Human substantia nigra neurons encode unexpected financial rewards

The brain's sensitivity to unexpected outcomes plays a fundamental role in an\ud organism's ability to adapt and learn new behaviors. Emerging research suggests that\ud midbrain dopaminergic neurons encode these unexpected outcomes. We used\ud microelectrode recordings during deep brain stimulation surgery to study neuronal activity in\ud the human substantia nigra (SN) while patients with Parkinson's disease engaged in a\ud probabilistic learning task motivated by virtual financial rewards. Based on a model of the ..

High-frequency oscillations (>200 Hz) in the human non-parkinsonian subthalamic nucleus

The human basal ganglia, and in particular the subthalamic nucleus (STN), can oscillate at surprisingly high frequencies, around 300 Hz [G. Foffani, A. Priori, M. Egidi, P. Rampini, F. Tamma, E. Caputo, K.A. Moxon, S. Cerutti, S. Barbieri, 300-Hz subthalamic oscillations in Parkinson's disease, Brain 126 (2003) 2153-2163]. It has been proposed that these oscillations could contribute to the mechanisms of action of deep brain stimulation (DBS) [G. Foffani, A. Priori, Deep brain stimulation in Parkinson's disease can mimic the 300 Hz subthalamic rhythm, Brain 129 (2006) E59]. However, the physiological role of high-frequency STN oscillations is questionable, because they have been observed only in patients with advanced Parkinson's disease and could therefore be secondary to the dopamine-depleted parkinsonian state. Here, we report high-frequency STN oscillations in the range of the 300-Hz rhythm during intraoperative microrecordings for DBS in an awake patient with focal dystonia as well as in a patient with essential tremor (ET). High-frequency STN oscillations are therefore not exclusively related to parkinsonian pathophysiology, but may represent a broader feature of human STN function