Molecular maps of neural activity and quiescence

The rapid accumulation of inducible transcription factors (ITFs), such as c-Fos and Zif268, in activated neurons combined with histological methods that offer detection at the cellular level are key features that have led to their wide use in visualizing activated neurons. There are two major drawbacks of ITFs that limit their use in the CNS--cell-type expression specificity and stimulus-transcription coupling uncertainty. Recent technical advances in the field of molecular activity mapping now permit dual-labeling approaches that help resolve some of these ambiguities and identify neurons that are activated by different sensory stimuli. Furthermore, the recent identification of the robl/LC7-like gene, which shows immediate-early repression after stimulation, may have utility in functional mapping where it can be used to delineate quiescent neurons and serve as a complement to molecular activity markers.