NeuroGrid: recording action potentials from the surface of the brain

Abstract

Recording from neural networks at the resolution of action potentials is critical for understanding how information is processed in the brain. Here, we address this challenge by developing an organic material-based, ultra-conformable, biocompatible and scalable neural interface array (the ‘NeuroGrid’) that can record both LFP and action potentials from superficial cortical neurons without penetrating the brain surface. Spikes with features of interneurons and pyramidal cells were simultaneously acquired by multiple neighboring electrodes of the NeuroGrid, allowing for isolation of putative single neurons in rats. Spiking activity demonstrated consistent phase modulation by ongoing brain oscillations and was stable in recordings exceeding one week. We also recorded LFP-modulated spiking activity intra-operatively in patients undergoing epilepsy surgery. The NeuroGrid constitutes an effective method for large-scale, stable recording of neuronal spikes in concert with local population synaptic activity, enhancing comprehension of neural processes across spatiotemporal scales and potentially facilitating diagnosis and therapy for brain disorders.

State-of-the-art MEMS and microsystem tools for brain research

“…Macroscale versions of an ECoG array are generally platinum discs soldered to metal wires and molded in medical grade silicone or polyurethane. These devices exist commercially, but a significant push toward microscale structures has revealed important physiological data that neuroscientists have embraced 23,68 . Advancing ECoG and EEG electrodes and their microsystems will be particularly useful for conducting neuroscience and neurology studies in human patients.…”

“…Others have further improved the flexibility by developing a polyimide array measuring only 2.5-μm thick supported by biodegradable silk to aid in placement 131 . Most recently, the Buzsáki group developed the 'NeuroGrid,' a 4-μm-thick parylene-C ECoG array featuring low-impedance electrodes and a pitch of 30 μm to enable tetrode sorting techniques, resulting in the ability to record single-cell activity in both rats and humans 23 (Figure 1g). This latest development is particularly significant because it overturned the long-standing assumption that single-unit recordings were only possible with intracortical microelectrodes.…”

Biomimetic Microelectronics for Regenerative Neuronal Cuff Implants

“…Furthermore, the demonstrated possibility to integrate the high-performance amplifi ers at the location where the signals of interest are acquired allows increasing the signal-to-noise ratio, which is of strong advantage for the diagnostic of neuronal activity. [27][28][29] Fabrication of microchannels with integrated electronics: To realize mechanically active, stimuli-responsive, and highperformance IGZO microelectronics, we formulated and The shape of the device can be deterministically chosen to be planar, bent, or self-assembled into a Swiss roll like microtube. c) The diameter of the microtube can be tuned by adjusting the thicknesses of the hydrogel layer, h H , and the stiff polyimide reinforcement layer, h P .…”

Intracranial neuronal ensemble recordings and analysis in epilepsy

“…The formerly mentioned mesoscale electrodes, like brain surface microcontacts may be capable to record unit activites from the surface as shown by the NeuroGrid project (Khodagholy et al, 2014). Finally, when having the activity of hundred thousands of neurons together the problem of analysis will need faster data processing techniques than we have already.…”