Electron micrographs illustrate the ultrastructure of GABAergic terminals (high density of gold particles) in the claustrum. GABAergic terminals that originate from dendrites (A-D, purple) contain vesicles that are clustered near synapses (arrows, asterisks in A and C indicate synapses shown at higher magnification in C and D). GABAergic dendritic terminals contact nonGABAergic dendrites (A, B, green) or GABAergic dendrites (B, D, blue; this dendrite also receives input from a nonGABAergic terminal, yellow). GABAergic terminals that presumably arise from axons (E-G, red) primarily contact nonGABAergic dendrites (E-F, green) and somata (G, green). Scale bar = 1 μm. Scale in A also applies to C. Scale in B also applies to D-G.