Involvement of the rat prefrontal cortex in cognitive functions: A centralrole for the prelimbic area

In this brief review, we address the cognitive functions of a subregion of the rat frontal cortex, the prelimbic cortex. Growing evidence suggests tha t the prelimbic cortex is involved in working memory, defined as the tempor ary storage of information required for its internal manipulation. However, several factors appear to modulate the extent to which prelimbic damage im pairs performance in delayed tasks. These factors, which contribute to the overall difficulty of the task, are related to the attentional requirement of the task and to the response selection mechanisms that underlie correct performance. Impairments induced by prelimbic cortical damage are increased when the task requires the rat to consistently focus its attention on the detection of external events and when the learning rule countradicts either spontaneously used or previously learned strategies. This overall pattern of deficit suggests that the prelimbic cortex is not a pure working memory system. Rather, it subtends a wide range of processes that are required for solving difficult problems. Together with anatomical evidence, the existen ce of functional similarities between the prelimbic cortex of the rat and t he dorsolateral prefrontal cortex of primates suggests some homolog between these regions across species. Therefore, the rat prelimbic cortex appears to provide a valuable model system for studying the precursors of higher le vel cognitive processes in nonhuman and human primates.