Optogenetic Mapping of Functional Connectivity in Freely Moving Mice via Insertable Wrapping Electrode Array Beneath the Skull

Abstract

Spatiotemporal mapping of neural interactions through electrocorticography (ECoG) is the key to understanding brain functions and disorders. For the entire brain cortical areas, this approach has been challenging, especially in freely moving states, owing to the need for extensive craniotomy. Here, we introduce a flexible microelectrode array system, termed iWEBS, which can be inserted through a small cranial slit and stably wrap onto the curved cortical surface. Using iWEBS, we measured dynamic changes of signals across major cortical domains, namely, somatosensory, motor, visual and retrosplenial areas, in freely moving mice. iWEBS robustly displayed somatosensory evoked potentials (SEPs) in corresponding cortical areas to specific somatosensory stimuli. We also used iWEBS for mapping functional interactions between cortical areas in the propagation of spike-and-wave discharges (SWDs), the neurological marker of absence seizures, triggered by optogenetic inhibition of a specific thalamic nucleus. This demonstrates that iWEBS represents a significant improvement over conventional ECoG recording methodologies and, therefore, is a competitive recording system for mapping wide-range brain connectivity under various behavioral conditions.

Bioresorbable Electrode Array for Electrophysiological and Pressure Signal Recording in the Brain

“…Figure b shows an image of the implantation of such a system in the intracranial space of a rat model. The implanted ECoG electrode and pressure sensor system are placed on the primary somatosensory cortex that refers to somatic senses, including the sense of touch, proprioception (sense of position and movement), and haptic perception . The craniectomy defect was sealed to isolate the intracranial cavity from the outside environment using dissolvable surgical glue and then the resected skull was replaced.…”

“…Often accompanied by tissue inflammation or mechanical damage, chronic implantation may cause irreversible brain damage . Electrocorticography (ECoG) electrodes, made on flexible substrates with plenary structures, are flexible and have good conformality, so that they have good signal recording capabilities . They can attach to the cortical surface of a brain conformally, enabling good and stable contact between the electrodes and the cortex, and measurement of electrophysiological signals with high signal to noise ratio (SNR).…”

“…They will not cause damage to the brain as it is flexible, plenary and very thin. Many flexible substrate materials have been investigated for the fabrication of flexible and biocompatible ECoG devices, including polyimide (PI), polydimethylsiloxane (PDMS), parylene, polymethylmethacrylate (PMMA), SU8, etc …”

Unconventional Inorganic‐Based Memristive Devices for Advanced Intelligent Systems

“…In particular, flexible memory is regarded as a vital component for high‐performance flexible electronics considering its fundamental functions in signal processing, data storage, and interdevice communication. Furthermore, a flexible artificial synapse can be employed in an implantable BMI, providing a valuable route to restore damaged neural functions such as vision, hearing, movement, and even complex cognitive behaviors …”

Bioelectric Medicine and Devices for the Treatment of Spinal Cord Injury

“…ECoG arrays have a higher spatial resolution than EEG (i.e. hundreds of microns vs. millimeters), broader recording bandwidth (0-200 vs. 0-40 Hz), higher maximum signal amplitude (50-100 vs. 10-20 μV), and far less vulnerability to muscle and other electrical artifacts [Park et al, 2016]. ECoG has been employed as a BMI to control prosthetic devices in NHP [Taylor et al, 2002;Moritz et al, 2008] and human subjects [Leuthardt et al, 2004].…”