Spatio-temporal modulation of light for stimulating and recording neuronal activity

The spectacular facets of light have made light ubiquitous in all fields of science. Light's interaction with matter allows for accurate manipulation of atomic and molecular structures that enabled fundamental breakthroughs in physics, chemistry, and biomedical research. The transfer of light's energy on molecules and genetically expressed proteins can be used to stimulate cells and emulate cellular processes such as synaptic inputs spatially distributed along the neuron's dendritic tree. Here, we show basic neuronal functions derived via numerical modelling and describe how we can use light to emulate these functions in order to provide a systematic study of the neuron's response. We focus on cortical pyramidal neurons and use the NEURON simulation environment to analyze how spatio-temporal stimulation patterns along various dendritic locations sets the neuron to fire an output. We then show an equivalent response from experiments via complex spatial light patterns for stimulating across different regions along the dendritic tree. Furthermore, we use the same spatial light patterns to simultaneously visualize neuronal responses via functional calcium imaging predicted via the same neuron model. Visualizing dendritic responses from back-propagating action potentials can provide new insights to some important features of dendritic computation.