The Thalamus - The Kernel in Your Mind

corbettw writes "This article on Yahoo Science News describes a new finding that explains how the thalamus is used by your brain to essentially boot your brain, and provide for central processing and control of all impulses going to and from the cortex. The article describes its function as an operating system, but from the description it actually seems closer to the functions of a kernel." From the article: "The finding, published last week in the journal Neuroscience, changes the way scientists understand nitric oxide's role in the brain, and it also has them rethinking the function of the thalamus, where it is released. The thalamus was thought to be a fairly primitive structure, sort of a gate that could either open and allow sensory information to stream into the cortex, the higher functioning part of the brain, or cut off the flow entirely. Godwin says the new research shows it's more accurate to think of the thalamus not as a gate but as a club bouncer, who doesn't simply allow a huge rush of people to go in or no one at all, but picks and chooses whom to let in and out. "

Comments

Re:The better question is, what do we call it?

[MillionthMonkey]

Does this mean we should call the brain the Brain/Thalamus? It's unfair to give the entire package precedence over the kernel, as one is useless without the other.

I used to study neuroscience. The thalamus is a HUGE bank of relay switches in the brain- all these trunk cables go into it from all over. Basically anything you're paying attention to involves some circuit going through the thalamus, and the way the thalamus works is what limits your ability to focus on multiple things at once. Once something becomes rote- like QWERTY typing or good guitar playing- the thalamus is no longer involved.

I have epilepsy- really bad seizures- and my brain gets really messed up on restarts because it regains function piece by piece. Occasionally I'll be totally conscious (forming some long term memories again), and watching stuff come back online- I can hear, then I can see, then I can recognize things I see, etc. There are intermediate states where I can see but not recognize things. The seizures start in the right temporal lobe, so the right hemisphere is completely screwed up, but if my left brain works I can compensate with higher functions. Usually I'm looking for water fountains because my head is really hot and sweaty after a seizure. I'll find a water fountain and think, is this a water fountain? Well it has a stream of stuff that looks drinkable... it has a thing coming out the side that you can turn... it MUST be a water fountain! I almost pissed on my wife's chair once after somehow figuring it was a toilet. But without thalamic activity I'd never be able to patch right brain functions and send sensory information to the forebrain from the left side. If I'm able to pay attention to something at all, then there is some thalamic function. Recognizing it is a different task.

The ability to form long term memories comes later and is a more distributed gradual process as areas of the cortex recover. I was in this cubicle working once... doing simple stuff like cleaning up someone's crappy code... then I started doing more mentally intense work, and I turned around after an hour or two and noticed my cubicle was a mess. Everyone said, "you had a seizure a few hours ago, don't you remember?"

Recently my brain has been passing through a metastable fugue state after really nasty seizures where I have partial function, but it's not me yet- it's like someone else. I answer yes/no questions completely differently, I don't recognize my wife, I fight with people if they get in my way, and I don't know where I'm going but I'm going somewhere, sometimes out the door. Usually no new memories are being formed; I have to go by what people tell me afterward. Apparently I'm getting better at fooling people in the fugue state because my speech in the fugue is starting to almost sound normal even though I have only partial brain function. One of these days I'm going to regain consciousness in jail.

Re:Research abstract

[mspohr]

Thanks for posting this abstract and link. Most articles in the popular press are written by idiots so it's good to go to the source.

From the abstract, it appears that the thalamus does act as a kind of "pacemaker" (or "motivator" as in R2D2).

The really important finding of the study is that this may be the path that alcohol uses to disrupt sleep.

Re:Yeesh

[Anonymous Coward]

How hard could it be to add some tracer isotopes to lithium salts, then use fMRI to see exactly what happens from start to finish?

Dead easy but not terribly useful. Watching the blinking lights on all the network cards tells you precious little about why the LAN just melted down. To be able to analyze problems, we need detailed information about how individual neurons work, how they interact with the glial cells and blood vessels, and the structure of the larger networks of neurons. Unfortunately the individual cells are fearsomely complicated, and the connection networks are even worse and change constantly. Another difficulty is that human brains have significant differences from even other mammals, so rapid progress would require a great deal of vivisection work on healthy subjects. (For some reason most potential subjects run away when you go after their skull with power tools.) This work will take a long time and cost a lot, but will eventually give solid answers about how the brain malfunctions.

As a stopgap, large genetic studies will be more fruitful. What we need is for gene sequencing to come down to the $1000/person range--and it's getting there. Then we take detailed medical histories and sequences from a hundred each of normals, bipolars, epileptics, and migraineurs. Comparing their genes will tell us which ion channels, transporters, receptors, and so forth are "hot spots". Once we know that, it's straightforward to find drugs that target just those proteins. Right now we're stuck with "dirty" drugs that madly stomp on all sorts of stuff at the same time, which means bizarre and evil side effects. (The antipsychotics and antiepileptics are notoriously dirty. The tricyclic antidepressants, which I take for chronic migraine, are only a little better.)

We're far more technologically advanced, but in all of my visits to neurologists or pdocs, I have never seen any meaningful technology in use.

Indeed. Right now the best diagnoses come from a conversation and a basic neurological exam. fMRI scans might be helpful, but the cost is very high, and it's hard to catch an intermittent event that happens the day before a migraine attack or manic episode.

Incidentally, I seem to remember that lithium acts as a sodium or potassium analog all over the body. It competes for the same transporters and ion channels, but acts just a little different. I think it also builds up in cells and changes their osmotic conditions (concentration of water versus everything else). The upshot is that it pushes many things a little out of equilibrium, putting them at new operating points where, for unclear reasons, they are less likely to oscillate.