Macaque fMR Imaging and ACFs

<p>(A) Imaging slices were aligned with the lateral sulcus to obtain a plane of auditory cortex activity on the lower bank of this sulcus (colored in translucent orange; STS, superior temporal sulcus). (B) Shows activations to broadband noise from one anesthetized animal. (C) Schematizes the possible ACFs contributing to activity in (B) [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b001" target="_blank">1</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b003" target="_blank">3</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b016" target="_blank">16</a>–<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b021" target="_blank">21</a>]. (D) Schematizes functional properties of ACFs that could distinguish them. Two of the three core or primary ACFs (blue) have frequency selective gradients, shown with arrows from low (L) to high (H) frequency selectivity. The question mark in the core field RT indicates limited evidence of such a gradient in primates [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b002" target="_blank">2</a>]. Anatomy suggests there could be seven or eight belt or non-primary ACFs (orange) [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b001" target="_blank">1</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b003" target="_blank">3</a>]. Only four of the belt ACFs have neurophysiologically described frequency gradients, and these fields are considered to be less responsive to single-frequency tones, preferring instead more complex sounds [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b016" target="_blank">16</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b018" target="_blank">18</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b019" target="_blank">19</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b021" target="_blank">21</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b028" target="_blank">28</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040215#pbio-0040215-b029" target="_blank">29</a>]. Abbreviations: Ec, external capsule; Cis, circular sulcus.