Anatomy and Physiology series: The Central Nervous System part II (aka...uh...um...Pillow Talk?...yeah, I'll go with that)

Alright so now we've got our lobes:  Occipital, Temporal, Parietal, and Frontal, and we know a little bit about what these guys do, so let's get more specific for the sake of understanding the system we use when we speak and sing.  So now, we're going to talk about the areas involved in language and speech production.  I'm going to lay it out from an auditory message we need to respond to (in speech...for now).  Let's say you're vocal coach has just stopped playing and asked you:  "Did you realize you're singing /e/ when it should be /ɛ/?"

Okay, so this message goes through your ear and ends up in your primary auditory cortex located in the temporal lobes.

shown in green here

This is where all of the pitches your coach put out (in terms of their intonation and inflection as well as vowel formants of their words and consonant pitches) and the loudness of their voice was processed.  All of this information got put together and sent off to the next region, Wernicke's area.

Wernicke's area is also located in the temporal lobe in the left hemisphere.  

Don't worry about Broca yet, we'll get to it below

Wernicke's area is known for attaching meaning to this auditory information from the primary auditory cortex (and visual info when you're reading).  It also seems to generate information in the form of linguistic rules like word meanings, etc.

Next, the information from Wernicke's area gets sent on to the arcuate fasciculus.  This is a little information highway that traverses the temporal lobe to the frontal lobe and connects Wernicke's area to Broca's area, and newer research shows that it also sends some information to premotor/motor areas as well.

So once all of this gets to Broca's area in the frontal cortex, the language gets comprehended at the syntactic (grammatical) level.  Function of Broca's area is a little fuzzy since reseachers are still trying to figure out exactly what goes on there, but in a nutshell, this area is involved in connecting incoming and outgoing messages to the motor act.  What's cool is that all language signals, even sign language, gets processed in Broca's where the outgoing message also comes through.  So while we're not sure of all the functions Broca's is involved in, it is definitely connected to the motor pathways we use for speech, gestures, sign language, and all other forms of communication.

The message  you want to say back to your coach, perhaps "Oh yes, bad habit of mine.  I need to work on that," will go through Broca's and get sent to the primary motor cortex located near the back of your frontal cortex.

Where your intended message will be sent out through the lower portions of your brain, to your brain stem and spine, and out to the muscles of your respiratory, laryngeal, and articulatory systems where your message is formed.

So what I've just outlined for everyone is something called the Wernicke-Geschwind model of the way the brain produces and analyses spoken language, but this model isn't considered the end-all-be-all of spoken language at this point.  Some of the problems with this specific model include an over-simplification of anatomical regions in speech (i.e. it seems to include more activity than just these areas, especially around the perisylvian cortex); inappropriate compartmentalizing of language into receptive and expressive parts (since evidence shows there are a lot of shared components to reception and expression); and inaccurate framing of language as a serial process (since brain imaging shows parallel pathways at work and more activity during all language tasks).  So while it's not an entirely accurate model of speech and language, it is the most basic one we've got for the moment.  And so, as a friend once told me, go ahead and put this information in a box for you to use, but leave the lid open (cause it's already changing in the research world).

*Seikel, J. A., King, D. W., & Drumright, D. G. (2010). Anatomy and physiology for speech, language, and hearing. Clifton Park, NY: Delmar.