Tracking Memory Operations with MEG
This week, Osipova et al. made use of the high temporal and spatial resolution of magnetoencephalography (MEG) to examine oscillatory activity associated with a memory task. The authors presented subjects with a series of pictures of buildings or landscapes in an encoding session. Then subjects were asked in a retrieval session whether they had previously viewed the images. During encoding, gamma (60C90 Hz) and theta (4.5C8.5 Hz) activity was stronger for items that were later remembered than for those that were later forgotten. Likewise, in the retrieval session, gamma and theta activity were stronger for recognized items than for correctly rejected items. Theta activity originated in parietotemporal areas, whereas gamma activity arose occipitally in Brodmann areas 18 and 19. The authors suggest that neural synchronization represented by occipital gamma activity may reflect either stronger drive to areas involved in memory or to reinforcement from those same areas.EGFR and Reactive Astrocytes
In this week's Journal, Liu et al. provide some insight on what makes a "reactive" astrocyte reactive. The authors look at activated astrocytes using several models of optic nerve injury. The epidermal growth factor receptor (EGFR) was not expressed by quiescent astrocytes but was upregulated in rat optic nerve astrocytes after ischemia, nerve transection, and in a chronic glaucoma model. The authors used several approac