As the most complex object known in the entire universe, the brain is a truly amazing organ. Despite accounting for around 2 percent of our weight, it is responsible for controlling almost every aspect of our bodies.

It is made up of a staggering 86 billion nerve cells that twist and weave together to form at least 100 trillion neural connections. And yet at some point – and we’re still none the wiser how – these connections do something extraordinary and consciousness sparks into existence. The human mind is created.  

But sometimes as we develop, this complex piece of biological machinery goes awry. Normally, the outcome isn't exactly great, but due to the surprising plasticity of the brain, there are some cases in which people can adapt. Here are some of the strangest brains found in people. 

A Wrinkleless Brain 

One of the weirdest brains ever found looks so odd that you might not even recognize it as a brain. An amorphous blob of jelly, this is a human brain that lacks wrinkles.

Known technically as lissencephaly, the condition is characterized by a lack of grooves (sulci) and folds (gyri) that are normally distinctive of the human brain. It is thought to be caused by a number of different things, including viral infections of the uterus or fetus during development, insufficient blood supply to the brain during development, as well as potential genetic elements.

Those who have the condition tend to experience a range of debilitating symptoms, from muscle spasms and seizures to a range of learning disabilities. A rare condition, it frequently cuts the life tragically short, with many sufferers dying before the age of 10, although there is one extraordinary case of an adult brain with the condition found preserved and stored at the back of a cupboard at the University of Texas.

Split-Brain

During the 1900s, a treatment for a range of psychiatric conditions such as hysteria and epilepsy was to sever the main link between the two hemispheres of the brain – known as the corpus callosum – under the belief that the disorders were a result of unconventional brain wiring. This usually results in a whole host of other curious neurological effects as the two halves of the brain can no longer communicate.

There are some people who are born entirely missing the corpus callosum and seem to be none the worse for it. However, people who have these connections severed later in life, so-called “split-brain” patients, lose the ability to do tasks that require both hemispheres to work in conjunction.

This can be shown in experiments in which patients are asked to close their eyes and then say what is being held in their left hand. Sensory information is then sent from the left hand to the right side of the brain (where the object is identified), but because the speech processing center is in the left side of the brain and the connections between the two have been cut, the patient simply cannot say what they are holding. Weirder still, if the patient is then asked to draw the object with their left hand, they can do so because the right side of the brain knows what it is.

Yet people born with the corpus callosum completely missing don’t have this problem, as research shows that the brain is more flexible than we imagined and can rewire itself during development to rebuild those missing connections.

Half a Brain

While missing sections of the brain, such as the corpus callosum, is not unheard of, one 24-year-old woman from China was truly an exception. Going to the hospital after suffering from bouts of dizziness and nausea, doctors found that she was missing her entire cerebellum.

Also known as the “little brain”, it plays an important role in motor control, language, voluntary movements, and balance. In fact, this woman’s mother said that she did not learn to speak until she was six and couldn’t even walk until she was seven. Even at the age of 24, the patient reportedly had issues with balance. And no wonder, where the cerebellum usually sits was a void filled with spinal fluid instead.

Although only representing about 10 percent of the brain's volume, the cerebellum accounts for a whopping 50 percent of the organ's neurons. The fact that this woman made it to the age of 24 without any other overt signs that she was missing such an integral part of her brain is quite incredible but not unheard of. She now joins a group of just nine known people to have lived without their entire cerebellum.

There is little information on what impact missing the cerebellum has on adults because those that are without one tend to die young and the anomaly is only discovered upon autopsy. This makes the case of the young Chinese woman of intense interest, as it gives doctors an incredible insight into what effect it may have.