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The Role of Ongoing Dendritic Oscillations in Single-Neuron Computation

Michiel Remme

ENS, France

The dendritic tree contributes significantly to the elementary computations a neuron can perform, both by its intricate morphology and its composition of active conductances. Recent data indicates that active dendritic conductances are often clustered into so-called hot-spots, and can support on-going membrane potential oscillations. Thus there may be multiple oscillators embedded in the cell's dendritic tree. Here we analyze, through mathematical analysis and numerical simulations of detailed biophysical models, the dynamics of such interacting dendritic oscillators and their impact on signal propagation in single neurons.

Combining weakly coupled oscillator methods with cable theory, we derived interaction functions for multiple oscillating dendritic compartments separated by less excitable membrane segments. In particular, we characterized how their phase locking properties depend on a) the intrinsic properties of the oscillators and b) the membrane properties of the segment connecting them. As a direct consequence, we show how the conductance load on the dendrite can modulate phase locking behavior. This suggests a new role for synaptic conductances impinging on the dendrites, particularly shunting inhibition, in controlling the coherence of ongoing dendritic activity. In turn, dendritic coherence is able to gate the integration and propagation of synaptic signals to the soma, ultimately leading to an effective control of somatic spike generation. We further posit that ongoing dendritic oscillations and their modulation by synaptic conductances may have a role in detecting statistical structure in the input, thereby determining the elementary computations performed by the dendritic tree.