MAPPING VISUAL RECOGNITION MEMORY THROUGH EXPRESSION OF THE IMMEDIATE-EARLY GENE C-FOS

To study brain regions involved in familiarity discrimination, rats we re shown sets of novel and familiar objects. On each trial two objects were shown simultaneously to a rat so that one eye saw a novel object while the other saw a familiar object. Thus novel and familiar object s were seen with the same conditions of alertness and eye movements. A ctivated neurones were revealed by staining for products of the immedi ate early gene c-fos. Familiar stimuli activated significantly fewer n eurones than novel stimuli in perirhinal cortex and area TE of tempora l cortex, and the ventral lateral geniculate nucleus of the thalamus, but not in the hippocampus or other areas sampled. These findings are discussed in relation to recognition memory.