Von Economo neurons in the anterior insula of the macaque monkey.

The anterior insular cortex (AIC) and its unique spindle-shaped von Economo neuron (VEN) emerged within the last decade as having a potentially major role in self-awareness and social cognition in humans. Invasive examination of the VEN has been precluded so far by the assumption that this neuron occurs among primates exclusively in humans and great apes. Here, we demonstrate the presence of the VEN in the agranular anterior insula of the macaque monkey. The morphology, size, laminar distribution, and proportional distribution of the monkey VEN suggest that it is at least a primal anatomical homolog of the human VEN. This finding sheds new light on the phylogeny of the VEN and AIC. Most importantly, it offers new and much-needed opportunities to investigate the primal connections and physiology of a neuron that could be crucial for human self-awareness, social cognition, and related neuropsychiatric disorders.