Table 2.
Tetrode lead field radii
| r100µV | r50µV | r25µV | ||
|---|---|---|---|---|
| Tetrode | Lead | (µm) | (µm) | (µm) |
| 03–0591 | CTR | 92±4 | 131 ±4 | 187±3 |
| ECC | 101 ±2 (71) | 139±3 (109) | 195 ±3 (167) | |
| 0603–3200 | CTR | 93±3 | 132±3 | 187±2 |
| ECC | 99±3 (64) | 139±4 (108) | 194±5 (167) | |
| 0703–0087 | CTR | 95±2 | 134±2 | 189±1 |
| ECC | 99±2 (74) | 138±4 (116) | 194±5 (175) | |
| 0703–0088 | CTR | 93±3 | 132±3 | 187±2 |
| ECC | 98±2 (75) | 137±3 (116) | 193±5 (171) | |
Field radii are defined at 3 criteria: r100µV, for characteristic (median) single unit signal levels required by unit isolation (at 4 times the characteristic noise levels), r50µV, for characteristic signal detection threshold (at 2 times the characteristic noise levels), and r25µV, for characteristic noise levels. The criterion field strengths are in equivalent probe potential (µV) obtained with a 5pA*m dipole source (typical for neurons in visual cortex) aligned with the field everywhere. Entries are mean ± the half-range of the radii measured along the x- and z-axis for the center lead, and along the cardinal directions within the tangent plane and along its surface normal in front for the eccentric lead. The smaller radii enclosed by the parenthesis are along the surface normal pointing behind the tetrode; they highlight the asymmetry specific to the eccentric leads