Lecture in the C-STAR series by Greg Hickok, PhD (University of California, Irvine), given on December 14th, 2017.

Abstract:
This talk reconsiders the functional anatomy of the ventral speech stream including a discussion of what we agree on, what is contentious, and how we might move forward. We start by clarifying the distinction between the two ways that the term “ventral stream” is used: in referring to (1) a process, mapping auditory speech input onto conceptual knowledge and (2) the anatomy involved in this process, predominantly the temporal lobe. These are logically independent ideas and keeping them distinct helps clarify discussions about the reliance of different processes, e.g., naming, on ”dorsal” versus “ventral stream” networks. Next, we’ll discuss points of agreement—that the superior and lateral temporal lobe is the major hub of the ventral stream—and summarize some old and new evidence for this view. Then, we will examine different claims about the major pathways within the ventral stream comparing the anterior versus posterior stream hypotheses. I will then propose a new model in which a mid-posterior superior temporal Auditory Phonological Area (APA) interfaces with two ventral streams, one anterior, which supports mapping auditory-phonological networks onto entity knowledge and one posterior, which supports mapping auditory-phonological systems onto event knowledge. I will end with some conjectures regarding the functional anatomy of syntactic processes, suggesting, following some recent proposals, that the posterior lateral temporal lobe is the critical hub.