Chronic recording longevity

Chronic recording longevity is the empirical question of how long an implanted interface keeps delivering usable signal, quantified with longitudinal metrics rather than a single date: the fraction of channels recording sortable single units (yield), mean single-unit amplitude and signal-to-noise ratio, the number of decodable degrees of freedom, and, clinically, the number of months or years of stable task control a participant retains.

Human intracortical arrays have in some participants supported useful neural control for several years with gradual decline, but group data show substantial variability across arrays and individuals and a general downward trend in well-isolated single-unit yield over time. Signals that integrate over larger tissue volumes, such as the local field potential and multiunit activity, are typically more durable than isolated single units, which is one reason decoders are often built to degrade gracefully onto coarser features.