A new paper examines how the brain keeps track of positive and negative outcomes: No unified reward prediction error in local field potentials from the human nucleus accumbens The authors, London-based neuroscientists Max-Philipp Stenner and colleagues, recorded electrical local field potentials (LFP) using electrodes implanted into the nucleus accumbens (NAcc) in six patients. The patients all suffered from epilepsy and the electrodes were being implanted to treat the disease. The authors made use of the electrodes to test a research question - does the NAcc encode reward prediction errors (RPEs)?