Phase-dependent synaptic changes in the hippocampal CA1 field underlying extinction processes in freely moving rats

Recent studies focus on the functional significance of a novel form of synaptic plasticity, low-frequency stimulation (LFS)-induced synaptic potentiation in the hippocampal CA1 area. In the present study, we elucidated dynamic changes in synaptic function in the CA1 field during extinction processes associated with context-dependent fear memory in freely moving rats, with a focus on LFS-induced synaptic plasticity. Synaptic transmission in the CA1 field was transiently depressed during each extinction trial, but synaptic efficacy was gradually enhanced by repeated extinction trials, accompanied by decreases in freezing. On the day following the extinction training, synaptic transmission did not show further changes during extinction retrieval, suggesting that the hippocampal synaptic transmission that underlies extinction processes changes in a phase-dependent manner. The synaptic potentiation produced by extinction training was mimicked by synaptic changes induced by LFS (0.5 Hz) in the group that previously received footshock conditioning. Furthermore, the expression of freezing during re-exposure to footshock box was significantly reduced in the LFS application group in a manner similar to the extinction group. These results suggest that LFS-induced synaptic plasticity may be associated with the extinction processes that underlie context-dependent fear memory. This hypothesis was supported by the fact that synaptic potentiation induced by extinction training did not occur in a juvenile stress model that exhibited extinction deficits. Given the similarity between these electrophysiological and behavioral data, LFS-induced synaptic plasticity may be related to extinction learning, with some aspects of neuronal oscillations, during the acquisition and/or consolidation of extinction memory.     

Dodecagonal quasicrystal in Mn-based quaternary alloys containing Cr,Ni and Si

A dodecagonal quasicrystal showing 12-fold symmetry forms in Mn-rich quaternary alloys containing 5.5 or 7.5 at.% Cr, 5.0 at.% Ni and 17.5 at.% Si. After annealing at 700 °C for 130 h, the quasicrystal precipitated in a matrix of β-Mn-type crystalline phase. The shape of the quasicrystal is needle-like having a length of several tens of micrometres. Electron diffraction as well as powder X-ray diffraction experiments has revealed the following characteristics of the quasicrystal: diffraction symmetry 12/mmm, the presence of systematic extinction for h₁h₂h₂h₁h₅-type reflections with odd h₅ index, and then five-dimensional space group P12₆/mmc. Indexing of the reflections indicated that the dimension of the common edge in the equilateral triangle–square tiling is 4.560 Å, and the periodicity is 4.626 Å along the 12-fold axis. This is the first example of the dodecagonal quasicrystal synthesized by ordinary metallurgical method in 3-d transition-metal alloys.     

The Effect of Episodic Future Thinking on Learning Intention: Focusing on English Learning Goal-Relevant Future Thinking in University Students1,2

We examined the effects of episodic future thinking related to achieving important learning goals on university students' learning intentions. Japanese university students (N = 70) participated in this experiment. Participants in the episodic future thinking condition were asked to imagine and describe events they would experience if they achieved their goals. In the semantic future thinking condition, we asked participants to describe their future selves after university graduation and rate the relevance of their future selves to their learning goals. Participants were then asked to respond to the learning intentions measures. Participants in the control condition responded to the measures of learning intentions after completing a questionnaire unrelated to future thinking. When the importance of goal attainment was high, participants in the episodic future thinking condition planned to study for significantly longer than those in the other conditions. Episodic future thinking related to achieving important learning goals strengthens learning intentions more than simple awareness of the future self and learning goals.     

Stress-Related Growth in Japanese Adolescents Experiencing High School Entrance Examinations

High school entrance examinations and preparation for them have become a highly stressful experience for many Japanese adolescents. This study examined the relationship between stress-related growth (SRG) and distress resulting from these exams from the perspective of positive meaning-making. Ninth graders (N = 183, 87 females, aged 14–15 years) of a public school in Tokyo participated in the study by responding to a questionnaire survey. Results indicated that meaning-making was positively correlated with SRG (r = .58, p < .001), whereas it was negatively correlated with distress (r = ?.20, p = .006). Moreover, SRG was negatively correlated with distress (r = ?.34, p < .001). Mediation analysis demonstrated that SRG positively mediates the relationship between meaning-making and distress, while distress negatively mediates the relationship between meaning-making and SRG. These results have implications for understanding the causal relationships between SRG and distress, from the perspective of positive meaning-making regarding high school entrance examinations in Japan.     

When a Seawall Is Visible: Infrastructure and Obstruction in Post-tsunami Reconstruction in Japan

The triple disaster of March 11, 2011 posed a formidable challenge for Japanese society in general, and for affected coastal communities in particular. In the immediate aftermath of the catastrophe, there was widespread support for the construction of high seawalls to protect communities. However, many communities began questioning this approach. In Maehama, the question of land reconstruction and protection gave rise to a set of complex responses. The government aimed to put in place even higher seawalls; however, the local community proposed instead to mark the boundary of high water with trees and stakes. These solutions instantiate different ways of infrastructuring the post-tsunami environment for safety; they carry different assumptions about infrastructure itself. Whereas the seawall solution was technical and quantitative, centering on the question of height, the boundary markers embedded qualitatively different assumptions about what makes a workable infrastructure. In particular, this difference centered on issue of visibility. On the one hand, the seawall was meant to slowly become unremarkable, whereas the boundary markers were specifically intended to maintain community memory. On the other hand, the seawall would make the sea itself invisible, whereas keeping the sea in sight is very important to villagers. However, the opposition between these forms of infrastructuring the environment was not total. A solution was gradually negotiated in which the sea wall and the boundary markers could complement each another. This situation highlights the intricate, transformable relation between visible and invisible forms of infrastructure.     

Ceiling Effects and Floor Effects of the Posttraumatic Growth Inventory

The current study investigated the effects of a brief psycho-educational presentation about posttraumatic growth (PTG: positive changes that may occur as a result of psychological struggle with a highly stressful life event) on the self-reported PTG by using the PTG Inventory (PTGI). Few empirical studies have investigated the possible ceiling or floor effects of the PTGI, despite researchers indicating the necessity of longitudinal studies to reveal the PTG processes. This study used a pre-test, brief presentation, and post-test longitudinal design to examine the effects of intervention among adolescents by considering the floor and ceiling effects of the PTGI. Participants, 54 high school students (37 females, 17 males, Mean age?=?15.92 years), completed the PTGI at three weeks interval. Results using the Latent Rank Theory approach demonstrated ceiling effects in students who reported a high degree of PTG at Time 1, and floor effects in students with low PTG at Time 1. Presentation effects were not evident even in those who reported a moderate degree of PTG at Time 1. These findings suggest that it is important to be aware of the ceiling/floor effects while measuring changes in PTG perception over time and that explaining the phenomenon of PTG is not likely to be enough to affect the PTG perceptions.     

Highly sensitive adolescents: The relationship between weekly life events and weekly socioemotional well-being

Recent research into Person × Environment interaction has supported the view that sensitivity to environmental influences is a susceptibility factor rather than a vulnerability factor. Given this perspective, this study examined the role of the adolescent’s sensory-processing sensitivity in the context of weekly life events and weekly socioemotional well-being. In the study, 114 adolescents repeatedly self-reported their sensitivity, recent life events, and recent socioemotional well-being in four surveys at one-week intervals. The results suggested the shape of Sensitivity × Life Events interaction significantly varied from week to week, which is consistent with the vantage sensitivity and diathesis–stress framework. In specific weeks, adolescents with high sensitivity are more likely to benefit from positive events than those with low sensitivity. These sensitive adolescents can be described as developmentally susceptibility rather than vulnerability.