Knowledge Vault 3/41 - G.TEC BCI & Neurotechnology Spring School 2024 - Day 4
Recording spikes from micro-electrocorticographic
array: Applications for brain-computer interface
Jack Yu Tung Lo, National Neuroscience Institute (SG)
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Concept Graph & Resume using Claude 3 Opus | Chat GPT4 | Llama 3:

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surface spikes. 1] B --> C[Invasive BMIs: high resolution,
surgical risks. 2] B --> D[Micro-ECoG electrodes:
tens to hundreds of microns. 3] B --> E[Spike detection crucial,
neurons have unique firing. 4] B --> F[Micro-ECoG less invasive
than intracortical arrays. 5] B --> G[Micro-ECoG can record
sparse layer 1 neurons. 6] G --> H[Cortex has 6 layers,
micro-ECoG targets layer 1. 7] H --> I[Cortical columns: layer 1
correlates with deeper layers. 8] H --> J[Layer 1 integrates
across cortical areas. 9] H --> K[Layer 1 neuron subtypes
classified by properties. 10] H --> L[Layer 1 mirrors deeper
layer response properties. 11] H --> M[Layer 1 extensively connected,
serves as integration hub. 12] G --> N[Studies show micro-ECoG
records layer 1 spikes. 13] G --> O[Rat motor cortex
micro-ECoG study. 14] O --> P[Decoded positions matched
actual, indicating spatial info. 15] O --> Q[Individual layer 1 neurons
showed spatially selective firing. 16] A --> R[Micro-ECoG limitations: positioning,
inflammation: needs optimization. 17] A --> S[Future work: characterize
layer 1 for BMIs. 18] A --> T[Thin-film micro-ECoG improves
brain surface adherence. 19] A --> U[Micro-ECoG may detect
non-spike surface signals. 20] A --> V[Micro-ECoG enables new
ways to study circuits. 21] B --> W[Spike recording demonstrated
across species and areas. 22] G --> X[Layer 1 likely conveys
distant and local activity. 23] A --> Y[Micro-ECoG invasiveness, costs,
long-term stability challenges. 24] Y --> Z[Adhesion improvements could
provide long-term recordings. 25] A --> AA[Common micro-ECoG materials:
gold, polymers: nanomaterials emerging. 26] A --> AB[Potential human applications
similar to intracortical arrays. 27] A --> AC[Key artifacts: movement noise,
physiological signals. 28] A --> AD[Global research on
micro-ECoG is ongoing. 29] A --> AE[Micro-ECoG enables studying
large-scale spiking activity. 30] class A,B,C,D,E,F,W,AC microECoG; class G,H,I,J,K,L,M,N,O,P,Q,X,AA layer1; class R,T,U,V,Y,Z,AB,AD limitations; class S,AE future;


1.- Microelectrocorticographic (micro-ECoG) arrays can record neural spikes from the cortical surface, with potential for brain-machine interfaces.

2.- Invasive brain-machine interfaces like micro-ECoG offer higher spatial and temporal resolution than non-invasive options, but with surgical risks.

3.- Micro-ECoG employs electrodes tens to hundreds of microns in size, allowing recording from small neuron populations.

4.- Detecting neural spikes or action potentials is crucial as each neuron has unique firing characteristics encoding rich information.

5.- Intracortical microelectrode arrays can record single neuron activity but risk tissue damage; micro-ECoG is less invasive.

6.- Simulation studies suggest micro-ECoG can record spikes from sparse layer 1 neurons closest to the cortical surface.

7.- The cortex has 6 layers; intracortical arrays typically record from deeper layers while micro-ECoG targets superficial layer 1.

8.- Cortical layers are vertically arranged into functional columns, with layer 1 neuron activity correlating with deeper layers.

9.- Layer 1 neurons play a role in integrating information across cortical areas through long-range connections.

10.- Several studies have classified the molecular, morphological and electrophysiological properties of layer 1 neuron subtypes.

11.- Layer 1 neurons are coupled to and mirror response properties of deeper layer neurons traditionally targeted by intracortical arrays.

12.- Layer 1 is extensively connected to various cortical and subcortical regions, serving as an integration hub.

13.- Multiple studies demonstrate micro-ECoG can record putative layer 1 neuron spikes in animals.

14.- The authors chronically implanted 32-channel micro-ECoG arrays in rat motor cortex and recorded during an open field task.

15.- Decoded positions from the layer 1 spike activity closely matched actual positions, indicating meaningful spatial information.

16.- Individual layer 1 neurons showed spatially selective firing, together encoding enough information to accurately decode position.

17.- Limitations of micro-ECoG include sensitivity to array positioning and inflammatory reactions; further optimization is needed.

18.- Future work should further characterize layer 1 neuron response properties relevant for brain-machine interface applications.

19.- Conformable thin-film micro-ECoG arrays improve adherence to the brain surface through flexibility and surface tension.

20.- Beyond spikes, micro-ECoG may also detect other signals like dendritic calcium spikes and axon potentials near the surface.

21.- The spatial resolution and large-scale coverage potential of micro-ECoG enables studying brain circuits in new ways.

22.- Spike recording was demonstrated in various species in sensory and motor areas, both anesthetized and behaving.

23.- Layer 1 neurons likely convey information from distant areas in addition to mirroring local activity.

24.- Micro-ECoG is comparably invasive to standard ECoG but may allow smaller craniotomies; costs are currently high.

25.- With better adhesion, micro-ECoG could provide stable long-term recordings; current signal quality tends to degrade after weeks.

26.- Common micro-ECoG materials include gold electrodes with polymers like PEDOT and Parylene; nanomaterials are an emerging option.

27.- Potential human applications are similar to intracortical arrays, including robotic prosthesis and cursor control.

28.- Key artifacts include movement-related noise, which may be reduced with wireless setups, and physiological signals.

29.- Several global research groups are working on micro-ECoG; the speaker is beginning work on neuroprosthetic applications.

30.- Micro-ECoG could enable new research paradigms by providing large-scale access to spiking activity for studying brain function.

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