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[0] Porada I, Bondar I, Spatz WB, Kruger J, Rabbit and monkey visual cortex: more than a year of recording with up to 64 microelectrodes.J Neurosci Methods 95:1, 13-28 (2000 Jan 31)

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ref: Kruger-2010.05 tags: microelectrode array nichrome 7 years rhesus electrophysiology MEA Kruger oblique inverted date: 01-29-2013 07:54 gmt revision:7 [6] [5] [4] [3] [2] [1] [head]

PMID-20577628[0] Seven years of recording from monkey cortex with a chronically implanted multiple electrode.

  • Seven years!! good recordings the whole time, too. As they say, this is a clinically realistic time period. Have they solved the problem?
  • Used 12.5um Ni-Cr-Al wire insulated with 3um of polymide.
    • Wires were then glued to an 8x8 connector block using conductive epoxy.
    • Glued the bundle together with a solution of plexiglas in dichloroethane.
    • Then introduced the 0.3mm bundle into a j-shaped cannula. This allowed them to approach the gray matter inverted, from below (the white matter).
    • implanted 64 ch array into ventral premotor cortex (arm representation?).
  • No apparent degradation of recording quality over that time.
  • Had some serious problems with the quality of their connector.
    • They recommend: "Rather, the contacts on the head should be made from noble metals and be flat or shallowly hollow, so that they can be easily cleaned, and no male contacts can break."
    • Really need to amplify and multiplex prior connector (imho).
  • Claim that them managed to record from two neurons on one channel for nearly 7 years (ch 54).
  • They cite us, but only to indicate that we recommend slow penetration of the brain. They agree with our results that lowering of individual electrodes is better than all at once.


[0] Kruger J, Caruana F, Volta RD, Rizzolatti G, Seven years of recording from monkey cortex with a chronically implanted multiple microelectrode.Front Neuroengineering 3 Issue 6 (2010 May 28)

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ref: Chestek-2009.09 tags: BMI problems address critique spike sorting Shenoy date: 01-23-2013 02:23 gmt revision:3 [2] [1] [0] [head]

IEEE-5332822 (pdf) Neural prosthetic systems: Current problems and future directions

  • Where there is unlikely to be improvements: spike sorting and spiking models.
  • Where there are likely to be dramatic improvements: non-stationarity of recorded waveforms, limitations of a linear mappings between neural activity and movement kinematics, and the low signal to noise ratio of the neural data.
  • Compare different sorting methods: threshold, single unit, multiunit, relative to decoding.
  • Plot waveform changes over an hour -- this contrasts with earlier work (?) {1032}
  • Figure 5: there is no obvious linear transform between neural activity and the kinematic parameters.
  • Suggest that linear models need to be replaced by the literature of how primates actually make reaches.
  • Discuss that offline performance is not at all the same as online; in the latter the user can learn and adapt on the fly!


Chestek, C.A. and Cunningham, J.P. and Gilja, V. and Nuyujukian, P. and Ryu, S.I. and Shenoy, K.V. Engineering in Medicine and Biology Society, 2009. EMBC 2009. Annual International Conference of the IEEE 3369 -3375 (2009)

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ref: BMI notes-0 tags: spike filtering rate_estimation BME 265 Henriquez date: 01-06-2012 03:06 gmt revision:1 [0] [head]


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ref: Porada-2000.01 tags: electrodes recording oblique inverted MEA arrays Kruger date: 01-05-2012 23:07 gmt revision:3 [2] [1] [0] [head]

PMID-10776811[0] More than a year of recording with up to 64 microelectrodes

  • for more than a year action potentials of good quality were obtained from most electrodes!
  • used 60mm-long, 12.5um Ni-Cr-Al (Isaohm) wire, polyimide insulated, soldered to microconnectors. Tips purely ('primitively') cut after bonding them to a piece of photographic film substrate.
  • implanted in the rabbit and marmoset V1 cortex from afar.
  • with the 8 rabbits they used a magnetic release to prevent excessive force from removing the implant.
  • used small sections of thicker wire to individually label the electrodes for x-ray; thusly could reconstruct the electrode positions. electrodes in the white matter were silent mais or menos.
  • the autocorrelation functions of the neurons generally look good; some of them do not have a refractory period though.
  • in GFAP-stained sections a single electrode track appeared as a hole of about 28 um wide. The outer diameter of the wire insulation as 18um. electrode tracts were not visible in cresyl violet tracts. the neurones near the electrode tips appeared normal.
  • we recorded signals for up to 711 days, during which time the recording quality did not degrade. nice, nice!
  • they think that the large length of free wire, running about 5mm through the brain provides a sufficient degree of friction so that locally the tissue is prevented from moving relative to the electrodes. They did not need to use microstimulation to improve recording quality.


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ref: Tehovnik-1996.03 tags: ICMS technique Tehovnik MIT 1996 current density microstimulation date: 12-29-2011 05:11 gmt revision:2 [1] [0] [head]

PMID-8815302[0] Electrical stimulation of neural tissue to evoke behavioral responses

  • reference to justify our current levels.
  • radial dispersion of current, inverse square falloff of excitability.
  • low currents (10 ua) can activate 10-1000 of neurons in cat M1 (allegedly).


[0] Tehovnik EJ, Electrical stimulation of neural tissue to evoke behavioral responses.J Neurosci Methods 65:1, 1-17 (1996 Mar)

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ref: Maass-2002.11 tags: Maass liquid state machine expansion LSM Markram computation cognition date: 12-06-2011 07:17 gmt revision:2 [1] [0] [head]

PMID-12433288[0] Real-time computing without stable states: a new framework for neural computation based on perturbations.

  • It is shown that the inherent transient dynamics of the high-dimensional dynamical system formed by a sufficiently large and heterogeneous neural circuit may serve as universal analog fading memory. Readout neurons can learn to extract in real time from the current state of such recurrent neural circuit information about current and past inputs that may be needed for diverse tasks.
    • Stable states, e.g. Turing machines and attractor-based networks are not requried!
    • How does this compare to Shenoy's result that neuronal dynamics converge to a 'stable' point just before movement?


[0] Maass W, Natschl├Ąger T, Markram H, Real-time computing without stable states: a new framework for neural computation based on perturbations.Neural Comput 14:11, 2531-60 (2002 Nov)

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ref: life-0 tags: IQ intelligence Flynn effect genetics facebook social utopia data machine learning date: 10-02-2009 14:19 gmt revision:1 [0] [head]


My theory on the Flynn effect - human intelligence IS increasing, and this is NOT stopping. Look at it from a ML perspective: there is more free time to get data, the data (and world) has almost unlimited complexity, the data is much higher quality and much easier to get (the vast internet & world!(travel)), there is (hopefully) more fuel to process that data (food!). Therefore, we are getting more complex, sophisticated, and intelligent. Also, the idea that less-intelligent people having more kids will somehow 'dilute' our genetic IQ is bullshit - intelligence is mostly a product of environment and education, and is tailored to the tasks we need to do; it is not (or only very weakly, except at the extremes) tied to the wetware. Besides, things are changing far too fast for genetics to follow.

Regarding this social media, like facebook and others, you could posit that social intelligence is increasing, along similar arguments to above: social data is seemingly more prevalent, more available, and people spend more time examining it. Yet this feels to be a weaker argument, as people have always been socializing, talking, etc., and I'm not sure if any of these social media have really increased it. Irregardless, people enjoy it - that's the important part.

My utopia for today :-)

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ref: notes-0 tags: low-power microprocessor design techniques ieee DSP date: 05-29-2007 03:30 gmt revision:2 [1] [0] [head]


also see IBM's eLite DSP project.