DENDRITESONBORDERS · Neuronal and dendritic recruitment on neocortical area borders

Neuronal and dendritic recruitment on neocortical area borders

One of the most striking features of cortex is the electrically active dendritic arbors of its neurons. Besides serving as a scaffold for synaptic inputs, dendrites can amplify inputs and act as computational subunits within a neuron. However, the relationship between dendritic processing and information flow through cortical networks remains to be understood in vivo. Decades of progress in neurophysiology has lead to a growing understanding of the richness of dendritic mechanisms and their powerful impact on cellular output. However our understanding derives largely from in vitro studies and extensions in vivo are surprisingly sparse in the literature. Because of this basic lack of information we still cannot identify general principles or rules that govern the relationship between dendritic processing and neural computation in vivo. This limits our capacity to predict the consequences of therapeutic interventions and it limits our capacity to explain the neural bases of behaviour. Both of these objectives are of critical importance to society. Therapeutic approaches usually target subcellular mechanisms. If we cannot predict the impact of subcellular manipulations at the level of neural circuits, we cannot rationally design novel therapies. This limits our ability to fight diseases in the brain. Failure of prediction also limits our ability to relate neural computation to behaviour, the ultimate output of the brain. A full understanding of how behaviour is generated remains a goal of vital importance to society and could unlock vast unknown possibilities in scientific and technological advancement. Our overall goal is to relate sub-cellular processes like synaptic integration to computations performed by large populations of neurons. In service of this larger goal, we focused in this project on dendritic integration in sensory neocortex because it presents experimental advantages as well as room for growth in this conceptual direction. Specifically, we have investigated the relationship between cortico-cortical communication, dendritic excitability, and brain state, a term used to refer to brain-wide regulatory processes like arousal. We focused on a specific cell type, one that represents one of the output channels of neocortex. We first investigated how correlated activity across cortical areas depends on sensory stimulation and brain state, and next investigated how the dendrites of these neurons are recruited under the same conditions. As a follow-up, we are currently performing experiments that bring these two sets of observations together.

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