FIGURE 1 | Extracellular neuronal recordings of oscillatory activity from the superficial layers of the SC. (A) Top panel shows the raw signal recorded in response to a light bar moving at a velocity of 5 deg s − 1 back and forth through the receptive field (RF). In this and all subsequent figures, horizontal arrows indicate the onset, duration, and direction of the moving stimulus. The bottom panel represents an enlarged part of the raw signal. An oscillatory pattern is clearly visible as single spikes or doublets appearing with a constant interval. (B) Spike waveforms of two cells selected from the recording in (A) . Only the unit with the higher amplitude (black line) was considered for further analysis. (C) Spike waveforms classified into two putative units based on the principal component analysis. Colors mimic those of the waveforms in panel (B) . (D) Inter-spike interval (ISI) histogram for the unit in (A,B) (black waveforms). The first peak reflects bursting activity (seen here as doublets), the other peaks indicate oscillatory activity. Insert represents an enlarged view of the beginning of the ISI to emphasize the presence of the refractory period. (E) Peri-stimulus time histogram (PSTH) divided into 200 bins for 10 repetitions of the stimulus presentation for the unit in (A–D) . (F) Corrected autocorrelogram (cACH) from the signal in (A) ; resolution 0.5ms. (G) Power spectrum calculated from the cACH in (F)