The evolution of auditory cortex: The core areas

Abstract

An alternative title might be What, if Anything, is AI? AI, of course, is primary auditory cortex, an area of cortex that likely all mammals have. Thus, this seems a naive or a puzzling question. Yet, an important issue is hidden in this question. And this type of question was formulated long ago: What, if anything, is a rabbit? (Wood 1957). Classification was the issue, and it concluded that rabbits had been mistakenly classified as rodents. That view has prevailed, and rabbits are now considered Lagomorphs. Some time ago, I asked What, if anything, is S1? (Kaas 1983). I felt that the term S1 was being used inconsistently to refer to four areas (areas 3a, 3b, 1 and 2) in human and other anthropoid primates, while only one of these areas was considered to be S1 (area 3b) in most mammals. Again, this pertains to the issue of proper identification. All mammals appear to have a region of auditory cortex, but the descriptions of how it is organized vary across species, and even between studies on the same species.