Multi-Domain Touchscreen-Based Cognitive Assessment of C57BL/6J Female Mice Shows Whole-Body Exposure to 56Fe Particle Space Radiation in Maturity Improves Discrimination Learning Yet Impairs Stimulus-Response Rule-Based Habit Learning

Astronauts during interplanetary missions will be exposed to galactic cosmic radiation, including charged particles like 56Fe. Most preclinical studies with mature, “astronaut-aged” rodents suggest space radiation diminishes performance in classical hippocampal- and prefrontal cortex-dependent tasks. However, a rodent cognitive touchscreen battery unexpectedly revealed 56Fe radiation improves the performance of C57BL/6J male mice in a hippocampal-dependent task (discrimination learning) without changing performance in a striatal-dependent task (rule-based learning). As there are conflicting results on whether the female rodent brain is preferentially injured by or resistant to charged particle exposure, and as the proportion of female vs. male astronauts is increasing, further study on how charged particles influence the touchscreen cognitive performance of female mice is warranted. We hypothesized that, similar to mature male mice, mature female C57BL/6J mice exposed to fractionated whole-body 56Fe irradiation (3 × 6.7cGy 56Fe over 5 days, 600 MeV/n) would improve performance vs. Sham conditions in touchscreen tasks relevant to hippocampal and prefrontal cortical function [e.g., location discrimination reversal (LDR) and extinction, respectively]. In LDR, 56Fe female mice more accurately discriminated two discrete conditioned stimuli relative to Sham mice, suggesting improved hippocampal function. However, 56Fe and Sham female mice acquired a new simple stimulus-response behavior and extinguished this acquired behavior at similar rates, suggesting similar prefrontal cortical function. Based on prior work on multiple memory systems, we next tested whether improved hippocampal-dependent function (discrimination learning) came at the expense of striatal stimulus-response rule-based habit learning (visuomotor conditional learning). Interestingly, 56Fe female mice took more days to reach criteria in this striatal-dependent rule-based test relative to Sham mice. Together, our data support the idea of competition between memory systems, as an 56Fe-induced decrease in striatal-based learning is associated with enhanced hippocampal-based learning. These data emphasize the power of using a touchscreen-based battery to advance our understanding of the effects of space radiation on mission critical cognitive function in females, and underscore the importance of preclinical space radiation risk studies measuring multiple cognitive processes, thereby preventing NASA’s risk assessments from being based on a single cognitive domain.

Customizing CAT administration of the PROMIS Misuse of Prescription Pain Medication Item Bank for patients with chronic pain

Objective The 22-item PROMIS®-Rx Pain Medication Misuse item bank (Bank-22) imposes a high response burden. This study aimed to characterize the performance of the Bank-22 in a computer adaptive testing (CAT) setting based on varied stopping rules. Methods The 22 items were administered to 288 patients. We performed a CAT simulation using default stopping rules (CATPROMIS). In 5 other simulations, a “best health” response rule was added to decrease response burden. This rule stopped CAT administration when a participant selected “never” to a specified number of initial Bank-22 items (2-6 in this study, designated CATAlt2-Alt6). The Bank-22 and 7-item short form (SF-7) scores were compared to scores based on CATPROMIS, and the 5 CAT variations. Results Bank-22 scores correlated highly with the SF-7 and CATPROMIS, Alt5, Alt6 scores (rs=.87-.95) and moderately with CATAlt2- Alt4 scores (rs=.63-.74). In all CAT conditions, the greatest differences with Bank-22 scores were at the lower end of misuse T-scores. The smallest differences with Bank-22 and CATPROMIS scores were observed with CATAlt5 and CATAlt6. Compared to the SF-7, CATAlt5 and CATAlt6 reduced overall response burden by about 42%. Finally, the correlations between PROMIS-Rx Misuse and Anxiety T-scores remained relatively unchanged across the conditions (rs=.31-.43, ps < .001). Conclusions Applying a stopping rule based on number of initial “best health” responses reduced response burden for respondents with lower levels of misuse. The tradeoff was less measurement precision for those individuals, which could be an acceptable tradeoff when the chief concern is in discriminating higher levels of misuse.

Direct Reciprocity and Model-Predictive Strategy Update Explain the Network Reciprocity Observed in Socioeconomic Networks

Network reciprocity has been successfully put forward (since M. A. Nowak and R. May’s, 1992, influential paper) as the simplest mechanism—requiring no strategical complexity—supporting the evolution of cooperation in biological and socioeconomic systems. The mechanism is actually the network, which makes agents’ interactions localized, while network reciprocity is the property of the underlying evolutionary process to favor cooperation in sparse rather than dense networks. In theoretical models, the property holds under imitative evolutionary processes, whereas cooperation disappears in any network if imitation is replaced by the more rational best-response rule of strategy update. In social experiments, network reciprocity has been observed, although the imitative behavior did not emerge. What did emerge is a form of conditional cooperation based on direct reciprocity—the propensity to cooperate with neighbors who previously cooperated. To resolve this inconsistency, network reciprocity has been recently shown in a model that rationally confronts the two main behaviors emerging in experiments—reciprocal cooperation and unconditional defection—with rationality introduced by extending the best-response rule to a multi-step predictive horizon. However, direct reciprocity was implemented in a non-standard way, by allowing cooperative agents to temporarily cut the interaction with defecting neighbors. Here, we make this result robust to the way cooperators reciprocate, by implementing direct reciprocity with the standard tit-for-tat strategy and deriving similar results.

Contributions of anterior cingulate cortex and basolateral amygdala to decision confidence and learning under uncertainty

The subjective sense of certainty, or confidence, in ambiguous sensory cues can alter the interpretation of reward feedback and facilitate learning. We trained rats to report the orientation of ambiguous visual stimuli according to a spatial stimulus-response rule that must be learned. Following choice, rats could wait a self-timed delay for reward or initiate a new trial. Waiting times increase with discrimination accuracy, demonstrating that this measure can be used as a proxy for confidence. Chemogenetic silencing of BLA shortens waiting times overall whereas ACC inhibition renders waiting times insensitive to confidence-modulating attributes of visual stimuli, suggesting contribution of ACC but not BLA to confidence computations. Subsequent reversal learning is enhanced by confidence. Both ACC and BLA inhibition block this enhancement but via differential adjustments in learning strategies and consistent use of learned rules. Altogether, we demonstrate dissociable roles for ACC and BLA in transmitting confidence and learning under uncertainty.

Dissociable roles for Anterior Cingulate Cortex and Basolateral Amygdala in Decision Confidence and Learning under Uncertainty

It has been suggested the subjective sense of certainty, or confidence, in ambiguous sensory cues can alter the interpretation of reward feedback and facilitate learning. We trained rats to report the orientation of ambiguous visual stimuli according to a spatial stimulus-response rule. Following choice, rats could wait a self-timed delay for reward or initiate a new trial. Waiting times increased with discrimination accuracy, demonstrating that this measure could be used as a proxy for confidence. Chemogenetic silencing of BLA shortened waiting times overall whereas ACC inhibition rendered waiting times insensitive to confidence-modulating attributes of visual stimuli, suggesting contribution of ACC but not BLA to confidence computations. Subsequent reversal learning was enhanced by confidence. Both ACC and BLA inhibition blocked this enhancement but via differential modulation of learning strategies and consistency in using learned rules. Altogether, we demonstrate dissociable roles for ACC and BLA in transmitting confidence and learning under uncertainty.

Evolution of extortion in the social-influenced prisoner’s dilemma

The introduction of extortion strategy has attracted much attention since it dominates any evolutionary opponent in iterated prisoner’s dilemma games. Despite several studies argue that extortion is difficult to survive under strategy imitation and birth–death updating rules in well-mixed populations, it has recently been proven that a myopic best response rule facilitate the evolution of cooperation and extortion. However, such updating rules require a strong assumption of complete knowledge of all players, which is unlikely to hold in social networks in reality. To solve this problem, we introduce the concept of social influence into the model to limit players’ knowledge within their neighborhood. It turns out that this myopia initiated by social influence prevents players from observing superior strategies and therefore enables cooperators and extortioners to be evolutionarily stable. We also suggest that heterogeneous networks contribute to the evolution of cooperation and extortion under such social influence.

FLAC3D Simulation for Dynamic Response of the Western Slope in Buzhaoba under Explosion

To study the dynamic response rule of the western slope in Buzhaoba under explosion, a vibrational wave was imposed on the slope. The FLAC3D program was utilized to simulate the rule. The distribution of stress field and the response of velocity were analyzed after blasting. The simulation result shows that the compressive stress increase step by step with the increase of the depth of slope, and as the elevation increases, the particle velocity appears an amplification effect, and the slope is mainly affected by the self-weight stress, and the blasting has little effect on the slope.

Experimental Modal Research on the Cutting System of EBZ-75 Type Boom-Roadheader

Based on the virtual prototype technology, using the ADAMS vibration analysis module, the displacement response rule of the main mechanism of the cutting system excited by sinusoidal harmonic excitation is obtained. And through the analysis of the results, the fact that 20HZ, 29HZ, 120HZ and 134 HZ are the sensitive frequency of the main mechanism is found out. Using the hammer test modal analysis methods to analysis cutting system of EBZ-75 type boom-roadheader, and compared with simulation results, the sensitive vibration frequency in vertical direction of the cutting system is achieved, which provides a test reference data for the optimize design of the cutting system.