OPTOGENETIC MANIPULATION OF DENDRITIC SIGNAL INTEGRATION

Layer 5 pyramidal neurons (L5PN) in the somatosensory cortex are essential for cortical processing and have been linked to higher order cognitive functions, including perception and consciousness. L5PNs integrate information across all cortical layers as their dendritic tree spans the entire cortical column. Key active properties of L5PNs arise from two main spiking zones: Na⁺ spikes initiated at the perisomatic region and Ca^{2 +} plateau potentials in the distal dendrites. Ca²⁺ signals travel from apical dendrites to the soma and shape the neuronal output. These signals are strongly modulated by dendritic G protein-coupled receptors (GPCRs).
In this project, we are investigating whether optoGPCRs are suitable for modulating signal integration in the dendrites of L5PCs. Using a combination of electrophysiology and optogenetics in brain slices we examine the effect of photocontrolled GPCR signals on supralinear dendritic events in L5PNs. We find that the efficiency of inhibition of synaptic transmitter release by optoGPCRs is not a predictive parameter for the functionality of optoGPCRs in dendrites. In future, optoGPCRs that have been optimized for dendritic applications will facilitate the investigation of the interaction between GPCR signaling cascades and Ca²⁺ signals in the integration of dendritic signals in L5PCs.