, 2001). The stable value information in the caudate tail may be transmitted to the superior colliculus through the substantia nigra pars reticulata so that monkeys make saccades preferentially to high-valued objects (Yasuda et al., 2012). Although these studies individually provide important data, it has been difficult to reach a unified view on basal ganglia functions. Our recording and inactivation experiments on the primate caudate head and tail provide insights in understanding how the basal ganglia normally control behavior in multiple but integrative ways and how behavior can be disrupted in multiple ways in basal ganglia disorders. Two adult male rhesus monkeys (Macaca mulatta, 8–9 kg) were used for the experiments.

All animal care and experimental procedures were approved BMS354825 by the National Eye Institute Animal Care and Use Committee and complied with the Public Health Service Policy on the humane care and use of laboratory animals. We implanted

a plastic head holder and a recording chamber to the skull under general anesthesia and sterile surgical conditions. The chamber was tilted laterally by 25° and was aimed at the caudate head, body, and tail. Two search coils were surgically implanted under the conjunctiva of the eyes to record eye movements. After the monkeys fully recovered from surgery, we started training them with flexible and stable value procedures. While the monkey was performing a task, we recorded the activity of single neurons in different subregions in the caudate nucleus using learn more conventional methods. The recording sites were determined with 1 mm spacing grid system, with the aid of MR images (4.7T, Bruker) obtained along the direction of the recording chamber. Single-unit recording was performed using glass-coated electrodes (Alpha-Omega). The electrode was inserted into the brain through a stainless-steel about guide tube and advanced by an oil-driven micromanipulator (MO-97A, Narishige). The electric signal from the electrode was amplified with a band-pass filter (2 Hz–10 kHz; BAK) and collected at 1 kHz. Neural spikes were isolated online using a custom voltage-time window discrimination software (MEX, LSR/NEI/NIH).

Behavioral tasks were controlled by a QNX-based real-time experimentation data acquisition system (REX, Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health [LSR/NEI/NIH]). The monkey sat in a primate chair, facing a frontoparallel screen 33 cm from the monkey’s eyes in a sound-attenuated and electrically shielded room. Visual stimuli generated by an active matrix liquid crystal display projector (PJ550, ViewSonic) were rear projected on the screen. We created the visual stimuli using fractal geometry. Their sizes were approximately 8° × 8°. This procedure allowed us to examine behavioral and neuronal encoding of flexible object values as they were being updated in blocks of trials (Figure 1A and Figure S1A).