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ref: -0 tags: rogers thermal oxide barrier neural implants ECoG coating accelerated lifetime test date: 12-28-2017 02:29 gmt revision:0 [head]

PMID-27791052 Ultrathin, transferred layers of thermally grown silicon dioxide as biofluid barriers for biointegrated flexible electronic systems

  • Thermal oxide proved the superior -- by far -- water barrier for encapsulation.
    • What about the edges?
  • Many of the polymer barrier layers look like inward-rectifiers:
  • Extensive simulations showing that the failure mode is from gradual dissolution of the SiO2 -> Si(OH)4.
    • Even then a 100nm layer is expected to last years.
    • Perhaps the same principle could be applied with barrier metals. Anodization or thermal oxidation to create a thick, nonporous passivation layer.
    • Should be possible with Al, Ta...

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ref: -0 tags: Peter Ledochowitsch ECoG parylene fabrication MEMS date: 09-25-2014 16:54 gmt revision:0 [head]

IEEE-5734604 (pdf) Fabrication and testing of a large area, high density, parylene MEMS µECoG array

  • Details 5-layer platinum parylene process for high density ECoG arrays.

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ref: -0 tags: hinton convolutional deep networks image recognition 2012 date: 01-11-2014 20:14 gmt revision:0 [head]

ImageNet Classification with Deep Convolutional Networks

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ref: -0 tags: polyimide electrodes ecog japan photosensitive date: 06-28-2013 01:50 gmt revision:0 [head]

PMID-22719725 Photosensitive-polyimide based method for fabricating various neural electrode architectures

  • Yasuhiro X. Kato,1,* Shigeto Furukawa,2 Kazuyuki Samejima,1 Naoyuki Hironaka,2 and Makio Kashino2
  • many typos in this paper (not that I should talk..) Yet still, it's informative.
  • 12um thick photosensitive polyimide + Cr/Au fabrication.
  • Wet etch (photodeveloper).
  • Wet release (ferric chloride) from glass substrate.
  • Soldered a connector to the polyimide w/ stiffener.
  • Note that polyimide tends to shrink (up to 29%) during baking, unlike parylene!
  • Suggest 20-40um diameter neural recording sites; they did not coat.

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ref: Ledochowitsch-2011.01 tags: Ledochowitsch transparent micro ECoG Peter date: 01-30-2013 07:01 gmt revision:2 [1] [0] [head]

PMID-22254956[0] A transparent μECoG array for simultaneous recording and optogenetic stimulation.

  • We present a 49-channel μECoG array with an electrode pitch of 800 μm and a 16-channel linear μECoG array with an electrode pitch of 200 μm.
  • The backing material was Parylene C. Transparent, sputtered indium tin oxide (ITO) was used in conjunction with e-beam evaporated gold to fabricate the electrodes

____References____

[0] Ledochowitsch P, Olivero E, Blanche T, Maharbiz MM, A transparent μECoG array for simultaneous recording and optogenetic stimulation.Conf Proc IEEE Eng Med Biol Soc 2011no Issue 2937-40 (2011)

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ref: Mallet-2008.04 tags: DBS oscillations STN beta 6-OHDA rats ECoG acute date: 02-29-2012 01:11 gmt revision:4 [3] [2] [1] [0] [head]

PMID-18448656[0] Disrupted dopamine transmission and the emergence of exaggerated beta oscillations in subthalamic nucleus and cerebral cortex.

  • STN has pronounced beta band oscillations in PD patients.
  • 6-OHDA rodent model (here) shows the same, depending on state.
    • Synchronization in both local cellular assemblies and broadly across the STN + ECoG.
    • ECoG looks causal in their studies.
    • Frequencies > 15 Hz, not lower (theta), as in other studies.
  • Excessively synchronized beta oscillations reduce the information coding capacity of STN neuronal ensembles, which may contribute to parkinsonian motor impairment.
  • Acute disruption of dopamine transmission in control animals with antagonists of D(1)/D(2) receptors did not exaggerate STN or cortical beta oscillations.
    • This despite the potent agonist induced catalepsy in the rats!
    • Must be neural plasticity & structural.
    • Takes > 4 days.
    • Actual striatal DA levels decrease within 1 h of midbrain 6-OHDA
  • Under normal conditions, beta synchronization may be useful for sensory-motor processing (Uhlhaas and Singer 2006).
  • Synchronized activity is preferentially transmitted due to temporal summation.

____References____

[0] Mallet N, Pogosyan A, Sharott A, Csicsvari J, Bolam JP, Brown P, Magill PJ, Disrupted dopamine transmission and the emergence of exaggerated beta oscillations in subthalamic nucleus and cerebral cortex.J Neurosci 28:18, 4795-806 (2008 Apr 30)

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ref: Brown-2001.12 tags: EMG ECoG motor control human coherence dopamine oscillations date: 01-19-2012 21:41 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-11765129[0] Cortical network resonance and motor activity in humans.

  • good review.
  • No coherence between ECoG and eMG below 12 Hz; frequency coherence around 18 Hz.
    • This seen only in high-resolution ECoG; lower resolution signals blurs the sharp peak.
  • Striking narrowband frequency of coherence.
  • ECoG - ECoG coherence not at same frequency as EMG-ECoG.
  • Marked task-dependence of these coherences, e.g. for wrist extension and flexion they observed similar EMG/ECoG coherences; for different tasks using the same muscles, different patterns of coherence.
  • Pyramidal cell discharge tends to be phase-locked to oscillations in the local field potential (Murthy and Fetz 1996)
    • All synchronization must ultimately be through spikes, as LFPs are not transmitted down the spinal cord.
  • Broadband coherence is pathological // they note it occurred during cortical myclonus (box 2)
  • Superficial chattering pyramidal cells (!!) firing bursts of frequency at 20 to 80 Hz, interconnected to produce spike doublets (Jefferys 1996).
  • Dopamine restores coherence between EMG and ECoG in a PD patient.

____References____

[0] Brown P, Marsden JF, Cortical network resonance and motor activity in humans.Neuroscientist 7:6, 518-27 (2001 Dec)

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ref: Blankertz-2006.06 tags: BMI EEG ECoG competiton 2006 date: 0-0-2007 0:0 revision:0 [head]

PMID-16792282 http://hardm.ath.cx:88/pdf/BCIcompetition2006.pdf