Binding

Of all the things that amaze me, one of the things that tops my list has got to be the "Binding Problem". Basically how this works, or is supposed to work, the different areas of the brain gather their information, sensory information, and from there they somehow integrate all of that information and create a single object.

This allows us to realize the fact that something that we see and hear is happening together, for instance seeing a light flash while there is a beep. Our brain will connect these two events and therefore allow us to perceive them as happening together. For an example of this you can look at a badly dubbed movie, your brain doesn't register the movement of the lips with the audio and therefore you realize it doesn't bind together. Take a look at the video to get a clearer idea about what I'm talking about. You can skip ahead about 2 and a half minutes to get to the better stuff.

One of the more interesting things that I have come across is the idea of using a mirror to "create" the sensation of having a third arm. By using a mirror to reflect an arm while having one arm hidden and then touching each of your fingers to your thumb for a minute or two you will end up feeling like you have three arms. Now I personally haven't witnessed this but I have heard that you can use this same technique to help alleviate some phantom limb pains. One of my professors once told us that there was a patient who had his hand amputated, but after the amputation his missing limb would start to cramp, and so to alleviate this he had to use a mirror and ball up his remaining hand into a tight fist and slowly release it. After a few repetitions of this the phantom pain subsided because the brain was tricked into thinking that the limb wasn't cramping anymore and was instead opening up.

How freaking cool is this!?

Temporal and Spatial Summation

One of the things that I find most interesting is temporal and spatial summation. Basically what this is, temporal summation has to do with time, whereas spatial has to do with space. Now summation adds stuff up, in the case of physiology it adds up the action potentials of the neuron(s). Ok so now we take a closer look at how this plays out in relation to the nervous system. Temporal summation takes the action potentials, that are much too light to trigger a response, and adds them up in order to finally trigger the response. For example, one drop of water on your head isn't enough to make you fix the leaky water pipe, but 20 water drops on your head in one minute is enough to make you take action and fix that leaky water pipe.

As you saw in the video spatial summation is similar to temporal summation, in that it adds different potentials in order to trigger an action potential. Only in this case the axon is receiving signals from different places instead of receiving signals from a signal neuron separated by time. If I am not mistaken this allows for a wide variety of ways that neurons can send and receive signals, and this in turn means that different signals can be sent by the same neuron. 

Refractory Period

The refractory period of an action potential keeps it from repeating itself over and over again. Of all the things I have read so far, this seems to be one of the more interesting, not only is there the absolute refractory period but also the relative refractory period. The difference between these two is that while the absolute one is short in time, it is impossible to overcome. As for the relative period, this period is longer than the absolute but given enough prodding it can be overcome allowing for the action potential to repeat. One example that I read of in a book is that of a toilet. After you flush the toilet it becomes impossible to flush it again, but if you wait a short time then you can flush the toilet (although with trouble). A good explanation of the refractory period can be seen in the  first six minutes of the video below.

As you can see in the video, at about 2:30, you can see the normal action potential threshold and the raised action potential that can be overcome in the relative refractory period. This was the most interesting part, the fact that our nervous system saw fit to leave a bit of wiggle room just in case there was a need for the action potential to repeat. This makes me wonder how exactly it would benefit an organism, whether it would prevent the organism from feeling pain over and over again, or maybe this helps the nerve cell keep from being used up and dying out.

Brain Size

One area that seemed so interesting to me is the fact that the size of brains tends to differ between men and women. Some research conducted by Dr. Ashton, who you can see in the video, found that the size difference is just a couple of percentage points, and is most likely due to the fact that men are just bigger. One thing of not is that men tend to have more gray matter and women more white matter, according to Ashton this usually accounts for why men are good in certain areas and women in other areas. This is in contrast to what I had come to believe, that despite size differences women were just as capable of excelling in male dominated areas but that social norms and expectations discouraged it. For instance math, this is a very male area, and women tend to be, at least this was the case, discouraged from pursuing math as a career, yet there are a few women who have contributed to this field. I like that Ashton kind of addresses this because she notes that the brain can be exercised so that certain areas increase in their mental capacities.

http://www.cbsnews.com/2100-500165_162-6890474.html