors and stress susceptibility, presented at the Neurobiology of Stress workshop in Boulder, CO, in June 2010. This symposium addressed factors linking stress plasticity and reactivity to stress pathology in animal models and in humans. Dr. J. Radley discussed studies demonstrating prefrontal cortical neuroplasticity and prefrontal control of hypothalamo-pituitary-adrenocortical axis function in rats, highlighting the emerging evidence of the critical role that this region plays in normal and pathological stress integration. Dr. M. Kabbaj summarized his studies of possible epigenetic mechanisms underlying behavioral differences in rat populations bred for differential stress reactivity. Dr. L. Jacobson described studies using a mouse model to explore the diverse actions of antidepressants in brain, suggesting mechanisms whereby antidepressants may be differentially effective in treating specific depression endophenotypes. Dr. R. Yehuda discussed the role of glucocorticoids in post-traumatic stress disorder (PTSD), indicating that low cortisol level may be a trait that predisposes the individual to development of the disorder. Furthermore, she presented evidence indicating that traumatic events can have transgenerational impact on cortisol reactivity and development of PTSD symptoms. Together, the symposium highlighted emerging themes regarding the role of brain reorganization, individual differences, and epigenetics in determining stress plasticity and pathology.     

Assessment of a response bias for aggression over functionally equivalent appropriate behavior

We evaluated the effects of a dense (fixed-ratio 1) schedule of reinforcement for an 11-year-old boy's mands for toys while aggression produced the same toys on various schedules chosen on the basis of a progressive-ratio probe. Based on the probe session data, we accurately predicted that aggression would be more probable than mands when the schedules were equal or slightly discrepant, but that mands would be more probable when the schedule discrepancy was large.     

Effects of spatial and symbolic precues on localization performance

One of the fundamental properties of spatial vision is the ability to localize objects in space. According to a recent proposal, accurate localization performance involves the operation of two systems: the attention system and the eye movement system. Upon stimulus presentation, attention is shifted to the target area: this provides coarse location information. Subsequently, a saccadic eye movement is executed: this provides fine location information. In this study we tested predictions derived from this model concerning the effects of precue information on localization performance. In a series of five experiments we manipulated duration of precue (71, 400, and 1,000 ms) and type of precue (spatial versus symbolic). Results showed that very short duration (i.e., 71 ms) spatial precues improved localization performance whereas very short duration symbolic precues did not. In contrast, the 1,000 ms duration precue condition showed similar amounts of precuing benefit for the spatial and symbolic precues. This pattern of differential precuing effects corroborated the two-process model of localization performance. Received: 24 June 1999 / Accepted: 28 January 2000     

Lack of the metabotropic glutamate receptor subtype 7 selectively modulates Theta rhythm and working memory

Metabotropic glutamate receptors (mGluRs) are known to play a role in synaptic plasticity and learning. We have previously shown that mGluR7 deletion in mice produces a selective working memory (WM) impairment, while other types of memory such as reference memory remain unaffected. Since WM has been associated with Theta activity (6-12 Hz) in EEGs, and since EEG abnormalities have been observed in these mice before, we studied the effect of mGluR7 gene ablation on EEG activity in the hippocampus, in particular in the Theta range, during performance of a WM task. In an eight-arm maze with four arms baited, mGluR7 knock-out (KO) and wild-type mice committed the same number of reference memory errors, whereas KOs committed more WM errors. While performing the task, KO mice showed substantially higher Theta amplitudes, and the ratio of Theta to overall EEG power was much increased. No change was seen in the Delta (0-5 Hz), or Gamma (30-40 Hz) EEG bands compared with controls. When recording EEGs during periods of rest in the home cages, no difference was seen between groups. These findings suggest that mGluR7 is important for modulation and control of Theta activity. Since only WM was affected, and only the Theta range of EEG activity was altered, these results show a correlation between Theta rhythm and WM performance, and therefore support the concept that Theta activity in the hippocampus is involved in WM storage.     

Effects of the presence of others on food intake: a normative interpretation

The authors review the effect of the presence of others on food intake. In social facilitation studies, people tend to eat more in groups than when alone. In modeling studies, the presence of others may facilitate or inhibit intake, depending on how much these other people eat. Studies of impression management demonstrate that people tend to eat less in the presence of others than when alone. The authors attempt to reconcile these divergent literatures by reference to a model of inhibitory norms that govern eating. In the presence of palatable food, and in the absence of clear signals of satiety, people look outward to cues from the environment to determine when to stop eating. Socially derived inhibitory norms can account for either increased or decreased intake in the presence of others, depending on how much the others eat and the extent to which one is eager to impress them.     

Speech errors, disfluencies, and self-repairs of stutterers in two accuracy conditions

The purpose of the present study was to see whether the covert repair hypothesis, which views normal disfluencies as the by-products of covert self-repairing of internal speech (programming) errors, applies to habitual stutterers. To this end, we examined the effects of emphasis on speech accuracy in stutterers on three sorts of incidents: speech errors, disfluencies (also including stuttering), and self-repairs. In a condition in which they performed a speech task under instructions stressing the accuracy of speaking, stutterers made considerably fewer speech errors, than in a condition in which speech accuracy could be ignored. On the other hand, disfluency and self-repair rates remained about the same. They did increase, however, relative to speech error rates with accuracy emphasis. A control group of normal speakers performed in a similar way. Apparently, disfluencies behaved like self-repairs. These results support the covert repair hypothesis of disfluency, both for stutterers and for normal speakers.     

The development of cognitive mapping of the large-scale environment

Two experiments were conducted to investigate the development of children's cognitive maps of large-scale environments. Kindergarten (Mean Age = 5?7), second (Mean Age = 7?7), and fifth (Mean Age = 10?7) graders walked through a large model town and were then required to construct the layout of building in that model from memory. Accuracy of construction increased as a function both of developmental level and repeated encounters with the layout. In Experiment 1, the separate effects of repeatedly walking through the town and repeatedly constructing it both increased the accuracy of the children's reconstructions. In Experiment 2, walking through the environment was no more effective than merely viewing it repeatedly. Young children's accuracy in bounded space (Experiment 1) was far more accurate than their performance in unbounded space (Experiment 2), while older children's accuracy was relatively unaffected by this variable.