|"The human brain has 100 billion neurons, each neuron is connected to 10 thousand neurons. Sitting on your shoulders is the most complicated object (system) in the known universe."
— Michio Kaku
The human brain is nature's most advanced and evolved system in the world. All human beings are born with one hundred billion neurons, which are utilized differently by different people. The human brain works similarly in every human being and is not much different from other animals. One might ask: How is creating systems analogous to brain function? There are several reasons we need to study the mechanics of the brain.
The human brain is the most complex organ of the human body; it participates in our decisions, thoughts, emotions, and even dreams every second of the day. You do not have to delve into the detailed biology of the nervous system to understand the functioning of the brain. The examples below are based on how an average person behaves in certain situations.
Our brain is only 2% of our body, yet it consumes 20% (about 30 Watts) of the body's energy. According to the Human Brain Project of the European Commission, we need about a gigawatt of energy (based on current technology) just to simulate 100 billion neurons. The energy is equivalent to powering up a large city. In another study done at Japanese research institute RIKEN, just one second of neuronal network activity simulation in real time took 40 minutes, using the Fujitsu K supercomputer, having more than 700,000 processor cores with 1.4 million GB of RAM. How does this amazing system process an enormous amount of information every second?
In our daily lives, we encounter many different types of stimuli — some require our attention while others do not. The RAS is like a switch that turns the brain on or off. RAS receives instructions from the sensory nerves that come from nerve endings in the face, eyes, ears, mouth, and other internal organs. These nerves regroup at the top of the spinal cord, but the messages they relay must pass through the RAS to enter the prefrontal cortex (the thinking brain). One can control the information that enters the prefrontal cortex by focusing on the important sensory input. The reactive or the automatic brain takes over the stressed, overwhelmed mind in which case what one experiences or "focuses on" is not in their control. You can think of RAS as the filter to the thinking brain. The brain would have to work very hard in the absence of RAS — so much that people would have frequent nervous breakdowns.
All sensory data is first sent to the thalamus located in the midbrain. The thalamus acts like a switchboard to send the sensory data (within 15 milliseconds) to another small part of the mid–brain called the amygdala. The data is also sent to the prefrontal cortex, the thinking brain, within 25 milliseconds. The amygdala is the emotional CPU with low capacity (around 12 million neurons) and limited pattern recognition capabilities. However, it is our personal bodyguard and provides the first line of defense by making us aware of situations. The amygdala reacts as soon as a negative emotion or anxiety is triggered and takes up most of the brain's available energy and oxygen. In the airplane scenario, since one's immediate focus is to get to their seat, all of the unfamiliar faces and things are rejected by the RAS. However, if it is a life and death situation (like someone pulling out a gun) the amygdala floods the cortex with chemicals to stop the processing of data. It is then the prefrontal cortex (another executive CPU) that gets the signal to shut down. Hence, most of us act without any conscious thought in the gun situation. Next time if you yell at someone, here is the perfect excuse: "my amygdala ate my cortex."
Contrarily, if there is a familiar face and even if one is not seriously looking, the RAS filter will pass the data from the amygdala to the prefrontal cortex — the executive CPU that is responsible for problem solving, analysis, organizing, planning, and creativity. The prefrontal cortex is located behind the forehead and is made up of a sophisticated neuron communication network that processes the data and helps one make decisions by extracting information from the long–term memory. Thus, the brain gives this data to the executive CPU. Let us say the output from the CPU is that you do not want to talk to this person. The last time you met this person, she/he had anger issues with you. Now you stop and wait for this person to look out the window, tiptoe past this person's seat, and sneak to your seat. Once your luggage is in the overhead bins, you take out your favorite book and relax. Thank you, neurons!
For the first time flight experience, the brain takes short term memories such as seat layouts in a plane, overhead bins, even the airplane's smell, and places it in the long term memory pool for your future experience. Sleep moves the RAM (Random Access Memory) or Flash Memory to the hard disk. Once our memories are in the long term pool, they become permanent until the person dies or suffers a serious mental disease.
What is happening in the brain? How does the brain process information? Science may not yet have all the answers, but scientists can measure the electrical activity in the brain to explain different phenomena. Our 100 billion neurons are specialized cells that we have since birth and last throughout the lifespan of a healthy person. Neurons store memory, and process and transmit data using electrical and chemical signals. They are connected to other neurons using dendrites and axon. The dendrites are close to the neurons and connect to other neurons using synapses. A single neuron can have more than 10,000 synapses, which send chemical and electrical signals to other neurons. What about the neurons that are connected far apart? For example, how does a signal from your finger go to the brain? Nature has solved that problem with axons. An axon is a long nerve fiber that transmits data to/from neurons from/to muscles. Some neurons can only have one axon, whereas others may not have any axon. You can think of axon as a long cable that connects multiple LAN (Local Area Networks). So in two LANs very few computers may be connected to other LAN, most of them will be linked with each other in local LAN.
How do neurons communicate? Every human is estimated to have 100 to 500 trillion synapses or connections. Each neuron is connected to other 10,000 neurons via synapses. The number of ways the data can flow between neurons is much larger than the number of stars in the whole universe. Consider the case of the Internet: Whenever we type the web address or URL (Uniform Resource Locator) using the domain name in the browser, the Internet does not understand the URL but works using the IP address. So, the URL request first goes to the DNS (Domain Name Server), which provides the IP address. Then, the request goes to the IP address, and some of the intermediate computers forward the request to the actual server. In all, you can reach the server not more than ten hops in between. Secondly, the information and the data exchanged between the computers is always the same.
On the other hand, the data is transmitted from one neuron to another neuron in the brain using electrical and chemical signals. The synapses are not physically connected to each other, but the neurotransmitters released by neurons transmit the data to the targeted neuron across the synapses. For each activity, the human brain immediately creates a neuronal circuit in the brain. Neurologists thought that this circuit is limited to certain parts of the brain for certain types of activities, but recent studies have indicated that the circuit can span the whole brain. The complexity of studying the human brain is that the data or neurotransmitters are not same between each neuron, unlike their digital counterparts. It seems that each neuron has a brain of its own and can trigger other neurons based on the chemical signal, or they may do nothing. It is like having a hundred billion CPUs with a hundred trillion connections.
Another striking feature of the human brain is that these connections are continuously being removed or created based on the behavior, environment, and neural processes of the individual; this is called neuroplasticity. For example, if a person loses a limb, the brain still receives the sensory signals of the limb. The person may sometimes feel pain, itching, burning sensations even though the limb is not there anymore. Over a period of months and years, the brain rewires itself to adjust to the lost limb.
Can we create a system that is as good as our brain? Most of us use email systems every day. Let us take an example of Microsoft's Outlook email system. To work like our brain, we can follow simple steps.
Security may not be the top priority for any corporations, but money is; corporations want to make money. We are fortunate that we have the capability to weave the intelligence of humans and nature into code. Can we create systems that can filter big data based on the user's previous actions and knowledge and transforms into information so that users can convert it into knowledge?