The neurobehavioral genetics of aggression

"Screen and intervene": governing risky brains

This article argues that a new diagram is emerging in the criminal justice system as it encounters developments in the neurosciences. This does not take the form that concerns many "neuroethicists" -- it does not entail a challenge to doctrines of free will and the notion of the autonomous legal subject -- but is developing around the themes of susceptibility, risk, pre-emption and precaution. I term this diagram "screen and intervene" and in this article I attempt to trace out this new configuration and consider some of the consequences.

Behavioral alterations in mice lacking the translation repressor 4E-BP2

The requirement for de novo protein synthesis during multiple forms of learning, memory and behavior is well-established; however, we are only beginning to uncover the regulatory mechanisms that govern this process. In order to determine how translation initiation is regulated during neuroplasticity we engineered mutant C57Bl/6J mice that lack the translation repressor eukaryotic initiation factor 4E-binding protein 2 (4E-BP2) and have previously demonstrated that 4E-BP2 plays a critical role in hippocampus-dependent synaptic plasticity and memory. Herein, we examined the 4E-BP2 knockout mice in a battery of paradigms to address motor activity and motor skill learning, anxiety and social dominance behaviors, working memory and conditioned taste aversion. We found that the 4E-BP2 knockout mice demonstrated altered activity in the rotating rod test, light/dark exploration test, spontaneous alternation T-maze and conditioned taste aversion test. The information gained from these studies builds a solid foundation for future studies on the specific role of 4E-BP2 in various types of behavior, and for a broader, more detailed examination of the mechanisms of translational control in the brain.

Social stress in laying hens: differential dopamine and corticosterone responses after intermingling different genetic strains of chickens

White Leghorn chickens were genetically selected for high (HGPS) or low (LGPS) group productivity and survivability. The selection resulted in two genetic lines with marked opposite changes in cannibalism and flightiness when housed in multiple-colony battery cages without beak trimming. The objective of the study was to examine whether the genetic selection differentially affected the neuroendocrine system of chickens from different strains in response to social stress. Based on the previous studies, social stress was induced by randomly pairing 17-wk-old hens from three genetic lines, i.e., HGPS, LGPS, and Dekalb XL (DXL), to form three mixed-line combinations. At 24 wk of age, the concentrations of plasma dopamine (DA) and corticosterone (CORT) showed no differences in DXL hens housed with HGPS or LGPS hens (P > 0.05). However, different regulations of DA and adrenal function were found between HGPS and LGPS hens when paired with DXL hens. Compared to HGPS hens, LGPS hens had greater levels of DA and CORT (P < 0.01 and P < 0.05, respectively). In addition, under the HGPS-LGPS social treatment, the concentrations of DA but not CORT were greater in LGPS hens than in HGPS hens (P < 0.05 and P > 0.05, respectively). The results indicated genetic selection for production and survivability differentially altered DA and CORT systems in response to social stress. The data suggested, compared to LGPS hens, HGPS hens had a better coping capability to social stress, which might have been responsible for their higher productivity and survivability.

Effects of group selection for productivity and longevity on blood concentrations of serotonin, catecholamines, and corticosterone of laying hens

Selection of a line of White Leghorn chickens for high group productivity and longevity resulted in reducing cannibalism and flightiness in multiple-hen cages. Improvements in survival might have been due to changes of physiological homeostasis. The objective of the present study was to test the hypothesis that genetic selection for high (HGPS) and low (LGPS) group productivity and survivability also altered regulation of neuroendocrine homeostasis. Hens were randomly assigned to individual cages at 17 wk of age. At 21 wk of age, blood concentrations of dopamine, epinephrine, norepinephrine, and serotonin were measured using HPLC assay. Blood concentrations of corticosterone were measured using radioimmunoassay. The LGPS hens had greater blood concentrations of dopamine and epinephrine than the HGPS hens (P < 0.01). The blood concentration of norepinephrine was not significantly different between the lines, but the ratio of epinephrine to norepinephrine was greater in the LGPS hens (P < 0.01). The blood concentrations of serotonin were also higher in the LGPS hens compared to those in the HGPS hens (P < 0.01). Although the HGPS hens tended to have a higher level of blood corticosterone, the difference was not significant (1.87 +/- 0.19 vs. 1.49 +/- 0.21 ng/mL; P = 0.08). The results suggest that selection for group productivity and survivability alters the chickens' neuroendocrine homeostasis, and these changes may correlate with its line-unique coping ability to domestic environments and survivability.

Genetic-environment analysis of sensitivity and acute tolerance to ethanol in mice

The purpose of this study was to characterize initial sensitivity (IS), acute functional tolerance (AFT), and rate of tolerance development to ethanol in lines of mice selected for aggression mice as well as to investigate the impact of isolate housing on these phenotypes. The results showed that for IS, there were no differences among treatment groups. For acute tolerance and rate of tolerance development, a Line x Sex x Housing interaction was present, with the response to housing being more pronounced in the low aggressive line than the high aggressive line, and the females being more affected than the males. Correlational analysis showed low to moderate associations between rate of tolerance development and IS, as well as between rate of tolerance and AFT. Housing condition significantly influenced female expression of ethanol phenotypes as compared to males. The line of the subject also influenced the magnitude of expression of these phenotypes. These findings suggest that environmental and genetic influences interact to influence acute tolerance and rate of tolerance development.