Electrode positioning.

<p>(A) Carbon fiber microelectrodes. Left: First design of microelectrode coated by a silica tube with 0.09 mm diameter, used in part of the early MFB stimulation experiments. Right: Microelectrode coated by a glass capillary, used for the most recordings in this study. Scale bar = 0.5 mm. Note the diameter next to the carbon fiber is thinner in the glass design (right). (B) Schematic drawing of the guide cannula (blue) (OD 0.7 mm, ID 0.42 mm). Left: An inset was placed to protect the inside of the tube when inserting into the brain. Right: The inset was replaced by the elongated carbon fiber microelectrode with a shaft of silica tube of 0.35 mm diameter. (C) Grid with vertical holes of 0.7 mm diameter and two manual-drive micromanipulators. (D) Coronal section immunostained with tyrosine hydroxylase (TH) showing the position of the striatum and MFB. (E) Schematic drawing of the grid on the monkey’s head. The electrode path is shown on the left MRI image. Note the electrode chamber on the skull, as visualized by filling with 2% agar.