Today, I am going to write something about a subject that is very dear to me. I am fascinated by this subject so I hope a little of my fascination rubs on to you. I am new to this subject, so I am not an expert. I hope that you will learn and come to appreciate this subject just as I have.
The subject that I am going to talk about is THE BRAIN. Yes, I know. There are a million different things that can be said about this one “master organ”. It is a 3 pound jelly (you can hold it in the palm of your hand!), made of 100 billion neurons. Neurons are a class of cells which make up the brain and nerves. The brain is such a wonderful organ that is can contemplate the vastness of the universe, contemplate the meaning of infinity, God… In fact, it can even contemplate itself contemplating the meaning of infinity. Self – awareness, according to me is the holy grail of neurosciences.
All these neurons together constitute the spectrum of human activities. To understand how the brain works, there are several different methods. One such method is to study the brain which has been damaged. If the damage is confined to a small region of the brain (either due to genetic change or a physical damage), then the brain itself doesn’t stop working altogether. There is no reduction in the cognitive ability on the whole. Instead, there is a highly selective loss of one function while other functions are preserved intact. This makes it easy to map the function onto the structure and understand how the structure contributes for the overall activity.
Here are a few examples which help you understand this process:
Example number 1: Capgras Syndrome
According to wiki, the Capgras delusion theory (or Capgras syndrome) is a disorder in which a person holds a delusion that a friend, spouse, parent, or other close family members have been replaced by identical-looking impostors. This is due to the damage to a very specific part of the brain called fusiform gyrus. It is also called discontinuous occipitotemporal gyrus. In layman terms, it can be called the face area of the brain. If there is damage to this particular part of brain you can no longer recognise people just by seeing their face. Mind you, you can still recognise them by hearing them. In fact, you won’t be able to recognise yourself in a mirror. Of course, you know it is you because it imitates your actions.
In this rare syndrome, the person will be completely lucid but still will not be able to recognise his own friends and family members. In the olden psychiatry textbooks, this can be explained by a Freudian principle – Oedipus complex in men and Electra complex in Women. According to this explanation, young children will have a strong sexual attraction to their parents (“father-fixated” and “mother-fixated”). As they grow up, the cortex develops and inhibits these latent sexual feelings. If there is a damage to the part of the brain which suppresses these feelings then the sexual arousal returns.
You have to understand that I don’t necessarily believe in this principle. It just happens to be one of the explanations that could successfully resolve the capgras delusion. But, this principle cannot explain why a person with capgras delusion has difficulty recognising his own pet. The whole Freudian explanation (Oedipus and Electra) don’t really work for pets, do they?
To explain it, scientists looked at visual areas in the brain (all 30 of them). The object is processed and sent to a small structure in the brain called fusiform gyrus where faces are perceived. From this structure, the message cascades into another structure called amygdala in the limbic system which is involved in gauging the emotional significance of the object that has been visualised.
The patient (With Capgras delusion) might have a problem in the area where the neurons connect the fusiform gyrus with the amygdala. So, he recognises his friends, parents etc, but the emotional significance of it is lost. So, the patient starts thinking of his own friends and family as imposters. (Scientists determined this based on galvanic skin response)
You can read more about this methodology here.
How is this complex neural circuitry set-up in the brain? What is the reason for it? Is it nature, nurture or genes?
Example number 2: Phantom Limb
Recently, an uncle of mine had an amputation done on his leg (above the knee) because the doctors found giant cell tumours below his knee cap. I started reading up about this peculiar feeling that he had post surgery. It was a vivid compelling experience for him. Of course, I knew what a phantom limb was but I never appreciated the severity of the situation. He was bed ridden for several months before the operation and experienced severe pain (due to a fracture to the same leg). His brain sent signals to his leg to move but it gets back visual feedback saying “NO”. This is called learned paralysis because it gets wired into the brain that even after sending a command, there is no appropriate result.
Even after the operation, he continued to feel that pain in the same place. He knew his limb was amputated. He could see it, but still he felt the pain. The learned paralysis allowed him to feel the pain. The phantom limb also behaves like a paralysed limb. The only way of dealing with this is to allow the brain to see that the phantom limb is moving according to the command. This can be done using a mirror box. A simple but ingenious creation by Vilayanur S. Ramachandran. You can read more about this here.
Example number 3: Synaesthesia
Synaesthesia is a neurologically-based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. In short, it is mingling of the senses.
In one common form of synaesthesia, letters or numbers are perceived as inherently coloured. 5 is red, 3 is green, 1 is white, 2 is blue so and so forth. These people are completely normal in other ways. Sometimes, sound and colour gets mixed up. C sharp is yellow, perhaps?
Did you know that synaesthesia is 8 times more common in artists, poets, novelists and other creative people?
In the brain, the “colour area” and the “number area” are next to each other. In people with synaesthesia, there is a crosslink between these two areas. This is because the gene which causes the changes in interneuronal connection. Usually, artists have a way of perceiving seemingly mundane things in a different way. (Her lips were like a volcano that’s hot – Elvis Presley). There is a link between these things. You can read more about this here.
Just a few more things to say: Each neuron makes 1000 – 10,000 contacts with other neurons in the brain. That is a lot! This blog is not a review of any one particular paper. I will leave that to someone who is an expert in that particular field. What I want to achieve by posting this blog is to create an interest in neurosciences amongst budding scientists. There are a lot of things being done in this particular area and yet, we have only taken baby steps in our understanding of the brain and its functions. If we join this research, then we will surely be able to understand more about ourselves and our behaviour.