Quantitative simulation of extracellular single unit recording from the surface of cortex

Hill, Mackenna; Rios, Estefania; Sudhakar, S; Roossien, Douglas H.; Caldwell, Ciara M; Cai, Dawen; Ahmed, Omar J.; Lempka, Scott F.; Chestek, Cynthia A.

doi:10.1088/1741-2552/aacdb8

Cited by 15 publications

(24 citation statements)

References 68 publications

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“…Voltage signals recorded are around the range of 100s µV and 1 mV while that quickly decreases to few µV for recording depth at 1 mm. [155] has reported similar observations: while 400 µV was recorded at a distance of 20 µm, it drastically dropped to 50 µV at only 60 µm away from the electrode (a 9.03 dB decrease). To investigate how the detectable depth for neural signal recording is affected by the implant size, the factors of power and noise need to be considered.…”

Section: Neural Signal Recordingsupporting

confidence: 57%

Challenges in Scaling Down of Free-Floating Implantable Neural Interfaces to Millimeter Scale

Yang

2020

IEEE Access

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Implantable neural interface devices are an emerging technology for continuous brain monitoring and brain-computer interface (BCI). Recording of electrical signals from neurons of interest has led to more efficient and personalized diagnosis, treatment, and prognosis of neurological disorders. It facilitates the dynamic mapping of the whole brain, improving our understanding of the links between brain functions and behaviors. Stimulation of targeted nerves and neurons has been utilized as an effective therapy for Parkinson's disease, essential tremor, dystonia, etc. It has also been developed as motor neuroprosthetic devices, improving the quality of life of many. Although initial designs were bulky, recent advances in semiconductor and nano-, micro-technology has enabled the miniaturization of such devices to the millimeter scale. Free-floating neural implants of miniature size are highly scalable to be distributed around the targeted region of interest more extensively. They are more clinically viable as they cause less disturbance to the body and induce less tissue immune response. However, these research efforts for scaling down have faced challenges resulted from decreasing the size of such implants, including issues pertaining to wireless powering, data communication, neural signal recording, and neural stimulation. Through extensive literature research and simulations, the limits and trade-offs regarding neural implant miniaturization are investigated and analyzed for each aspect of the challenges. State-of-the-art development and future trends for advanced neural interfaces are also explored. INDEX TERMS Implantable neural interface, neural signal recording and stimulation, wireless power transfer, millimeter size, free-floating neural probes.

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Section: Neural Signal Recordingsupporting

confidence: 57%

Challenges in Scaling Down of Free-Floating Implantable Neural Interfaces to Millimeter Scale

Yang

2020

IEEE Access

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“…Low surface area and low impedance electrode contacts, along with the conformality of the arrays to the brain surface, are important characteristics for recording putative action potential activity from the brain surface as demonstrated in this study and in previous mammalian studies (Khodagholy et al, 2015(Khodagholy et al, , 2016. In a modeling study (Hill et al, 2018) evaluating critical characteristics for recording action potentials from the cortical surface of the rat, small electrode surface area facilitates retention of action potential amplitude relative to larger electrodes. However, as surface area decreases for an electrode of a given material, the impedance will increase and, consequently, thermal recording noise will also increase.…”

Section: Discussionmentioning

confidence: 55%

“…Furthermore, if electrodes are further from the cortical surface and have cerebral spinal fluid (CSF) under electrode contacts, this could cause shunting that would obscure action potential recording. The modeling study (Hill et al, 2018) also suggests that the conformal insulation of the electrode array substrate around the electrode may also be important for resolving action potentials. Surface insulation effectively creates a reflection of charges that does not exist at the natural conductive CSF interface.…”

Section: Discussionmentioning

confidence: 94%

“…Electrode array conformality is also of importance for recording quality. According to the modeling study (Hill et al, 2018), neuron cell bodies (in the rat preparation) must be within 60 µm of a 100 µm 2 electrode contact (our electrodes have a 314 µm 2 surface area, which should reduce the distance requirement). Furthermore, if electrodes are further from the cortical surface and have cerebral spinal fluid (CSF) under electrode contacts, this could cause shunting that would obscure action potential recording.…”

Section: Discussionmentioning

confidence: 99%

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Stimulus Driven Single Unit Activity From Micro-Electrocorticography

et al. 2020

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High-fidelity measurements of neural activity can enable advancements in our understanding of the neural basis of complex behaviors such as speech, audition, and language, and are critical for developing neural prostheses that address impairments to these abilities due to disease or injury. We develop a novel high resolution, thin-film micro-electrocorticography (micro-ECoG) array that enables highfidelity surface measurements of neural activity from songbirds, a well-established animal model for studying speech behavior. With this device, we provide the first demonstration of sensory-evoked modulation of surface-recorded single unit responses. We establish that single unit activity is consistently sensed from micro-ECoG electrodes over the surface of sensorimotor nucleus HVC (used as a proper name) in anesthetized European starlings, and validate responses with correlated firing in single units recorded simultaneously at surface and depth. The results establish a platform for high-fidelity recording from the surface of subcortical structures that will accelerate neurophysiological studies, and development of novel electrode arrays and neural prostheses.

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“…Although not impacted by superficial tissue layers of the head, intracranial electrophysiology is still subject to the effects of multiple tissue boundaries and properties. This has motivated studies on the effect of electrical potentials caused by tissue properties (Pettersen et al, 2006 ; Einevoll et al, 2007 ; Goto et al, 2010 ; Slutzky et al, 2010 ; Bleichner et al, 2011 ; Rice et al, 2013 ; Brodnick et al, 2019 ), the presence of the electrode and its effect on the surrounding tissue (Ollikainen et al, 2000 ; Blanche et al, 2005 ; Moffitt and McIntyre, 2005 ), or a combination of both effects (Zhang et al, 2006 ; von Ellenrieder et al, 2012 ; Ness et al, 2015 ; Hill et al, 2018 ). The scale of the effects described in previous work ranges from changes local to the electrode that alter the amplitude of single action potentials to whole-head EEG models altered by the presence of an insulating, subdurally implanted ECoG grid.…”

Section: Introductionmentioning

confidence: 99%

Impact of Brain Surface Boundary Conditions on Electrophysiology and Implications for Electrocorticography

et al. 2020

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Volume conduction of electrical potentials in the brain is highly influenced by the material properties and geometry of the tissue and recording devices implanted into the tissue. These effects are very large in EEG due to the volume conduction through the skull and scalp but are often neglected in intracranial electrophysiology. When considering penetrating electrodes deep in the brain, the assumption of an infinite and homogenous medium can be used when the sources are far enough from the brain surface and the electrodes to minimize the boundary effect. When the electrodes are recording from the brain's surface the effect of the boundary cannot be neglected, and the large surface area and commonly used insulating materials in surface electrode arrays may further increase the effect by altering the nature of the boundary in the immediate vicinity of the electrodes. This gives the experimenter some control over the spatial profiles of the potentials by appropriate design of the electrode arrays. We construct a simple three-layer model to describe the effect of material properties and geometry above the brain surface on the electric potentials and conduct empirical experiments to validate this model. A laminar electrode array is used to measure the effect of insulating and relatively conducting layers above the cortical surface by recording evoked potentials alternating between a dried surface and saline covering layer, respectively. Empirically, we find that an insulating boundary amplifies the potentials relative to conductive saline by about a factor of 4, and that the effect is not constrained to potentials that originate near the surface. The model is applied to predict the influence of array design and implantation procedure on the recording amplitude and spatial selectivity of the surface electrode arrays.

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Quantitative simulation of extracellular single unit recording from the surface of cortex

Abstract: Overall, the model suggests single-unit surface recording is limited to neurons in layer 1 and further improvement in electrode design is needed.

Cited by 15 publications

References 68 publications

Challenges in Scaling Down of Free-Floating Implantable Neural Interfaces to Millimeter Scale

Challenges in Scaling Down of Free-Floating Implantable Neural Interfaces to Millimeter Scale

Stimulus Driven Single Unit Activity From Micro-Electrocorticography

Impact of Brain Surface Boundary Conditions on Electrophysiology and Implications for Electrocorticography

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