Neural activity of multiple fields in the auditory cortex of anesthetized guinea pigs in response to pure tones was visualized by optical recording using a voltage-sensitive dye (RH795). Ten auditory fields were identified based on the tonotopic organization and response latency: the core fields consisting of the primary (AI) and secondary (AII) fields and surrounding belt areas consisting of dorso-anterior (DA), dorsal (D), dorso-posterior (DP), posterior (P), ventro-posterior (VP), ventro-medial (VM), ventro-anterior (VA) and ventral (V) fields. Tonotopic organization was observed in all the fields apart from DA, D, DP and V. Spatio-temporal displays suggest that the auditory information spreads from the core fields of AI and AII to belt fields via three distinct (dorsocaudal, caudal and ventrorostral) pathways.