Ichneumonwasp
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- Joined
- Feb 2, 2006
- Messages
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I have a simple? question for anyone out there who has knowledge of information processing and information systems.
How much info can be coded with different frequencies?
The brain is obviously a very complex organ, and one of the things that it does -- nearly constantly -- is loop information from one area to another at different frequencies. We know already that significant information that is transmitted through individual neurons is coded with the frequency of the firing of those neurons. For instance, you put on your shoes and the light touch receptors in your feet fire because there has been a change from baseline, and their increased firing continues for a while. If the same degree of pressure remains for a set period (different for different receptors, since some only increase firing with the initial change and others continue firing at incresed rates for longer), then the firing rate drops. You still "sense" the presence of the shoe (neurons are still firing but at a different rate), but you are not aware of it because there is no change going on and no reason for you to be aware of the shoe any longer. The change in awareness probably occurs at several levels, but there is clearly a drop off in firing even at the receptor level.
The same sort of thing occurs within neuron arrays -- they loop information to other centers at a particular frequency, and that frequency can change based on what you are doing. A simple example is the normal waking EEG. With eyes open -- which cuases an obvious change in input info -- the dominant frequencies are in the beta range (> 13 Hz, with most being around 18-22 Hz). With eyes closed and the subject relaxed the dominant frequency in the occipital area is generally in the alpha range (8-12 Hz). These frequencies represent a summation of end-plate potentials, so they are due not to single neuron firing, but loops of information between different brain structures.
What I am interested in finding out from anyone who might know is how much information could be coded within those frequencies themselves?
The reason I ask is this. My way of looking at how the brain is put together (and its function) is that we have many different levels of information coding. There is direct line information -- neuron one releases neurotransmitter to affect neuron 2. Then we have a greater level of complexity in the linking of large arrays of neurons -- much of how this works in the visual system has been worked out for simple feature detection. Then we have large systems that loop information to keep themselves constantly updated. This is what our cerebellum does, for instance, when it takes position sense info and links it to visual info and info from the supplementary motor cortex responsible for motor planning -- there is a constant loop of updating position sense info and a separate loop of info comparing position sense to intended target based on where the target is and what we want to do with the target (like catch a ball). We have constantly looping information about "feelings" that Antonio Damasio has written fairly extensively about -- we don't just have a simple brain program for "fear" but have the program, which can be impacted by perception, which then causes release of stress hormones, which causes body changes, in turn the body changes are sensed by peripheral receptors, which in turn send info to the amygdala ("fear center") and hypothalamus, which continue to loop back and forth ("watching" each other). We have a similar system for pleasure which uses the median forebrain bundle for a conduit. We have a similar system for motivation/will that uses the orbitofrontal cortex and anterior cingulate gyrus. All of these systems work by constantly updating themselves on what is intended and what is actually happening within the body and within the external environment.
How much information could be encoded within those loops?
And then, finally, imagine a set of neurons whose job it is to constantly keep updated on the happenings of each of the systems that loop info from lower centers to the cortex. How much information could be encoded within a system that basically watches every other system and is activated by any changes in either of the two big environments (internal and external)? Keep in mind that there are many different frequencies of information exchange -- Fourier analysis has identified at least five big arbitrary frequency cut-offs (if you are a lumper) four of which we use in everyday EEG analysis -- DELTA (1-3 Hz), THETA(4-7 Hz), ALPHA (8-12 Hz), and BETA (>13 Hz with arbitrary cut-off) with another much higher frequency range in the GAMMA (~40 Hz).
This thing we call consciousness is very difficult to discuss in part because there are many things meant by consciousness. There is the level of being awake, which is clearly necessary for it, and we are fond of saying when someone is either asleep or in coma that they are unconscious. There is the level of awareness of the external environment. And there is a higher level that involves a sense of subjective self-awareness. The subjective self-awareness bit is the part that is supposedly so difficult to explain. But consider this -- we all have the experience of being zombies. Driving down the road, you "zone out" and find yourself at your exit. You must have been aware of the outside environment to be able to drive without mishap, but you were not aware that you were aware of the environment. Why? Simple -- you go on autopilot when the experience is completely familiar like the presence of your shoes. There isn't any change in the environment, or not enough, to impact the higher problem solving system that we call consciousness (at least this highest level). Environment changes (you reach your exit), and you suddenly become conscious -- aware -- of what is going on around you, so that you can look at the external or internal environment and your relationship to it so that you can solve whatever problem arises. New environmental input changes the relationship between the sytems, their information flow, and we use the self-awareness system to reconcile this new input with "ourselves".
One of the claims is that the trillions of synapses just can't account for all of this. But what about the levels of information that could be encoded within the looping systems that the brain employs all the time?
How much info can be coded with different frequencies?
The brain is obviously a very complex organ, and one of the things that it does -- nearly constantly -- is loop information from one area to another at different frequencies. We know already that significant information that is transmitted through individual neurons is coded with the frequency of the firing of those neurons. For instance, you put on your shoes and the light touch receptors in your feet fire because there has been a change from baseline, and their increased firing continues for a while. If the same degree of pressure remains for a set period (different for different receptors, since some only increase firing with the initial change and others continue firing at incresed rates for longer), then the firing rate drops. You still "sense" the presence of the shoe (neurons are still firing but at a different rate), but you are not aware of it because there is no change going on and no reason for you to be aware of the shoe any longer. The change in awareness probably occurs at several levels, but there is clearly a drop off in firing even at the receptor level.
The same sort of thing occurs within neuron arrays -- they loop information to other centers at a particular frequency, and that frequency can change based on what you are doing. A simple example is the normal waking EEG. With eyes open -- which cuases an obvious change in input info -- the dominant frequencies are in the beta range (> 13 Hz, with most being around 18-22 Hz). With eyes closed and the subject relaxed the dominant frequency in the occipital area is generally in the alpha range (8-12 Hz). These frequencies represent a summation of end-plate potentials, so they are due not to single neuron firing, but loops of information between different brain structures.
What I am interested in finding out from anyone who might know is how much information could be coded within those frequencies themselves?
The reason I ask is this. My way of looking at how the brain is put together (and its function) is that we have many different levels of information coding. There is direct line information -- neuron one releases neurotransmitter to affect neuron 2. Then we have a greater level of complexity in the linking of large arrays of neurons -- much of how this works in the visual system has been worked out for simple feature detection. Then we have large systems that loop information to keep themselves constantly updated. This is what our cerebellum does, for instance, when it takes position sense info and links it to visual info and info from the supplementary motor cortex responsible for motor planning -- there is a constant loop of updating position sense info and a separate loop of info comparing position sense to intended target based on where the target is and what we want to do with the target (like catch a ball). We have constantly looping information about "feelings" that Antonio Damasio has written fairly extensively about -- we don't just have a simple brain program for "fear" but have the program, which can be impacted by perception, which then causes release of stress hormones, which causes body changes, in turn the body changes are sensed by peripheral receptors, which in turn send info to the amygdala ("fear center") and hypothalamus, which continue to loop back and forth ("watching" each other). We have a similar system for pleasure which uses the median forebrain bundle for a conduit. We have a similar system for motivation/will that uses the orbitofrontal cortex and anterior cingulate gyrus. All of these systems work by constantly updating themselves on what is intended and what is actually happening within the body and within the external environment.
How much information could be encoded within those loops?
And then, finally, imagine a set of neurons whose job it is to constantly keep updated on the happenings of each of the systems that loop info from lower centers to the cortex. How much information could be encoded within a system that basically watches every other system and is activated by any changes in either of the two big environments (internal and external)? Keep in mind that there are many different frequencies of information exchange -- Fourier analysis has identified at least five big arbitrary frequency cut-offs (if you are a lumper) four of which we use in everyday EEG analysis -- DELTA (1-3 Hz), THETA(4-7 Hz), ALPHA (8-12 Hz), and BETA (>13 Hz with arbitrary cut-off) with another much higher frequency range in the GAMMA (~40 Hz).
This thing we call consciousness is very difficult to discuss in part because there are many things meant by consciousness. There is the level of being awake, which is clearly necessary for it, and we are fond of saying when someone is either asleep or in coma that they are unconscious. There is the level of awareness of the external environment. And there is a higher level that involves a sense of subjective self-awareness. The subjective self-awareness bit is the part that is supposedly so difficult to explain. But consider this -- we all have the experience of being zombies. Driving down the road, you "zone out" and find yourself at your exit. You must have been aware of the outside environment to be able to drive without mishap, but you were not aware that you were aware of the environment. Why? Simple -- you go on autopilot when the experience is completely familiar like the presence of your shoes. There isn't any change in the environment, or not enough, to impact the higher problem solving system that we call consciousness (at least this highest level). Environment changes (you reach your exit), and you suddenly become conscious -- aware -- of what is going on around you, so that you can look at the external or internal environment and your relationship to it so that you can solve whatever problem arises. New environmental input changes the relationship between the sytems, their information flow, and we use the self-awareness system to reconcile this new input with "ourselves".
One of the claims is that the trillions of synapses just can't account for all of this. But what about the levels of information that could be encoded within the looping systems that the brain employs all the time?