Monitoring of nonspatial information within working memory in the common marmoset (Callithrix jacchus).

The mid-dorsolateral prefrontal cortical region (areas 46 and 9/46) is critical for the monitoring of information in working memory both in the macaque monkey brain and the human brain. The presence of this cytoarchitectonic region in the New World marmoset brain was in debate, but recent anatomical evidence demonstrated a limited area 46. This finding raised the question of the extent to which the marmoset brain can support the cognitive control process of monitoring information within working memory. This cognitive control process was assessed in adult marmosets and was shown to be limited to the monitoring of only two items in contrast to macaque monkeys, who can monitor as many as five items in working memory. The results are consistent with the limited development of the relevant prefrontal region in the marmoset and contribute to understanding the evolution of higher cognitive control processes in the primate brain.