Analysis of cortical processing of sound-evoked inputs: from single spines to cortical populations

Mammalian cortical neurons compute sensory information that arrives through numerous synaptic inputs located on their dendrites. Single neurons integrate these functional inputs into one functional output which is more or less tuned to sensory stimulation. How does a neuron compute all these functional inputs? How does a functional neuronal network compute? These two questions are fundamental to neuroscience and other fields as they could represent the starting point for reconstructing brain function. In order to better understand this process, we have combined in vivo two photon calcium imaging and electrophysiology in order to look at the inputs and the outputs of layer 3 cortical neurons in the mouse auditory cortex at the same time. Sound-evoked dendritic events could be observed also in the absence of firing as well as preceding the firing output. Furthermore, population imaging in unanesthetized mice revealed the tonotopy in deep cortical layers. Together with my colleagues, I have established the method of targeted multi-cell electroporation (TMTE) which allowed us to explore tonotopy in deeper cortical layers as well as single cell electroporation combined with cell-attached recordings which allowed us to explore the connection between spine and dendrite signaling in vivo together with the cell's output.