Monday, August 3, 2009

Maps and streams in auditory cortex -- continued, take 4

The final statement I'd like to comment on from Rauschecker and Scott's recent paper is this:

4. "The postero-medial planum temporale area ... is an auditory area important in the act of articulation" p. 721.

The planum temporale clearly contains auditory cortex. However, not all of the PT is auditory. The posterior 1/3 or so corresponds to cytoarchitectonic area Tpt (yellow shade in figure below).

Tpt is not auditory cortex. But don't take my word for it. Here's a quote from Galaburda & Sanides:

Area Tpt represents a transitional type of cortex between the specialized isocortices of the auditory region and the more generalized isocortex (integration cortex) of the inferior parietal lobule. -Galaburda & Sanides 1980, p. 609

Given that many of Rauschecker and Scott's arguments are based on macaque data, here is a quote re: monkey area Tpt:

Tpt is an auditory-related multisensory area, but not part of auditory cortex. -Smiley, Hackett, et al. 2007

Why should we care that area Tpt is not part of auditory cortex? Because (i) it shows clearly that thinking about the planum temporale as a single functional area performing a single computational operation is misguided and (ii) it supports the view that the posterior sector of the PT is involved in something else besides auditory computations, for example, sensory(not just auditory!)-motor integration.


Rauschecker, J., & Scott, S. (2009). Maps and streams in the auditory cortex: nonhuman primates illuminate human speech processing Nature Neuroscience, 12 (6), 718-724 DOI: 10.1038/nn.2331

Galaburda, A., & Sanides, F. (1980). Cytoarchitectonic organization of the human auditory cortex. Journal of Comparative Neurology, 190, 597-610.

Smiley, J. F., Hackett, T. A., Ulbert, I., Karmas, G., Lakatos, P., Javitt, D. C., & Schroeder, C. E. (2007). Multisensory convergence in auditory cortex, I. Cortical connections of the caudal superior temporal plane in macaque monkeys. J Comp Neurol, 502(6), 894-923.


Jonas said...

Greg, I am with you on your call for more scrutiny on PT subdivisions. I solemnly swear to become more specific with my own PT data and claims based on it. To this end, could you kindly refer me to the paper you got this PT figure from? Did I miss this one? Best, J.

Greg Hickok said...

That figure is my rendition of the subdivisions reported in Galaburda & Sanides 1980.

Here's a link to my paper which is still in press.