At the completion of the lesion, the wound was closed in anatomical layers. Nonsteroidal anti-inflammatory analgesic (0.2 mg/kg meloxicam, orally) and antibiotic (8.75 mg/kg amoxicillin, orally) treatment was administered for 5 days postoperatively. All surgery was carried out under sterile conditions with the aid of a binocular microscope. The wound was closed in anatomical layers. At least 2 weeks were allowed for recovery before testing resumed. When the animals had completed their testing they were anesthetized with sodium pentobarbitone and perfused with 90% saline and 10% formalin. The brains

were then removed and placed in 10% sucrose formalin until they sank. The brains were blocked in the coronal plane at the level of the most medial part of the central sulcus. Each brain was cut in 50-μm coronal CP-868596 datasheet sections. Every tenth section was retained for analysis and stained with Cresyl violet. All training and testing was conducted while the animals were in a transport cage inside a

modified Wisconsin General Testing Apparatus (WGTA; Fig. 1A). HDAC inhibitor A Plexiglas box measuring 70 × 11 × 11 cm with a hinged back was fixed to the WGTA 20 cm in front of the transport cage. In addition behind the box, 50 cm from the front of the transport cage, was a PC monitor for presenting visual stimuli. On each trial, stimuli could be presented either in the box or on the PC monitor. The stimuli presented in the box could be one of the following: 20 neutral control ‘junk’ objects and two fear-inducing stimuli (a static rubber snake or a moving wooden snake).

Stimuli presented on the screen were video clips 30 s in length and were one of two human stimuli (two unknown staring human faces), one of five social stimuli [a large (11 kg) monkey staring, a monkey (8 kg) exhibiting affiliative behaviours (lip-smacking), a monkey (9 kg) inspecting a transport cage or a monkey (5 kg) with food, and a female macaque (5 g) with prominent perineal swelling] or a moving, neutral control stimulus (a moving randomly changing coloured object; Fig. 3B). The video clips were chosen because it made it possible to compare the effects of mOFC lesions with the effects of ACCg lesions; the stimuli had previously been used in an investigation of the effects of ACCg lesions (Rudebeck Methocarbamol et al., 2006). The social stimuli were chosen because they were expected to elicit varying degrees of interest from control monkeys (and indeed this proved to be the case as explained below). Video stimuli were clips taken from longer videos of other monkeys in the colony recorded while they were in either transport cages or primate chairs. At the time of testing all the monkeys in the video social stimuli were novel to the subjects. All videos were taken using a Panasonic EZ35 mini-DV camera and edited using Adobe Premier Pro 1.5 software. Videos were played using Windows media player version 9.0.