UC San Diego

The mechanisms linking inducible transcription factor (ITF) activity with neuronal connectivity and receptive field properties are of great interest, but poorly understood. Of note, the immediate early gene transcription factor (IEG-TF), neuronal PAS domain 4 (NPAS4), is an ITF that is expressed exclusively in response to neuronal activity or depolarization. In the mouse visual cortex, NPAS4 is expressed at high levels during the critical period, a time during development in which neural plasticity is increased. To study NPAS4 in the visual cortex, we have elected to use in vivo calcium imaging. However, it is not known if GCaMP expression affects neuronal development or the induction of NPAS4. By utilizing in utero electroporation, we aimed to introduce GCaMP into the pyramidal neurons of the mouse visual cortex and analyze the function of the cells that were electroporated. We first found that the cells electroporated with GCaMP in early development are neurons. In addition, expression of GCaMP does not impact basal or stimulus-dependent induction of NPAS4 in the visual cortex of mice. Thus, GCaMP can be used to study the impact of NPAS4 expression on neurons in vivo without disrupting endogenous NPAS4 induction.