두뇌 매핑 작동 방식

인간의 뇌 는 1,000억 개의 뉴런과 지지 세포 로 이루어진 매듭입니다 . 우리는 그곳에 평생의 추억 을 저장할 수 있습니다 . 소네트를 쓰고 비행기 를 만드는 데 사용할 수 있습니다 . 물론, 코끼리의 뇌 는 더 크고, 더 무겁고, 더 많은 뉴런을 가지고 있지만, 코끼리도 우리의 능력이 부족합니다. 궁금해? 과학자들은 확실합니다. 이것이 그들이 완료하는 데 수십 년이 걸릴 수 있는 상당한 프로젝트인 인간 두뇌를 매핑하는 이유 중 하나입니다.

뇌 지도 작성은 뇌의 구조를 기능과 연관시키거나 어떤 부분이 우리에게 특정 능력을 부여하는지 찾으려고 시도합니다. 예를 들어, 우리 뇌의 어떤 부분이 창의적이거나 논리적이게 합니까? 이것을 기능의 현지화 라고 합니다 .

뇌 기능 매핑에서 과학자들은 다양한 작업을 수행하는 뇌를 관찰하기 위해 이미징을 사용합니다. 텍사스 대학교 샌안토니오의 신경생물학자인 Charles Wilson은 기능의 국소화를 다음과 같이 설명합니다.

두뇌 매핑은 또한 외부에서 내부를 봅니다. 예를 들어 학습 및 노화 과정 을 통해 두뇌가 물리적으로 어떻게 변화하는지 연구하여 환경이 두뇌 구조를 어떻게 변화시키는지 조사합니다 . 뇌 지도 작성은 또한 정신 질환 및 기타 뇌 질환 동안 뇌에서 물리적으로 무엇이 잘못되었는지 조사합니다.

마지막으로, 뇌 지도 작성은 뇌 구조에 대한 철저한 그림을 제공하는 것을 목표로 합니다. Google 어스 는 지구의 위성 이미지를 보여주고 대륙, 국가, 주, 도시, 고속도로, 거리 및 건물을 확대합니다. 우리 뇌의 완전한 구조 지도도 비슷할 수 있습니다. 그것은 우리의 전체 두뇌를 보여줄 수 있습니다. 모든 영역, 기능 엽, 특수 센터, 뇌 부분, 뉴런 회로, 단일 뉴런, 뉴런 사이의 접합부, 그리고 마지막으로 뉴런 부분을 연결하는 두꺼운 뉴런 "다발". 과학자들은 여전히 ​​이 거대한 지도를 형성할 수 있는 부분을 개발하고 있습니다.

브레인 매핑은 다양한 도구 모음입니다. 연구원은 뇌의 이미지를 수집하고 그 이미지를 데이터로 변환한 다음 해당 데이터를 사용하여 뇌가 발달함에 따라 어떤 일이 발생하는지 분석해야 합니다.

연구자들이 뇌를 매핑하는 방법을 알아보려면 계속 읽으십시오.

내용물

1. 뇌 매핑 기술 및 방법
2. 두뇌 매핑의 사용
3. Brain Atlas: 뇌 지도를 사용하는 방법
4. 완전한 두뇌 지도

과학자들은 뇌의 구조와 기능을 연구하기 위해 많은 방법을 사용합니다. 건강한 뇌의 사진을 찍어 병든 뇌와 비교합니다. 또한, 그들은 인간, 영장류 및 작은 포유류의 뇌를 조사하고 무척추 동물의 더 작은 신경계가 어떻게 작동하는지 이해하려고 노력합니다. 현미경 수준에서 그들은 또한 뉴런을 검사합니다.

다음은 뇌 지도 작성에 사용되는 몇 가지 도구입니다. 이러한 기술은 뇌의 이미지를 촬영합니다.

다음 기술은 뇌 활동을 검사합니다.

새로운 방법을 통해 연구자들은 손상되지 않은 뇌에서 뉴런 간의 모든 연결을 볼 수 있습니다. 이 연구 분야를 연결체( connectomics)라고 합니다. 뇌의 "배선 다이어그램"을 코넥톰이라고 합니다 [ 출처: Lichtman ]. 새로운 기술을 개발한 그룹을 이끈 하버드 생물학자인 Jeff Lichtman은 "최근까지 우리는 이러한 배선도를 얻을 희망이 없었습니다. "우리는 개별 세포를 볼 수 있었지만 한 번에 모두 볼 수는 없었습니다."

One such technique, known as Brainbow, labels every neuron in a live animal's brain a different color. By generating images of the animal's brain, scientists can see where and how neurons connect to each other. As the animal grows and ages, they can also watch how the neurons change connections.

Another technique uses the ATLUM, or automatic tape-collecting lathe ultramicrotome. This machine reads the wiring diagram of a brain. "We do something akin to paring an apple," explains Lichtman. "We essentially shave off a spiral cut as we rotate the brain on a lathe and put this ribbon of tissue onto a tape. We'll eventually get a hugely long tape, which is essentially the whole brain. Using an electron microscope , we will image that to see the structure of the wiring."

So far, Brainbow and the ATLUM are being used only to study animals with relatively small brains, like mice.

So, what's the point? What, if anything, can mapping accomplish? Learn what we can learn from mapping the human brain on the next page.

Can a phMRI study pain?

In a study at Britain's Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, researchers recorded images of patients' brains as their skin was burned and as the patients received increasing doses of painkiller. Pain centers in patients' brains became less active as the drug doses increased. This straightforward measure of a drug's effect in the brain may eventually be used to test psychiatric drugs [source: Matthews].

Why would scientists take on the arduous task of brain mapping? The answer is simple, says Lichtman: to understand our brains more intimately. We have never seen a diagram of how all of the neurons in the brain connect. As Jeff Lichtman puts it, "A lot of our thinking about the brain is based on incomplete knowledge of what is actually there. So we would like to see what is actually there."

The brain's wiring diagram may help us better understand how we learn and adapt, says Lichtman. "We start out being less well adapted to our environment than any other animal. By the time we're adults, we can use tools that our genetic heritage couldn't possibly have taught our nervous system to use -- like iPods. No other animal can do that. During our development, we must wire ourselves to [be able to] use these machines."

Brain mapping is also of practical use to doctors. Neurosurgeons use brain mapping to plan safer surgeries. One treatment for epilepsy, for example, removes the affected part of the brain. Using functional MRI and EEG, surgeons can locate the seizure center in a patient's brain -- as well as areas that are active during speaking and moving -- down to the millimeter. These images tell doctors what to leave and what to cut out.

Brain imaging is not only used in treatment. It is used to diagnose neurodegenerative diseases like Parkinson's and Alzheimer's [source: Wilson]. Using tagging techniques like PET, doctors look for drops in certain brain chemicals, or they may use MRI to examine shrinkages in areas show tissue loss. Over time, doctors can map what the brain looks like as diseases progress or as treatments work [source: Institute for Neurodegenerative Disorders].

Developmental disorders like autism may have a structural basis in the brain. Lichtman points out that autism is thought to involve a series of wrong connections between neurons. By applying Brainbow to a mouse with autism, researchers might see the wiring diagram evolve to find out how, when and if the wiring goes wrong.

Scientists have also sought to illustrate the effects of various mental illnesses in the brain, with some success. Brain imaging on these patients revealed structural abnormalities. For example, structural MRI has shown that schizophrenic patients lose matter in the temporal and prefrontal cortex over time [Source: Rapoport]. These findings have yet to lead to treatments.

Panic disorder , bipolar disorder , depression , anxiety, eating disorders and more are being examined using different brain imaging techniques, but how do we interpret scientists' findings? More importantly, where can we see them? Find out on the next page.

Sarcasm Mapped. Consciousness Still Elusive.

Doctors and scientists have learned more from brain mapping than this article can cover. Here are two highlights:

• Sarcasm: We detect sarcasm using a brain region called the right parahippocampal gyrus. Researchers discovered this using functional MRI on patients with deterioration in that region and have lost all sense of sarcasm [source: Hurley].
• Consciousness: According to Rodolfo Llinas of New York University, we can divide the brain into a synchronization center deep in the brain and neuron loops that give us higher thought. We feel conscious when the center keeps the loops working in harmony. But if either part is damaged, we may lose some or all consciousness, says Nicholas Schiff at Cornell University's Weill Medical College. This may explain why patients with no outward signs of consciousness for years may show completely normal brain activity in response to a familiar voice. They have loops working in isolation, like the neural networks that process language [source: Zimmer].

Neuroinformatics places all the data we have on the brain on the Internet in usable form. The data include images, models of neuron behavior and maps of the genes that are "turned on" in different brain regions. By making the data sharable and searchable, brain researchers can piggyback off of one another's studies and discover more.

Engineers are writing software to help brain researchers share and compare data. Software now analyzes, for instance, whether MRIs of Alzheimer's patients with different brain sizes and shapes have similar brain features. Are men with a certain brain architecture predisposed to bipolar disorder? This question, and many others, may one day be answered by computer programs that re-analyze images of past patients rather than by studying new ones.

Here are examples of brain atlases that researchers can mine for answers:

Images aren't the only source of information. Here are examples of databases brain researchers use:

Now that we can map the human brain, how far have we gotten? Are we done yet? Are we even close? Find out on the next page.

After imaging the brains of populations large enough to generate statistics, researchers have made sophisticated brain maps. There are maps to illustrate where we lose brain volume as we age, as AIDS progresses and as we use methamphetamines.

What would a complete map of the human brain look like? That depends on your interests. If you thirst to know the brain's structure, you might want to see that hypothetical Google Earth version that can begin with a picture of our cortex and zoom in to neuron number 888,898,432,857.

This complete, Google Earth type of map is stalled at many points. One such point is the imaging of all of the human brain's neurons and their connections. Even getting this data in the mouse is painstaking, says Harvard biologist Jeff Lichtman. At the rate the ATLUM and an electron microscope are now working, getting a map of all the interconnected neurons in the mouse brain would take 200,000 weeks, Lichtman estimates. The data would be "bigger than all the data on the Internet -- bigger than all the data in all the libraries in the world," he says. "At the moment, the kind of storage that's possible on computers is not quite up to task." The only "brain" for which we have a complete map of interconnecting neurons belongs to C. elegans, "a worm that's a millimeter long and has 300 nerve cells," says Lichtman.

Again, your definition of a complete brain map depends on your interests. If you're a neuropsychiatrist, for example, a complete map of the brain might be a time-lapse image showing how bipolar disorder unfolds in the brain from birth to the first symptom and what lithium does to stop the process.

That might not be enough for you. You might want to know the function of the brain's every last inch. Unfortunately, that's impossible. We can't capture functions that happen too quickly or too slowly, says neurobiologist Charles Wilson. Other processes take a lifetime. No imaging study has followed someone from birth to death . "No method that we know of handles every time of interest. No method we know of handles more than a tiny piece of it," says Wilson. At this point, Lichtman says there is no current effort underway to integrate all of these maps into one.

But there's no fundamental reason why we can't eventually have any - or all -- of these maps, says Wilson. "The problems are all practical technology problems that can be overcome. As with any map, if you start with a crude map, it's better than no map. And you don't need a new map. You just add information to the old map to make it more refined. We aren't going to wake up one day and have this. We are going to add a little today, a little tomorrow, and at some point, we are going to say, 'Wow, this is starting to look pretty good.'"

For more information on the process of brain mapping, take a look at the next page.

You Use It All

It is a myth that we use only 10 percent of our brains. We use it all. Brain images have collectively documented activity in all parts. What's more, damage to a small area can wipe out major abilities. Read more about the 10 percent brain myth on professor Eric Chudler's website at the University of Washington.

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