Site Density
Number of recording sites per unit length along the probe.
Site density describes how closely spaced recording sites are along a probe, usually expressed as sites per millimeter or micrometers between adjacent sites. This determines the spatial resolution of your recordings.
Why it matters: Higher density provides finer spatial sampling, allowing better discrimination of signals from different neurons or tissue layers. However, very high density may record redundant information from the same neurons on multiple sites.
Density classifications:
- Low density (50-100 µm spacing): Distinct sampling, minimal redundancy
- Medium density (25-50 µm spacing): Good spatial resolution, some overlap
- High density (10-25 µm spacing): Very fine sampling, significant overlap
Single neuron considerations: A single neuron's electrical field typically extends 50-100 µm, so sites closer than this will detect the same cell. This redundancy can improve spike sorting accuracy but increases data processing requirements.
Depth profiling: For studies mapping activity across cortical layers, higher density provides better laminar resolution. For counting unique neurons, spacing should match or exceed the detection radius.