Propagation of action potential activity in a predefined microtunnel neural network

Abstract

A polydimethylsiloxane (PDMS) microtunnel device with two wells is aligned and attached on top of a multi-electrode-array (MEA). Neurons are grown first in one well and allowed to propagate axons through the tunnels into a second well. After ten days cells are plated in the second well, with much lower likelihood of extending axons back to the first well, with the intent of creating unidirectional connectivity between populations of neurons in the two wells. Here we report electrophysiological evidence that supports the hypothesis that the dominant information flow is in the desired direction. This was done by measuring the propagation speed and direction of individual action potentials, with the result that 84% of the spikes propagated in the desired direction. Further, we recorded globally synchronized burst activity on each of the electrodes, identified the timing of the first spike on each electrode, recorded locally synchronized burst activity which is found only in the second well and does not propagate back to the first well, and concluded that this measure of burst propagation supports the hypothesis of a unidirectionally connected network. Two hypotheses are discussed for mechanism underlying the activity pattern of the particular neural networks.

Large Extracellular Spikes Recordable From Axons in Microtunnels

“…In the late 60's Clark and Plonsey [4] indicated that the magnitude of an extracellular potential from a nerve fiber within a nerve trunk could be 20 times greater than in an infinite medium. Although microtunnel-like devices for neural applications were originally developed in the late 70's [5], it is only recently that the microtunnel technology has become popular for neuroscience research in general [6]–[13]. In these devices a typical tunnel is designed with dimensions near or below 10 um, (e.g.…”

Stimulation with a Low-Amplitude, Digitized Synaptic Signal to Invoke Robust Activity within Neuronal Networks on Multielectrode Arrays

“…It provides localized stimulation with a specificity approaching that of microarrays using predefined tunnels that restrict the directionality of axonal outgrowth (and therefore restrict the directionality of signal propagation (32). Our altered signaling and circuit design is readily reversible to classical settings, which can allow localized versus global stimulation and monitoring of the same neuronal networks.…”

Integration of pre-aligned liquid metal electrodes for neural stimulation within a user-friendly microfluidic platform

“…To achieve subcellular alignment, electrodes can be aligned manually using micromanipulators or microelectrodes patterned onto a bottom substrate can be aligned with a compartmentalized chamber to guide the placement of subcellular process (as has been done for microelectrode recording). 9,10 Both of these possibilities require cumbersome preparation and alignment steps for each device.…”