Fig. 1: Recordings of single LGN neurons.

a Postoperative coronal MR images from Patient #1 (image used with permission from reference #16) and Patient #2. The electrode trajectory targeted the LGN (yellow box). b The probe was comprised of a high impedance (0.8–0.9 MΩ) microelectrode and a macroelectrode for stimulation (Image courtesy of InoMed Neurocare Ltd.). Two microelectrodes were used in each patient to map spiking activity on a trajectory through the LGN. c Raw data (1 s segments) at each position along the trajectory of the central electrode in Patient #1. The depth relates to a preoperatively defined anatomical target. In Patient #1 spiking activity was apparent from −2mm (indicated by the dashed red line) to +4.5 mm. d Power-spectrum at one depth while the patient viewed an 8 Hz flickering light source. There were clear 8 Hz tracking and several harmonics. e The ratio of power 8 Hz to 5 Hz of the two microelectrodes (C1, central and P1, posterior) in Patient #1. Visually driven activity occurred from −2.0 to +3.5 mm, and was used to estimate the upper and lower boundaries of the LGN. f At each depth/electrode we sorted spike waveforms using WaveClus3. The auto-correlograms, cross-correlograms (black), and the waveforms are shown from the three units at a depth of +1.5 mm (1 single unit, 2 multi-units, see Methods). Error bars indicate ±1 standard deviation. In Patient #1, we recorded from 3 single-units and 13 multi-units. g A zoomed in view of the spiking responses from microelectrode P1 in response to 8 Hz flicker. A single-unit (red spikes) showed bursts of spiking whereas a simultaneously recorded multi-unit (blue spikes) fired predominantly to the opposite phase of the flicker. In this subject, the synchronization between the stimulus and the recording system was not present and we therefore estimated the stimulus phase (indicated by the black and gray horizontal bars above the graph). The auto-correlation function (h) and power spectrum (i) of the single-unit shown in (g). Bursting activity caused a peak at approximately 170 Hz. The bursts in Patient #1 had a typical inter-spike interval of 4.0–6.0 ms, slightly longer than in previous studies (e.g., ref. ³²). Error-bars indicate ±1 s.e.m. Source data are provided as a Source Data file.