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Ed Hartouni
Trad climber
Livermore, CA
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Jan 12, 2015 - 08:01pm PT
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Nature 509, 331 (2014)
http://www.nature.com/nature/journal/v509/n7500/full/nature13240.html
Space–time wiring specificity supports direction selectivity in the retina
Jinseop S. Kim, Matthew J. Greene, Aleksandar Zlateski, Kisuk Lee, Mark Richardson, Srinivas C. Turaga, Michael Purcaro, Matthew Balkam, Amy Robinson, Bardia F. Behabadi, Michael Campos, Winfried Denk, H. Sebastian Seung & the EyeWirers
Abstract
How does the mammalian retina detect motion? This classic problem in visual neuroscience has remained unsolved for 50 years. In search of clues, here we reconstruct Off-type starburst amacrine cells (SACs) and bipolar cells (BCs) in serial electron microscopic images with help from EyeWire, an online community of ‘citizen neuroscientists’. On the basis of quantitative analyses of contact area and branch depth in the retina, we find evidence that one BC type prefers to wire with a SAC dendrite near the SAC soma, whereas another BC type prefers to wire far from the soma. The near type is known to lag the far type in time of visual response. A mathematical model shows how such ‘space–time wiring specificity’ could endow SAC dendrites with receptive fields that are oriented in space–time and therefore respond selectively to stimuli that move in the outward direction from the soma.
Compared to cognitive functions such as language, the visual detection of motion may seem trivial, yet the underlying neural mechanisms have remained elusive for half a century1,2. Some retinal outputs (ganglion cells) respond selectively to visual stimuli moving in particular directions, whereas retinal inputs (photoreceptors) lack direction selectivity (DS). How does DS emerge from the microcircuitry connecting inputs to outputs?
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This work focused on Off BC–SAC circuitry. An analogous sustained–transient distinction can also be made for On BC types7,8. It remains to be seen whether their connectivity with On SACs depends on distance from the soma. If this turns out to be the case, then the model of Fig. 6 could serve as a general theory of motion detection by both On and Off SACs. The model filter of Fig. 6a also resembles the spatiotemporal receptive field of the J type of ganglion cell (see Fig. 3b of ref. 29).
Neural activity imaging30 and connectomic analysis31 have recently identified a plausible candidate for the site of DS emergence in the fly visual system. If our theory is correct, then the analogies between insect and mammalian motion detection1 are more far-reaching than previously suspected, with fly T4 and T5 cells corresponding to On and Off SAC dendrites in both connectivity and function.
A glimmer of space–time wiring specificity can even be seen in the structure of the SAC itself. As BC types with different time lags arborize at different IPL [inner plexiform layer] depths, IPL depth can be regarded as a time axis. Therefore, the slight tilt of the SAC dendrites in the IPL (Fig. 5a) could be related to the orientation of the SAC receptive field in space–time (Fig. 6a). However, dendritic tilt alone is not sufficient to predict our model, as co-stratification sometimes fails to predict contact (Figs 4d and 5b). For example, co-stratification predicts strong BC4 connectivity to distal SAC dendrites. This would favour an inward preferred direction, contrary to what is observed, because BC2 leads (not lags) BC4 in visual responses7.
The idea that contact (or connectivity) can be inferred from co-stratification is sometimes known as Peters’ rule32, and has also been applied to estimate neocortical connectivity33–35.The present work shows that fairly subtle violations of Peters’ rule may be important for visual function. Previous research suggests that On–Off direction-selective ganglion cells inherit their DS from SAC inputs owing to a strong violation of Peters’ rule9,36–38.
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 12, 2015 - 08:40pm PT
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http://www.nature.com/ncomms/2014/140409/ncomms4639/full/ncomms4639.html
NATURE COMMUNICATIONS|5:3639 | DOI: 10.1038|ncomms4639
Olfactory projectome in the zebrafish forebrain revealed by genetic single-neuron labelling
Nobuhiko Miyasaka, Ignacio Arganda-Carreras, Noriko Wakisaka, Miwa Masuda, Uygar Sümbül, H. Sebastian Seung & Yoshihiro Yoshihara
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Animals use the sense of smell to monitor chemical cues in their environment, which provide vital information for food searching, predator avoidance, mate choice and social interactions. The odour information is initially represented as a discrete pattern of neural activities across a glomerular array on the olfactory bulb (OB), which results from axonal convergence of olfactory sensory neurons (OSNs) expressing the same olfactory receptors1. Glomeruli responsive to structurally related odorants are often clustered within defined regions of the OB2–5, establishing a chemotopic map of molecular features, so-called odour map. The odour map in the OB is transmitted by output neurons, mitral cells, to higher olfactory centres and eventually translated to elicit appropriate behavioural and physiological responses. Recent anatomical studies in mice showed that axons from identified glomeruli project diffusely throughout the piriform cortex6–9, the largest target area of the OB, and that piriform neurons receive convergent inputs from multiple mitral cells distributed throughout the OB10. These findings are consistent with an optical imaging study that found no apparent spatial organization of odour-evoked activity patterns in the piriform cortex11. In contrast, the anterior olfactory nucleus and the cortical amygdala receive topographic and biased projections from the OB, respectively9,10. Thus, a conceptual organization has been proposed in which the secondary olfactory pathway bifurcates to transform odour information into stereotyped and random representations, features suited for directing innate and learned behaviours, respectively12,13. However, it is not entirely clear how projections of individual output neurons to multiple brain areas are organized, because each of these studies in mice analysed only a small fraction of mitral cells and/or a restricted subset of its target areas.
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The olfactory circuits we describe in zebrafish provide insights into anatomical similarity and dissimilarity with those of insects and mammals, especially with Drosophila and mouse. In all the three species, individual output neurons in the OB or the antennal lobe send axons to multiple brain areas. Each brain area appears to adopt one of two major strategies of projections to be received: (1) restricted and stereotyped projections with respect to glomerular classes for the fly lateral horn14, zebrafish Hb and mouse cortical amygdala9,10; (2) broad and random projections for the fly mushroom body49, zebrafish pTel (Dp), and mouse piriform cortex9,10. Thus, our findings support the idea that the two distinct modes of connectivity patterns (stereotyped and random), which are suitable for innate and learned behaviours, are applicable to all animal species as a fundamental principle for olfactory representations in higher brain centres. As to the axon branching of output neurons innervating the same glomerulus, highly diverse patterns are observed in zebrafish and mouse6,7, compared with more stereotyped one in Drosophila16,17. Furthermore, we find in zebrafish that choice of target areas in the forebrain by output neurons innervating the same glomerulus is not always the same. Thus, the increased diversity of projections in vertebrates may serve to enhance the ability to perform combinatorial processing of odour information beyond the OB.
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BLUEBLOCR
Social climber
joshua tree
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Jan 12, 2015 - 09:35pm PT
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Very interesting stuff,ED!
How does DS emerge from the microcircuitry connecting inputs to outputs?
shouldn't this say;
"How does DS emerge in the microcircuitry connecting inputs to outputs?"?
seems like if the retina doesn't know DS, and doesn't need to know it to do its job. The eye-balls DS might not be determined until it collaborates with where the rest of the body is in its referenced space-time? Another words, the retina cant know direction whithout first knowing the direction of the head.
OR
We've invented a switch that produces light. Now we need to learn how light invented a switch to produce meat.
couldn't get into EyeWire. Almost queer that they would use people sitting still staring at a flatscreen to test for DS? Seems like climbers would be a better labrat
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 12, 2015 - 09:57pm PT
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they use the people to map the connections...
actually, to help train their artificial intelligence algorithms to map the connections.
I think your question is interesting:
shouldn't this say;
"How does DS emerge in the microcircuitry connecting inputs to outputs?"?
and is at the crux of the two discussions going on in this thread. The question asked in the papers are just exactly right... they presume that something like directional selectivity "emerges" out of the functioning of a cell network.
Signals go in, and signals come out, transformed and encoding information, such as motion. How does this happen?
It isn't "in" the microcircuitry, it doesn't have to be, the behavior of the network of cells produces the information just by acting in a rather well defined manner to local stimulation, they don't "know" themselves what they are doing, they just react, electrochemically, to the stimulus.
the paper on the zebrafish is interesting because it shows that olfactory sensing provides information to a place that "looks up" the stereotype of the stimulus, but also to a place where those stimuli are free to associate with other stimuli, which you might imagine has to do with the ability to find associations that aren't "wired in" to the network, a place that allows the network to learn.
once again, this is a community of cells just doing their thing... reacting to a local stimulus...
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healyje
Trad climber
Portland, Oregon
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Jan 13, 2015 - 12:06am PT
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Why is the 'emergence' of sights, sounds, smells and tastes any different than consciousness relative to the brain? Do we see without eyes? Hear without ears? Smell without a nose? Taste without a tongue? Each connect to extensive processing subsystems within the brain which in turn present our conscious mind with highly aggregated and processed 'results'.
No brain > no sights, no sounds, no smells, and no tastes. It is not a big leap to no brain > no consciousness.
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paul roehl
Boulder climber
california
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Jan 13, 2015 - 01:08am PT
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That all brain function is a product of chemical and electrical process is a given.
The problem is that there appears to be an experiencer beyond those functions making judgements based on those functions.
How can this be?
I am not my body. I am not my thoughts. I am the entity beyond these functions. I am the analyzer and judge and beneficiary of these functions, yet I stand apart as the observer... I am the sufferer and the joyous experiencer, the benefiting consciousness that remains a mystery and wonders at itself.
One may disassemble the radio and discover its workings without ever hearing the music it once played.
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healyje
Trad climber
Portland, Oregon
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Jan 13, 2015 - 05:37am PT
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I can assure you there is way, way more going on in my comment than chemistry or electrical currents or the "parts of a radio"...
I have some significant hearing issues and because of my experience dealing with them on a daily basis for forty years I have some fairly uncommon insight into how sounds are processed into the language we 'hear'.
Every time you perceive and 'hear' the spoken word, you are being handed the result of a significant amount of subconscious pre-processing. Basically, between the time sounds enter your ears and the time when you perceive a word or phrase, an enormous amount of work is happening to deliver to you some particle of language which corresponds to that sound and which 'fits' or makes sense in the context of your reality at that moment. That 'work' or 'pre-processing' is spot on 99.9% of the time and so most of us never think about how we get all those words we hear when people speak.
I on the other hand, get handed complete nonsense by that pre-processing on a fairly regular basis. I've been in meetings and been handed "it's currently snowing bells in ping pong" ("it's currently showing well in Hong Kong"). I've been asked about the "thermal efficiency and peat moss of data centers" (that would be "heat loss", but I also have a horticulture degree and soils studies in addition to Comp Sci, so to my pre-processor 'peat moss' seemed like a decent candidate).
The result is sometimes I have to stop and evaluate the possible relationships between three things: the original sound (yes, it's still in there), the phrase I was given by my subconscious, and my current 'context' and attempt to piece together what the person most likely said. All that happens fairly quickly, both the incorrect [subconscious] pre-processing and my conscious reevaluation.
One the big questions this all gives rise to is how does my subconscious contextualize sounds into words in the context of the ideas or [subjective] experience current in my conscious mind? Oh, I get the sounds into words thing, pretty straightforward stuff - until you come to picking the right words contextualized for this moment in my conscious 'world'. (And that doesn't even include merging in lip reading which I also do to augment sounds in a noisy environment).
The subconscious processing of sound into words happens 'invisibly' to, and entirely independent from, your conscious mind and your [subjective] experience. From my perspective as both a conscious human and a software engineer with some AI experience I actually find the interplay between the two and general questions of subconscious mind almost more fascinating than that of the conscious mind.
So when folks talk about the a universal consciousness I can't quite stop from jumping to the notion of a universal caste system of consciousnesses 'out there'. I mean, like are there ghostly universal subconsciousnesses also floating about?
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BASE104
Social climber
An Oil Field
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Jan 13, 2015 - 06:29am PT
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You need only look at various societies to see that morality is not innate. We are not moral because of evolution. Quite the contrary. Morals are often moments when you do not defeat your opponent on purpose.
Any of you have kids? If you have ever raised a child, you will notice that altruism is not something that we are born with. Young children are very selfish. It takes years to teach some of them to share.
Morals are social constructs, and they vary across a huge spectrum.
In that sense, I would say that religion is the main source of morality in modern man. Now, I don't need to say that I am not in any way religious again, but it has served that purpose around the world.
If we are entering a post religious age, morality will probably keep keeping on just fine without religion. It has with me.
Just compare religions and morality around the world. There is quite a bit of difference. Jan would be the expert here; it is an anthropology matter.
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BASE104
Social climber
An Oil Field
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Jan 13, 2015 - 06:38am PT
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I am not my body. I am not my thoughts. I am the entity beyond these functions
What evidence do you have to offer that supports this notion, Paul? It is easy to make statements like that without any supporting evidence.
The interesting word that you use is "beyond." You have stepped off of ground and entered the world of spiritism.
I would say that you are your thoughts and actions as much as you are a very complicated brain and its related systems.
Ed has been posting these articles. They aren't really physics related, they are biology papers, which strive to answer real questions about how perception functions.
What else do you want us to be, other than a smart animal, Gods?
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High Fructose Corn Spirit
Gym climber
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Jan 13, 2015 - 06:45am PT
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Interesting and spot on post, healyje. Relates in some ways to my own experience in the 80s as a communications engineer in electronic voice recognition research and development (my undergrad and first post-grad work experience). A lot of the processing is sophisticated enough even in electronics that another 20-30 years had to go by before such a system could be mass consumer practical (cheap, accurate); that speaks to enormous sophistication.
The argument Paul is advancing, which employs either radio receiver or lens analogy as a thinking tool, has been addressed by many scientists (bio-engineers, neuroscientists) most esp in recent years. You could make the argument but it really amounts to grasping at straws and usually by the hands-on-lab-inexperienced or else the technically-challenged folks ideologically motivated.
The question remains: how does the brain implement all the many wonders it does.
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High Fructose Corn Spirit
Gym climber
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Jan 13, 2015 - 06:59am PT
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"You need only look at various societies to see that morality is not innate..."
In the spirit of Wikipedia, this statement needs clarity and disambiguation. Otherwise, as written, it is incorrect. As eeyonkee rightly pointed out there is more than one component, level or layer (however you prefer to think of it) to morality (or morality systems or moral drives or sentiments). There is an innate layer (obviously) and there is a cultural layer (obviously) that together turn out a moral blend or composite of the two.
//Morals are social constructs, and they vary across a huge spectrum...
In that sense, I would say that religion is the main source of morality in modern man.//
It is obvious BASE is only considering the socialization (or acculturation) component. He should spend more time in the animal world where evidence of morality (protecting young, for starters, cheating, tit for tat, fair and square dealing) abounds at the innate (genetics-driven) level.
"religion is the main source of morality in modern man." -BASE
This is just the sort of baseless myth / bs that so many secular progressive, evidence-based types are trying to dispel.
.....
BASE, I thought you were a Michael Shermer fan. If so, Shermer to the rescue on the bases of morality: The Science of Good and Evil, by Michael Shermer.
And speaking of Shermer, he's got a brand new lecture up...
http://apps.carleton.edu/events/convocations/audio_video/?item_id=1231895
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WBraun
climber
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Jan 13, 2015 - 07:43am PT
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No brain > no sights, no sounds, no smells, and no tastes. It is not a big leap to no brain > no consciousness.
That's not true at all ever.
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BLUEBLOCR
Social climber
joshua tree
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Jan 13, 2015 - 08:52am PT
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in the animal world where evidence of morality (protecting young, for starters, cheating, tit for tat, fair and square dealing) abounds at the innate (genetics-driven) level.
Your only describing natural selection by experimenting with cause-n-effect.
but you have to see it that way right?
If they were innate wouldn't they be called laws, and not morals. we choose to live by, or not live by a moral everyday. Another distinction of a moral is that it's a judgement call. And its not about reward, it is about honor and dignity, and not being selfish but selfless.
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 13, 2015 - 09:10am PT
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my point in posting those articles is that science often is concerned with answering relatively small questions.
in these two papers, serious work has been done to make a connection graph of cells in various structures of brains. doing this carefully reveals much more than "just the map" though the map is critical in those revelations.
the authors of the papers didn't start with the question: how do I explain the wonders of consciousness? they start out with: gee, how is motion perceived? doing that correctly they obtain a set of insights that might open up the bigger question.
this is reductive... and constructive.
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This also points to some deeper issues of morality. A modern take on ancient ideas of the oneness of life, which is evident in our DNA, parts of which are shared, and certainly forms the basis of life. The "do unto others..." morality shrivels when we expand "others" to include all life, or if not, it expands to a place most of us wouldn't accept. The universality of structures created out of the DNA "plans" span a huge variety of life, yet we feel little remorse in piecing the brain of a fruit fly, zebrafish or even a mouse. All life seems to literally feed off of life, photosynths and chemosynths being the source of abiotic energy generation... after that its eat or be eaten...
what is the morality of the way we treat life given that we are all assembled using the same stuff, just in slightly different instantiations?
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Tvash
climber
Seattle
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Jan 13, 2015 - 09:38am PT
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Whatever our shared morality is, it supports in the aggregate the continuation of the species practicing it.
Would it be moral for a band of Homo to eat Grandma and the runt of the litter?
Given the right survival circumstances, it could be.
The book The Sparrow describes a world with two intelligent species. One preys on the other.
Moral?
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High Fructose Corn Spirit
Gym climber
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Jan 13, 2015 - 09:42am PT
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Eyewire tutorial help...
[Click to View YouTube Video]
http://www.youtube.com/watch?v=Z6ENAPXN9Lc
I spent an hour last night trying to figure out why my browsers, both of them, weren't giving me the 3d cube. Reloaded flash. Reloaded Firefox. No change. Now suddenly this morning the tutorial works. In full. At last.
This concept of "citizen science" or "crowd science" is a very cool emergence of social media. It's going to help solve a lot of previously unsolvable problems, I think.
I think I'll play these games a bit - using eyewire as a model - to give me a better sense of several of the basic ideas.
"Citizen science"!
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paul roehl
Boulder climber
california
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Jan 13, 2015 - 10:57am PT
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Would it be moral for a band of Homo to eat Grandma and the runt of the litter?
Given the right survival circumstances, it could be.
That cannibalism can be morally just by virtue of its relativistic context seems a bit nonsense doesn’t it? What then cannot be justified as moral? Perhaps we can find a moral justification for genocide?
On what basis does granny’s survival provide evolutionary success? When the elderly are too old to contribute to the whole why shouldn’t they be eliminated… perhaps at 65 in their sleep… The notion that morality is tied simply to evolutionary success seems problematic IMHO.
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