Postextinction infusion of a mitogen-activated protein kinase inhibitor into the medial prefrontal cortex impairs memory of the extinction of conditioned fear

We investigated whether postextinction training infusion of PD098059, a selective inhibitor of mitogen-activated protein kinase (MAPK) activation, into the medial prefrontal cortex, would impair retention of extinction learning in rats. We found that immediate, but not late (2 or 4 h), postextinction infusion of PD098059 provoked a full return of conditioned freezing. These results suggest that activation of prefrontal MAPK in early stages of postextinction training participates in processes that protect against spontaneous recovery of aversive responses.     

Absolute Probability Functions for Intuitionistic Propositional Logic

Provided here is a characterisation of absolute probability functions for intuitionistic (propositional) logic L, i.e. a set of constraints on the unary functions P from the statements of L to the reals, which insures that (i) if a statement A of L is provable in L, then P(A) = 1 for every P, L's axiomatisation being thus sound in the probabilistic sense, and (ii) if P(A) = 1 for every P, then A is provable in L, L's axiomatisation being thus complete in the probabilistic sense. As there are theorems of classical (propositional) logic that are not intuitionistic ones, there are unary probability functions for intuitionistic logic that are not classical ones. Provided here because of this is a means of singling out the classical probability functions from among the intuitionistic ones.     

Hippocampal train stimulation modulates recall of fear extinction independently of prefrontal cortex synaptic plasticity and lesions

It has been shown that long-term potentiation (LTP) develops in the connection between the mediodorsal thalamus (MD) and the medial prefrontal cortex (mPFC) and between the hippocampus (HPC) and the mPFC following fear extinction, and correlates with extinction retention. However, recent lesion studies have shown that combined lesions of the MD and mPFC do not interfere with extinction learning and retention, while inactivation of the dorsal HPC disrupts fear extinction memory. Here we found in rats that immediate post-training HPC low-frequency stimulation (LFS) suppressed extinction-related LTP in the HPC-mPFC pathway and induced difficulties in extinction recall. HPC tetanus, applied several hours later, failed to re-establish mPFC LTP but facilitated recall of extinction. Delayed post-training HPC LFS also provoked mPFC depotentiation and difficulties with extinction recall. HPC tetanus abolished these two effects. We also found that damage to the mPFC induced fear return only in rats that received HPC LFS following extinction training. HPC tetanus also reversed this behavioral effect of HPC LFS in lesioned rats. These data suggest that the HPC interacts with the mPFC during fear extinction, but can modulate fear extinction independently of this interaction.     

Reorganization of learning-associated prefrontal synaptic plasticity between the recall of recent and remote fear extinction memory

We have previously shown that fear extinction is accompanied by an increase of synaptic efficacy in inputs from the ventral hippocampus (vHPC) and mediodorsal thalamus (MD) to the medial prefrontal cortex (mPFC) and that disrupting these changes to mPFC synaptic transmission compromises extinction processes. The aim of this study was to examine whether these extinction-related changes undergo further plasticity as the memory of extinction becomes more remote. Changes in synaptic efficacy in both vHPC-mPFC and MD-mPFC inputs were consequently analyzed when the memory was either 1 d or 7 d old. Increases of synaptic efficacy in the vHPC-mPFC pathway were observed when the memory was 1 d old, but not 7 d after initial extinction. In contrast, potentiation of synaptic efficacy in the MD-mPFC pathway increased over time. In rats that received low-frequency vHPC stimulation immediately after extinction, both vHPC-mPFC and MD-mPFC inputs failed to develop potentiation, and the recall of extinction (both recent and remote memories) was impaired. These findings suggest that post-extinction potentiation in vHPC-mPFC inputs may be necessary for both the recall of recent memory and post-extinction potentiation in the MD-mPFC inputs. This late potentiation process may be required for the recall of remote extinction memory.     

More evidence for a dual-process model of conditional reasoning

Many studies have shown that the deductive inferences that people make have global properties that reflect the statistical information implicit in the premises. This suggests that such reasoning can be explained by a single, underlying probabilistic model. In contrast, the dual process model of conditional reasoning (Verschueren, Schaeken, & d'Ydewalle, 2005b) proposes that people can use either a logical, counterexample-based strategy or a probabilistic one. In two studies, we presented reasoners with sequences of affirmation-of-the-consequent inferences that differed with respect to the statistical properties of the premises, either explicitly or implicitly. As predicted by the dual-process model, an analysis of individual response patterns showed the presence of two distinct strategies, with use of the counterexample strategy being associated with higher levels of abstract-reasoning competence. Use of the counterexample strategy was facilitated by the explicit presentation of counterexample information. In a further study, we then examined explicitly probabilistic inferences. This study showed that although most reasoners made statistically appropriate inferences, the ability to make more-accurate inferences was associated with higher levels of abstract reasoning competence. These results show that deductive inferential reasoning cannot be explained by a single, unitary process and that any analysis of reasoning must consider individual differences in strategy use.     

Francis Xavier: Figure of Exile and Holiness

Abstract

Francis Xavier was one of the great Christian figures of the 16th century. The aim of this article is to delineate some of the important, and sometimes underemphasised, influences on his life in order to help shed light on the motivation which inspired his activities. It sets him first within a brief account of his family background, university education and life-changing friendship with Ignatius Loyola, which is described as generating ‘the undying archetype of the twin, with Loyola at the centre of the universe and Xavier at its periphery, complementing each other as perfectly as the point and the circle’. Against the background of ‘ever-present’ Islam, it then addresses Xavier's experiences with the corrupt and rather secularised Portuguese colonial environment in India and East Asia, and the royal ecclesiastical patronage exercised under the Padroado system, which led him to the role of a ‘counter-figure’ an exile or castaway, lançado or degregado. Japanese culture and religion and Xavier's fascination with China are two further areas explored. Permeating this account is the question of the nature of Xavier's spiritual life and personal holiness, within which his adventurous voyages may ultimately be seen as an immense pilgrimage and as the sign of a sanctity that was augmented rather than diminished by the obscurity of his death.     

Conditional reasoning,frequency of counterexamples,and the effect of response modality

Geiger and Oberauer (2007) found that when asked to reason with conditionals, people are very sensitive to information about the relative frequency of exceptions to conditional rules and quite insensitive to the relative number of disabling conditions. They asked participants to rate their degree of certainty in a conclusion. In the following studies, we investigated the possibility that this kind of response encourages a more probabilistic mode of processing compared with the usual dichotomous response. In Study 1, participants were given a variant of the problems used by Geiger and Oberauer with either the samescaled response format or a dichotomouscategorical response. The results with the scaled response were identical to those of Geiger and Oberauer. However, the results with the categorical response presented a very different profile. In Study 2, we presented similar problems using only frequency information, followed by a set of abstract conditional reasoning problems. The participants who performed better on the abstract problems showed a significantly different response profile than those who did worse on the abstract problems in the categorical response condition. No such difference was observed in the scaled response condition. These results show that response modality strongly affects the way in which information is processed in otherwise identical inferential problems and they are consistent with the idea that scaled responses promote a probabilistic mode of processing.