Transcranial Calcium Macro-Imaging From the Auditory Cortex of Thy1-Cre-Driven GCaMP8 Transgenic Rats.

BACKGROUND: Genetically encoded calcium indicators such as GCaMP enable us to monitor neuronal activities from living animals at synaptic levels as well as at whole-brain levels. However, the genetic variation of GCaMP transgenic rats is limited compared with the various demands for neuroscience studies on rats. METHOD: We established two transgenic rat lines: one expressing Cre recombinase under the control of the Thy1 promoter and another knock-in line carrying a floxed STOP cassette followed by GCaMP8 inserted into the β-actin locus. We mated these two transgenic rats and produced the Thy1-Cre-driven GCaMP8-expressing rats. RESULTS: = 1.2%. The rise time reaching the peak response was approximately 150 ms, and the half decay time was about 150 ms. CONCLUSIONS: These results suggest that the present GCaMP8-expressing rats as well as their parental transgenic rat strains offer a new tool for cortical macro-imaging and functional mapping with the transcranial approach.