Spike Sorting Method Based on Two-Stage Radial Basis Function Networks - Advances in Computational Science and Engineering - page 102

3 Data Source
3.1 Obtain Raw Signals and Add White Noise
To evaluate the network in a range of noise intensity, experiments have been down with
synthetic signals. The signals used in the paper are from the Neural Signal Simulator. The
circuit simulates the output of a Cyberkinetics 100-electrode array. Each virtual electrode
is simulated as detecting microvolt signals from three separate neurons located at dif-
ferent distances from the recording site. The amplitudes of the three action potentials as
well as the kinetics of their responses differ in a manner consistent with real world sig-
nals. In the signal simulator, Local Field Potentials are also run. The simulation on each
output channel consists of a sequence of three individual action potentials that 'fire' one
after the other at a 1s intervals, figure 1. This firing sequence repeats nine times. Then,
every 10 seconds, a one second burst of activity is simulated. The burst consists of the
same train of three individual action potentials, and they are repeated with an inter action
potential interval of 10 milliseconds. The output impedance of each of the 128 output
channels is 220k. This simulates the output impedances of the electrodes of the Cy-
berkinetics array. The amplitudes of the three action potentials are 300, 250, and 200µV.
Fig. 2. Output of Neural Signal Simulator. (a) Specifications of the Action Potential from the
Simulator. In every 10 seconds, a one second burst of activity is simulated, which consists of the
same train of three individual action potentials, and they are repeated with an inter action po-
tential interval of 10 milliseconds. The amplitudes of the three action potentials are 300, 250, and
200µV. (b) Waveforms of the Raw Signal from the Simulator. Pinnacles in the waveforms
represents spikes that recorded by the electrode. The waveform contains local field potential as
well, in low-frequency, one kind of disturb in the action potential analysis, which can be elimi-
nated by differential treatment.