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The Wonders of the BrainUnveiling the remarkable functions of the brain
Koh Soo-min  |  soominkoh@yonsei.ac.kr
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승인 2014.05.05  23:29:41
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“How can a three-pound mass of jelly that you can hold in your palm imagine angels, contemplate the meaning of infinity, and even question its own place in the cosmos?”

 

   IT IS amazing when you think about it. This is a description of the most mysterious organ of ours – the human brain – by V. S. Ramachandran, who is one of the most renowned neuroscientists of the day. We use this powerful organ every day, sometimes consciously and sometimes not. Yet, despite its vital necessity and frequent usage in our life, studying the human brain is one of the hardest quests for any scientists. This is because of the complex interrelationship between the brain nerve cells, which in an average person there are more than a staggering 80 billion. The infinite number of nerve cells interact with each other constantly, thereby creating an entire spectrum of human abilities. Due to its complexity, one of the best ways to understand the human brain is by studying patients who have suffered an injury in one particular area of the brain. This simplifies matters, because a damage to one area of the brain implies that there has been a highly selective injury in the brain. In this case, the patient is perfectly normal in all other aspects. However, when the patient is trying to perform one particular task that uses the damaged part of the brain, a neurological disorder arises. Through this simple yet ingenious method, neuroscientists began making amazing discoveries in the area of neuroscience. Then now, let us look. Let us venture into this curious world of neurology and explore the endless ability of the human brain, by analysing brain patients – just like a neuroscientist.  

Capgras Delusion: “Are you an imposter?”

   As a living and breathing human being, we always interact with other people. Then what would it be like if we cannot recognise people anymore? What if we cannot differentiate between friends, families and strangers? In fact, it is one of the most important roles of the human brain to allow us to recognise and differentiate different people. How does the brain aid us in doing that? There is a particular area in the brain specifically devoted to “recognising faces.” It is commonly referred as the “face-area” of the brain, and is scientifically termed the “fusiform gyrus.” When the fusiform gyrus is damaged, the patient naturally loses the ability to recognise anyone’s face – even one’s own. This is a relatively common condition called the “damaged fusiform gyrus,” but there is a related, yet more uncommon condition that is also academically obscure. It is called the Capgras Delusion.

   When the patient suffering from Capgras Delusion looks at his mother for instance, he has no problem in recognising her, unlike patients of “damaged fusiform gyrus.” ‘Yes, this looks like my mother,’ the patient will think. However, the oddity begins here: “This looks just like my mother, but it must be someone else *pretending* to be my mother.” Curiously, the patient will forbid himself from believing that the familiar person is not a genuine figure, but he will instead opt to believe that the familiar figure before him is an imposter. Could a brain damage in a particular area account for this inexplicable phenomenon?

   In order to understand Capgras Delusion, it is important to outline how humans emotionally react to vision. First, a visual stimulus enters through our eyes. Then the stimulus travels to the visual area of the brain to stimulate the fusiform gyrus, where the “face” of visual stimulus is perceived. Afterwards, “amygdala,” the part of the brain that is responsible for emotions is stimulated. Finally, when the amygdala judges that the visual stimulus it received is of significant emotional importance, it sends a message to the autonomic nervous system* to cause reactions in the body, in response to the emotion caused by the vision. The reaction can vary from perspiring, having faster heat rate, to even being sexually aroused. However, in the case of Capgras Delusion patients, this entire course of emotions being developed by the visual stimulus is not processed in the same way. What is suspected to have occurred to them is that the “wire” connecting the amygdala to the autonomic nervous system is cut. This means that the fusiform gyrus is perfectly intact, hence allowing the patient to recognise the face of his mother, for example. However, because of the malfunctioning “wire,” the person does not “feel” any physical response – such as warmth – happening to his body that should normally come as an emotional reaction to seeing his own mother. What this means is simple. The patient’s ability to see and recognise is undamaged. His emotional area functions, so he can feel emotions. However, he cannot have a physical *response* to a vision because of the malfunctioning connection in the brain. Such disconnection confuses the patient – and fooling oneself into believing that even their most loved ones are in fact an imposter, seems to them as the only “logical” explanation. 

Charles Bonnet Syndrome: “I saw a man in ponchos jumping around”

   James Thurber, a popular cartoonist and author in the United States in 1930s was well-known for his imagination. Most of the time, it is considered that diverse visual stimuli are a source of such good imagination like Thurber’s. Perhaps therefore, it may be hard to believe that Thurber suffered from bad vision since he was six years of age, and had become completely blind by the time he was 35. In his book “Phantoms in the Brain,” Ramachandran suggests one radical idea – he believes that blindness may have been the major birthplace of Thurber’s wild imagination.

   “I like to watch the television in the afternoon,” comments an old lady nearing her 90s. Surprisingly, she is blind. “That’s when my ‘visitors’ most likely appear.” This is an account of an old lady interviewed by psychotherapist Deborah Bier. The interviewed lady and James Thurber have two things in common: they are both blind, and they have both suffered from Charles Bonnet Syndrome – a disorder found in 10% of blind or visually impaired people.

   Charles Bonnet Syndrome is a brain disorder whereby a patient sees hallucinations. The hallucinations caused by this syndrome is subtly different from psychotic hallucinations, notes the neurologist Oliver Sacks. Unlike psychotic hallucinations that induce feeling of fear, interest, or confusion and emotionally interact with the patient, the hallucinations caused by Charles Bonnet Syndrome consist of images that are completely random and often times totally meaningless to the patient himself. For instance, the patient suffering from Charles Bonnet syndrome may “see” geometric shapes, objects, scenery, people, or even cartoon characters all amidst their blindness. Those hallucinations are in full-colour, move around like in our daily lives, and do so without a sound – it is just like watching a soundless and repetitive movie. Intriguing – how can blind people “see” those images? How are they triggered from the human brain?

   With the recent advances in science, it has become possible for neurologists to take Functional Magnetic Resonance Imaging (FMRI) – which is a process of tracking brain activity using MRI – on patients while they are hallucinating. Upon analysis of FMRI it was found that *different* parts of visual areas of brain are activated depending on what *kinds* of hallucination the patient is experiencing. When patients are having primary geometric hallucinations – seeing shapes and patterns – the FMRI revealed that the primary visual cortex is activated. On the other hand, when patients see images of people, the fusiform gyrus is activated. What is more, if we look in greater detail, the fusiform gyrus is separated into amazingly detailed parts, and each small part is devoted to recognising a particular feature of the face. For example, the area in the anterior part of this gyrus is devoted to recognising teeth and eye in particular. This does not only apply to the fusiform gyrus – there is an area of the brain that is devoted to recognising buildings or cartoon characters, for instance, and when analysed in detail, that area of the brain is yet again separated into parts that is devoted to recognising specific cartoons or particular feature of buildings.

   In fact, there are even specific *cells* that are activated when one sees or recognises something in particular. To quote from Sacks, “you may not only have ‘car cells,’ [but] you may also have ‘Aston Martin cells [or ‘Mini Cooper cells’, or ‘Ferrari cells’].’” What happens with patients of Charles Bonnet Syndrome is that those cells are convulsively activated. This occurs due to their visual problems or blindness, which means they are not receiving real visual stimulus that acts as a signal to “turn on” those memory cells. Therefore in blindness, suddenly and unexpectedly, random memory cells that are perfectly unrelated to the patient’s consciousness, thoughts or activities are activated – creating a cascade of compelling visual hallucinations. In the case of Thurber, these arbitrary and wild hallucinations could have been his source of his endless imaginations.

*                 *                 *

   It is genuinely an intriguing discovery to find out how deceiving yet powerful the human brains can be. Countless milestones are being achieved by neuroscientists every day in the field of brain science, but the human brain still remains deep in the labyrinth, luring our attention for more mysterious discoveries. And mysterious they are: a fascinating organ that consists of billions of neurons and capable of millions of tasks. Let us never forget the beauty that the mystery of this organ holds:

“…any single brain, including yours, is made up of atoms that were forged in the hearts of countless, far-flung stars billions of years ago. These particles drifted for eons and light-years until gravity and change brought them together here, now. These atoms now form a conglomerate- your brain- that can not only ponder the very stars that gave it birth but can also think about its own ability to think and wonder. With the arrival of humans, it has been said, the universe has suddenly become conscious of itself. This, truly, it the greatest mystery of all.” (V.S.Ramachandran)

 

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