Table 2.
Coefficients of determination, expressed as r2 × 100%, for the Pearson product-moment correlations between neuronal density and each of the four outcome metrics listed in column 1. The neuronal activities used to compute the outcome metrics were recorded during the three sessions spanning 2 weeks before the animals were sacrificed. The neuron density surrounding each of the 54 tip sites was determined by dividing the number of neuronal profiles 20–150 μm from the centers of each tip site by the area of that region. In column 2, the neuron density so determined was divided by (normalized on) the neuron density within the annulus spanning 160–175 μm from the center of the tip site. In column 3, the neuron density (between 20 and 150 μm from the tip sites) was not normalized on the neuron density in the annulus spanning 160–175 μm from the center of the same electrode site.
| Outcome metric | r2 × 100% neuron density normalized | r2 × 100% neuron density not normalized |
|---|---|---|
| S/N, largest 10% of APs with S/N ⩾3 | 49.2% | 10% |
| S/N, all APs with S/N ⩾3 | 26% | 5% |
| Amplitude of largest 10% of APs | 67% | 34% |
| Amplitude of all APs w S/N ⩾3 | 57.8% | 15% |