Saturday, April 21, 2007

Connectivity

Neural networks, both simulated in software and naturally neuronal (sorry this alliteration is horribly har- err... difficult to shake), are wicked cool. I want to attempt to apply the connectionist paradigm to a network made of real neurons. There are three significant hurdles:
  • 1) Getting the neurons to connect up where and how you want them to.
  • 2) Stimulating specific cells within the network you have built.
  • 3) Measuring the response of the network to stimuli you have provided.
If you can control a network of real cells then you have a bio-computer. Now, imagine this is possible in a microfluidic device.... then you can start to teach a mini-brain! Okay okay so this is pie-in-the-sky science, but the what-ifs keep this game exciting :D

7 comments:

marlene bowen said...

If I could understand any of what you are talking about I might make a comment! but as it is ......

Elliot said...

Can't you just put some frogspawn into a jar and wait for it to turn into a frog? Only joking, of course! Sounds interesting. How do you make neurons connect to each other (are the connecting bits called axons?)? Can you grow axons easily? Sorry, I'm talking out my arse, I know practically zero about neurophysiology. Just forget I spoke.

Natalie Andrew said...

Hi Elliot,

Errrm, no, apparently neurons (with their associated axons and dendrites) are tricky to grow. They need to be harvested from brains and cultured on a 'feeder layer' of cells that supply them with nutrients. Invertebrate neurons are easier - no myelination and they're huge - but I'm not sure how to get hold of crayfish! Once you've got happy neurons, however, the axons (outputs) and dendrites (inputs) connect of their own accord, clever little blighters.

I may well also be talking out of my arse at this point, need to keep reading :D

Elliot said...

How long can they stay viable once the inverterbrate is dead? Could you use lobsters? I'm assuming they have them on sale live over there for cookery. Would you be the one (de-)braining them?

Natalie Andrew said...

A quick search on t'internet reveals that lobster ganglia can be cultured for at least 7 weeks in the absence of the err, rest of the lobster. These are found throughout the body rather than being the brain itself though. I guess I'd have to sit a lot of animal handling courses and ethical training etc before I could do this myself. Perhaps I should take your advice and practice on one at the dinner table.

I would rather use neuronal stem cells - easy to grow (and they're just a renewable cell line so no debraining necessary) and then you can make them differentiate when ever you'd like (then they're difficult again I think). Again with the need-to-read-more.

Elliot said...

I that what you get from crayfish? Are they special in some way?

Natalie Andrew said...

Ummm, having problems with the deixis, if you mean do you get neuronal stem cells from crayfish then the answer, I think, is no. PC-12 neuronal precursor cells are derived from rat adrenal gland tumours. Since they are tumour-derived they will keep proliferating ad infinitum. The idea is to give them a hormone that transforms them into neuron-like cells - close enough to normal neurons to serve as a good model.

Is that what you meant?