Difference between revisions of "Von Economo neuron"

From NeuronBank
Jump to: navigation, search
Line 1: Line 1:
++++++++''This page is, until the end of this week, under construction.''+++++++++
+
[[Image:dendriteVEN.jpg|right|thumb|300px|Figure 1. Photomicrographs of soma and proximal dendrites of (a) a
 
+
pyramidal and (b) the VENs stained with the Golgi method. Photomicrogaphs
 
+
are montages taken of several planes and/or fields of view.
 +
Scale bar applies to both images. [9]]]
 
== Basic information ==
 
== Basic information ==
[[Image:voneconomo.jpg|right|thumb|300px|Figure 1. Von Economo neuron compared to Pyramidal neuron [8]]]  
+
[[Image:voneconomo.jpg|right|thumb|200px|Figure 2. Von Economo neuron compared to Pyramidal neuron [8]]]  
  
 
'''Spindle''' or '''Von Economo neurons (VENs)''' occur in primates (humans, gorillas, chimpanzees, bonobos, and orangutans), and while previously thought to be unique to the great apes, have more recently been found in cetaceans (humpback, fin, killer, and sperm whales).''
 
'''Spindle''' or '''Von Economo neurons (VENs)''' occur in primates (humans, gorillas, chimpanzees, bonobos, and orangutans), and while previously thought to be unique to the great apes, have more recently been found in cetaceans (humpback, fin, killer, and sperm whales).''
Line 15: Line 16:
 
than the average layer 5 pyramidal cell. [4]  VENs are relatively rare, and thought to make up 1-2% of the Layer 5 neurons in ACC. [2]  In FI, VENs are 30% more numerous in the right hemisphere than  the left. [6]
 
than the average layer 5 pyramidal cell. [4]  VENs are relatively rare, and thought to make up 1-2% of the Layer 5 neurons in ACC. [2]  In FI, VENs are 30% more numerous in the right hemisphere than  the left. [6]
  
 
+
[[Image:locVEN.jpg|center|thumb|812px|Figure 3. Regions of the brain containing Von Economo neurons (VENs). (a) A lateral view of the brain, with fronto-insular cortex (FI) shown in red. (b) A medial view of the
 +
brain, with anterior cingulate cortex (ACC) shown in red. Adapted from Von Economo and Koskinas [1]. [6]]]
  
 
== Molecular profile ==
 
== Molecular profile ==
Line 31: Line 33:
  
 
== Ontogeny and Phylogeny ==
 
== Ontogeny and Phylogeny ==
 +
 +
[[Image:ven primates.jpg|right|thumb|600px|Figure 4. Primate cladogram detailing the species examined for VENs. Species in red have VENs in the FI. Pongids have VENs in the ACC only. [8]]]
  
 
VENs develop late both ontogenetically and phylogenetically.
 
VENs develop late both ontogenetically and phylogenetically.
  
They first appear in the 35th week
+
Ontogenetically, VENs first appear in the 35th week
 
of gestation; at birth only about 15% of the postnatal
 
of gestation; at birth only about 15% of the postnatal
 
number are present. The adult number is
 
number are present. The adult number is
 
attained by 4 years of age. [6]
 
attained by 4 years of age. [6]
  
Analyses of over 30 mammalian species have failed to find VENs except in primates and cetaceans. Among primates, including the lesser apes (gibbons), VENs have only been observed in the great apes (humans, gorillas, chimpanzees, bonobos, and orangutans).
+
Analyses of over 30 mammalian species have failed to find VENs except in primates and cetaceans. Among primates, including the lesser apes (gibbons), VENs have only been observed in the great apes (humans, gorillas, chimpanzees, bonobos, and orangutans). [3]
 
 
[[Image:ven primates.jpg|center|thumb|600px|Figure 2. Primate cladogram detailing the species examined for VENs. Species in red have VENs in the FI. Pongids have VENs in the ACC only. [8]]]
 
 
 
Among hominids, humans have the most VENs, both in terms of absolute number and relative percentage compared to total number of neurons. In decreasing order of total number of VENs, they are found in humans, bonobos, chimpanzees, gorillas, and orangutans. In humans and bonobos, VENs are distributed in clusters of 3-6 neurons, while in other apes they show no such pattern of distribution. [3,4]
 
  
[[Image:VENmontage.jpg|thumb|600px|Figure 3. Von Economo neurons in layer Vb of the anterior cingulate cortex in human (A), bonobo (B), common chimpanzee (C), gorilla (D), and orangutan (E). In all of these species the VENs display similar morphology and apparent somatic size. Note the clusters of VENs in the through-focus photomontage from the human and in the bonobo, whereas isolated neurons are observed in the three other great apes. (F-H) No VENs are present in the anterior cingulate cortex of the white-handed gibbon (F), Patas monkey (G), or ring-tailed lemur (H). ''Bar = 50 µm (A), 80 µm (B-E and H), and 120 µm (F and G).'' [3]]]
+
Among hominids, humans have the most VENs, both in terms of absolute number and relative percentage compared to total number of neurons. In decreasing order of total number of VENs, they are found in humans, bonobos, chimpanzees, gorillas, and orangutans. In humans and bonobos, VENs are distributed in clusters of 3-6 neurons, while in other apes they show no such pattern of distribution. In analyses of total number of VENs present in FI of both hemispheres, the average adult human was found to have 193,000 cells, a 4 year old human child had 184,000, the average human newborn had 28,200, a gorilla had 16,710, a bonobo had 2,159, and a chimpanzee had 1,808. [3,4]
  
 +
[[Image:VENmontage.jpg|thumb|812px|Figure 5. Von Economo neurons in layer Vb of the anterior cingulate cortex in human (A), bonobo (B), common chimpanzee (C), gorilla (D), and orangutan (E). In all of these species the VENs display similar morphology and apparent somatic size. Note the clusters of VENs in the through-focus photomontage from the human and in the bonobo, whereas isolated neurons are observed in the three other great apes. (F-H) No VENs are present in the anterior cingulate cortex of the white-handed gibbon (F), Patas monkey (G), or ring-tailed lemur (H). ''Bar = 50 µm (A), 80 µm (B-E and H), and 120 µm (F and G).'' [3]]]
  
 +
That their relative abundance and clustering in species co-varies with a species' phylogenetic proximity to humans has led to speculation that VENs are important to evolution and cognition.  That they occur in hominids and pongids (but no other primates) suggests that VENs evolved relatively recently: approximately 15-20 million years ago, prior to the evolutionary divergence of orangutans and hominids. [3,4]  Their recent discovery in some whales suggests a second, independent evolution of VENs in cetaceans. [11]  VENs may not have the same function in both sorts of organism, however. [10]
  
 +
"The phylogeny of VENs make sense given their evolutionary context. The great apes are highly social animals that must engage in rapid decision-making to navigate complex social environs. Of the great apes, the most solitary is the orangutan. Similarly, they display the fewest VENs. Humans and bonobos have arguably the most complex social interactions, and display not only high numbers of VENs but also a similar clustered distribution, whereas in the common chimpanzee, gorilla, and orang, VENs are found in isolated arrangements." [8]
  
 +
== Function and Behavior ==
  
 +
The FI and ACC, where VENs are located, have been implicated in social reasoning, emotion, and monitoring of visceral autonomic activity, among other functions. ACC projects to the frontopolar cortex, which has been implicated in cognitive dissonance and uncertainty.  Because of these purported functions in the areas in which VENs are located, and because their morphology suggests them as fast projection neurons, researchers have speculated that VENs have an important role to play in intuition, which allows us to overcome uncertainty, make quick decisions, and resolve cognitive dissonance. [6]
  
 
+
Because they evolved recently, VENs may be particularly susceptible to dysfunction.  Abnormal VEN development has been implicated in autism [6] and selective degeneration of VENs has been observed in Alzheimer's and dementia [12].
 
 
 
 
== Behavior ==
 
  
 
== References ==
 
== References ==
Line 82: Line 84:
 
[8] http://neurotransponder.blogspot.com/2005/12/von-economo-neurons-intuition-and.html
 
[8] http://neurotransponder.blogspot.com/2005/12/von-economo-neurons-intuition-and.html
  
 +
[9] Watson, K. K., et al. (2006) Dendritic architecture of the von Economo neurons. Neuroscience. 141:1107-1112.
 +
 +
[10] Balter, M. (2006) Well-Wired Whales. ScienceNOW Daily News. November 27, 2006. http://sciencenow.sciencemag.org/cgi/content/full/2006/1127/1
  
 +
[11] Hof, P. and Van Der Gucht, E. (2007) Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae (Cetacea, Mysticeti, Balaenopteridae). The Anatomical Record 290, 1-31
  
 +
[12] Seeley, W. W., et al. (2006) Early frontotemporal dementia targets neurons unique to apes and humans. Ann. Neurol. 60(6):660-667.
  
 
== Additional information ==
 
== Additional information ==

Revision as of 05:55, 26 August 2008

Figure 1. Photomicrographs of soma and proximal dendrites of (a) a pyramidal and (b) the VENs stained with the Golgi method. Photomicrogaphs are montages taken of several planes and/or fields of view. Scale bar applies to both images. [9]

Basic information

Figure 2. Von Economo neuron compared to Pyramidal neuron [8]

Spindle or Von Economo neurons (VENs) occur in primates (humans, gorillas, chimpanzees, bonobos, and orangutans), and while previously thought to be unique to the great apes, have more recently been found in cetaceans (humpback, fin, killer, and sperm whales).

Neuronal Type: Projection Neuron


Anatomy

VENs are bipolar neurons with one large apical axon and a single basal dendrite. They are found exclusively in layer Vb of the anterior cingulate cortex (ACC) and frontoinsular cortex (FI), and have also recently been identified in human dorsolateral prefrontal cortex (DLPFC) (Brodmann area 9). [7] Its large apical axon and high-volume, elongated soma is similar to that of the fast-conducting, cortical pyramidal neuron, but the VEN lacks the pyramidal neuron's large array of basal dendrites and the average VEN is 4.6 times larger than the average layer 5 pyramidal cell. [4] VENs are relatively rare, and thought to make up 1-2% of the Layer 5 neurons in ACC. [2] In FI, VENs are 30% more numerous in the right hemisphere than the left. [6]

Figure 3. Regions of the brain containing Von Economo neurons (VENs). (a) A lateral view of the brain, with fronto-insular cortex (FI) shown in red. (b) A medial view of the brain, with anterior cingulate cortex (ACC) shown in red. Adapted from Von Economo and Koskinas [1]. [6]

Molecular profile

  • Neurotransmitter Receptors: vasopressin 1a, dopamine d3, serotonin 2b [6]

Physiology

Synaptic Connections

Though currently unknown where VENs ultimately project to, studies in monkeys indicate that ACC and FI connect to a wide range of areas: prefrontal, orbitofrontal, insular and anterior temporal cortices, amygdala, hypothalamus, and various thalamic nuclei.

Ontogeny and Phylogeny

Figure 4. Primate cladogram detailing the species examined for VENs. Species in red have VENs in the FI. Pongids have VENs in the ACC only. [8]

VENs develop late both ontogenetically and phylogenetically.

Ontogenetically, VENs first appear in the 35th week of gestation; at birth only about 15% of the postnatal number are present. The adult number is attained by 4 years of age. [6]

Analyses of over 30 mammalian species have failed to find VENs except in primates and cetaceans. Among primates, including the lesser apes (gibbons), VENs have only been observed in the great apes (humans, gorillas, chimpanzees, bonobos, and orangutans). [3]

Among hominids, humans have the most VENs, both in terms of absolute number and relative percentage compared to total number of neurons. In decreasing order of total number of VENs, they are found in humans, bonobos, chimpanzees, gorillas, and orangutans. In humans and bonobos, VENs are distributed in clusters of 3-6 neurons, while in other apes they show no such pattern of distribution. In analyses of total number of VENs present in FI of both hemispheres, the average adult human was found to have 193,000 cells, a 4 year old human child had 184,000, the average human newborn had 28,200, a gorilla had 16,710, a bonobo had 2,159, and a chimpanzee had 1,808. [3,4]

Figure 5. Von Economo neurons in layer Vb of the anterior cingulate cortex in human (A), bonobo (B), common chimpanzee (C), gorilla (D), and orangutan (E). In all of these species the VENs display similar morphology and apparent somatic size. Note the clusters of VENs in the through-focus photomontage from the human and in the bonobo, whereas isolated neurons are observed in the three other great apes. (F-H) No VENs are present in the anterior cingulate cortex of the white-handed gibbon (F), Patas monkey (G), or ring-tailed lemur (H). Bar = 50 µm (A), 80 µm (B-E and H), and 120 µm (F and G). [3]

That their relative abundance and clustering in species co-varies with a species' phylogenetic proximity to humans has led to speculation that VENs are important to evolution and cognition. That they occur in hominids and pongids (but no other primates) suggests that VENs evolved relatively recently: approximately 15-20 million years ago, prior to the evolutionary divergence of orangutans and hominids. [3,4] Their recent discovery in some whales suggests a second, independent evolution of VENs in cetaceans. [11] VENs may not have the same function in both sorts of organism, however. [10]

"The phylogeny of VENs make sense given their evolutionary context. The great apes are highly social animals that must engage in rapid decision-making to navigate complex social environs. Of the great apes, the most solitary is the orangutan. Similarly, they display the fewest VENs. Humans and bonobos have arguably the most complex social interactions, and display not only high numbers of VENs but also a similar clustered distribution, whereas in the common chimpanzee, gorilla, and orang, VENs are found in isolated arrangements." [8]

Function and Behavior

The FI and ACC, where VENs are located, have been implicated in social reasoning, emotion, and monitoring of visceral autonomic activity, among other functions. ACC projects to the frontopolar cortex, which has been implicated in cognitive dissonance and uncertainty. Because of these purported functions in the areas in which VENs are located, and because their morphology suggests them as fast projection neurons, researchers have speculated that VENs have an important role to play in intuition, which allows us to overcome uncertainty, make quick decisions, and resolve cognitive dissonance. [6]

Because they evolved recently, VENs may be particularly susceptible to dysfunction. Abnormal VEN development has been implicated in autism [6] and selective degeneration of VENs has been observed in Alzheimer's and dementia [12].

References

[1] Von Economo, C. and Koskinas, G. (1925) Die Cytoarchitectonik der Hirnrinde des erwachsenen Menschen, Springer

[2] Nimchinsky, E.A. et al. (1995) Spindle neurons of the human anterior cingulate cortex. J. Comp. Neurol. 355, 27–37

[3] Nimchinsky, E.A. et al. (1999) A neuronal morphologic type unique to humans and great apes. Proc. Natl. Acad. Sci. U. S. A. 96, 5268–5273

[4] Allman, J. et al. (2002) Two phylogenetic specializations in the human brain. Neuroscientist 8, 335–345

[5] Sherwood, C.C. et al. (2003) Evolution of specialized pyramidal neurons in primate visual and motor cortex. Brain Behav. Evol. 61, 28–44

[6] Allman, J.M. et al. (2005) Intuition and autism: a possible role for Von Economo neurons. TRENDS in Cognitive Sciences 9:8, 367-373

[7] Fajardo, C. et al. (2008) Von Economo neurons are present in the dorsolateral (dysgranular) prefrontal cortex of humans. Neuroscience Letters 435:3, 215-218

[8] http://neurotransponder.blogspot.com/2005/12/von-economo-neurons-intuition-and.html

[9] Watson, K. K., et al. (2006) Dendritic architecture of the von Economo neurons. Neuroscience. 141:1107-1112.

[10] Balter, M. (2006) Well-Wired Whales. ScienceNOW Daily News. November 27, 2006. http://sciencenow.sciencemag.org/cgi/content/full/2006/1127/1

[11] Hof, P. and Van Der Gucht, E. (2007) Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae (Cetacea, Mysticeti, Balaenopteridae). The Anatomical Record 290, 1-31

[12] Seeley, W. W., et al. (2006) Early frontotemporal dementia targets neurons unique to apes and humans. Ann. Neurol. 60(6):660-667.

Additional information

link title