Brain activity with 5 senses removed

[Mr Skeptic]

Not really. There's at least sensors for pressure, hot, cold, any light, redish light, greenish light, bluish light, and I think there are several more sensors for taste and smell each.

[dichotomy]

Not really. There's at least sensors for pressure, hot, cold, any light, redish light, greenish light, bluish light, and I think there are several more sensors for taste and smell each.

 

Hi Skeptic,

are these solely human sensors? Or are you covering a broader biological group here?

 

I'm interested to hear just how many different human sensors have been identified to date.

It seems to me, after reading CDawin's post, that there is 1. chemo-reception, 2. sight, 3. vibration.

 

XTC's 'senses working overtime' might have to be changed to, "I've got 1,2,3 senses working overtime"

[tvp45]

Then maybe you can walk across a tightrope without falling, without any practice? Because your sense of balance is so fine tuned?

 

 

 

 

So, you are saying in reality there are only three senses? Due to the type of receptors that are used for each sense? Which is balance related to? I'd guess touch?

 

Cheers.

 

No, the skill of balance is learned, just as the skill of interpreting sounds is learned. The sense of balance is innate as is the sense of hearing. Both involve the same kinds of inputs to the same organ and are carried along the same nerve. The actual number of senses remains up in the air, but more than five is over a hundred years old in neurology.

[dichotomy]

No, the skill of balance is learned, just as the skill of interpreting sounds is learned. The sense of balance is innate as is the sense of hearing. Both involve the same kinds of inputs to the same organ and are carried along the same nerve. The actual number of senses remains up in the air, but more than five is over a hundred years old in neurology.

 

The obvious difference between hearing and balance is that we don’t practice hearing, its automatic. But we do practice balance. Balance seems to be a developed skill that relies on the other senses for its very existence; hearing is an automatic sense that responds to vibrations. What I’m getting at is that the 5 senses (or is it really 3 senses) are central to any other ‘sense’ existing. Is this correct?

If we were born into and lived in zero gravity space (no land horizon to be seen), would our “sense” of balance even develop? Our senses of sight, sound, touch, smell and taste would, because they are indeed innate.

[iNow]

If we were born into and lived in zero gravity space (no land horizon to be seen), would our “sense” of balance even develop?

 

Yes, but the concept of balance itself would be vastly different. The balance would develop, but would not be equipped at all to deal with Earth's gravity. This does not mean, however, that it's not balance in it's given context.

[dichotomy]

Yes, but the concept of balance itself would be vastly different. The balance would develop, but would not be equipped at all to deal with Earth's gravity. This does not mean, however, that it's not balance in it's given context.

 

Yes, then you may agree that balance is "developed", as you state, and not an automatic sense in the same way hearing is. I'm still not sure that balance is relevant or indeed would develop at all in zero G. A 'sense' of direction would be useful, but direction doesn't necessarily need balance, does it? Direction only needs reference points, like an object floating in front of you that you reach out for?

 

Of course, this implies that some senses are automatic (ie. the 5 senses) and some are only functional if they are practiced into being (and eventually becoming automatic, like riding a bike), such as balance? So shouldn't senses be defined as being automatic perceptions and not practiced/learned ones?

[iNow]

I'm still not sure that balance is relevant or indeed would develop at all in zero G. A 'sense' of direction would be useful, but direction doesn't necessarily need balance, does it?

Yes, if you are rotating and have no cues to air resistance then you need the balance system to sense direction.

 

You should probably try to learn more about balance before asking such quesitons. It has more to do with fluid in the inner ear and how that fluid presses against tiny little hairs called cilia resulting in a neural cascade to our autonomic systems... It's much more than what allows us to walk across a narrow beam, it's also what gives us bed spins after drinking too much alcohol.

[Glider]

No, the skill of balance is learned, just as the skill of interpreting sounds is learned. The sense of balance is innate as is the sense of hearing. Both involve the same kinds of inputs to the same organ and are carried along the same nerve.

True, but it's not quite as simple as just being born with the necessary hardware. We also need to develop the cortical structures required to interpret the signals.

 

For example, we're all born with eyes and a primary visual cortex, but if the visual cortex is deprived of signals from the eyes for the first few months of life, it never develops the ability to interpret those signals and the individual will be blind.

 

This was shown by Hubel and Wiesel in the 60s. They sutured kittens eyelids closed in one eye (those bastards!) and after three months, removed the sutures and and found that although the eye and cortex were intact, the animals remained blind in the eye that had been closed for the first three months. The majority of cells in the striate cortex only responded to signals from the eye that had been left open.

 

This effect is not seen in adult cats, which indicates a 'sensitive' period of neural plasticity in which incoming signals from sense organs are required for the relevant cortical areas to develop the ability to interpret them.

 

Here is Torsten Wiesel's Nobel lecture (1981) entitled 'THE POSTNATAL DEVELOPMENT OF THE VISUAL CORTEX AND THE INFLUENCE OF ENVIRONMENT'.

[tvp45]

True, but it's not quite as simple as just being born with the necessary hardware. We also need to develop the cortical structures required to interpret the signals.

 

For example, we're all born with eyes and a primary visual cortex, but if the visual cortex is deprived of signals from the eyes for the first few months of life, it never develops the ability to interpret those signals and the individual will be blind.

 

This was shown by Hubel and Wiesel in the 60s. They sutured kittens eyelids closed in one eye (those bastards!) and after three months, removed the sutures and and found that although the eye and cortex were intact, the animals remained blind in the eye that had been closed for the first three months. The majority of cells in the striate cortex only responded to signals from the eye that had been left open.

 

This effect is not seen in adult cats, which indicates a 'sensitive' period of neural plasticity in which incoming signals from sense organs are required for the relevant cortical areas to develop the ability to interpret them.

 

Here is Torsten Wiesel's Nobel lecture (1981) entitled 'THE POSTNATAL DEVELOPMENT OF THE VISUAL CORTEX AND THE INFLUENCE OF ENVIRONMENT'.

 

That's absolutely true. There have been some studies of how, in people born blind, the visual cortex is "high-jacked" by another sensory input. But, that's not the point of my argument. My point is that the sense of balance is as innate as the sense of hearing is as innate as the sense of vision. All require cortical development.

[dichotomy]

True, but it's not quite as simple as just being born with the necessary hardware. We also need to develop the cortical structures required to interpret the signals.

 

For example, we're all born with eyes and a primary visual cortex, but if the visual cortex is deprived of signals from the eyes for the first few months of life, it never develops the ability to interpret those signals and the individual will be blind.

 

This was shown by Hubel and Wiesel in the 60s. They sutured kittens eyelids closed in one eye (those bastards!) and after three months, removed the sutures and and found that although the eye and cortex were intact, the animals remained blind in the eye that had been closed for the first three months. The majority of cells in the striate cortex only responded to signals from the eye that had been left open.

 

This effect is not seen in adult cats, which indicates a 'sensitive' period of neural plasticity in which incoming signals from sense organs are required for the relevant cortical areas to develop the ability to interpret them.

 

Here is Torsten Wiesel's Nobel lecture (1981) entitled 'THE POSTNATAL DEVELOPMENT OF THE VISUAL CORTEX AND THE INFLUENCE OF ENVIRONMENT'.

 

You have convinced me that balance is a sense.

I didn't realize that sight could be so easily disabled by simply blocking perfectly good vision for a few months. I would have thought that after a few more months, or years, of the 'blind fold' being removed it would become operational again.

 

Thanks for the link.

 

You should probably try to learn more about balance before asking such quesitons.

 

Oh, I do. I just like asking the questions first!

[Glider]

That's absolutely true. There have been some studies of how, in people born blind, the visual cortex is "high-jacked" by another sensory input. But, that's not the point of my argument. My point is that the sense of balance is as innate as the sense of hearing is as innate as the sense of vision. All require cortical development.

Ah, I see. Well, that's true. The senses are innate insofar as we are all born with the kit required to see, hear, touch and so-on. A battery of different receptor types; chemo, mechano, thermo, and photo, is a part of our basic make-up so yes, your point is inarguable, senses are innate.

 

That's absolutely true. There have been some studies of how, in people born blind, the visual cortex is "high-jacked" by another sensory input. But, that's not the point of my argument. My point is that the sense of balance is as innate as the sense of hearing is as innate as the sense of vision. All require cortical development.

Ah, I see. Well, that's true. The senses are innate insofar as we are all born with the kit required to see, hear, touch and so-on. A battery of different receptor types; chemo, mechano, thermo, and photo, is a part of our basic make-up so yes, your point is inarguable, senses are innate.

 

You have convinced me that balance is a sense.

I didn't realize that sight could be so easily disabled by simply blocking perfectly good vision for a few months. I would have thought that after a few more months' date=' or years, of the 'blind fold' being removed it would become operational again.

 

Thanks for the link.[/quote']Yes, it's a bit like pre-plug and play computers. They would check for active ports on boot-up and if the thing you wanted to use wasn't already plugged in, the system would ignore that port until it was restarted.

 

In the case of the brain, the first few months of life is a period of massive neural plasticity. Pathways are formed and reinforced and unused pathways degenerate and neurons that do not find active connections undergo apoptosis. This is a very critical period in the development of the CNS, but it is temporary. If cells and pathways in the visual areas are not reinforced during this time, they will never form. Instead, as tvp45 says, the functions of those areas will be taken over by more active areas proximal to them.

[dichotomy]

In the case of the brain, the first few months of life is a period of massive neural plasticity. Pathways are formed and reinforced and unused pathways degenerate and neurons that do not find active connections undergo apoptosis. This is a very critical period in the development of the CNS, but it is temporary. If cells and pathways in the visual areas are not reinforced during this time, they will never form. Instead, as tvp45 says, the functions of those areas will be taken over by more active areas proximal to them.

 

Ok, what happens when the extreme opposite occurs, i.e. the sense in question (say sight) is overloaded with information?

 

Also, are there any promising advances with scientists working on reactivating neural plasticity in adult brains? I think my parents answer would be to eat more lambs brains.

[Glider]

Ok, what happens when the extreme opposite occurs, i.e. the sense in question (say sight) is overloaded with information?

Interesting question. I don't know of any research on that specific question. There are two possible modes for overstimulation; complexity (in the case of vision this would involve lots of motion and colour and patterns), and intensity.

 

I don't think you could possibly overload a primary sense organ with complexity. It would detect and transduce everything within its physiological capability and, conversly, fail to transduce anything outside of its range.

 

The higher areas of the CNS though would be highly stimulated. I don't think this would be a bad thing as those areas would recieve no more information than the primary tranducers could send, so they'd just be exposed to a very rich stimuli. You'd probably end up with an individual slightly more sensitive to detail (in vision or hearing) than normal.

 

That's not to say their vision or hearing would be more acute, but that the relevant sensory areas in the cortex had developed to handle more complex information. So, the individual wouldn't detect any more than anybody else, but they might [/i]notice[/i] more within it (most people actually notice, i.e. are consciously aware of, very little of what they see or hear).

 

Overloading with intensity on the other hand (very intense light or loud sounds etc.), could be bad. I think this would result in desensitisation of the primary receptor cells and the result would be that normal level stimuli would no longer be enough to trigger 'normative' responses and the senses would be dulled.

 

Also, are there any promising advances with scientists working on reactivating neural plasticity in adult brains? I think my parents answer would be to eat more lambs brains.

Yes. There's lots of research on how neural plasticity might be used to counter the effects of cerebral vascular accidents (CVAs, or 'strokes') and degenrative conditions such as Parkinson's disease which involves the degeneration of dopamine producing cells in the substantia nigra. There's also similar research in Alzheimer's. Also, there's ongoing research with the aim of finding ways of regenerating neurons damaged in spinal injuries. The spine is a part of the central nervous system (as opposed to the peripheral nervous system) and a problem is that there is a lot less nerve growth hormone (NGH) in the CNS. Peripheral nerves will regrow under the right sonditions (albeit slowly; about 1mm a month), but CNS neurons won't.

 

I don't think much of that research involves eating lamb's brains though, but I could be wrong. I haven't read the research for a while.