NMDA receptor-dependent processes in the medial prefrontal cortex are important for acquisition and the early stage of consolidation during trace, but not delay eyeblink conditioning

Permanent lesions in the medial prefrontal cortex (mPFC) affect acquisition of conditioned responses (CRs) during trace eyeblink conditioning and retention of remotely acquired CRs. To clarify further roles of the mPFC in this type of learning, we investigated the participation of the mPFC in mnemonic processes both during and after daily conditioning using local microinfusion of the GABA(A) receptor agonist muscimol or the NMDA receptor antagonist APV into the rat mPFC. Muscimol infusions into the mPFC before daily conditioning significantly retarded CR acquisition and reduced CR expression if applied after sufficient learning. APV infusion also impaired acquisition of CRs, but not expression of well-learned CRs. When infusions were made immediately after daily conditioning, acquisition of the CR was partially impaired in both the muscimol and APV infusion groups. In contrast, rats that received muscimol infusions 3 h after daily conditioning exhibited improvement in their CR performance comparable to that of the control group. Both the pre- and post-conditioning infusion of muscimol had no effect on acquisition in the delay paradigm. These results suggest that the mPFC participates in both acquisition of a CR and the early stage of consolidation of memory in trace, but not delay eyeblink conditioning by NMDA receptor-mediated operations.     

An electrophysiological comparison of visual categorization and recognition memory

Object categorization emphasizes the similarities that bind exemplars into categories, whereas recognition memory emphasizes the specific identification of previously encountered exemplars. Mathematical modeling has highlighted similarities in the computational requirements of these tasks, but neuropsychological research has suggested that categorization and recognition may depend on separate brain systems. Following training with families of novel visual shapes (blobs), event-related brain potentials (ERPs) were recorded during both categorization and recognition tasks. ERPs related to early visual processing (N1, 156–200 msec) were sensitive to category membership. Middle latency ERPs (FN400 effects, 300–500 msec) were sensitive to both category membership and old/new differences. Later ERPs (parietal effects, 400–800 msec) were primarily affected by old/new differences. Thus, there was a temporal transition so that earlier processes were more sensitive to categorical discrimination and later processes were more sensitive to recognition-related discrimination. Aspects of these results are consistent with both mathematical modeling and neuropsychological perspectives.     

Novel long-period stacking-ordered structure of martensite in zirconium–cobalt–palladium alloys

A novel long-period stacking-ordered (LPSO) structure of a martensitic phase in a Zr–Co–Pd alloy was discovered and characterized by means of conventional transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy. The new phase had a 6O structure and its lattice parameters were estimated to be a = 0.34, b = 0.45 and c = 1.53 nm. The formation mechanism and the space group of the LPSO structure are described.     

A new "fat face" illusion

We report a novel fat face illusion that when two identical images of the same face are aligned vertically, the face at the bottom appears 'fatter'. This illusion emerged when the faces were shown upright, but not inverted, with the size of the illusion being 4%. When the faces were presented upside down, the illusion did not emerge. Also, when upright clocks were shown in the same vertically aligned fashion, we did not observe the illusion, indicating that the fat illusion does not generalize to every category of canonically upright objects with similar geometric shape as a face.     

Modesty in self‐presentation: A comparison between the USA and Japan

Japanese participants in Study 1 exhibited a self‐effacing tendency when no reason for their self‐evaluation was provided. However, they exhibited a self‐enhancing tendency when they were offered a monetary reward for the correct evaluation. In Study 2, Americans, especially American men, exhibited a self‐enhancing tendency whereas Japanese exhibited a self‐effacing tendency when no reason for making the evaluation was presented. This cultural difference disappeared when participants were provided with a monetary reward for correctly evaluating their performance level. These results support the view that the modesty observed in self‐evaluation among Japanese participants is a ‘default strategy’ to avoid offending others.