Laminar termination in the FAES of non-auditory inputs from the SIV. In (A), the coronal section shows the injection site (black area) in the dorsal bank of the anterior ectosylvian sulcus corresponding to the location of SIV (scale = 1 mm). (B) Coronal sections through the anterior (left), middle, and posterior (right) regions of the FAES (borders indicated by dashed gray lines; layer 4 indicated by dotted gray line) displaying terminal boutons (1 black dot = 1 bouton; scale = 1 mm) labeled from the SIV injection site. The lateral view of cortex (C) illustrates the location (vertical lines) of the coronal sections through the SIV (shown in A) and FAES (B). (D) is a micrograph (×1000, oil; scale = 10 μm) taken of representative SIV-labeled axons and boutons (indicated at white arrows) within the FAES. When the number of boutons labeled from the SIV were counted within the supragranular versus infragranular layers of the FAES for this case, the overwhelming proportion was identified within supragranular layers, as quantitatively summarized in E (mean = 75% ± 4.7 SE). Similarly, (F) the levels of boutons labeled from SIV for all cases and sections predominantly (mean = 77% ± 2.3 SE) terminated within the supragranular layers of the FAES.