you are not logged in, login. new entry
text: sort by
tags: modified
type: chronology
hide / edit[1] / print
ref: -0 tags: US employment top 100 bar chart date: 11-12-2018 00:02 gmt revision:1 [0] [head]

After briefly searching the web, I could not find a chart of the top 100 occupations in the US. After downloading the data from the US Bureau of Labor Statistics, made this chart:

Click for full-size.

Surprising how very service heavy our economy is.

hide / edit[0] / print
ref: -0 tags: neural recording topologies circuits operational transconductance amplifiers date: 01-02-2013 20:00 gmt revision:0 [head]

PMID-22163863 Recent advances in neural recording microsystems.

  • Decent review. Has some depth on the critical first step of amplification.

hide / edit[12] / print
ref: RodriguezOroz-2001.09 tags: STN SNr parkinsons disease single unit recording spain 2001 tremor oscillations DBS somatotopy organization date: 02-22-2012 18:24 gmt revision:12 [11] [10] [9] [8] [7] [6] [head]

PMID-11522580[0] The subthalamic nucleus in Parkinson's disease: somatotopic organization and physiological characteristics

  • Looks like they discovered exactly what we have discovered ... only in 2001. This is both good and bad.
    • From the abstract: "Neurones responding to movement were of the irregular or tonic type, and were found in the dorsolateral region of the STN. Neurones with oscillatory and low frequency activity did not respond to movement and were in the ventral one-third of the nucleus. Thirty-eight tremor-related neurones were recorded."
  • Again, from the abstract: "The findings of this study indicate that the somatotopic arrangement and electrophysiological features of the STN in Parkinson's disease patients are similar to those found in monkeys."
  • It may be that we want to test differential modulation / oscillation: look for differences between rest and activity, if there is sufficient support for both these in the files we have.
  • These people were much, much more careful about localization of their single-electrode tracks. E.g. they calculated electrode location relative the DBS electrode stereotatically, and referenced this to the postoperative MRI location of the treatment electrode.
  • Many more (32% of 350 neurons) responded to active or passive movement.
  • Of this same set, 15% (31 neurons) had a firing rate with rhythmical activity; 38 neurons had rhythmic activity associated with oscillatory EMG, but most of these were responsive to passive stimulation.
  • Autocorrelation of the neuronal bursting and tremor peaked at mean 7Hz, while autocorr. of EMG peaked at mean 5Hz.
  • This whole paragraph is highly interesting: ''The neuronal response associated with active movements was studied by simultaneous recording of neuronal EMG activity of the limbs. Five tremor-related neurons, recorded while a voluntary movement was performed, were available for analysis. Voluntary activation of a particular limb segment arrested the tremor. This was associated with a change in the discharges of the recorded neuron, which fired at a slower rate and in synchrony with the voluntary movement. On occasions, freezing of the voluntary movement ensued and tremor reappeared, changing the neuronal activity back to the typical 4-5Hz tremor-related activity. The cross-correlation analysis of two such neurons showed a peak frequency of 4.63 and 4.88 Hz for tremor-related activity, and 1.5 to 1.38 Hz during voluntary movement. Whether neuronal discharges in the STN preceded or followed EMG activity of the limbs could not be precisely established under the present conditions.
  • Somatotopic representation in the STN is expected from normal and MTPT-treated monkeys. Indeed, somatotopy is enhanced int he GPm of MTPT-treated monkeys.
    • This somatotopy is likely to result from organized afferent from the primary motor cortex (M1) to dorsolateral STN; this is the target of DBS treatment. Ventral and medial STN seems to project to associative and limbic cortical regions.
    • It seems they think the STN is generally not diseased, it is just a useful target for stimulating without evoked movement as in M1. This is consistent with optogenetic studies by Deisseroth [1].
    • Supporting this: "DBS of STN in Parkinson's disease improves executive motor functions, but aggravates conditional associative learning.
  • Interesting: In Parkinson's disease patients with tremor, Levy and colleagues found synchronization and a high firing rate (>10Hz) while recording pairs of neurons >600um apart.
  • Recordings of cortical activity through EEG and STN LFP showed significant coherence in the beta and gamma frequency bands during movement - consistent with corticosubthalamic motor projection. ... and suggest that the STN neurons involved in parkinsonian tremor are the same as the ones ativated during the performance of a voluntary movement. (! -- I agree with this.)
  • More: The reciprocal inhibitory-excitatory connections tightly linking the GPe and the STN may generate self-perpetuating oscillations.

Old notes:

  • this paper concentrates on STN electrophysiology in PD.
    • has a rather excellent list of references.
  • found a somatotopic organization in the STN, with most motor-related units more irregular and in the dorsolateral STN.
  • found a substantial fraction of tremor-synchronized neurons.
  • conclude that the somatotopic organization is about the same as in monkeys (?) (!)
  • M1 projects to STN, as verified through anterograde tracing studies. [1] These neurons increase their firing rate in response to passive movements.
  • there appears to be a relatively-complete representation of the body in the dorsolateral STN.


[0] Rodriguez-Oroz MC, Rodriguez M, Guridi J, Mewes K, Chockkman V, Vitek J, DeLong MR, Obeso JA, The subthalamic nucleus in Parkinson's disease: somatotopic organization and physiological characteristics.Brain 124:Pt 9, 1777-90 (2001 Sep)
[1] Gradinaru V, Mogri M, Thompson KR, Henderson JM, Deisseroth K, Optical deconstruction of parkinsonian neural circuitry.Science 324:5925, 354-9 (2009 Apr 17)

hide / edit[19] / print
ref: -2008 tags: OCZ NIA teardown autopsy BMI BCI date: 01-06-2012 03:09 gmt revision:19 [18] [17] [16] [15] [14] [13] [head]

Recently we bought a OCZ NIA device for our lab. Having designed similar hardware myself, I simply *had to* take the thing apart to inspect it, as others have done -- see Joe Pit's teardown (with schematic!!). Of course, I graciously let the others try it for a few hours (it doesn't work all that well) before taking the anodized, extruded, surface- ground aluminum case apart. Below is the top side of the 4-layer circuit board inside the case, as well as a key to indicate the function of the labeled devices. (some of the labels are hard to read due to the clutter of the silkscreen on the board; sorry).

  • A - Input connector. Center channel is isolated ground; outside two channels are the signal. They had to make this custom so people couldn't plug it into other (possibly dangerous) stuff.
  • B - Input current limiting resistors, in series with signal, 4.02K
  • C - Dual capacitor from input channels to shared ground (I think; the cap has 4 contacts, 2 at the end, 2 in the middle; I assume they use this package to get very accurately matched capacitance so as not to hurt the CMRR of the instrumentation amplifier).
  • D - Gain-setting resistor, 1.00K. Sets the instrumentation amplifier gain to 50 (I think).
    • I do not know what devices were intended for the 1206 footprints above and below this resistor...
  • E - Instrumentation amplifier, Analog Devices logo, AD8220 by my guess, A-grade. Measures the difference in voltage between the two input channels (left and right electrodes on the headband).
  • F - 47 ohm resistors & capacitors to filter the power supply to the instrumentation amplifier.
  • H - Opamp, Texas Instruments OPA348A. Looks like it is used as feedback to the instrumentation amplifier reference pin to effect highpass operation (?).
  • I - Quad opamp, TI OPA4348A. Used to filter the signal; I did not go through the filter topology, but they might have copied it off the AD8220 datasheet ;)
  • J - Stereo ADC, Texas Instruments (Burr-Brown logo, TI bought BB) PCM1803A. Only one channel is used. 24 bits, 96khz max sampling rate; device in master mode (Mode1 = 0V, Mode0 = 3.3v); Fs = SCLK/512 -> sampling rate = 3.90625 KHz.
  • K - Three channel digital isolator, Analog Devices ADUM1300. Transmits the ADC's DOUT, BCK, and LRCLK signals to the USB (non-isolated) side.
  • L - Two-channel optical (?) isolator; unknown type; used to drive the ADC's SCLK and some other signal ?
    • from Joe Pits: "Yeah, optical isolator with logic gates for high speed I guess (HCPL2631S). I'm also not sure what the second signal does, it goes to U4 (JSR marking). I suspect it could be a switch which adds C14 + R17 in the feedback loop of U2C (see the schematic). But I don't know what the reason for this is."
  • M - Isolated supply daughterboard, Texas Instruments logo, very simple design: driver is 2 BJTs (which get hot!) in push-pull topology; bases are driven by windings on the toroidal transformer; transformer center tap seems to go to USB VCC. Output is +-5V.
  • N - +3.9V, +3.3, and -3.9V power supply circuitry. I cannot identify the SOT-23-5's and SC-70's here.
  • O - PIC18F2455, with USB 2.0 (obviously!) SOIC-28 package.
    • device comes up as (on my Linux box, Debian Lenny, kernel 2.6.24):
      • usb 4-1: new full speed USB device using uhci_hcd and address 8
      • hiddev96hidraw1: USB HID v1.10 Device [Brain Actuated Technologies Neural Impulse Actuator Prototype 1.0] on usb-0000:00:1a.1-1
    • I'll put up a usbmon trace later, maybe.
  • P - Transistors for driving the tricolor LEDS on the bottom of the board.
  • Q - 16.0000 MHz crystal. Needed for correct USB timing; clocks the PIC at 48Mhz.
  • R - USB type B connector. Note the ferrites to the left. (I though they were fuses, but I accidentally shorted Vdd to ground while probing the programming connector, and these let out a little smoke rather than blowing completely. Had they been fuses, they would be open circuit now. This is consistent with Joe Pit's analysis.)
  • S - 74HCT595A 8-bit shift registers, to convert the serial data into parallel data for the PIC to read in. 3 devices = 24 bits in total.
    • Note that the 74HCT595A has a output enable, which permits the PIC to read the 3 bytes of the sample sequentially. Otherwise, as Stefan Jung (via the openeeg-list) points out, the PIC would not have enough data pins (28 pins vs. 24 bits)!
  • T - 74HCT393, Texas Instruments logo, Dual 4-bit binary ripple counter. Used to drive the ADC with a 2Mhz clock, which puts the sampling rate at (as before) 3.90625 KHz.
  • U - Programming connector. That's right, a programming connector! Looks to be the same as a PIC ICSP connector (pointed out on hack a day)
    • So far as I can tell:
      • Pin 1 = +5V, PIC pin 1, (through 100 ohm resistor), Vpp (?)
      • Pin 2 = PIC pin 20 , Vdd
      • Pin 3 = PIC pin 19 , Vss
      • Pin 4 = PIC pin 28 (through 100 ohm resistor), PGD
      • Pin 5 = PIC pin 27 (through 100 ohm resistor), PGC
    • I do not know if the device can be reprogrammed, though it looks that way.
    • from here - bootloader (to address 0x07ff) can be read, but everything above that is read-protected.
Bottom of board, showing the (very bright!) tricolor LEDs


hide / edit[0] / print
ref: Friston-2002.1 tags: neuroscience philosophy feedback top-down sensory integration inference date: 10-25-2011 23:24 gmt revision:0 [head]

PMID-12450490 Functional integration and inference in the brain

  • Extra-classical tuning: tuning is dependent on behavioral context (motor) or stimulus context (sensory). Author proposes that neuroimaging can be used to investigate it in humans.
  • "Information theory can, in principle, proceed using only forward connections. However, it turns out that this is only possible when processes generating sensory inputs are invertible and independent. Invertibility is precluded when the cause of a percept and the context in which it is engendered interact." -- proof? citations? Makes sense though.
  • Argues for the rather simplistic proof of backward connections via neuroimaging..

hide / edit[1] / print
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 :-)

hide / edit[1] / print
ref: work-0 tags: ocaml toplevel ocamlfind date: 06-24-2009 14:52 gmt revision:1 [0] [head]

Ocaml has an interactive top level, but in order to make this useful (e.g. for inspecting the types of variables, trying out code before compiling it), you need to import libraries and modules. If you have ocamlfind on your system (I think this is the requirement..), do this with: #use "topfind";; at the ocaml prompt, then #require"package names" . e.g:

tlh24@chimera:~/svn/m8ta/yushin$ ledit | ocaml
        Objective Caml version 3.10.2

# #use "topfind";;
- : unit = ()
Findlib has been successfully loaded. Additional directives:
  #require "package";;      to load a package
  #list;;                   to list the available packages
  #camlp4o;;                to load camlp4 (standard syntax)
  #camlp4r;;                to load camlp4 (revised syntax)
  #predicates "p,q,...";;   to set these predicates
  Topfind.reset();;         to force that packages will be reloaded
  #thread;;                 to enable threads

- : unit = ()
# #require "bigarray,gsl";;
/usr/lib/ocaml/3.10.2/bigarray.cma: loaded
/usr/lib/ocaml/3.10.2/gsl: added to search path
/usr/lib/ocaml/3.10.2/gsl/gsl.cma: loaded
# #require "pcre,unix,str";;
/usr/lib/ocaml/3.10.2/pcre: added to search path
/usr/lib/ocaml/3.10.2/pcre/pcre.cma: loaded
/usr/lib/ocaml/3.10.2/unix.cma: loaded
/usr/lib/ocaml/3.10.2/str.cma: loaded
# Pcre.pmatch
- : ?iflags:Pcre.irflag ->
    ?flags:Pcre.rflag list ->
    ?rex:Pcre.regexp ->
    ?pat:string -> ?pos:int -> ?callout:Pcre.callout -> string -> bool
= <fun>
# let m = Gsl_matrix.create 3 3;;
val m : Gsl_matrix.matrix = <abstr>
# m;;
- : Gsl_matrix.matrix = <abstr>
# m.{1,1};;
- : float = 6.94305623882282e-310
# m.{0,0};;
- : float = 6.94305568087725e-310
# m.{1,1} <- 1.0 ;;
- : unit = ()
# m.{2,2} <- 2.0 ;;
- : unit = ()
# let mstr = Marshal.to_string m [] ;;


hide / edit[2] / print
ref: Dum-2003.01 tags: cerebellum dentate_nucleus projections cerebrum prefrontal posterior_pareital M1 PM thalamus somatotopic date: 03-11-2007 04:42 gmt revision:2 [1] [0] [head]

PMID-12522208 An unfolded map of the cerebellar dentate nucleus and its projections to the cerebral cortex

  • the dentate nucleus of the cerebellum projects to (at least four sections of if not all) of the cerebral cortex in a spatially-organized way.
    • dentate nucleus projects via the ventral anterior (VA) nucleus of the thalamus
    • dentate nucleus receives projections from the lateral hemispheres of the cerebellum (neocerebellum), which receives extensive collaterals from the pyramidal tract.