Ask a Neuroscience Professor

[stormbind]

Hello Professor,

Roughly speaking, David Marr theorised that the brain's central function is statistical pattern recognition carried out in a very high-dimensional space. How many dimensions? (not a serious question)

Basic building blocks of this system are codons. Could a codon be a single cell that that fires an electric charge in the presence of certain statistical patterns? (semi-serious)

Marr and Poggio defined two high levels of understanding. Computational: The understanding of any information processing system is incomplete without insight into the problems it faces. Algorithmic: The understanding of any information processing system is incomplete without a notion of the form that possible solutions to these problems can take. Is there any viable challenge to the theory of Marr and Poggio? (very interesting)

Thank you very much!

P.S. In your opinion, what is Creativity?

 

[Rambuchan]

Thanks for your previous answers. Here's another thing I often wondered about:

Is there an explanation for the experience of déjà vu?

Sorry if it's already been asked. I did a "search thread" but it didn't come up with anything.

 

[Mark1031]

I was listening to an interview with Brenda Milner (of HM fame*) where she was discussing her estate after she dies.

Is there a reason why neuroscientists aren't more accepting of cryonics, preserving the brain in order to be awoken and repaired later? I'd think that most (successful) neursoscientists are materialists and I don't know what's wrong with the cryonics 'theory' such that it's ignored.

Well I believe that the cellular damage during freezing and thawing is still too extensive to make it useful. Plus who is going to want to bring back all these old brains assuming the technology were available.

 

[Mark1031]

@ Stormbind. I read a bit of what Marr was saying and TBH it is not my area and I don’t really understand it. I have heard him referred to in terms of reviving and formalizing some of the ideas of Hebb on how synapses change with use and how this could function to store information. He died almost 30 yrs ago.

I am going to start reading more in this area of computational neuro. For me (and I think for him) a big question is what is a neural representation? What is it about which neurons fire and how and when they fire that provides meaning. I think I have a way of directly addressing this question.

Creativity is seeing something different than 99.9% of people in the same set of information. (IMO)

 

[Mark1031]

Is there an explanation for the experience of déjà vu?

Don't know. It is an interesting question but hard to get at experimentally.

 

[Perfection]

When are we gonna be able to read people's minds?

 

[Mark1031]

When are we gonna be able to read people's minds?

To some extent people worry that neuroimaging can do that now. Not exact thoughts but if I show you images of violence and it lights up your pleasure center in the brain maybe you are a sociopath that should be locked up preventively.

 

[El_Machinae]

Well I believe that the cellular damage during freezing and thawing is still too extensive to make it useful. Plus who is going to want to bring back all these old brains assuming the technology were available.

Well, the freezing damage doesn't really matter because the information is preserved in a stable and predictable way. The cracks in the dendrites, etc., would be visible and thus you could rewire them quite easily.

It's the thawing that's the problem, and I believe that the goal is to avoid thawing until the thawing can be done safely.

But, in your opinion, the entire thing is a pipedream and obviously rediculous? I didn't know, thanks.

When are we gonna be able to read people's minds?

We need about a 100x increase in resolution and then we'd need a lot of data in order to standardize a reading to a person's specific brain. I'd expect in over 50 years, unless the technology trend continues in a Kurzweilian curve.

The main problem is that fMRI is too expensive, and so the researchers don't get as much time on the machines as people would like. We need cheaper MRIs and higher resolution MRIs.

Finally, in my opinon, the lower functions (brain stem, hormones, etc.) need to be cracked first.

 

[C~G]

Thanks for your previous answers. Here's another thing I often wondered about:

Is there an explanation for the experience of déjà vu?

Sorry if it's already been asked. I did a "search thread" but it didn't come up with anything.

I think it has to do how we process our memories and possible little glitch in it's working.

In other words when you process an experience on hand you suddenly find pieces of information that seem to suggest you have experienced something similar before. It's possible it's because your brain takes some time to process the current experience (especially if you're tired and aren't focusing) and the short time gap means that the memory is stored twice, meaning that you don't have conscious experience about the first but only the latter one which makes you believe you have experienced it before, which is kind of true...you have experienced it maybe just split of a second ago.

I get déjà vus when I'm usually tired which would seem to suggest that explanation might be correct. Then again...

Other explanation (which could also complent the first one) is that while recalling your memory you suddenly recognise similar pattern of experience from earlier life. It doesn't have to be exact even though it appears to be so, just similar kind of recognition pattern resulting from recordings of different feelings provided by senses etc. This kind of pattern recognition plays important part when it comes to memory.

But then again I'm just a layman so what I know...

 

[Birdjaguar]

When are we gonna be able to read people's minds?

My wife reads my mind all the time.

But you probably meant something more along the lines of "Hear what other people are thinking." I am not sure what "mechanism" would enable the electrical impulses and connections in my brain to be "picked up" in the brain of another, let alone be interpreted.

 

[El_Machinae]

http://www.sfn.org/am2007/

Are these being recorded, and is there a way to watch the presentations online?

On a more personal note, are you letting neuroscience friends bunk at your place for this (so they don't need a hotel)?

 

[Damnyankee]

How close do you think Man is in creating an artificial limb that can effectively interface with the brain?

 

[Ayatollah So]

I am going to start reading more in this area of computational neuro. For me (and I think for him [Marr]) a big question is what is a neural representation? What is it about which neurons fire and how and when they fire that provides meaning. I think I have a way of directly addressing this question.

Let me know if you get anywhere with this. I'm very interested in what neuro and/or psych people have to say about the semantic link between neural representations and the world outside the organism.

 

[Fifty]

Is there any diffence between the following fields, and if so, what is that difference:

1. cognitive psychology
2. cognitive neuroscience
3. cognitive science

 

[.Shane.]

Is a Doctorate's Degree prerequisite for a faculty position at a college?

I'm betting Mark answered this somewhere in this thread, but here's how it is, at least in History/Liberal arts...

At the JC/CC level, no, a PhD is not required, though a MA is. Granted for many institutions a PhD will make you a better candidate.

At the 4 year level, generally speaking, yes, a PhD is required. However many 4 year Colleges do not have this requirement as they're accredited as Colleges and not as Universities. That said, they will still very heavily prefer, if not require (it depends on the institution) a PhD.

 

[Mark1031]

http://www.sfn.org/am2007/

Are these being recorded, and is there a way to watch the presentations online?

On a more personal note, are you letting neuroscience friends bunk at your place for this (so they don't need a hotel)?

Not that I know of. You have to pay quite a lot ot attend the meeting. It would be great to have these on line but it wouldn't be free and it would cause many people not to attend the actual meeting which would be bad for the SFN.

No one stayed with me but I have had a lot of lunches and dinners and a party at my house.

How close do you think Man is in creating an artificial limb that can effectively interface with the brain?

Don't know but neural silica interface and implants is a hot area.

Is there any diffence between the following fields, and if so, what is that difference:

1. cognitive psychology
2. cognitive neuroscience
3. cognitive science

Not really. Cognitive [blank] tends to focus more on human studies with imaging and the like. Cog Sci is the name I've heard most for a department level distinction. Cog Neuro would focus more on imaging/brain mechanisms. Cog Psych more on behavior.

 

[.Shane.]

Mark,

I'm sure you've seen these super-cool images of the brain.

Other than looking super-cool, what are the practical applications of these? Will they do this to humans at some point?

 

[El_Machinae]

Have you ever tried to do a puzzle with the cardboard-side-up? I'd imagine that colour-coding the neurons is a bit like being allowed to flip the pieces over when doing a puzzle!

http://www.physorg.com/news108388589.html

LaFerla, Mathew Blurton-Jones and Tritia Yamasaki performed their experiments using a new type of genetically engineered mouse that develops brain lesions in areas designated by the scientists. For this study, they destroyed cells in the hippocampus, an area of the brain vital to memory formation and where neurons often die.

Do you know what mouse is being talked about? What's done to make it easier to target a lesion, or is the targetted lesion pre-determined (a bit like Huntington's, I guess)? I'm under the impression that a heavy portion of lesions are caused by a temporary ischemia in a targetted artery.

 

[Mark1031]

Mark,

I'm sure you've seen these super-cool images of the brain.

Other than looking super-cool, what are the practical applications of these? Will they do this to humans at some point?

They are useful for getting more precise circuit diagrams for local areas. They look cool and were done in a clever way but I think I have much cooler mice http://keepuris.wordpress.com/2007/09/01/.

There will be an explosion of new understanding of the brain in the next 5 years using various genetically modified mice. The technology it there to go in and manipulate specific discrete memories to begin to understand how the activity of neurons put together a representation of the world.

These things will not be done in humans by and large as they involve genetic manipulation of the germ line.

 

[Mark1031]

Have you ever tried to do a puzzle with the cardboard-side-up? I'd imagine that colour-coding the neurons is a bit like being allowed to flip the pieces over when doing a puzzle!

http://www.physorg.com/news108388589.html

Do you know what mouse is being talked about? What's done to make it easier to target a lesion, or is the targetted lesion pre-determined (a bit like Huntington's, I guess)? I'm under the impression that a heavy portion of lesions are caused by a temporary ischemia in a targetted artery.

The link was about autism mice. Leferla studies Alzheimers so I assume it is some mouse with the Alz lesions specifically targetted to the hippocampus.