Von Economo neurons: what they are, where they are and where they work

Von Economo neurons are a special class of nerve cells, First described just under a century ago, features humans and great apes.

They are special because of their particular spindle-shaped structure and because they are involved in complex cognitive processes related to socialization, empathy, intuition, or complex decision-making.

In this article, we explain what these types of neurons are, where we can locate them, what is their structure and what functions they perform, and what happens when these cells grow abnormally.

  • We recommend that you read: [“Tipos de neuronas: características y funciones”](Types of neurons: characteristics and functions)

Von Economo neurons: definition, location and development

Constantin Von Economo, the discoverer of spindle neurons.

Von Economo neurons, also known as spindle neurons, are named after the Austrian psychiatrist and neurologist. Constantin F. De Economo, Who in 1926 provided a detailed description of the morphology and cortical distribution of this type of neuron.

Von Economo was also the first scientist to show that these spindle-shaped (spindle-shaped) cells are specialized neurons located primarily in the Vb layer of the anterior cingulate cortex and the frontal island cortex.

Tapered neurons, unlike most types of nerve cells, are present in great apes. (Gorillas, chimpanzees, bonobos and orangutans) and in humans, but absent in other types of primates.

Von Economo neurons develop late, both ontogenetically and phylogenetically. These cells first appear at week 35 of gestation; at birth, only about 15% of postnatal quantities are present, and by four years, numbers of adults are present.

Spindle cells are thought to have evolved around 15 million years ago, before the evolutionary divergence of orangutans and hominids, according to research. Its discovery in some whales suggests that there could be a second independent evolution of this type of neuron.

The observation that Von Economo cells are found in a very large group of animals has led to the assumption that they are of great importance in human evolution and brain function.

The fact that these neurons have been discovered in other species (such as whales) suggests that they may be an obligatory neural adaptation in large brains, allowing rapid processing and transfer of information according to very specific projections, and which have evolved in relation to social emergence. behaviours.

structure

Von Economo described these cell types as neurons that exhibit an unusual shape and spindle length., Oriented perpendicular to the pial surface of the cortex, with a large apical axon and a single basal dendrite, almost equal in width to its soma.

Its large apical axon and elongated soma with large volume are similar to those of the pyramidal cortical neuron, but Von Economo neurons do not have the many basal dendrites that pyramidal cells do, and in their site receives inputs from a sub – relatively small set of crust; furthermore, spindle neurons are about five times the size of layer V pyramidal neurons (on average).

Its structural similarity to pyramidal neurons suggests that these neurons can perform similar functions, and because the speed at which neurons conduct information usually coincides with the diameter of their axons, large Von Economo neurons can do so very quickly, compared to other neurons.

However, Von Economo neurons are relatively rare in a region such as the anterior cingulate cortex, as they make up only 1-2% of the total number of neurons in this area of ​​the brain.

In the frontal insular cortex, these neurons are 30% more numerous in the right hemisphere than in the left hemisphere.; a process of hemispherical differentiation that occurs during the first four years of postnatal development in humans.

functions

Research suggests that the frontal island cortex and the anterior cingulate cortex, regions of the brain in which more spindle neurons have been located, are involved in social reasoning, empathy, emotions and the monitoring of autonomic visceral activity, Among other functions.

The anterior cingulate cortex has projections to the frontopolar cortex, which has been associated with processes of cognitive dissonance and uncertainty. Considering the morphology of Von Economo cells, they have been described as fast-projecting neurons, and due to the functions of the areas from which they are supposed to receive and project information, they are believed to play an important role in intuition, quick decision making and resolving cognitive dissonance processes.

Tapered neurons help channel neural signals from deep regions of the cortex to relatively distant parts of the brain. Signals from the anterior cingulate cortex have been observed to be received in Brodmann’s zone 10, in the frontopolar cortex, where regulation of cognitive dissonance and disambiguation between alternatives is believed to occur.

On the other hand, in humans, intense emotions activate the anterior cingulate cortex, as it transmits neural signals from the amygdala, a primary center for processing emotions to the frontal cortex. The anterior cingulate cortex is also active in demanding tasks that require judgment and discrimination, as well as in error detection.

The anterior cingulate cortex is also involved in autonomic functions, including motor and digestive functions., While playing a role in regulating blood pressure and heart rate.

The important olfactory and gustatory capacities of the cingulate cortex and the frontal island cortex appear to have dissipated in the course of evolution, to now occupy improved functions related to higher cognition, ranging from planning and self-awareness to role play and deception.

It should also be noted that the decreased olfactory function of humans, compared to other primates, could be related to the fact that spindle cells located in crucial neural centers have only two dendrites instead of several, resulting in integration.

Disorders related to the abnormal development of these neurons

The abnormal development of Von Economo neurons has been linked to various personality disorders and neurodevelopmental disorders., Especially those characterized by distortions of reality, impaired thinking, speech disorders and social withdrawal.

In addition, the development and abnormal functioning of this type of neuron has been implicated in disorders such as autism, as several studies have shown that fused neurons are involved in the cognitive processes involved in the rapid intuitive evaluation of situations. complex. In this regard, it has been suggested that they could be part of the circuits that support human social networks.

Von Economo neurons have been proposed to relate to areas of the brain associated with theory of mind, by transmitting information from the cingulate cortex and frontoinsular areas to the frontal and temporal cortex, where quick hunches are combined with slower deliberative judgments.

In autism spectrum disorders, spindle neurons would not develop properly, and this failure could be partly responsible for the social difficulties that emerge from the application of faulty intuition processes.

On another side, selective degeneration of spindle neurons has also been observed in diseases such as Alzheimer’s disease and dementia. For example, in patients with frontotemporal dementia, a neurodegenerative disorder that causes As the person loses empathy and becomes erratic and unresponsive, 70% of Von Economo neurons are found to be damaged.

Finally, it should be noted that some research has suggested that the abnormal development of these neurons may be linked to the pathogenesis of schizophrenia, although no results have been obtained. conclusive to date.

Bibliographical references:

  • Allman, JM, Watson, KK, Tetreault, NA and Hakeem, AY (2005). Intuition and autism: a possible role for Von Economo neurons. Trends in Cognitive Science, 9 (8), 367-373.

  • Seeley, WW, Carlin, DA, Allman, JM, Macedo, MN, Bush, C., Miller, BL and DeArmond, SJ (2006). The initial frontotemporal dementia targets neurons unique to monkeys and humans. Annals of Neurology: Official Journal of the American Neurological Association and the Child Neurology Society, 60 (6), 660-667.

  • Watson, KK, Jones, TK and Allman, JM (2006). Dendritic architecture of von Economo neurons. Neurosciences, 141 (3), 1107-1112.

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