Читать книгу The Handbook of Speech Perception - Группа авторов - Страница 43

So far, in the first half of this chapter we have talked about how speech is represented in the inner ear and auditory nerve, and along the subcortical pathways. However, for speech to be perceived, the percolation of auditory information must reach the cortex. Etymologically, the word cortex is Latin for “rind,” which is fitting as the cerebral cortex covers the outer surface of the brain – much like a rind covers citrus fruit. Small mammals like mice and trees shrews are endowed with relatively smooth cortices, while the cerebral cortices of larger mammals, including humans (Homo sapiens) and, even more impressively, African bush elephants (Loxodonta africana), exhibit a high degree of cortical folding (Prothero & Sundsten, 1984). The more folded, wrinkled, or crumpled your cortex, the more surface area can fit into your skull. This is important because a larger cortex (relative to body size) means more neurons, and more neurons generally mean more computational power (Jerison, 1973). For example, in difficult, noisy listening conditions, the human brain appears to recruit additional cortical regions (Davis & Johnsrude, 2003) which we shall come back to in the next few sections. In this section, we begin our journey through the auditory cortex by touching on the first cortical areas to receive auditory inputs: the primary auditory cortex.