Neuroscience happens to be one of my favorite areas of sciences, other favorite being Physics. I attended a couple of interesting schools related to the area a while ago, and I keep coming back to thinking about the questions posed and the research pursued in the area.
Neuroscience is study of the nervous system. Central Nervous System (CNS) consists of the brain and the spinal cord and peripheral nervous system connects other organs of the body to CNS through nerves. A human brain has about 10^11 neurons each connected to about 10,000 others forming a network of 10^15 nodes, all packed within an area of the size of our fist, inside our skull. It is thus a great example of an embedded system maximizing its performance within the given constraints of area, energy & functional units available. The jobs it has to do are also quite varied and comply almost everything that we all do!
parts of Central nervous system
So much of general knowledge, and now we plunge on to some interesting research questions.
Molyneux’s problem Our sensory organs (eyes, nose, ears, skin, tongue..) are connected to different areas of the brain through nerves. Now imagine that until a certain point in time, someone has never seen the world but has experienced it only through the sense of touch. So if you place 2 objects, a spherical one and a cube shaped one, the person would differentiate them by how they felt on touching. Now if the person got the sense of vision & if the same cube and spherical objects were put in front of them, would the person be able to say which one is cube and which is sphere without touching them?
Question whether one sense would infer knowledge to another one instantaneously. Answer to this question is explored through a framework called Project Prakash in Prof. Pawan Sinha’s Lab at MIT. People with impaired vision but whose vision could be corrected through surgery are operated and then experiments are carried out.A beautiful scientific as well as humanitarian mission!
Another remarkable ability of our brain, termed Plasticity, is to alter the connections between the neurons through experience. Different brain areas are devoted to doing different jobs and when some sensing modality is degraded, the brain area devoted to processing that information is assigned some other work. Of course, this ability of the brain is highly functional at a younger age than in an adult but still the brain does rewire. Human cortex is fully wired at the time of birth but for a few other animals, it is not the case. Ferrets are an example of such species. At Prof. Mriganka Sur’s lab at MIT what was done to test the extreme ability of brain reorganization was to wire the nerves from the eyes to the area of the brain dedicated to hearing, in new-born ferrets. If brain didn’t reorganize, would the animal hear what it saw?! Hard to imagine, but the experiment revealed that the brain did reorganize the auditory cortex to process visual information.
I remember having asked Prof. Sur whether the brain areas would have reorganized if the wiring was swapped back; to which he replied those weren’t easy experiments and one couldn’t answer these with that ease. Of course! 🙂
During his guest talk at NBRC, he also mentioned that we tend to compare the human brain with the most current technology; previously thinking it is sort of clocks and lightwork and nowadays comparing it to computers (and just as we compared it to an Embedded System). Definitely, a massive parallel processing system that our brain is and the plethora of tasks it performs, we might not near any single artificial system equivalence for it! For more interesting work, check out Sur Lab.
When we see some action being performed by someone else,usually we experience some fraction of it too. It could be tendency to yawn when someone else around yawns to feeling sad when seeing a traumatic situation to learning something by observing an instructor perform an action. There are a whole type of neurons dedicated to processing ‘imitation’ or the act of observing an action and are called mirror neurons.
Dr. Giacomo Rizzolatti’s group while conducting experiments on monkeys for understanding certain movement tasks found that certain neurons responded not only to grasp movements of its own but also to similar movement of the experimenter’s. A great deal of understanding about neural mechanisms behind understanding actions were thus provided by mirror neurons.
Vision is one of our most important senses and so a large area of the brain is devoted to processing visual information. How difficult it is a problem computationally, we might realize through the simple Captchas that we fill up every now and then to tell a computer that it’s a human here.
Dr. Thomas Albright from Salk Institute gave a talk on Contextual influences on visual processing and posed the problem of vision as follows:
Central problem of vision
There are 2 problems, a physical problem and a biological problem. Image of the outside world formed on the back of our retina has discrete features such as color information, brightness information, distance information etc. All this discrete information is processed in the brain to gain a continuous visual perception.
He said it as an ill-posed problem as there is not enough information in the discrete features obtained in the retina image for a unique representation of every visual scene; yet amazingly, we usually are fairly sure of what’s around us! 🙂
S.P. Arun gave a talk on object recognition in a quite different format, that from an engineer’s perspective. Was quite interesting. He said that some researchers like to believe that to solve the problem of vision, we might not necessarily need inspiration from biological systems just as man invented wheel though nature gave us legs , while some researchers believe that for the ultimate answer we would need to look through nature’s mechanisms.
Intuition is one of our powerful abilities. Some of the work at Dr. Keiji Tanaka’s lab at RIKEN, Japan is about finding the neural basis of expert intuition. In games like chess,players do not compute every possible combination of the moves but through experience gain a sense of intuition towards what might be the next best move.
Dr. Tanaka’s lab conducted some fMRI studies of expert shogi (a Japanese board game) players to understand what areas of the brain might be involved in generation of intuition.
Brain controlled interfaces are always fascinating, so something about work in that direction. Movement of our limbs is translation of motor commands from the brain to our muscles. So could we direct these motor commands to move an artificial actuator? Prof. Andrew Schwartz lab at UPitt does quite interesting work on developing neuroprosthetics.
major areas of the cerebral cortex
Invasive multi-electrode arrays need to be implanted in the motor cortex to record the firing pattern from population of neurons for different movements. (consider a neuron as a switch: when it fires, it means it is turned on)
Cosine Tuning What was found while recording such firing patterns for movement tasks in monkeys was that neurons have directionality or preferred directions of motion. If the motion was in the direction of the preferred direction of motion,the firing rate of the neurons would be high and in angles away from preferred direction, it would fire less and less. Thus the firing pattern could be modeled as a cosine!
Cosine tuning (preferred angle : ~270 degrees)
Quite recently researchers at University of Washington have done some studies on brain to brain communications in humans, transferring commands from one brain wirelessly to another to do a certain action! Crazyy!
Interesting places to look for Neuroscience Research in India:
National Brain Research Center (NBRC) at Manesar
Center for NeuroScience (CNS) at IISc Bangalore
National Center for Biological Sciences (NCBS), Bangalore..
Thank you NBRC & IISc for the amazing schools which we could attend! Hope to catch up with some more interesting work soon!
National Brain Research Center, Manesar 🙂
DST SERC School participants @ NBRC , Spring ’11
main building of Indian Institute of Science (IISc)
participants of Brain & Cognition workshop, IISc Bangalore [Summer ’11]