Efficiency
We mentioned neuronal capturing cost and you may LFP gamma stamina and you can level frequency within the V1 of 5 anesthetized macaque monkeys, to own floating sinusoidal gratings of different brands, contrasts, orientations and you can masked with various degrees of noises.
Around the personal internet, normalized gamma stamina dropped doubled when gratings have been masked which have 80% noise, as well as the average level frequency moved on from 42
We analyzed a common set of sites across conditions-those that were activated by the smallest grating. The average LFP spectra showed nearly a twofold increase in gamma power with larger gratings (Fig. 2A, left), with a more apparent bump in the gamma range. We quantified the change in gamma power (25–55 Hz) by normalizing to its maximum across stimulus sizes at each site, and then averaging across sites (n = 209 sites). This normalized gamma power increased monotonically from 0.67 ± 0.02 for the smallest grating to 0.93 ± 0.01 for the largest (p < 0.0001, Wilcoxon signed-rank test; Fig. 2A, middle, black). Similar effects were seen in each individual animal (faint black lines, indicating average effect in each animal). Over the same range of sizes, the gamma peak frequency at individual recording sites decreased from 50.5 ± 0.2 to 37.9 ± 0.1 Hz (p < 0.0001, t test; Fig. 2A, middle, red; data from each animal in faint red). Thus, gamma power and peak frequency were modulated in opposite ways by stimulus size: an increase in gamma power was associated with a decrease in peak frequency. The simultaneously recorded neuronal responses showed strong suppression for large gratings, with the normalized spike rate decreasing from 0.86 ± 0.02 to 0.41 ± 0.02 (p < 0.0001, Wilcoxon signed-rank test; Fig. 2A, right).
Gamma energy, height regularity, and neuronal firing rate a variety of stimuli manipulations in the V1. A great, Kept, Stamina spectra away from LFP to possess gratings of different types (n = 209 sites). Dashed line suggests the gamma energy having natural interest. Center, Height frequency on gamma variety (thick red range) and stabilized gamma energy (thick black range). The fresh light contours imply an average studies regarding for each creature. Dashed range indicates the fresh gamma energy getting natural pastime. Right, Stabilized neuronal responses (heavy black range). Faint outlines indicate the average studies out of for each and every animal. B, Left, Power spectra out of LFP for different quantities of music-hiding (n = 228 internet). Center, Level volume and you can normalized gamma power. Best, Normalized neuronal shooting rate. C, Remaining, Electricity spectra away from LFP for several stimuli contrasts (letter = ninety websites). Center, Level volume and you can stabilized gamma strength. Right, Stabilized neuronal answers. D, Leftover, Fuel spectra from LFP to have gratings of different orientations (letter = 209 internet). Center, Peak regularity and stabilized gamma energy. 
Best, Stabilized neuronal responses. Every mistake pubs indicate SEM.
We next measured gamma induced by large gratings (10°) masked with different levels of noise. Noise was generated by replacing different proportions of the gratings with random large pixels of the same mean luminance (see Materials and Methods). We used large gratings because these induced the most gamma power, for which the peak frequency was most clearly defined. Masking noise reduced gamma power (see also Jia et al., 2011), and caused the peak frequency of the average spectrum to shift lower (Fig. 2B, left; n = 228 sites). 2 ± 0.1 Hz to 30.1 ± 0.4 Hz (p < 0.0001, t test; Fig. 2B, middle). Thus, for masking noise, gamma power and peak frequency were positively correlated across stimulus conditions: a ma power was associated with a decrease in peak frequency. Despite prominent changes in gamma, population neuronal firing rates were not affected by noise masking (ANOVA: F = 1.18, p = 0.14; Fig. 2B, right). The normalized spike rate for the unperturbed gratings was indistinguishable from the 80% noise condition (0.79 ± 0.02 vs 0.78 ± 0.01; p = 0.04, Wilcoxon signed-rank test).
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