Von Economo Neurons in the Anterior Insula of the Macaque Monkey

Abstract

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.

Inter-individual variability in metacognitive ability for visuomotor performance and underlying brain structures

“…Abundant research has highlighted the complex neuronal architecture and functional specialization of the human insula (Allman et al, 2010(Allman et al, , 2011Craig, 2009;Evrard, Forro, & Logothetis, 2012), including a special role in sensorimotor integration through its widespread connectivity with various brain regions including the lateral prefrontal cortex as well as anterior cingulate and amygdala (Cauda et al, 2013). The most anterior part of the insula is associated not only with emotional and visceral functions (Craig, 2009), but also more cognitive functions such as error monitoring (Klein et al, 2007) and attentional shifts (Sridharan, Levitin, & Menon, 2008).…”

Modular architectonic organization of the insula in the macaque monkey

“…Finally, the available evidence suggests that the agranular areas integrate interoceptive activity, particularly gustatory and metaboreceptive activity, with olfactory signals relevant to visceral and homeostatic functions associated with feeding behavior, as others have suggested (for a review, see Price, 2007). Notably, one of the agranular areas, Ial, contains von Economo neurons (Evrard et al, 2012), which could have a special role in multimodal interoceptive integration and efferent control of homeostatic, emotional, and social responses (Allman et al, 2011).…”

“…As noted by Carmichael and Price (1994), its distinguishing characteristic is "radial striations" in layer 5. Area Ial is also the main area of macaque insular cortex in which large spindle-shaped neurons similar to human von Economo neurons (VENs) can be found in layer 5 (Evrard et al, 2012). Area Iai is characterized by the disappearance of layer 2, thick and densely packed sublayers 3a and 3b of equal thickness, a large, dense, and darkly stained sublayer 5a with a thicker, sparser 5b, and a thick, sublaminated layer 6 with a partially horizontal orientation.…”

A Subtype of Inhibitory Interneuron with Intrinsic Persistent Activity in Human and Monkey Neocortex

“…In addition to the great expansion of cortical volume during evolution, unique cell types in the human neocortex may contribute to its versatile mental abilities. For example, the Von Economo neurons (VENs) with distinct morphological characters have only been found in large-brained mammals, including human and nonhuman primates (Economo and Parker, 1929;Evrard et al, 2012;Nimchinsky et al, 1999). This specialized cell type may contribute to the rapid transmission of social information and self-awareness (Allman et al, 2005;Seeley et al, 2006).…”