Time delays in the b/c cycle operate on the level of individual neurons

Recent studies suggested that small time delays among synchronized responses can convey information about visual stimuli. We compared these delays across different types of synchronized signals: single-unit action potentials, multi-unit action potentials, and local field potentials obtained with invasive recordings from cat visual cortex and magnetoencephalographic and electroencephalographic signals recorded from the scalp of human beings. In the signals that reflected more localized sources, time delays were larger and more selective for stimulus properties than in the signals that reflected more large-scale sources. The results suggest that a cortical code for stimulus features that exploits time delays operates predominantly across individual neurons rather than across larger anatomical structures such as brain areas. NeuroReport 21:746–750 c 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.