A feasibility study of multi-site,intracellular recordings from mammalian neurons by extracellular gold mushroom-shaped microelectrodes.

ABSTRACT

The development of multi-electrode array platforms for large scale recording of neurons is at the forefront of neuro-engineering research efforts. Recently we demonstrated, at the proof-of-concept level, a breakthrough neuron-microelectrode interface in which cultured Aplysia neurons tightly engulf gold mushroom-shaped microelectrodes (gMµEs). While maintaining their extracellular position, the gMµEs record synaptic- and action-potentials with characteristic features of intracellular recordings. Here we examined the feasibility of using gMµEs for intracellular recordings from mammalian neurons. To that end we experimentally examined the innate size limits of cultured rat hippocampal neurons to engulf gMµEs and measured the width of the "extracellular" cleft formed between the neurons and the gold surface. Using the experimental results we next analyzed the expected range of gMµEs-neuron electrical coupling coefficients. We estimated that sufficient electrical coupling levels to record attenuated synaptic- and action-potentials can be reached using the gMµE-neuron configuration. The definition of the engulfment limits of the gMµEs caps diameter at ≤2-2.5 µm and the estimated electrical coupling coefficients from the simulations pave the way for rational development and application of the gMµE based concept for in-cell recordings from mammalian neurons.