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Published November 2008 | public
Journal Article

Selective reduction of Von Economo neuron number in agenesis of the corpus callosum

Abstract

Von Economo neurons (VENs) are large spindle-shaped neurons localized to anterior cingulate cortex (ACC) and fronto-insular cortex (FI). VENs appear late in development in humans, are a recent phylogenetic specialization, and are selectively destroyed in frontotemporal dementia, a disease which profoundly disrupts social functioning and self-awareness. Agenesis of the corpus callosum (AgCC) is a congenital disorder that can have significant effects on social and emotional behaviors, including alexithymia, difficulty intuiting the emotional states of others, and deficits in self- and social-awareness that can impair humor, comprehension of non-literal or affective language, and social judgment. To test the hypothesis that VEN number is selectively reduced in AgCC, we used stereology to obtain unbiased estimates of total neuron number and VEN number in postmortem brain specimens of four normal adult controls, two adults with isolated callosal dysgenesis, and one adult whose corpus callosum and ACC were severely atrophied due to a non-fatal cerebral arterial infarction. The partial agenesis case had approximately half as many VENs as did the four normal controls, both in ACC and FI. In the complete agenesis case the VENs were almost entirely absent. The percentage of neurons in FI that are VENs was reduced in callosal agenesis, but was actually slightly above normal in the stroke patient. These results indicate that the VEN population is selectively reduced in AgCC, but that the VENs do not depend on having an intact corpus callosum. We conclude that in agenesis of the corpus callosum the reduction in the number of VENs is not the direct result of the failure of this structure to develop, but may instead be another consequence of the genetic disruption that caused the agenesis. The reduction of the VEN population could help to explain some of the social and emotional deficits that are seen in this disorder.

Additional Information

© Springer-Verlag 2008. Received: 15 January 2008 / Revised: 10 September 2008 / Accepted: 11 September 2008 / Published online: 25 September 2008. We thank Archibald Fobbs, Curator of the Yakovlev Brain Collection, National Museum of Health and Medicine for his generous assistance in providing access to the acallosal and control specimens, and to Dr. D. Wolfe of the Mount Sinai School of Medicine for generously providing access to the cerebral infarction specimen. We also wish to thank Ralph Adolphs, Warren Brown and J. Michael Tyszka for their valuable discussions of this project. This research was generously funded by grants from the James S. McDonnell Foundation, the Gordon and Betty Moore Foundation, the David and Lucile Packard Foundation, and the Gustavus and Louise PfeiVer Foundation.

Additional details

Created:
August 22, 2023
Modified:
October 17, 2023