Our brains gives us the power to speak, imagine and solve problems. It's truly an amazing organ. See pictures of the human brain on the next few pages to learn about its structure, parts and what happens when things go wrong in the brain.
The human brain isn't the prettiest of sights. It's made of approximately 100 billion nerve cells called neurons. The cortex, or outer covering, can be seen here, and is folded to allow the large surface area of the brain to fit in the skull.
The brain has been an area of study for quite some time. In this photo, doctors examine the brain of assassinated Russian revolutionary Leon Trotsky in 1940. See the brain that started it all next.
The study of phrenology (the brain and mind) is said to have begun with this brain. It belonged to a man called Leborgne who suffered from inability to diction because of a brain lesion. He was treated by Paul Broca (1824-1880). The brain can be found at the Dupuytren museum in Paris. The next human brain is also on public display.
This brain was provided by an anonymous donor for The Real Brain exhibit in Bristol, England. The average human brain is about 2 percent of body weight and is typically beige, pink and off-white in color. See how the brain fits in the skull next.
MRI scans make the brain visible underneath the eight bones in the skull that protect it. These scans have taught us much about the brain and can determine problems such as stroke, brain infection, tumors and multiple sclerosis.
There are four main lobes on the exterior of the brain: frontal (thoughts), temporal (smell and sound), parietal (sense processing) and occipital (sight). See a colored MRI scan of the brain next to learn more.
Here is a colored MRI scan of the brain, with the brain stem in the lower right in blue. The brain stem regulates the central nervous system, sleep cycles and cardiac and respiratory function. See a CAT scan brain image next.
CAT scans form a full three-dimensional computer model by using X-ray detectors that revolve around the body, or the brain in this case. See what the brain looks like with a CT scan on the next page.
CT scans provide a view of internal organs, bones, soft tissue and blood vessels. They're commonly used with head injuries, aneurysms and bleeding within the brain. Take a look at brain activity next.
All the action in your brain occurs at synapses, where electrical pulses carrying messages leap across gaps between cells. Here is a brain scan comparison of this activity. The image on the right represents the scan of someone with memory loss. The red color shows maximum healthy blood flow. See what parts of the brain this activity is occurring in next.
Here is an underside view of the brain showing lobes and also the pons that relays brain signals, the cerebellum that handles motor control and the olfactory bulb that assists in the perception of odors.
If you were to slice the brain in half, you would see these internal parts. The cingulate sulcus is a brain fold. The corpus callosum plays the important role of connecting the left and right cerebral hemispheres. The anterior commissure is part of the path for pain, the midbrain is a part of the central nervous system and the medula deals with autonomic, involuntary functions such as breathing and heart rate. See the next page to view a real half of a human brain.
A doctor hold the defective, right side of three-year-old Jody Miller's brain which was removed during surgery for Rasmussen's encephalitis, a condition that causes seizures every few minutes. The right side of brain typically controls the muscles on the left side of the body and is more dominant for processing music and visual imagery. The person on the next page also had brain surgery for seizures.
A diagnostic grid of electrodes was implanted in Chris Cotter's brain in 1995. Doctors determined what portion of his brain was causing his seizures by analyzing information from the grid during the episodes. They were then able to not disturb healthy parts of his brain in a future surgery. How does brain surgery actually work? Find out next.
Brain surgery involves removing the hair on the head, making a cut on the scalp and drilling one or more holes through the skull. This surgery is often necessary to treat bleeding/blood clots in the brain, tumors, skull fracture, epilepsy, pressure on the brain or the condition on the next page.
Here a brain scan reveals brain cancer. Tumors, such as the one in blue above, can be without cancereous cells or malignant. Symptoms of brain cancer might include headaches, nausea and problems with walking, balance, thinking and muscle spasms or numbness. Next, see what might be implanted in the brain during surgery.
An implantable deep brain stimulation device delivers carefully controlled electrical pulses to precisely targeted areas of the brain involved in motor control. It can reduce muscle tremors and restore control over fine movements for those with Parkinson's Disease. Brain surgery might also help the next condition.
Adi Roche with Vitali and Tatiana Prokopenko and daughter Sasha in Gomel, Belarus. Sasha has acute hydrocephalus, more commonly known as fluid on the brain. The defect was caused by the Chernobyl nuclear power station explosion in northern Ukraine. Treatments can include inserting a tube into the cerebral ventricles to bypass the flow obstruction.
After brain surgery there are scars to heal. This patient has 17 stainless steel staples going up the back of his head. Learn how the medical field is improving brain surgery next.
Many brain banks around the world store human brains for research to help improve brain surgery technique and study brain disorders and conditions. Here a technician holds a specimen at the Brain Bank at Johns Hopkins. Technology is also trying to harness the power of the brain. See the next page to learn more.
This man is playing a game of pinball using his thoughts to control the paddles. Learn more about brain-computer interfaces on the next page.
Scientists demonstrate the brain-computer interface. Every time we think, move, feel or remember something, our neurons are at work. That work is carried out by small electric signals that zip from neuron to neuron. Scientists can detect those signals, interpret what they mean and use them to direct a device of some kind. See what brain neurons look like next.
Brain neurons contain a cell body, an axon, or cable-like projection, and dendrites, which are nerve endings. See the different types of brain neurons next.
Neurons have different shapes depending on their functions. Interneurons carry information between motor and sensory neurons. Sensory neurons carry information to the central nervous system. Motoneurons carry signals from the central nervous system to the muscles, skin, and glands and pyramidal neurons are involved with motor control and cognitive ability. To learn more about the brain, check out our Brain & Central Nervous System articles.