Using an identical paradigm to that used by Rudebeck et al. (2006), we tested social valuation in four macaques before and after mOFC lesions. Furthermore, utilization of the same behavioural Vincristine solubility dmso protocol allowed us to compare the mOFC lesion results with the anterior cingulate gyrus (ACCg) lesion results obtained by Rudebeck et al. (2006). To ascertain whether any potential impairment in social valuation was associated with impairment in fundamental aspects of reward-guided decision-making we also tested both mOFC and ACCg animals, pre- and postoperatively, on identical probabilistic two-choice
decision tasks with visual stimuli. The effects of ACCg lesions on social valuation have previously been published (Rudebeck et al., 2006) but the effect of ACCg lesions on the probabilistic decision-making tasks has not been reported. Four male rhesus macaque monkeys (Macaca mulatta) aged between 7 and 10 years and weighing between 9 and 13.5 kg received mOFC lesions. All animals were maintained on a 12-h light–dark cycle and had 24-h ad lib access to water, apart from
when they were testing. All experiments were conducted in accordance with the United Kingdom Scientific Procedures Act (1986). The following section summarizes the details of the surgery, anesthesia and histological protocols for the mOFC-lesioned JNK inhibitor animals. Procedures specific to the lesions made in the comparison groups in orbital and ventrolateral prefrontal cortex (PFv+o) and anterior cingulalte gyrus (ACCg) have been published previously (Rudebeck et al., 2006). In the current study, at least 12 h before surgery macaques were treated with an antibiotic (8.75 mg/kg amoxicillin, i.m.) and a steroidal anti-inflammatory
(20 mg/kg methylprednisolone, i.m.) to reduce the risk of postoperative infection, oedema and inflammation. Additional supplements of steroids were given at 4- to 6-h intervals during surgery. On the morning of surgery, animals were sedated with ketamine (10 mg/kg, i.m.) and xylazine (0.5 mg/kg, i.m.) and given injections of atropine (0.05 mg/kg), an opioid (0.01 mg/kg Dolichyl-phosphate-mannose-protein mannosyltransferase buprenorphine) and a nonsteriodal anti-inflammatory (0.2 mg/kg meloxicam) to reduce secretions and provide analgesia, respectively. They were also treated with an H2 receptor antagonist (1 mg/kg ranitidine) to protect against gastric ulceration, which might otherwise have occurred as a result of administering both steroidal and nonsteroidal anti-inflammatory treatments. Macaques were then moved to the operating theatre where they were intubated, switched onto isoflurane anesthesia (1–2%, to effect, in 100% oxygen), and placed in a head holder. The head was shaved and cleaned using antimicrobial scrub and alcohol. A midline incision was made, the tissue retracted in anatomical layers, and a bilateral bone flap removed. All lesions were made by aspiration with a fine-gauge sucker.