Erk Subasi's shared items
Michael Jackson just died while Iran is in turmoil. I am reminded of a passage in Marjane Satrapi’s wonderful graphic novel Persepolis, a memoir of growing up in revolutionary Iran in the 80’s.
(Read the book to see how it ends.)
I wonder how much coincidences of news event timing can influence perceptions. Clearly, large news stories can crowd out other ones. Are there any other effects of joint appearances? Celebrity deaths are fairly exogenous shocks — there might be a nice natural experiment somewhere here.
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Principles of neural ensemble physiology underlying the operation of brain-machine interfaces.
Nat Rev Neurosci. 2009 Jul;10(7):530-40
Authors: Nicolelis MA, Lebedev MA
Research on brain-machine interfaces has been ongoing for at least a decade. During this period, simultaneous recordings of the extracellular electrical activity of hundreds of individual neurons have been used for direct, real-time control of various artificial devices. Brain-machine interfaces have also added greatly to our knowledge of the fundamental physiological principles governing the operation of large neural ensembles. Further understanding of these principles is likely to have a key role in the future development of neuroprosthetics for restoring mobility in severely paralysed patients.
PMID: 19543222 [PubMed - indexed for MEDLINE]
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Context-specific grasp movement representation in the macaque anterior intraparietal area.
J Neurosci. 2009 May 20;29(20):6436-48
Authors: Baumann MA, Fluet MC, Scherberger H
To perform grasping movements, the hand is shaped according to the form of the target object and the intended manipulation, which in turn depends on the context of the action. The anterior intraparietal cortex (AIP) is strongly involved in the sensorimotor transformation of grasping movements, but the extent to which it encodes context-specific information for hand grasping is unclear. To explore this issue, we recorded 571 single-units in AIP of two macaques during a delayed grasping task, in which animals were instructed by an external context cue (LED) to perform power or precision grips on a handle that was presented in various orientations. While 55% of the recorded neurons encoded the object orientation from the cue epoch on, the number of cells encoding the grip type increased from 25% during the cue epoch to 58% during movement execution. Furthermore, a classification of cells according to the time of their tuning onset revealed differences in the function and anatomical location of early- versus late-tuned cells. In a cue separation task, when the object was presented first, neurons representing power or precision grips were activated simultaneously until the actual grip type was instructed. In contrast, when the grasp type instruction was presented before the object, type information was only weakly represented in AIP, but was strongly encoded after the grasp target was revealed. We conclude that AIP encodes context specific hand grasping movements to perceived objects, but in the absence of a grasp target, the encoding of context information is weak.
PMID: 19458215 [PubMed - indexed for MEDLINE]
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The Science of Neural Interface Systems.
Annu Rev Neurosci. 2009 Mar 24;
Authors: Hatsopoulos NG, Donoghue JP
The ultimate goal of neural interface research is to create links between the nervous system and the outside world either by stimulating or by recording from neural tissue to treat or assist people with sensory, motor, or other disabilities of neural function. Although electrical stimulation systems have already reached widespread clinical application, neural interfaces that record neural signals to decipher movement intentions are only now beginning to develop into clinically viable systems to help paralyzed people. We begin by reviewing state-of-the-art research and early-stage clinical recording systems and focus on systems that record single-unit action potentials. We then address the potential for neural interface research to enhance basic scientific understanding of brain function by offering unique insights in neural coding and representation, plasticity, brain-behavior relations, and the neurobiology of disease. Finally, we discuss technical and scientific challenges faced by these systems before they are widely adopted by severely motor-disabled patients. Expected final online publication date for the Annual Review of Neuroscience Volume 32 is June 16, 2009. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
PMID: 19400719 [PubMed - as supplied by publisher]
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Movement intention after parietal cortex stimulation in humans.
Science. 2009 May 8;324(5928):811-3
Authors: Desmurget M, Reilly KT, Richard N, Szathmari A, Mottolese C, Sirigu A
Parietal and premotor cortex regions are serious contenders for bringing motor intentions and motor responses into awareness. We used electrical stimulation in seven patients undergoing awake brain surgery. Stimulating the right inferior parietal regions triggered a strong intention and desire to move the contralateral hand, arm, or foot, whereas stimulating the left inferior parietal region provoked the intention to move the lips and to talk. When stimulation intensity was increased in parietal areas, participants believed they had really performed these movements, although no electromyographic activity was detected. Stimulation of the premotor region triggered overt mouth and contralateral limb movements. Yet, patients firmly denied that they had moved. Conscious intention and motor awareness thus arise from increased parietal activity before movement execution.
PMID: 19423830 [PubMed - in process]
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For the past few months, between writing books and my day job, I’ve been working on a project with my friend Jesper called Freerisk.
A few months ago after we first heard Tim O’Reilly’s “Work on stuff that matters” speech, we started talking about what issues, besides the environmental concerns mentioned in his speech, were import to us that we actually had the skills to work on. We came to the idea of how hackers could help the financial system, particularly when it came to evaluating default-risk of companies or looking for fraudulent behavior.
The financial system itself has always been very closed. The government republishes filings by the SEC in a variety of messy formats, but those who want clean data need to pay subscription fees and have very limited republication rights. So our plan is to make Freerisk a huge open data store of financial data taken primarily from company filings. It’s all going to be available to download or query using standards like SPARQL.
On top of that, there will be APIs for building risk models and submitting your results. We hope to show that “financial hackers” can come up with more interesting and accurate calculators that can model a wider variety of risk scenarios.
If you’re interested in this, several people have written about the project:
- Harvard Business Review
- Fast Company Interview
- O’Reilly Radar on Freerisk
- Innovation Lab Write up (Danish)
- Next 6 Presentation Followup
We’ve also given several presentations. The O’Reilly emerging technologies conference was kind enough to make and post a video of our talk there (this was our first one, so it’s a little rough, but it should give you a good idea!)
We are looking for people who are interested in getting involved in this project. We have started a discussion group called Open Finance Hackers (just started, nothing there yet). If you’re interested in this at all, please email me and join the group.
