Simultaneous cortical fluorescence imaging and LFP recording in striatum after optogenetic striatal stimulation

Striatum is involved in cortico-basal ganglia-thalamocortical loop and divided in dorsolateral, dorsomedial and ventral striatum, which are anatomically and functionally distinct. Cortico-striatal connectivity plays a fundamental role in planning movements and cognitive processes. Since striato-cortical communications is largely unexplored, to dissect its connectivity we used a tapered optical fiber implanted unilaterally to optogenetically stimulate targeted domains of striatum in channelrhodopsin(ChR2)-expressing Drd1-Cre awake mice. By changing the light input angle, the illumination is gradually moved along the fiber for striatal region-selective illumination. A microelectrode implanted on the fiber allowed recording of the local field potential from dorsolateral striatum during stimulation. Mice were transfected with AAV9-syn-GCaMP6f for large-scale recording of striatal-evoked neuronal activity using wide-field calcium imaging over right hemisphere. This combination of tools is used to highlight the functional correlation of selected striatal domains with both spatiotemporal cortical patterns over the right cortical mantle, evoked-striatal LFP and evoked-behavior. Preliminary results showed that optogenetic activation of DRD1+-neurons in dorsomedial striatum evoked complex forelimb movements associated with large calcium transients in motor cortex.