ashennell

CAn you just clarify what you are asking here. Is this basically it: if you could theoretically disable the immune reaction caused during the transfusion of an incompatiable blood type would there be any other effects? if so then: It the antigens are disbaled temporarily then when they 'reactivate' the original problem would arise again. If you could permanently disactivate the antigens then this wouldnt be a problem. However, antigen disactivation is probably not an option. The antigens are functioning surface proteins of the red blood cells - they need to be there (as far as I know). If you were able to neutralise any immune problems then the blood should be fine in the body. I can't see any reason why not. But if this was easy then I think someone would have done it by now.

NO, I think that is pretty clear. Of course, consciousness could result because of the use of neurons or because of the computations performed by them or both. I would guess that it is dependant on the particular processes rather than the wy they are implemented. I'm not quite sure how everything else we have been discussing boils down into this one point, - but never mind I'm happy to end it here.

I'm sorry Bascule but this just shows the limits of your understanding in this area. The Hodgkin-Huxley equation models the membrane potential given the concentrations of different ion channel species within the membrane. This allows us to stimulate action potentials and model their propagation along axons etc. Does this mean we understand the information processing performed by neurons - no. This is still a hugely active area of research - the trend at the moment is looking at networks as non-linear dynamic systems, as systems that exhibit stability in a number of different attractor states. There are a huge number of different analyses of spike train encoding that use statistical or information-theoretic approaches. Why? Becuse we don't know how these spike trains encode stimuli. Copying and undertsnding are two different things. What exactly defines a human neural network, what makes it special. Ahh your answer.. What are low-level and high level-structure? Could you be any more more general and unspecific. There are in fact huge similaries between all mammalian brains at most levels of analysis. The gross structures are the same and changes across species are subtle and progressive. You will notice that your HPC chip was designed from recording rodent HPC slices and is going to be hopefully used in humans. the fact is that no one knows what produces or determines consciousness. How far can you abstract and simplify the 'conscious' neural network before you lose consciousness? If people really knew whats is going on then they could answer these kind of questions. It is quite clear from your posts that you don't know what our present level of knowledge is. You seem to have a romanticised version in your head - if you worked on modelling parts of the nervous system every day I think you would maybe realise just how little we know for sure.

Mmm. yes some. What do you want to know? The effects of alcohol are pretty complex. Alcohol does not interact with any one particular neurotransmitter system or receptor subtype. Or do you want to know about how various neurotransmitter systems vary during chonic alcohol use? Maybe this should be in the Neuroscience Forum instead.

I think you are probably overestimating what we have actually achieved, there has been progress for sure but there are a huge number holes. We don't have any basic definition of the 'neural code' and mathematical models of neurons tend to match behaviour without really providing us with underlying understanding of what they are actually doing. There are a lot of books and news reports out there that are basically propaganda - they make it seem like we have just about cracked the whole brain. Maybe in a few years or decades we will but there is nothing in science to suggest that this is already happening right now. I've heard the quote 'Neuroscience is like physics before Newton' - I'm not sure who originally said it but it is definately still true. I would also agree with DV8 2XL that the Blue Brain project has yet to prove itself, the same can be said for the HPC chip. You don't really believe that it is this simple do you? There are a huge number of different types of neural network, biological, biologically inspired and otherwise. Are they all conscious systems? If not then why do particular neural networks produce consciouness and not others?

Bascule - Sorry, I think my last post was a little terse. Just to clarify, I agree that processes in the brain, as everywhere else, are determinsitic. I don't think that a quantum explanation is necessary as I have already argued. I simply used the term non-algorithmic to imply heuristic. Heuristics are derterministic too. But they are not algorithmic in the sense that they don't necessarily produce the correct answer or the optimal solution. So I would define an algorithm as a set of rules or produces that can be followed to reach a correct solution. I assumed that the original use of non-agorithmic in this tread implied the same thing. It does seem that they actually meant non-determinsitc.

I think the use of the word algorithm has different meanings here. From wikipedia: also from wikipedia: In this sense I would stay that most neurophysiologists and cognitive scientists would agree that the brain is heuristic and not algorithmic.

mild hallucinations associated with migraines are usually called migraine auras or visual migraine aura hallucinations. They are quite common. if you google for "migraine aura" or "migraine hallucination" there should be a lot of info out there.

DV8 2XL - thanks for the link to this article you have made. You certainly seem to know this topic inside out. So, I have a question for you. I dont understand the reasoning right at the beginning. Human thought processes are non-algorithm (which I agree with) therefore a quantum exaplanation is required. Why can't the brain just use a heurisitic mechanism with any necessary pseudo-randomness required being derived from processing noise within the system or small chaotic deviations in the environment? What does it mean to say that human thought is sound? If these are the main reasons people give for needing a quantum explanation could you explain a little more. TIA. I don't know but it seems to me that something being deterministic is not that important - what is more important is whether you can predict it or not. i.e. something that is deterministic is not necessarily predicatable given limitations on the model you can use.

I dont think so. Even probablisitc changes are based on determinsitic processes - chaotic determinism. I think the important point is that from our viewpoint the world is probablistic - not random and not deterministic.

Have you been reading Dennet's new book ?

Microtubules have structural functions - they are part of the cytoskeleton. they are also involved in intracellular transport. I think they are involved in transport of chemicals along axons e.g. neurotranmitters. However, what I can say for certain is that after studying neuroscience for 8 years I have never come across any case where microtubules make a significant impact on the way neurons process information. there are some very detailed single-cell models of different neuron types arounf. They mimic the electrical properties of real neurons quite well. The important factors in achieving this are a similar morphology (e.g. dendrite length and diameter) and matching the ratio of the different ion channels present. Microtubules are not required.

If we look at the substrate for this kind of precessing, namely the visual cortical areas of the 'what' pathway, then there is a hierarchical organisation althought it is not by any means completely sequential. Perhaps the most important addition to your first diagram would be a seqeunce of connections going in the opposite direction. The visual system contains both bottom-up and top-down flows of information. As a rule of thumb, bottom-up information flows level-by-level up the hierarchy while top-down information can often be passed down a number of steps at a time. For example the highest level in the hierarchy could projet to 2 or 3 levels below it. This is a more accurate abstraction of the organisation. It would take quite a lot to explain why this really the wrong way to look at how the brain is organised. The feedback projections are important. For example if wish to see if our cup has a square handle or rounded handle then this top down 'question' could alter way the bottom-up information is processed so the specific details of the object are focused on instead of the whole. Perceptual processing is context sensitive. Selective attention is probably our subjective experience of this process in action. Conscious awareness of the cup probably works a little differently - we don't necessarily only become aware of the cup at the top of the perceptual hierarchy. I'm not sure if this is relevant to your question. Part of your point about losing the details is certainly true. In some cases we find it very hard to not perceive the top-level concept and only see the detail. I notice you have memory at the top of the hierarchy- I'm not sure that this is completely accurate but anyway imagine trying to store the details of a cup without the concept of the cup into memory. The reason why this dosn't happen is not because we can't (because of connectiviety) but because the individual parts of an object have no behavioural significance on their own. I hope this is useful. Maybe it is a little confusing?

This part of the quantum theory of consciousness has always bothered me. Microtubules are not specific to neurons, they occur in all cell types as far as I am aware. There functions across different cell types are similar and usually structural. Specifically, there is no known link between microtubules and the information processing role of neurons. Wikipedia gives a bit more info - http://en.wikipedia.org/wiki/Microtubules So maybe their is a quantum explanation for consciousness but I doubt that it would have anything to do with microtubules.

Sorry, My last post dosn't make sense. I can't seem to editit now but should be - Nicotine can kill a human if you ingest a sufficient amount. I think the lethal dose is about 60 mg.

So I was wrong then. I think I could spend a whole light year trying to get my head round this stuff and still not figure it out

I think my answer is possibly wrong. Im not a physicist. I was under the impression that time 'stopped' if you travel at the speed of light. i.e - If my interpretation is correct then when your bus reaches c everything freezes - you would not be able to turn the light on. If you could still see anything then I guess it would be a frozen image. There are normally millions of physics experts around here so im sure one could set us all right.

I'm not an expert on this so perhaps someone can correct me. I'm just interested to see if a can actually get something right regarding speed of light stuff. If the bus is travelling at the speed of light then you would experience no passage of time if you are in the bus. Therefore you could not move forward - there would be no time for you to move forward in. This may be very wrong! Edit: Looks like I was wrong then.

Just to add - the reason cells actually take an active roll in their own death is because it is an efficient, safe and fast process. That fast that it is a recently discovered process, relatively speaking. Apoptosis (programmed cell death) prevents cell contents from being leaked into the intercellular space, as would happen during cell lysis. This kind of leaking can cause problems for the surrounding cells as would be caused from physical tissue damage. There are other benifits of apoptosis as well. I think most of those have been covered already.

when I was an undergrad everyone used to drink vodka and redbull. we used to go through tonnes of that stuff. I can't stand the sight of it now. Anyway, I think that you would probably get severe alcohol poisoning before you had problems from mixing these two drugs. I can't say that is a scientific evaluation - just from personal experience.

I just want to clarify one point in Gliders response. Don't get me wrong - his answers better than I could manage. However, DA release on the nucleus accumbens is not associated with the sensation of pleasure (as far as we know). This theory, the anhedonia hypothesis, was proposed but subsequently retracted. At the moment no-one is quite sure exactly what it does - it is certainly involved in addiction and motivation. A more recent hypothesis, the incentive salience hypothesis links it with 'wanting' the reward and not with 'liking' the reward. This may not be perfect either.

Illusions from within are hallucinations rather than illusions. They are not the same thing.

Nicotine can kill a human if you ingest a sufficient amount. I think the lethal dose is about 60 mg.

This is kind of the view that I had. I have only one cognitive psychology textbook but they are not even mentioned in passing. Models are usefuls tools in any area of science but if a model is known to be over-simplified or innacurate then its use should be discouraged.

As I understand it the concepts of the Ego and Id were introduced by Freud. These terms have croped up on a number of threads in both the psychology and neuroscience forums here recently. To what extent are these concepts actually used in modern cognitive psychology? Are they used by phychiatrists? Is there any value in their use at all? I was under the impression that they were basically outdated.