Synaptrode: neural interface at the synapse level

Abstract

Electrical recording and stimulation of neurons is used both by neuroscientists to gain insight into neural network dynamics and clinicians to diagnose or treat various neuropathologies. Current electrophysiology paradigms are limited in that subpopulations of neurons within the network cannot be selectively addressed without the use of difficult and low yield techniques such as optogenetically tagged recordings, not suitable for use in the clinic. With the synaptrode, we aim to address these limitations by adding versatility to the current electrophysiology hardware, without the need for auxiliary tools or modifications to the subject. This versatility consists of a manufacturing technology where electrodes make synapse-like connections with selected subpopulations of neurons enabled by the molecular code of cell adhesion molecules (CAMs). Using the molecular specificity of CAMs we can selectively induce presynaptic or postsynaptic connections to neurons, allowing separate monitoring and stimulation channels for efferent and afferent neuron-to-neural prostheses connections. The challenge we face is to create electrodes that are small enough to interface with single neurites and yet do not exhibit impedance values prohibitively large to reliably perform electrophysiology experiments. Combining the differential coding properties of CAMs immobilized at the electrodes with the ease and the speed of electrical readout of neuronal activity, we envision a technology that would enable accelerated research in closed loop electrophysiology paradigms for health, industry, and academic applications.