Electrophysiological characterization of neurons in the subthalamic nucleus.

<p><i>(</i><b><i>A</i></b><i>)</i> A single spike from an STN neuron recorded <i>in vivo</i>. <i>(</i><b><i>B</i></b><i>)</i> Histological verification of the recording site in the STN, counterstained with neutral red. Scale bar: 200 µm. Examples of action potential traces, showing the three characteristic firing patterns of STN neurons. <i>(</i><b><i>C</i></b><i>)</i> Tonic firing pattern, in which the density histogram follows a Gaussian distribution. <i>(</i><b><i>D</i></b><i>)</i> Random firing pattern, in which the density histogram represents a Poisson distribution. <i>(</i><b><i>E</i></b><i>)</i> Bursting firing pattern, in which the density histogram represents a distribution significantly different from a Poisson distribution, with a significantly positive skewness of the density discharge distribution histogram.