sensory capacity of the human brain

[easychair]

Is there a neuroscientist in the house?

I'm curious to know if the human brain is specifically wired to process information just from the sensory tools (eyes, ears, nose, etc) of the human body.

If it were possible to isolate a human brain in a chemical soup and wire it for sight, sound, and so on, could the brain process input that went beyond the limits of natural human sensory organs? Could it see like an eagle, hear like a bat, etc., or would it short circuit, for lack of a better term?

[MadHatter]

I am not a neuroscientist.


Medical science has successfully created artificial sight devices and electrically connected them to the brain. That would indicate the brain is able to process sensory information not originated in the actual organ.

Given that the brain can do this, the quality of the input devices (eyes, ears, nose, etc.) may be the limiting factor, rather than the brain itself.

[easychair]

I am not a neuroscientist.


Medical science has successfully created artificial sight devices and electrically connected them to the brain. That would indicate the brain is able to process sensory information not originated in the actual organ.

Given that the brain can do this, the quality of the input devices (eyes, ears, nose, etc.) may be the limiting factor, rather than the brain itself.

I hadn't heard that sight can be restored with artificial devices. Seems like that would be big news.

So let's say that we could create an artificial nose with the sensory capacity of a bloodhound. A bloodhound's olfactory sense is something like a hundred million times more acute than ours. Could the human brain process that kind of olfactory input?

[travc]

Also not a neuroscientist, but...

The brain can learn to use different inputs. It isn't as efficient (at least in the cases I know of) as the processing it was "designed" to do, but it can handle it. However, I don't know of attempts to put more informaiton into the sensory pipeline, and it seems to me that the neural networks that actually do the processing would saturate at some point (and evolutionarly, that point shouldn't be much beyond the nominal sensory input rate).

People have had electodes planted into the visual cortex and auditory cortex, and although the inputs are quite different than what would be comming from a normal eye or ear, they do figure out how to make some sense of signals. Starting with a baby, we'd probably see much better results, but that hasn't been done for the obvious reason.

[Majestyk]

I hadn't heard that sight can be restored with artificial devices. Seems like that would be big news. Recent DOE update on research http://www.energy.gov/engine/content.do?PUBLIC_ID=16769&BT_CODE=PR_PRESSRELEASES&TT_CODE=PRESSRELEASE
"At today’s announcement in Chicago, the first patient to receive a prototype implant in 2002 described what it was like being able to “see� large letters and to differentiate between a cup, a plate and a knife after being blind for over 50 years."

A reference of other methods being researched http://insight.med.utah.edu/research/normann/normann.htm

[Its Own Level]

Is there a neuroscientist in the house? It looks like I'm the only one on duty right now. Hopefully I can help.

I'm curious to know if the human brain is specifically wired to process information just from the sensory tools (eyes, ears, nose, etc) of the human body.Let's see if I understand your question. You seem to be asking whether the brain would be capable of interpreting electrical signals other than those normally provided by its various sensory organs. This is certainly the case. As others have pointed out, various sensory prostheses have been successfully implanted in people. Cochlear implants have provided hearing to tens of thousands of otherwise deaf people, and, while still mostly in experimental settings, light-sensing implants have restored rudimentary vision to blind people.

If it were possible to isolate a human brain in a chemical soup and wire it for sight, sound, and so on, could the brain process input that went beyond the limits of natural human sensory organs? Could it see like an eagle,The development of the visual system depends very much upon a type of spontaneous electrical input that it receives from the retina. Therefore, those parts of the brain that construct our visual experience are shaped by and 'customized' for the type of input provided by our retinas. Were you to attach some sort of higher resolution 'supereye' to the visual inputs of our brain, I would think it unlikely that the brain could extract much additional information. The visual system retains a pretty impressive degree of plasticity even into adulthood, though, so I could imagine it adapting to utilize at least some of the additional information it is receiving. Take that as the somewhat informed intuition that it really is, though. hear like a bat, etc., or would it short circuit, for lack of a better term?The same principles are at work in the case that we would try to 'soup up' the auditory system, but please allow me to make an additional point. There are at least two ways that a sensory ability might be enhanced: 1)Improving the transduction of the physical inputs -- be they odors, light, acoustic vibrations, etc. -- into coded electrical impulses. 2)Improving the processing of the coded electrical impulses received by the brain. The difference between bat hearing and human hearing is much more a case of 2 than of 1. They have devoted huge areas of their brains to the processing of auditory information, and so their hearing provides a better 'picture' of their environment than ours does. So if we were to graft bat ears onto a human brain, we would hear relatively little difference. If we were to somehow plug all of the auditory signal processing parts of a bat's brain into the auditory stream of our brains, even our human ears could provide us with a batlike passive sonar 'picture' of our surroundings.

[easychair]

It looks like I'm the only one on duty right now. Hopefully I can help.

Let's see if I understand your question. You seem to be asking whether the brain would be capable of interpreting electrical signals other than those normally provided by its various sensory organs. This is certainly the case. As others have pointed out, various sensory prostheses have been successfully implanted in people. Cochlear implants have provided hearing to tens of thousands of otherwise deaf people, and, while still mostly in experimental settings, light-sensing implants have restored rudimentary vision to blind people.

The development of the visual system depends very much upon a type of spontaneous electrical input that it receives from the retina. Therefore, those parts of the brain that construct our visual experience are shaped by and 'customized' for the type of input provided by our retinas. Were you to attach some sort of higher resolution 'supereye' to the visual inputs of our brain, I would think it unlikely that the brain could extract much additional information. The visual system retains a pretty impressive degree of plasticity even into adulthood, though, so I could imagine it adapting to utilize at least some of the additional information it is receiving. Take that as the somewhat informed intuition that it really is, though. The same principles are at work in the case that we would try to 'soup up' the auditory system, but please allow me to make an additional point. There are at least two ways that a sensory ability might be enhanced: 1)Improving the transduction of the physical inputs -- be they odors, light, acoustic vibrations, etc. -- into coded electrical impulses. 2)Improving the processing of the coded electrical impulses received by the brain. The difference between bat hearing and human hearing is much more a case of 2 than of 1. They have devoted huge areas of their brains to the processing of auditory information, and so their hearing provides a better 'picture' of their environment than ours does. So if we were to graft bat ears onto a human brain, we would hear relatively little difference. If we were to somehow plug all of the auditory signal processing parts of a bat's brain into the auditory stream of our brains, even our human ears could provide us with a batlike passive sonar 'picture' of our surroundings.

Thank you for the clear explanation. Some people say that the intellectual capacity of the human brain might some day be artificially enhanced so I wondered if the same would be true of our senses.

I have heard of cochlear implants but I had no idea so much progress had been made with vision loss. Don't know where I've been.

[whichphilosophy]

It looks like I'm the only one on duty right now. Hopefully I can help.

Let's see if I understand your question. You seem to be asking whether the brain would be capable of interpreting electrical signals other than those normally provided by its various sensory organs. This is certainly the case. As others have pointed out, various sensory prostheses have been successfully implanted in people. Cochlear implants have provided hearing to tens of thousands of otherwise deaf people, and, while still mostly in experimental settings, light-sensing implants have restored rudimentary vision to blind people.

The development of the visual system depends very much upon a type of spontaneous electrical input that it receives from the retina. Therefore, those parts of the brain that construct our visual experience are shaped by and 'customized' for the type of input provided by our retinas. Were you to attach some sort of higher resolution 'supereye' to the visual inputs of our brain, I would think it unlikely that the brain could extract much additional information. The visual system retains a pretty impressive degree of plasticity even into adulthood, though, so I could imagine it adapting to utilize at least some of the additional information it is receiving. Take that as the somewhat informed intuition that it really is, though. The same principles are at work in the case that we would try to 'soup up' the auditory system, but please allow me to make an additional point. There are at least two ways that a sensory ability might be enhanced: 1)Improving the transduction of the physical inputs -- be they odors, light, acoustic vibrations, etc. -- into coded electrical impulses. 2)Improving the processing of the coded electrical impulses received by the brain. The difference between bat hearing and human hearing is much more a case of 2 than of 1. They have devoted huge areas of their brains to the processing of auditory information, and so their hearing provides a better 'picture' of their environment than ours does. So if we were to graft bat ears onto a human brain, we would hear relatively little difference. If we were to somehow plug all of the auditory signal processing parts of a bat's brain into the auditory stream of our brains, even our human ears could provide us with a batlike passive sonar 'picture' of our surroundings.

As a complete ignoranus of the subject I think nonetheless, neuroscience is a science to shape the future alongside medicine. I did see a program about a scientist who has been sucessfully restoring site with a contraversial process of wiring up the brain to a mini camera. I didn't have a note book at the time and missed this (National Geographic next week).

As it's successfully mapped the brain it's a start. I'm sure that this may lead to treatments on paralysis resulting from broken spines and controlling artifical limbs so as they can be operated like an existing limb.

Some sugest that neuroscience is sort of replacing the soul (which it neither disproves or proves exists). I don't see the intent here (not meaning to open another thread) but this is more fit as a new (super) genius science of mechanical operations that through discoveries will restore damaged sensory or physical abilities, or in some cases restore them for the first time.

In some cases we can say that science fiction will be come and in some cases has already come, .........well science.

[Schneibster]

It looks like I'm the only one on duty right now. Hopefully I can help.I find this subject endlessly fascinating and would like to make some comments from a signal transmission and data processing point of view. I'd welcome the input of someone with experience in this field to help me mold my opinions in this area. I'll presume upon your kindness to the extent of this post. Thanks in advance.

I'm curious to know if the human brain is specifically wired to process information just from the sensory tools (eyes, ears, nose, etc) of the human body.Let's see if I understand your question. You seem to be asking whether the brain would be capable of interpreting electrical signals other than those normally provided by its various sensory organs. This is certainly the case. As others have pointed out, various sensory prostheses have been successfully implanted in people. Cochlear implants have provided hearing to tens of thousands of otherwise deaf people, and, while still mostly in experimental settings, light-sensing implants have restored rudimentary vision to blind people.My understanding is that the brain (the visual cortex) is specifically wired to detect patterns within the visual field. These patterns include (but certainly are not limited to): a vertical edge; a horizontal edge; a diagonal edge; a corner. These are patterns of retinal activity and relative inactivity that are present in "patches" that are arbitrarily imposed on the field of view. It is my understanding that these mechanisms are "hard wired," i.e. these nerve pathways are not "learned" as a result of environmental input, but are developed in a highly predictable fashion that varies little from person to person, and (unless I have grossly misunderstood) is common to at least all mammals and may even be common to more than that.

There are higher-level pattern recognition entities as well, which can recognize the lower-level patterns when they are in motion across the patch, or across the field of view, and this implies that there is a certain amount of "buffer space" built in to this processing area, since detection of motion requires comparison of pictures from the past with pictures of the present.

Now I'd like to investigate the communications protocol used by the human nervous system. "Protocol" is a signal processing technical term. It requires the definition of several ancillary concepts in order to be understood. The first is "message." This is the objective information content which is to be transmitted. The second is a pair: "source" and "destination." The source is the point of origin of the message (note: not necessarily of the origin of the information!); the destination is the point of reception of the message (note: not necessarily where the message will be processed or acted upon!). The third is "encoding." The encoding of a message is the previously agreed upon manner in which the information to be sent will be represented in the protocol. So, a protocol involves the identification of the sender, the identification of the receiver, the encoding of the message, and one more thing: identification of the beginning and end of the message. Protocols can also be "layered," which means that a complete message is re-encoded in a different protocol and encapsulated with addressing (source and destination) and beginning and ending information. This allows the transmission of messages on networks that may not all use the same protocol.

When the action potential is transmitting the impulse along an axon, the source and destination are obvious; however, when the message is being transmitted across a synaptic gap between the terminal buttons of the axon of a source neuron and the dendrites of a destination neuron, the source of the message is by no means clear to any further neuron that might receive the message from the destination neuron's axon (assuming that the destination neuron processes the incoming message as exceeding the threshold necessary to alter its behavior).

The encoding of the message is simple: the rate of signals on the axon. It's very important to understand that, unlike in digital electronics, where a single fire/don't fire decision is made per input cycle, the nervous system uses various rates to indicate messages; there is an "idle" rate that indicates that there is currently no event occurring, and various higher rates that are interpreted as intensities of the event that particular neuron is associated with. This results in a very different type of dynamic response than major communications networks, including both computer and voice. The only thing that comes close to it is "traffic analysis," a type of intelligence gathering in which the frequency of calls and their destinations is used to evaluate enemy response to information when the content of the calls cannot be monitored. We simply do not engineer our networks this way.

Similarly, as a result of this unique architecture, there is no real identifiable "beginning" or "ending" to a message. Rather, we gradually (gradually that is on a per-signal basis; it takes perhaps several milliseconds for us to begin to react to a stimulus) become aware of a condition and react to it, rather than receiving a message and reacting only when it is completely understood. For obvious reasons, this is a far more successful strategy for survival, but it can lead to false reactions that can then be exploited by predators or competitors. Luckily for us, our extensive reportoire of actions renders us dangerous prey at best, and fatal prey most often.

So, as a result, we have to consider exactly how our senses operate, and how that is encoded into nerve impulses and delivered to the brain, to give a good answer to easychair's question. We also need to see how these mechanisms differ in different animals.

Sight is delivered from the retina, which are complex in and of themselves; there is not merely direct detection of incident photons, but cross-linking that increases the sensitivity without decreasing the signal-to-noise ratio in a manner that has only recently become understood by signal processing equipment designers. Once the ganglia are involved, the signals (after mediation to improve their characteristics) are propagated into action potentials and sent along the axons to the brain.

This process is essentially the same for all sighted animals. The details of the retinal preprocessing may vary; but essentially they all do the same. Here is something to consider though: even if you received eyes from another human, it is extremely unlikely that you would be able to use them without extensive retraining. The pattern of retina cannot be the same, nor can the attachments of ganglia to the optic nerve, or the termini of the axons into the lateral geniculate nucleus. Thus, babies are not born able to see- they must begin to associate the nervous input from their eyes with stimuli, then they can see. You would go through the same process- and it might even be worse, since your pattern of retinal ganglial axons would already have established sight for you. You would see flashes in various places on your visual field without association, rhyme, or reason.

Differences between animals include the fact that only humans and other great apes have tricolor vision- the remainder of the animal world has bicolor vision at best, they are lacking the red cones. However, some animals have an incredibly high rod density; cats for instance can see much more detailed images than we can, but they cannot see the color detail we can. Nor is their total resolution at the center of the field of view any better than ours; its just that they have more detail elsewhere than in the center than we do. I don't have any information on other animals; anyone who wants to dig it up is more than welcome.

If it were possible to isolate a human brain in a chemical soup and wire it for sight, sound, and so on, could the brain process input that went beyond the limits of natural human sensory organs? Could it see like an eagle,The development of the visual system depends very much upon a type of spontaneous electrical input that it receives from the retina. Therefore, those parts of the brain that construct our visual experience are shaped by and 'customized' for the type of input provided by our retinas. Were you to attach some sort of higher resolution 'supereye' to the visual inputs of our brain, I would think it unlikely that the brain could extract much additional information. The visual system retains a pretty impressive degree of plasticity even into adulthood, though, so I could imagine it adapting to utilize at least some of the additional information it is receiving. Take that as the somewhat informed intuition that it really is, though. My impression is that the density of human resolution is one of the greatest around, at the center of our field of view. I think that what an eagle has that we do not is a more powerful lens and a differently constructed eye. IIRC, they do not see nearly as well as we do close up; but they can see the movements of a small prey animal from hundreds or thousands of feet up in the sky. I suspect based simply on relative size that we could process the information from more than just two eagle eyes, but I do not know for sure. I very strongly suspect that we could learn to process the information from two of them, but again I cannot be too sure, and I would be surprised if it were easy, or if some kind of interface equipment would not be needed to translate the signals the eagle's ganglia uses into what would be appropriate for us.

hear like a bat, etc., or would it short circuit, for lack of a better term?The same principles are at work in the case that we would try to 'soup up' the auditory system, but please allow me to make an additional point. There are at least two ways that a sensory ability might be enhanced: 1)Improving the transduction of the physical inputs -- be they odors, light, acoustic vibrations, etc. -- into coded electrical impulses. 2)Improving the processing of the coded electrical impulses received by the brain. The difference between bat hearing and human hearing is much more a case of 2 than of 1. They have devoted huge areas of their brains to the processing of auditory information, and so their hearing provides a better 'picture' of their environment than ours does. So if we were to graft bat ears onto a human brain, we would hear relatively little difference. If we were to somehow plug all of the auditory signal processing parts of a bat's brain into the auditory stream of our brains, even our human ears could provide us with a batlike passive sonar 'picture' of our surroundings.This agrees closely with my knowledge of echolocation in cetaceans. Extensive studies have shown that this is not merely a case of more sensitive hearing, but also more sensitive distinction of the directionality of an incoming sound. Their time sense is much more sensitive than ours. In addition, they have multiple pathways for the sound, and can both hear and echolocate at the same time, using the same equipment. Finally, the signals are processed in a center we lack, where the images that are formed from the incoming information are formed. It works much like our visual cortex, but forms three-dimensional patterns instead of two-dimensional that are transformed in processing into binocular 3-d vision. Their sense of their position, and the positions of objects they echolocate around them in relation to them and to each other is far more comprehensive and accurate than ours. So its unlikely that we could do what they do, even if we had their transducers; we'd need extra equipment in our brains.