Figure 3.

Single-unit and local field potential (LFP) recordings confirm ocular-dominance preferences. Ch1, 2, and 3 are recorded from three sites indicated with arrows in Figure 1A. (A) Raster and peristimulus time histograms (PSTHs) plots of typical single neuron spiking responses. Three columns represent three individual neurons recorded from three neighboring microelectrodes (Ch1, Ch2, and Ch3) that were carefully positioned on different eye columns. The top and bottom panels show the same neuron's response to the left and right eye stimuli, respectively. In each panel below the raster plot, the corresponding PSTHs are displayed (calculated with 10 milliseconds bin size). Each row in the raster stands for one stimulus period, 4.5-second long, and the colored dots represent the action potentials of the neurons. The spike rates of Ch1 and Ch3 neurons during left eye stimulation are significantly higher than that to right eye stimulation (P<0.0001); the firing of Ch2 neuron responds in an opposite way (P<0.0001). Thus, the eye preferences measured by the spiking responses are consistent with the columnar maps obtained by imaging. (B) Spectrograms of LFP signals recorded simultaneously with the spikes shown in panel A (Ch1, Ch2, and Ch3). The top and bottom panels of each column represent the LFP response to the left and right eye stimuli, respectively. Similar to the spiking responses in panel A, the increased power (mainly in the γ-band LFP) of Ch1 and Ch3 during left eye stimulation are significantly higher than those of right eye stimulation (P<0.0001), whereas the LFP recorded in Ch2 responds in an opposite way (P<0.0001). Color bar shows the relative changes in the LFP power compared with the baseline period in dB unit.