A second in the mind

      Your friend innocently states "It gets harder as you go on."
      A second later, being the oh so witty person that you are, you respond with "That's what she said."
      But let's slow that second down and see the processes in your brain that allow you to make such hilarious and not at all crude remarks.

      We begin our journey in the inner ear where hair cells moved by vibrations in fluid, itself moved by the pressure waves of sound, changes those vibrations into electrical impulses in nerve fibres. This data, as well as some other sound information collected in the inner ear, is transmitted along the vestibulocochlear nerve. There are seven different points along the way, each having their own important functions, but as I'm in no way qualified to even remotely understand their significance and because I can't really go into every single process in the brain because I might never finish, I'm going to give a slightly shortened interpretation of these processes. The important thing is that the sound data reaches the primary auditory cortex. This is the most important part of the brain regarding sound and from here pitch and volume are ascertained. What I've said so far is, to the best of my (and Wikipedia's) knowledge, agreed upon and well understood by most of the scientific community. However, neurology is an incredibly complex science, not least because no two people's brains work in the exact same way. Because of this a lot of the remainder of the post will be based on the best information available, but it must be understood that it is in no way a complete picture of the brain's functions.
      Areas around the auditory cortex are then sent the information from the cortex and process it as language. This includes processing the syntactic and semantic information and keeping it in the working memory. Other parts of the brain, such as Broca's area and Wernicke's area, are very important in understanding the meaning of words in context. This understanding of context will be important later.
      All the while that this is happening visual information is also being processed. I've elected to not go into quite as much detail here for the sake of my sanity, but rest assured that visual processing is just as, if not more, complicated as audio processing. Once the very complex process of the visual information coming from the eye, onto the retina and then along the optic nerve is complete we eventually arrive at the visual cortex. Here a lot of amazing stuff happens, such as the perception of shape, colour and depth, as well as pattern recognition, movement perception and countless other functions. I feel it is very important to again stress that each paragraph here really can barely be fully explained in an entire textbook, so I'm forced to give a very simplified explanation of the processes that really doesn't do justice to the complexity involved. But anyway, another part of the brain that processes visual information is the fusiform gyrus in the temporal lobe. This part of the brain is important to us as it is connected with face recognition, so without it you might well end up relaying your witty retort to a chair. Once the person has been recognised, which will require access to the long term memory, which we could spend years learning about, so for now we'll again just say it's complex, the information about this person is sent to the limbic system, which is an important part of the brain with respect to emotion. Here an associated emotion is connected with the face, which is part of the mechanism that stops you from making inappropriate remarks to your boss. Unless your boss is into that sort of thing and you're looking to get a raise, but the processes in the brain for that little bit of immorality should be saved for another time. At the same time as this the brain also processes the facial expression and tone of your friend, which it then interprets and responds to with an appropriate change to your emotions.
      So now you've got an input, you've decoded sound and image to work out what your friend is talking about, you have two options: you can stand there, blank faced and drool like a moron, or you can respond. Seeing as we know the latter will make you seem like a bit of an immature pillock you should probably have gone with the former, but no, you're going to respond. Quick side note, on spell-checking pillock I discovered it comes from an obsolete Norwegian word meaning dickhead. So, even if your knowledge of neurology isn't increased by this post you can't claim it was a complete waste of your time. But anyway, you've chosen to respond to your friend. Now, remember how I said that the Broca's area and Wernicke's area help understand the context of speech? Well that's important now because while they did that they also spat out a few meanings that you know aren't what your friend meant. It's worth noting that humour is a particularly poorly understood part of neuroscience, so there are no doubt major functions in play that we're unaware of. Anyway, as well as processing speech Broca's area is also has important functions in speech production. Also, if you were going to name something, wouldn't you steer clear of using your name followed by the word area, just to stop people thinking you are somewhat preoccupied with your groin? But yeah, Broca's area, speech production etc. Oh, it also is connected with gesturing while you speak, which is an important part of making crude jokes. A lot of the parts of the brain associated with creating the output are the same as the ones that processed the input. For example you are again checking emotional signs when forming this joke. As the joke you're making is one which has attached to it a meaning that isn't really immediately apparent to someone unfamiliar with "That's what she said." jokes, you'll also be processing whether or not the person will even get it.
      Now you've chosen the words you want to say and the order they're going to come out the only thing left is to say them. I have completely glossed over a lot of the functions used here, you'll notice for example that I haven't even touched on your memory storing tens of thousands of words and their associated meanings, or the syntactic formation of the sentence. The reason for this is, quite simply, it's bleeding difficult to research everything while having any hope of meeting my midnight deadline. Besides, it would just become impractically large. Which, by the way, is what she said. But where was I? Ah yes, you're about to try to actually speak. Again, I'm going to be quite brief here, but now more because my computer has decided it doesn't like me so research is getting quite difficult. The exact reason it doesn't like me is hard to tell, maybe it's just the state of the economy that's put it in a bad mood, maybe it's my personality, or maybe it's the fact that I'm running it at nearly twice capacity. We'll never really know. But yes, you want to speak. Firstly the part of your brain that controls your lungs is going to receive a signal telling it how to exhale. Then you're going to move your mouth. Several parts of the brain are used here but the main ones are (apparently) the bilateral supplementary motor area, the left posterior inferior frontal gyrus, the left insula, the left Primary motor cortex and temporal cortex. Factor into this the parts of your brain that will control gesturing and facial expressions and what follows is a beautiful ballet with every part of your body in synch, in time. And now, at long last, you have said "That's what she said." Now all that remains is for your friend to give you the look of disapproval.

      And all of that happens in less than a second. In fact, much, much more than that happens. And it's happening right now. From solving complex differential equations to working out how to itch a hard to itch place, the brain is always amazing. Basically, I've just used over a thousand words to simply say, your brain is awesome.