Generalization through the recurrent interaction of episodic memories: a model of the hippocampal system

In this article, we present a perspective on the role of the hippocampal system in generalization, instantiated in a computational model called REMERGE (recurrency and episodic memory results in generalization). We expose a fundamental, but neglected, tension between prevailing computational theories that emphasize the function of the hippocampus in pattern separation (Marr, 1971; McClelland, McNaughton, & O'Reilly, 1995), and empirical support for its role in generalization and flexible relational memory (Cohen & Eichenbaum, 1993; Eichenbaum, 1999). Our account provides a means by which to resolve this conflict, by demonstrating that the basic representational scheme envisioned by complementary learning systems theory (McClelland et al., 1995), which relies upon orthogonalized codes in the hippocampus, is compatible with efficient generalization-as long as there is recurrence rather than unidirectional flow within the hippocampal circuit or, more widely, between the hippocampus and neocortex. We propose that recurrent similarity computation, a process that facilitates the discovery of higher-order relationships between a set of related experiences, expands the scope of classical exemplar-based models of memory (e.g., Nosofsky, 1984) and allows the hippocampus to support generalization through interactions that unfold within a dynamically created memory space.     

The role of disgust emotions in the observer response to facial disfigurement

Social intrusions by observers are commonly reported by those with disfiguring conditions. This study examined the role of disgust emotions in the observer response. A group of students (N = 48) completed quantitative questionnaires measuring extent of disfigurement, whilst viewing images of faces with varying disfigurements. Another group of students (N = 84) completed quantitative questionnaires measuring level of disgust elicited by the same images. Disgust sensitivity was measured using the Disgust Scale Revised. Observers reported greater levels of disgust (p < .01) with increasing severity of facial disfigurement. Individuals with a higher disgust sensitivity reported increased levels of disgust in response to faces of mild (p = .03), moderate (p = .02) and severe (p < .01) disfigurement compared to those with a lower disgust sensitivity. This provides an explanatory framework for the avoidance reactions of observers and may be important in understanding variability in adjustment following disfigurement.     

Synthesis of nanostructured vanadium powder by high-energy ball milling: X-ray diffraction and high-resolution electron microscopy characterization

Vanadium metal powders, ball milled with different surfactants viz., stearic acid, KCl and NaCl, have been studied by X-ray diffraction and transmission electron microscopy. The surfactants alter the microstructural and morphological characteristics of the powders. Ball milling with stearic acid results in solid-state amorphization, while powders milled with KCl yield vanadium–tungsten carbide nanocomposite mixtures. NaCl proved to be an excellent surfactant for obtaining nanostructured fusion-grade vanadium powders. In order to understand the reaction mechanism behind any interstitial addition in the ball-milled powders, CHNOS analysis was performed.