Bouton population analysis of prefrontal and temporal terminations in TRN and subcortical structures. A, Mean major diameter of boutons from axons originating in prefrontal cortices or TE/Ts1 and terminating in TRN, VA, MD, caudate, and amygdala. Range of diameters of boutons is also indicated (solid bars). B, Cluster analysis of the diameter of boutons terminating in TRN, VA, MD, caudate, and amygdala emanating from prefrontal cortices or TE1/Ts1. The latter are clearly small.