Modulation of synaptic signaling by calcium feedback loops in dendritic spines

Cortical circuits rely on strong recurrent excitations to sustain mental representations. Most of these recurrent excitatory connections are received by small membranous protrusions called dendritic spines that cover the neuron’s dendritic shaft. The specific function of spines has been debated for decades as either being purely biochemical, where calcium gradients implement input-specific synaptic plasticity, or electrical, where spines function as electrical compartments that modify synaptic potentials. Recent experimental evidence has shown, however, that spines are indeed electrically isolated from their parent neurons and are capable of activating independently in subthreshold potentials. This electric isolation can be a mechanism for neuromodulation to control the regime of a cortical circuit’s effective recurrence. In this project, we simulate a spatial neuron model with a single spine on a dendrite and a minimal set of channels to study how voltage-dependent calcium feedback loops and calcium-dependent potassium channels in the spine can modify the neuron synaptic potential, and the implications this may have on cortical circuits like attractor networks. This project also examines the effect of spine morphology on the effectiveness of spine-based modulation.