Fig. 8

SUA is modulated by cognitive performance in the battery of verbal and gaze-tracking tasks where neurons respond to specific words. (a) Cumulative density plot of all overlaid action potential waveforms (n = 9543) confirms the highest density (warm colors) around the average amplitude values. (c) Histogram of the inter-spike intervals (ISI; each bin is 1 ms) reveals an irregular firing pattern with most spikes fired at ISI >3 ms (beyond the refractory period) and <200 ms, reflecting moderate bursting without a single predominant rhythm (red line is the smoothed average). (d) Summary of all spikes detected throughout the entire recording session shows a stable firing rate (orange line) and spike amplitude (blue line) across time. (e) Neurons responding to specific words increase their firing rate after the onset and peak just before the offset of the preferred words. The Word Screening Task consists of five trials, where 180 words from the pool are presented in five blocks - once per block. Word presentation within each block follows the same order; the left upper panel shows an example of ten words. Raster and the line plot below summarize spiking rate of the neuron shown in a–d in response to five presentations of preferred (red) and non-preferred (black) words. Summary of all spiking responses to preferred stimuli (N = 4 patients, n = 139 cells) confirms elevated firing rates in anticipation of the next word presentation and during encoding of preferred words displayed on the computer screen (gray area).