Transgenic Mouse Lines
The Allen Brain Observatory contains data collected via two-photon calcium imaging to quantify neuron activity in the mouse neocortex in response to visual stimuli. The use of a fluorescent calcium indicator, GCaMP6f, was used to register neural activity in the visual cortex of transgenic mice exposed to various visual stimuli. Calcium influx associated with neural activity results in transient increases in fluorescence of GCaMP6-GFP. These experiments use the transgenic mouse line Ai93, in which GCaMP6f expression is dependent on the activity of both Cre recombinase and the tetracycline-controlled transactivator protein (tTA). Triple transgenic mice (Ai93, tTA, Cre) were generated by first crossing Ai93 mice with Camk2a-tTA mice, which preferentially express tTA in forebrain excitatory neurons. Double transgenic mice were then crossed with a Cre driver line to generate mice in which GCaMP6f expression is induced in the specific populations of neurons that express both Cre and tTA.
Specific expression is driven by the following Cre driver lines (click to open serial two-photon images of florescent GCaMP6-GFP expression in the triple transgenic mouse line):
In the Transgenic Characterization section of the Allen Brain Observatory, data is available to view the native GCaMP6 fluorescence for each line using 2-photon serial tomography as performed on animals that have not undergone surgery, described in the “Visual Coding Overview” whitepaper in the Documentation tab.