Fig. 3.

Comparison of the dorsal STN border on 7.0-T T2-weighted MRI with its electrophysiologically determined border (MER). a Coronally orientated image of left and right mesencephalic and diencephalic areas: the STN (almond shaped) is situated above the substantia nigra. b The microelectrode trajectory (white dotted line) is superimposed on MRI; the bottom part penetrates the STN. The white box is drawn around this bottom part and enlarged in b′. b′ MER results at 3 stereotactic depths (−3.5, −2.0, and −0.5 mm compared to the planned target depth) along the microelectrode trajectory. The electrophysiological STN at −0.5 mm relative to the planned target depth (green dot) corresponded with the STN representation on 7.0-T MRI. However, at −3.5 and −2.0 mm relative to the planned target depth, the microelectrode trajectory was situated within STN representation on 7.0-T MRI without showing electrophysiological STN activity (red dots). Thus, the dorsal STN border on 7.0-T MRI was located more dorsal than the dorsal STN border on MER.