Syringe Injectable Electronics: Brain Probes with ‘Neurophilic’ Tissue Interfaces for Stable Long-Term Brain Mapping at Single Neuron Level

Summary

Date: 
January 27, 2016 - 1:00pm
Location: 
Northwest 243
About the Speaker
Name: 
Guosong Hong (Lieber Lab)

Implanted metal and silicon based neural probes have contributed substantially to understanding brain circuits, yet these tools remain limited because recorded signals shift away and are ultimately lost from targeted neurons on a week-scale, and there is general signal degradation due to chronic immune response and relative shear motion of the brain and probes. Recently, we have described mesh electronics with micrometer feature sizes and an effective bending stiffness similar to neurons and neural tissue, and have shown that it is possible to deliver the mesh electronics into targeted brain regions of live rodents with single-neuron precision by syringe injection, and that the mesh electronics exhibits negligible immune response on at least a 1-month time-scale. Here we described our strategies for precise targeted delivery of the mesh electronics and subsequent bonding to standard interfaces for chronic electrophysiology studies, which will be the focus of this presentation. We will show that the syringe injectable electronics yield highly stable, multiplexed local field potential (LFP) and single-unit spike recordings from mouse brains over at least six months. Systematic analyses of the chronic recordings exhibit several key features, including nearly unchanged single-unit sorted spikes, principal components, and average spike component waveforms, as well as, stable inter-spike firing interval histograms for the distinct spike components over this half-year period. In addition, LFP/single-unit phase-locking analyses of data recorded in the hippocampus showed that the firings of distinct spike components are phase-locked to theta oscillations. Together these results suggest strongly that the injected mesh electronics are capable of monitoring the same individual neurons and neural circuit without any signal degradation over the measured half-year period. Moreover, stable neural responses to chronic electrical stimulation, simultaneous measurements from mesh electronics in distinct brain regions and free-moving animal recordings will be discussed. The long-term stable interface between electronics and brain tissue at the single neuron/neural circuit level opens up unique applications for chronic investigations of brain circuit evolution from learning and memory to closed-loop treatment/monitoring of neurodegenerative diseases and brain-machine interfaces, and moreover, the unique characteristics of the syringe-injectable mesh electronics can open up unique opportunities in other areas, such as the retina and spinal cord.