20XUAS regulatory sequences are separated from sequence encoding jGCaMP7f by a "SPARC-D" module that comprises: a full-length attP site of 60bp, a STOP cassette, a second attP site (60bp, full-length site), a spacer and an attB site. phiC31:int catalyzes irreversible recombination between the attB site and one of the two attP sites; if the attP site upstream of the STOP cassette is utilized, the STOP cassette is excised, permitting expression of jGCaMP7f, while if the attP site downstream of the STOP cassette is utilized, only the spacer is removed, and the STOP cassette is preserved. The "SPARC-D" module typically results in expression of the effector (in this case jGCaMP7f) in approximately 45% of cells.