Studies as to how a brain forms speech continue to develop. It is understood that when speaking a very high-speed process occurs, in which our brain retrieves words before we speak them out. There is evidence to say that “the syntactic gender of a noun is retrieved about 40 ms earlier than its first phonological segment”2. That’s rather efficient.
The cortical and subcortical areas and frontal lobes are regions used in the articulation of speech. Nota and Honda write that “Within the cerebral cortex, the sensorimotor area is commonly observed to be active, while other areas often show disagreements.”3 These authors admit that while we have attempted to learn about the neural mechanisms related to speech since the 1600s, many questions remain4.
Neurotransmitters required for speaking would include 1) glutamate, in an excitatory manner that can increase and decrease in strength which may be helpful depending upon the rate, volume and tone with which we speak, and 2) acetylcholine which acts between motor nerves and muscles required in articulation. There is still much to learn the way our brain activates during the activity of speech, both physically and in the neurotransmitters that come into play.
Nota, Yukiki and Honda, Kiyoshi, “Brain regions involved in motor control of speech”. Acoust. Sci & Tech 25:4 (2004:286).
Rogers, Kara, The Brain and the Nervous System. (2011: 106) New York: Britannia Educational Publishing.
Van Turennout, Miranda; Hagoort, Peter and Brown, Colin M. (2007) “Brain Activity During Speaking: From Syntax to Phonology in 40 Milliseconds”. Science Vol. 280 (April 1998:572-574).