Newseater - Adult Edition

Glia, Vol. 52, No. 4. (December 2005), pp. 289-300.

Human glial fibrillary acidic protein-delta (GFAP-delta) is a GFAP protein isoform that is encoded by an alternative splice variant of the GFAP-gene. As a result, GFAP-delta protein differs from the predominant splice form, GFAP-alpha, by its C-terminal protein sequence. In this study, we show that GFAP-delta protein is not expressed by all GFAP-expressing astrocytes but specifically by a subpopulation located in the subpial zone of the cerebral cortex, the subgranular zone of the hippocampus, and, most intensely, by a ribbon of astrocytes following the ependymal layer of the cerebral ventricles. Therefore, at least in the sub ventricular zone (SVZ), GFAP-delta specifically marks the population of astrocytes that contain the neural stem cells in the adult human brain. Interestingly, the SVZ astrocytes actively splice GFAP-delta transcripts, in contrast to astrocytes adjacent to this layer. Furthermore, we show that GFAP-delta protein, unlike GFAP-alpha, is not upregulated in astrogliosis. Our data therefore indicate a different functional role for GFAP-delta in astrocyte physiology. Finally, transfection studies showed that GFAP-delta protein expression has a negative effect on GFAP filament formation, and therefore could be important for modulating intermediate filament cytoskeletal properties, possibly facilitating astrocyte motility. Further studies on GFAP-delta and the cells that express it are important for gaining insights into its function during differentiation, migration and during health and disease.

Original post by RF Roelofs

Cognition, Vol. 89, No. 1. (August 2003), pp. 25-41.

By 6 years, children have a sophisticated adult-like theory of mind that enables them not only to understand the actions of social agents in terms of underlying mental states, but also to distinguish between their own mental states and those of others. Despite this, we argue that even adults do not reliably use this sophisticated ability for the very purpose for which it is designed, to interpret the actions of others. In Experiment 1, a person who played the role of “director” in a communication game instructed a participant to move certain objects around in a grid. Before receiving instructions, participants hid an object in a bag, such that they but not the director would know its identity. Occasionally, the descriptions that the director used to refer to a mutually-visible object more closely matched the identity of the object hidden in the bag. Although they clearly knew that the director did not know the identity of the hidden object, they often took it as the referent of the director’s description, sometimes even attempting to comply with the instruction by actually moving the bag itself. In Experiment 2 this occurred even when the participants believed that the director had a false belief about the identity of the hidden object, i.e. that she thought that a different object was in the bag. These results show a stark dissociation between an ability to reflectively distinguish one’s own beliefs from others’, and the routine deployment of this ability in interpreting the actions of others. We propose that this dissociation indicates that important elements of the adult’s theory of mind are not fully incorporated into the human comprehension system.

Original post by Boaz Keysar