The sophistication of our current nerve/machine technology is not refined enough to attempt this, I don't think. Perhaps replacement of many of our body parts, but not the entire thing at once.
@brain trauma: Ever heard of a bone saw? Sheesh, you don't need to shatter the head to get the brain out. Just cut the skull away piece by piece.
@seraph: I retract my previous statement, our technology is good enough. We can rebuild him, better, faster, stronger!
@Relearning: Actually, you may be surprised how easy it is for the brain to reroute nerve mappings. See the balance sensor on your tongue or the same sensor used to see.

Energy levels? What? Please stop learning science from chinese acupuncture manuals...

HAHAHA - dude you get a cell.... right then you got the molecule if you haven't heard of that.... then an atom wow you shurley havn't heard that one befor then finely we got something we call energy... what subjects did you take in high school?

Energy is the capacity to do work of a system. Taking away bits of your body does decrease the energy of your system because you are removing matter, which is directly convertible to energy, but you as a person would not feel less energetic. That is a psychological phenomenon. Entirely unrelated.

It looks like you sure as hell didn't take biology... also, I don't get to pick my classes, though biology is among those that I attend.

Energy, you say? Well, we've got thermal energy, kinetic energy, electrical energy, potential energy and more. However, none of these account for the life of a cell. Well, that assuming that the cell isn't being boiled or frozen or electrocuted or smashed with a mallet. This energy that you most likely are referring to is ATP, and it isn't just bound to your torso like electrons to a proton. It's found in every single damn cell, and they keep forming it for their entire lifespan, as long as there's oxygen and glucose available.
Long story short: Ain't no silly energy keeping you alive, it's all in the ♥♥♥♥' ATP. Which is a molecule btw.
Even shorter story: What Duh said + some more.

But anyways, as has been stated before, a human brain could (maybe) physiologically survive if disembodied and supplied with the needed resources, but psychologically? That's another matter entirely, on which i don't know crap about. I do get to have psychology later on year 3 in high school, though, but none of you can possibly care enough to wait that long.
Right now, i'm wondering why we'd even want living human brains in jars, when you could just nick some braincells from a rat or something.

There is something called "Education". Look into it. /sarcasm
Seriously, what are you talking about? A brain wouldn't need a body to survive, just use a pump(artificial heart) to deliver nutrient and oxygen enriched blood to the brain, and tada. Canned brains.

The trauma aspect does seem like a problem. If we can figure out specific nerve pathways and connections, and make a body or artificial nervous system at least that mimics a human body well enough, then a brain could think it's just going through brainbot puberty or something like that.

umm the rat is not going to comply with you and if we were to put someones' brain in a jar they (maybe) would probably understand you

Based off of my primitive knowledge of how the brain works, you wouid need some wiring to the brain to channel electrical pulses to, say, move a robotic arm, as well as a a constantly refreshing supply of blood, nutrients, etc. However, based off of how complex the whole body system is, and how little we currently know about the chemistry of the brain, artificially creating all of the the chemicals needed to trigger the basic receptors in the brain which govern normal human behavior would be pretty much impossible (we can't even make artificial blood for people, as far as I know). Therefore, you would need to do the complex operation of taking a steady supply of naturally produced blood, serotonin, opiates, cannaboids from an unfortunate human body and supplying them to the brain in regulated doses. This would sort of defeat the purpose of a disembodied brain, because you would need to keep a body with the brain, or maybe several bodies, to continue supplying it with these chemicals. This would mean no little awesome brain probes flying around in space. The blood draining would also kill people over time, so you would need a steady supply of them to keep refreshing the brain if it were going on a galactic voyage. This is makes a good use of the zombies in cortex command. Zombies have a lot of blood, come in huge numbers, and don't care about dying. They would be perfect for feeding the brain.

eventually we will be able to make all those things though. and you just need to recycle the materials, not make hundreds of donor bodies.

Erm... you can just make the mixture of nutrients artificially.
And what the hell is GloveDude on about? We know what energy is. We also know what an atom is. You, evidently, haven't the slightest infinitesimally accurate understanding of how energy works.

But draining blood and serotonin from zombies is so much more fun....

Also, how on earth do you expect to make red blood cells? We can't even make the most simple cells right now, by the time we can make red blood cells, we will be able to make computers much more complex in every way than a human brain. You also can't "recycle" blood. Red blood cells die very quickly. You could, however create sustainable red blood cells if you attached a spleen, liver, and some hemopoetic tissues, and got them to make a steady supply of red blood cells. You could regulate production with a machine that supplied these organs with hormones at regular intervals.

Imagine, a disembodied brain, with a spleen and liver attached, mounted onto a zombie torso in an astronaut suit.

You don't need red blood cells, you just need oxygen and fluid in which to pass other chemicals.

Do we really even need to do that? We have blood banks and ways to effectively oxygenate blood. That's a lot of the problem on its own.

Blood cells die, and you want the brain to be as self-sufficient as possible. They have several prototypes of oxygen-carrying fluids now. Wiki article because I'm too lazy to find scientific articles.