A few weeks ago, I gave into my desire of buying a Kinect for my Xbox 360 for the sole purpose of playing the game Fruit Ninja Kinect. Over my winter break, after a crazy semester of medical school, I had the wonderful chance to play the game on my cousin’s 360 console and immediately fell in love with the chopping and slicing of virtual fruit. I’m sure that part of the entertainment was being able to cut fruit that you never had to buy (it’s sort of expensive!), but I’m also sure that the juicy sound effects had to do something with my addiction to the game. I bought the game and it became an instant hit with my family; and after maybe two days of playing Fruit Ninja Kinect, I had unlocked every special feature of the game. It wasn’t until my arms became sore from a few days of straight playing that I began to ponder about what really went into playing this addictive game (a symptom of being a medical student). And so, having just started my physiology class and having had a previous semester filled with neurobiology and gross anatomy, I wanted to connect the dots and create a story.
So let us pretend for a minute, a situation where you are in front of an imaginary television screen that is hooked up to your Xbox 360 with Fruit Ninja Kinect being the game of choice. Your first fruit pops up in a stylistic fashion from the bottom of the screen, and you execute a slicing motion with your arm to cut the fruit (add juicy sound effect as fruit is being cut). However, what actually goes into that single swinging motion is actually an integration of many different ones that happen subconsciously and almost instantly.
Vision is an amazing and powerful sense. The retina in your eyes alone has about ten distinct layers of a combination of neurons, photoreceptors, membranes, and other cells that allow for you to sense the outside world through your eyes. And the way that you perceive that deliciously looking fruit being popped up into the air is not just because you see a fruit; but because you also recognize spatial dimensions, the amount of luminance that is conveyed, the contrast between colors, the sense of motion found in the fruit twirling in space, and more. This package of information is transferred to what we know as the occipital lobe, or the part of the brain in the back of your head, in a pathway that involves many crossing over events and dissection of the visual field into top, bottom, left, and right compartments. In essence, the way that an image is projected on the retina is actually inverted and reversed, and when transferred to the brain, is meticulously divided further into distinct pathways of information. It is incredible that we can make sense of what we see in the first place! Furthermore, after visual recognition of an object, there are different lobes in your brain that help with the process of voluntary action through individual steps of attention to that object, the identification of what it is, and ultimately what to do or the idea of planning. Once you and your brain agree to the plan of cutting the digital fruit, your musculoskeletal system is accessed through the interface of your nervous system. Using your shoulder, chest, and arm muscle groups which are innervated by many different nerves, you are finally able to cut the fruit with your arms and achieve success!
What we perceive as a simple motion of cutting a digital fruit in a video game is actually a complicated set of mechanisms and integration of various physiological systems. I have mentioned the visual and nervous system in combination with your musculoskeletal system; however, there are more “behind the scenes” organ systems which also help you in accomplishing this task – systems such as your cardiovascular system that help to perfuse blood and energy to your muscles and brain in conjunction with your pulmonary system. If we wanted to take a step further, an added layer to the complexity is the idea of metabolism on a molecular level. Metabolism can be thought as the underlying energy industry in your body that serves to power your organ systems, and to allow the interaction and exchange between them. I’m sure that I have missed the mentioning of a plethora of other mechanisms that help me to cut my deliciously looking digital fruit, but one thing is for sure – we are amazing. Imagine what goes into a task that is a hundred times more complicated than just looking at something and swinging your arms!
-J.W.