bl

802 ms·

1.
by bl 11y ago
Oops. You're correct: a 2x1 vector is two-dimensional, a 3x1 vector is three-dimensional, etc. <Trying to remember the terminology from linear algebra 15 years ago.> Each element of the mx1 vector represents a magnitude along an
2.
by bl 11y ago
I'll give a try... Imagine three, 4-by-1 vectors, each "one-dimensional". Twelve total scalars, each vector with four rows and one column. Arrange these three vectors side by side and merge them into a single 4-by-3 matrix. T
3.
by bl 12y ago
Drat! I committed an error similar to the one I was griping against: being technically sloppy. Believe it or not, I paused for half a heartbeat while typing fixed and triangulation while I was typing and thought to myself "Should I
4.
by bl 12y ago
The Mosers' work is very much deserving recognition. They've made fundamental discoveries with really beautiful experiments (well-designed, well-executed, thorough). On a personal note, I referenced their work on place cells as
5.
by bl 13y ago
I like your gist of putting the hypothesis to test, but there are serious practical factors that would prevent your proposed experiments. Small- and medium-sized mammals (e.g., rodents and primates, respectively) are somewhat convenient for
6.
by bl 13y ago
I hope no one interpreted my statements to suggest that anything you said was wrong. Just trying to fill in details. I merely want to avoid prematurely narrowing the range of functions that are possible. If we, for the moment, think of the
7.
by bl 13y ago
"Processing" doesn't have a consensus definition in the neuroscience community, but a neuroscientist could, with good justification, use that definition if they had a particular experimental scenario. In this article, Smith,
8.
by bl 13y ago
"[I]t looks I could design a dendritic tree geometry for almost any boolean function of the inputs". That's my outlook on the structure-function link between dendritic morphology and dendritic information processing, with the
9.
by bl 13y ago
The voltage change (i.e., depolarization) is not strictly local. In some cases, depending on the actual geometry of the dendrite and the particular complement of voltage-activated ion channels, the voltage change as a result of neurotransmi
10.
by bl 13y ago
If you are interested in making a very stretched analogy, demonstrating dendritic information processing is like realizing that a CPU's transistor is actually itself a little CPU that is itself capable of quite sophisticated computatio
11.
by bl 15y ago
Mr. Park's original piece on slopegraphs: http://charliepark.org/slopegraphs/ Previous Hacker News discussion of Mr. Park's original piece: http://news.ycombinator.com/item?id=2753343
12.
A slopegraph update(charliepark.org)
1 points by bl 15y ago|1 comments
13.
by bl 15y ago
Strictly speaking, there is still some cell division shortly after birth and into the early phases of post-natal development. So the brain increases in size, slightly, via that method. But mostly it is from the elaboration of the dendritic
14.
by bl 15y ago
Synapse "rewiring" is not typically how we think memories are formed in adult animals. Mostly it is done by modulating the strengths of the existing connections (this process involves signaling cascades and protein expression, so it does ta
15.
by bl 15y ago
"[I]t's a bit of a stretch to say that they've rewritten the rules of refraction." Indeed. It appears more akin to the situation we have with classical and quantum mechanics: classical (Newtonian) mechanics fairly accurately describe the be
16.
by bl 15y ago
"[T]hese companies do nothing for us." I agree 99%. The one thing they do for us, and the one thing that any alternative system would have to replicate, is provide a signal of quality through their history and prestige. The whole constell
17.
by bl 15y ago
I'd be very interested to know more details about the structure of the RAM units. (Neither the original article nor the IBM press release at http://www-03.ibm.com/press/us/en/pressrelease/35251.wss talk much about it. The videos on the Sy
18.
by bl 15y ago
If you are used to CoffeScript and python and feel like you're trudging through syrup when you work on HTML, you might check out SHPAML ( http://shpaml.webfactional.com/ ). I found SHPAML to be more closely related to those two than HAML an
19.
by bl 15y ago
Sorry to be pessimistic, but my sense is, "No, there will not be a Steve Jobs of biotechnology." Mr. Jobs has done a remarkable job producing sleek, fun-to-use, affordable, somewhat disposable devices and building Apple into a company that
20.
by bl 15y ago
My goodness, was that a terrible omission on my part.
21.
by bl 15y ago
I may have made a mistake: risky and methodical are orthogonal. Space flight is inherently dangerous and the thousands of smart NASA workers were surely aware of the natural dangers, but their jobs were to minimize them. Thus, the appar
22.
by bl 15y ago
Apart from the sheer awe of landing on the moon with that era's technology and the resulting scientific harvest, I am fascinated by the engineering process. I can't settle on whether it was methodically safe or recklessly dangerous. Conside
23.
by bl 15y ago
I quite agree: I don't think megapixels will get us very far, if we could even formulate a consensus definition. I much prefer a perception/discrimination measure, as you said, and as it seems neuroscientists in the visual field have settle
24.
by bl 15y ago
True, a rod or cone cell (collectively, "photoreceptors") is the smallest, indivisible detector unit in the retina, but in normal visual processing (i.e., daylight-lit scenes), they probably never operate in isolation. The photoreceptor s
25.
by bl 15y ago
Maximum firing rate differs between neuron types (i.e., cortical pyramidal neurons versus cerebellar Purkinje neurons) dependent upon cellular membrane properties (dendrite diameter and ion channel distributions, etc.), but a good rule-of-t