Imaging neuronal activity in the central and peripheral nervous systems using new Thy1.2-GCaMP6 transgenic mouse lines

Background: The genetically encoded calcium (Ca²⁺) sensor GCaMP6 has been widely used for imaging Ca²⁺ transients in neuronal somata, dendrites, and synapses.

New method: Here we describe five new transgenic mouse lines expressing GCaMP6F (fast) or GCaMP6S (slow) in the central and peripheral nervous system under the control of theThy1.2 promoter.

Results: These transgenic lines exhibit stable and layer-specific expression of GCaMP6 in multiple brain regions. They have several unique features compared to existing Thy1.2-GCaMP6 mice, including sparse expression of GCaMP6 in layer V pyramidal neurons of the cerebral cortex, motor neurons in the spinal cord, as well as sensory neurons in dorsal root ganglia (DRG). We further demonstrate that these mouse lines allow for robust detection of Ca²⁺ transients in neuronal somata and apical dendrites in the cerebral cortex of both anesthetized and awake behaving mice, as well as in DRG neurons.

Comparison with existing method(s): These transgenic lines allows Ca²⁺ imaging of dendrites and somas of pyramidal neurons in specific cortical layers that is difficult to achieve with existing methods.

Conclusions: These GCaMP6 transgenic lines thus provide useful tools for functional analysis of neuronal circuits in both central and peripheral nervous systems.