One important aspect of memory is association of different modality components/inputs.Associative memory is reflected in neuronal activities in different cortices after intensive training.This paper presents most direct evidences of the establishment of associative memory traces in the rat auditory cortex.We produced a conditioned association between cortical electrical activation and a visual stimulus, visualizing the physiological memory traces, i.e., auditory neuronal responses to the visual stimulus after conditioning.To confirm the visuoauditory memory behaviorally, we first associate the sound with the visual stimulus.The sound stimulus was then associated with the reward, and the establishment and recall of the associative memory was proven when the rat successfully secnred the reward after the sound stimulus was replaced by the visual stimulus for the first time.The early and lasting appearance of memory traces indicates that the neocortex is involved in memory storage earlier than the hippocampus-neocortex transfer model suggested.