Friday, July 24, 2009

Maps and streams in auditory cortex -- continued, take 3

Here is another statement by Rauschecker and Scott:

3. "The postero-dorsal stream interfaces with premotor areas and pivots around inferior parietal cortex, where a quick sketch of sensory event information is compared with a predictive efference copy" p. 722, figure caption.

The problem I have with this statement is not the predictive efference copy idea (we, particularly David, along with others have proposed the same previously), but with the idea that the "inferior parietal cortex" is the pivot. I'm using their figure 5 to judge the location they have in mind for this region and based on evidence localizing sensory-motor processes in speech, it is much too dorsal. In fact, I would argue that the critical region is in the vicinity of the planum temporale/parietal operculum. This is where area Spt lives, which is an area that seems to support sensory-motor functions of the sort referred to by R&S. The inferior parietal cortex area depicted by R&S more closely corresponds to a possible target of Rauchecker's spatial "where" processing stream. There is no evidence that I am aware of that links speech-related sensory-motor processes to this location.

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