The organization of memory for familiar songs

Investigated the organizing principles in memory for familiar songs in 2 experiments. It was hypothesized that individuals do not store and remember each song in isolation. Rather, there exists a rich system of relationships among tunes that can be revealed through similarity rating studies and memory tasks. One initial assumption was the division of relations among tunes into musical (e.g., tempo, rhythm) and nonmusical similarity. In Exp I, 20 undergraduates were asked to sort 60 familiar tunes into groups according to both musical and nonmusical criteria. Clustering analyses showed clear patterns of nonmusical similarity but few instances of musical similarity. Exp II, with 16 Ss, explored the psychological validity of the nonmusical relationships revealed in Exp I. A speeded verification task showed that songs similar to each other are confused more often than are distantly related songs. A free-recall task showed greater clustering for closely related songs than for distantly related ones. The relationship between these studies and studies of semantic memory is discussed. Also, the contribution of musical training and individual knowledge to the organization of the memory system is considered. (19 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Frog oocytes to unveil the structure and supramolecular organization of human transport proteins

Structural analyses of heterologously expressed mammalian membrane proteins remain a great challenge given that microgram to milligram amounts of correctly folded and highly purified proteins are required. Here, we present a novel method for the expression and affinity purification of recombinant mammalian and in particular human transport proteins in Xenopus laevis frog oocytes. The method was validated for four human and one murine transporter. Negative stain transmission electron microscopy (TEM) and single particle analysis (SPA) of two of these transporters, i.e., the potassium-chloride cotransporter 4 (KCC4) and the aquaporin-1 (AQP1) water channel, revealed the expected quaternary structures within homogeneous preparations, and thus correct protein folding and assembly. This is the first time a cation-chloride cotransporter (SLC12) family member is isolated, and its shape, dimensions, low-resolution structure and oligomeric state determined by TEM, i.e., by a direct method. Finally, we were able to grow 2D crystals of human AQP1. The ability of AQP1 to crystallize was a strong indicator for the structural integrity of the purified recombinant protein. This approach will open the way for the structure determination of many human membrane transporters taking full advantage of the Xenopus laevis oocyte expression system that generally yields robust functional expression.