That's right, this summer I finally nabbed a summer research position! Instead of spending my summer working at a cashier at a grocery store, I'll be out doing science! I really am beyond thrilled. In any case, I thought this research opportunity would be the perfect chance to return to my blogging. I went on an extended hiatus this year thanks to an over-loaded schedule (18 hours plus lab!) and a dearth of creativity. But now I'm back and pumped to share my exploits in the wonderful world of neuroscience.
Just so this entry isn't purely an update on my life, I do have something to share as well. It's a little program called the game of life. It was created by John Conway and relies on 4 simple rules.
1. Any live cell with fewer than two live neighbors dies, due to "loneliness."
2. Any live cell with two or three live neighbors lives onto the next generation.
3. Any live cell with exactly three live neighbors dies, due to "overcrowding."
4. Any dead cell with exactly three live neighbors becomes a live cell through "reproduction."
Although the rules seem incredibly simplistic, they create the building blocks to impressively complex systems. Here's a little taste:
Clearly, certain starting configurations give rise to highly complicated systems. I argue that this is similar to the direction we should be looking to in neural modeling. We know a single neuron receives input from its neighbors and depending on that input, sends a signal of its own. This is very much like the cells in the game of life which change or 'fire' depending on how their neighbors are acting.
While you can't draw an exact 1:1 correlation between the two systems, it still shares a property of emergence whereby cells flickering on and off create complex, interacting grids with an unique output. I don't know if anyone has pursued this kind of modeling in the years since the Game of Life was first developed, but I'd be curious to hear what my readers have to say about this.
And for those who can't get enough of the crazy constructs created in the Game of Life, for you:
I think to understand how the brain works, there are multiple levels of complexity that you have to look at, just like with conway's game of life.
ReplyDeleteAt the very bottom is the biochemistry - the cell signalling as mediated by neurotransmitters and receptors. Signal transduction, protein expression, that sort of thing. These are studied mostly with cell cultures, and this level of research (at least theoretically) produces pharmaceuticals that modulate neural function chemically.
The next level up is neuronal circuits, for example, the long term potentiation circuits in the hippocampus, or the association circuits in the cerebellum. These are studied with electrode recordings in slices of brain tissue, or by mapping anterograde or retrograde cytoplasmic transport along the axons. the latest research has been genetically modifying neurons to express different colours of fluorescent protein in vivo, then suspending the tissue in a gel matrix, digesting away the irrelevent tissue, and then using confocal microscopy to trace the remaining pathways. There's been a lot of work in understanding the regular columnar structure of the neocortex, whereas the deeper brain areas are much harder to map because they are not regular.
The next level up that i know of is a lot more anatomical and has to do with processing pathways. extensive work has been done with the visual systems of cats and other mammals where the architecture of the neocortex has been mapped functionally. For example, it is known that there are rows and rows of columns of cortex in V1 that detect differently oriented edges, and output from these edge detectors feed corner detectors, which feed form detectors, and so forth, up the visual processing pathway. Understanding these pathways explains a lot of cases of visual agnosia, and and we start getting into the realm of clinical psychology.
Further up the scale we get into fmri studies which ask questions like, "what parts of the brain are active when we solve these problems", and so forth. these are looking at swaths of brain neuronal activation or depression so big that they require alterations in blood flow.
The next level up that i know of (and there probably are levels in between that i'm not aware of) starts to get into cognitive psychology. at this point you're dealing with concepts like consciousness, attention, memory, motivation, etc: phenomena that require coordinated actions of entire systems of the brain. there's a lot of psychological theories involved at this level, and a lot of research is work that attempt to reconcile psychological theories made by the likes of William James with modern neuroimaging methods.
The next level up, at the upper end of cognitive psychology, you start getting into philosophical questions like what wisdom is, what intelligence is, what happiness is, and so forth. There are a ton of great books that explore these issues, and as you can imagine they get really complex, very difficult to test, and are extremely powerful. the theories i found here inform my decision making on a daily basis!