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[0] Suner S, Fellows MR, Vargas-Irwin C, Nakata GK, Donoghue JP, Reliability of signals from a chronically implanted, silicon-based electrode array in non-human primate primary motor cortex.IEEE Trans Neural Syst Rehabil Eng 13:4, 524-41 (2005 Dec)

[0] DeLong MR, Strick PL, Relation of basal ganglia, cerebellum, and motor cortex units to ramp and ballistic limb movements.Brain Res 71:2-3, 327-35 (1974 May 17)

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ref: -0 tags: parylene plasma ALD insulation long-term saline PBS testing date: 04-02-2014 21:32 gmt revision:0 [head]

PMID-23024377 Plasma-assisted atomic layer deposition of Al(2)O(3) and parylene C bi-layer encapsulation for chronic implantable electronics.

  • This report presents an encapsulation scheme that combines Al(2)O(3) by atomic layer deposition with parylene C.
  • Al2O3 layer deposited using PAALD process-500 cycles of TMA + O2 gas.
  • Alumina and parylene coating lasted at least 3 times longer than parylene coated samples tested at 80 °C
    • That's it?
  • The consistency of leakage current suggests that no obvious corrosion was occurring to the Al2O3 film. The extremely low leakage current (≤20 pA) was excellent for IDEs after roughly three years of equivalent soaking time at 37 °C.
    • Still, they warn that it may not work as well for in-vivo devices, which are subject to tethering forces and micromotion.

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ref: -0 tags: polyimide platinum electrodes Spain longitudinal intrafasicular adhesion delamination date: 10-05-2013 22:24 gmt revision:4 [3] [2] [1] [0] [head]

PMID-17278585 Assessment of biocompatibility of chronically implanted polyimide and platinum intrafascicular electrodes. 2007

  • Designed platinum/polyimide longitudinal intrafasicular electrodes (LIFEs)
    • 25um PT/Ir, insulated to 60-75um diameter. PT/IR has a young's modulus of 202 Gpa.
      • Plated with platinum black under sonication, as this forms a tougher surface than without sonication.
      • See also: PMID-20485478 Improving impedance of implantable microwire multi-electrode arrays by ultrasonic electroplating of durable platinum black. Desai SA, Rolston JD, Guo L, Potter SM. 2010
    • Polyimide PI2611, 10um thick, 50mm long, 220um wide in the electrode segment.
  • Implanted into rat sciatic nerve for 3 months.
  • These electrodes have been tested in people for two days:
    • Electrical stimulation through the implanted electrodes elicited graded sensations of touch, joint movement, and position, referring to the missing limb. This suggested that peripheral nerve interfaces could be used to provide amputees with prosthetic limbs with sensory feedback and volitional control that is more natural than what is possible with current myoelectric and body-powered prostheses.
  • CMAPs = compound muscle action potentials.
  • CNAPs = compound nerve action potentials.
  • Platinum wire LIFE performed very similarly to the thin-film polyimide LIFE in most all tests, with slightly higher potentials recorded by the larger polyimide probe.
  • 'Higher encapsulation with the polyimide probes! Geometry?
  • However, the polyimide LIFEs induced less functional decline than the wire LIFEs.
  • Other polyimide studies [14] [16] [24] -- one of which they observed a 70% reduction of tensile strength after 11 months of implantation.
    • [14] F. J. Rodríguez, D. Ceballos, M. Schüttler, E. Valderrama, T. Stieglitz, and X. Navarro, “Polyimide cuff electrodes for peripheral nerve stimulation,” J. Neurosci. Meth., vol. 98, pp. 105–118, 2000.
    • [16] N. Lago, D. Ceballos, F. J. Rodríguez, T. Stieglitz, and X. Navarro, “Long term assessment of axonal regeneration through polyimide regenerative electrodes to interface the peripheral nerve,” Biomaterials, vol. 26, pp. 2021–2031, 2005.
    • [24] M. Schuettler, K. P. Koch, and T. Stieglitz, “Investigations on explanted micromachined nerve electrodes,” in Proc. 8th Annu. Int. Conf. Int. Functional Electrical Stimulation Soc., Maroochydore, Australia, 2003, pp. 306–310.
      • The technology of sandwiching a metallization layer between two layers of polyimide seems to be suitable, because no delamination of the polyimide layers was observed even after 11 months. The right choice of metals for building the electrical conductive elements of the microelectrodes is crucial. Ti/Au/Ti/Pt layers tend to flake off from polyimide while delamination of Ti/Pt layers was not observed. However, adhesion of Ti/Pt layers was investigated after 2.5 months of implantation while Ti/Au/Ti/Pt layers were exposed after 11 months to the biological system. In previous research projects, surgeons also reported on delamination of Ti/Au layers from polyimide substrate after three months. Unfortunately, we had no possibility of inspecting these microelectrodes in our laboratory.
      • See also {1250}

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ref: Suner-2005.12 tags: Suner Utah probe electrophysiology reliability chronic electrode recording longevity histology MEA date: 01-31-2013 22:27 gmt revision:7 [6] [5] [4] [3] [2] [1] [head]

PMID-16425835Reliability of signals from a chronically implanted, silicon-based electrode array in non-human primate primary motor cortex

  • claim that they have done a logitudinal development series that included 39 array implants in 18 monkeys.
  • can get reliable recordings out to 3 months (only? probably the array was forced out of the brain?)
    • however, it seems that their recording quality did not decrease dramatically over those 3 months.
  • excellent methods section.
  • also {1027}

____References____

{1027}
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ref: Suner-2005.12 tags: MEA Utah reliability longevity SNR date: 01-25-2013 02:03 gmt revision:7 [6] [5] [4] [3] [2] [1] [head]

PMID-16425835[0] Reliability of signals from a chronically implanted, silicon-based electrode array

  • see {597}
  • Percutaneous connector used pressure-fitted pogo pins, as Gary was thinking of.
  • Utah array coated in parylene for this exp.
    • After implantation, array and cortex was covered in gore-tex (to prevent dura adhesion) -- they do not highlight this fact.
  • polyester insulated 25um gold wires as leads.
  • Reasonable SNR over 82, 172, 154 days.
  • One monkey had an array to 569 days -- 76 electrodes still provided good or fair waveforms.
  • ancilary (?) measure of tuning of the neurons. most neurons were not tuned.
  • SNR calculated as peak-peak of waveform divided by 2x standard deviation of signal.
  • A total of 36 implants in 16 other monkeys, which were not systematically evaluated for reliability here, provided successful recordings for up to 1264 days. Most of these studies ended because of headcap failure.
    • They no longer use dental acrylic -- only titanium bone screws.
  • 50-800K impedance
  • Improvement of the signal quality and increased yield, for which there was no clear trend in the three animals, may result from recovery produced by variations in the initial insertion injury.
  • The cortical capillary bed is densely packed, with spacing on the order of 40um in primate cortical tissue [27] ( vasculature ) -- they suppose that variance may be due to this.

____References____

[0] Suner S, Fellows MR, Vargas-Irwin C, Nakata GK, Donoghue JP, Reliability of signals from a chronically implanted, silicon-based electrode array in non-human primate primary motor cortex.IEEE Trans Neural Syst Rehabil Eng 13:4, 524-41 (2005 Dec)

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ref: Rennaker-2005.03 tags: electrode recording longevity mechanical insertion Oklahoma MEA date: 01-25-2013 01:21 gmt revision:3 [2] [1] [0] [head]

PMID-15698656[0] A comparison of chronic multi-channel cortical implantation techniques: manual versus mechanical insertion.

  • Over 60% of the animals implanted with the mechanical insertion device had driven activity at week 6
    • whereas none of the animals with manually inserted arrays exhibited functional responses after 3 weeks.
      • Roughly identical responses immediately following surgery.
      • Could be that the manual inserter had horizontal movement / shear. (This is solveable with a stereotax).
      • Other research showed little difference in tissue response at 10um/s or 100um/s PMID-21896383[1]
  • Multi-wire electrodes.
  • Mechanical insertion device was capable of rapidly inserting the electrode without visible compression of the brain.
  • Response measured relative to auditory stimulus.
  • Their insertion device looks like a pen.

____References____

[0] Rennaker RL, Street S, Ruyle AM, Sloan AM, A comparison of chronic multi-channel cortical implantation techniques: manual versus mechanical insertion.J Neurosci Methods 142:2, 169-76 (2005 Mar 30)
[1] Welkenhuysen M, Andrei A, Ameye L, Eberle W, Nuttin B, Effect of insertion speed on tissue response and insertion mechanics of a chronically implanted silicon-based neural probe.IEEE Trans Biomed Eng 58:11, 3250-9 (2011 Nov)

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ref: -0 tags: delong georgoupolos basal ganglia DBS date: 03-05-2012 22:04 gmt revision:2 [1] [0] [head]

PMID-6389041 Functional organization of the basal ganglia: contributions of single-cell recording studies.

  • CAn't seem to find the paper ... these observations are from the abstract.
  • phasic changes in neural discharge in relation to movements of specific body parts (e.g. leg, arm, neck, face);
  • short-latency (sensory) neural responses to passive joint rotation;
  • a somatotopic organization of movement-related neurons in GPe, GPi, and STN;
  • a clustering of functionally similar neurons in the putamen and globus pallidus;
  • greater representation of the proximal than of the distal portion of the limb;
  • changes in neural activity in reaction-time tasks, suggesting a greater role of the basal ganglia in the execution than in the initiation of movement in this paradigm; a clear relation of neuronal activity to direction, amplitude (?velocity) of movement, and force;
  • a preferential relation of neural activity to the direction of movement, rather than to the pattern of muscular activity.
  • suggest that the basal ganglia may play a role in the control of movement parameters rather than (or independent of) the pattern of muscular activity.
  • The presence of somatotopic organization in the putamen and globus pallidus, together with known topographic striopallidal connections, suggests that segregated, parallel cortico-subcortical loops subserve 'motor' and 'complex' functions.

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ref: Wichmann-1994.08 tags: STN normal physiology delong wichmann date: 02-27-2012 22:05 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-7983514[0] The Primate Subthalamic Nucleus. 1. Functional Properties in Intact Animals.

  • Lots of cells -- 301 cells in the STN, 1589 microstimulation sites, 72 cross-correlation pairs.
  • 55% modulated to passive contralateral movement, 86% of these to muscle palpitation, 25% to light touch.
  • Caudalventral STN devoid of calls responding to touch or movement.
  • Somatotopic organization: lateral arm, medial leg.
    • Representation of proximal muscles / portions much larger than distal portions, consistent with Carpenter 1950.
  • Mostly rate increases in response to step tracking tasks, usually uniphasic.
  • 40ua, 200-500 ms train duration, 400 Hz did not produce movement. Stimulation of the lateral borders often led to eye movements.
  • 11% of pairs were seen to be synchronized, separated by 100-200um.
    • Much smaller than in the cortex.
    • This strongly supports the concept of functional segregation in the basal ganglia-thalamocortical pathways.
  • Mean firing rate 23 Hz old studies, 19 Hz present study.
  • "Most hypotheses concerning the role of the basal ganglia in movement were derived from experience with diseases originating in the basal ganglia or from experiments involving the activation or inactivation of large parts of BG nuclei. These results are notoriously hard to interpret, because gross changes in motor circuit activity likely results in rather nonspecific activity changes in multiple parts of the neuraxis, unlike minute alterations in the firing patterns of individual neurons in the basal ganglia may have under physiological conditions".
  • Basal ganglia may have a role in the late phases of movement, perhaps even their termination.
  • "More is known about the role of the indirect pathway in the pathophysiology of movement disorders such as Parkinson's disease and ballism than in the control of normal movement." word, yes.

____References____

[0] Wichmann T, Bergman H, DeLong MR, The primate subthalamic nucleus. I. Functional properties in intact animals.J Neurophysiol 72:2, 494-506 (1994 Aug)

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ref: DeLong-1985.02 tags: globus pallidus subthalamic STN electrophysiology Georgopoulos DeLong DBS date: 02-24-2012 21:50 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-3981228[0] Primate globus pallidus and subthalamic nucleus: functional organization

  • cells respond to arm, leg, and orofacial movements (mostly in the arm tho)
  • ~25% of these responded to passive joint movement - the latency is in accord with proprioceptive driving.
  • arm-related neurons were found throughout the rostrocaudal extent of both globus pallidus segments
  • look @ the articles that cite this!

____References____

[0] DeLong MR, Crutcher MD, Georgopoulos AP, Primate globus pallidus and subthalamic nucleus: functional organization.J Neurophysiol 53:2, 530-43 (1985 Feb)

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ref: -0 tags: globus pallidus delong response tuning date: 02-24-2012 21:41 gmt revision:1 [0] [head]

PMID-4997823 Activity of Pallidal Neurons During Movement

  • GPe activity notably different from GPi.
    • "So characteristic were the discharge patterns of units in each segment that early in the course of the experiment ti be came apparent when the electrode entered and left each segment.
  • Two types of cells in GPe:
    • High frequency with periods of quiet (85%)
    • Low frequency with bursts.
  • Only one type in GPi: continuous HF discharge, 10-100 Hz, mean 63 Hz.
  • Mostly contralateral, ~ 15% ipsilateral related discharge.
  • Leg and arm responding units intermixed.
  • Conclusion: pallidus not involved in reflexes.
  • Substantia innominata = region posterior the pallidus, contains the nucleus basalis.
  • I'd really like to get recordings of this quality!

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ref: life-0 tags: FORA longnow video lecture date: 07-07-2009 17:16 gmt revision:2 [1] [0] [head]

shows that I'd like to watch:

excellent lecture by Saul Griffith:

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ref: Shadmehr-1997.01 tags: Shadmehr human long term memory learning motor M1 cortex date: 03-25-2009 15:29 gmt revision:2 [1] [0] [head]

PMID-8987766[0] Functional Stages in the Formation of Human Long-Term Motor Memory

  • We demonstrate that two motor maps may be learned and retained, but only if the training sessions in the tasks are separated by an interval of ~5 hr.
  • Analysis of the after-effects suggests that with a short temporal distance, learning of the second task leads to an unlearning of the internal model for the first.
  • many many citations!

____References____

[0] Shadmehr R, Brashers-Krug T, Functional stages in the formation of human long-term motor memory.J Neurosci 17:1, 409-19 (1997 Jan 1)

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ref: DeLong-1974.05 tags: motor control basal ganglia cerebellum motor cortex DeLong putamen original date: 04-09-2007 01:51 gmt revision:1 [0] [head]

PMID-4219745[0] Relation of basal ganglia, cerebellum, and motor cortex units to ramp and ballistic limb movements.

  • monkey trained to make both ballistic movement and slow, pulling movements by pulling a manipulandum between three targets.
  • cells in the putamen discharged preferentially during slow movements.
    • consistent with a sequence / temporal scaling (?) role.
    • also consistent with the cerebellum creating rapid/feedforward trajectories.
  • cells in the motor cortex discharged for both types of movements, though a bit more for ballisic type movements (where the forces were higher).
  • paper is thankfully short and concise.
    • and also humble: "the mere correlation of unit discharge with some aspect of a movement without knowledge of the peripheral site influenced by the unit under study can only provide grounds for speculation".

____References____