Washington: Researchers have uncovered rare brain cells in monkeys, which can be tied to self-awareness and empathy in humans.
Max Planck scientists found that the anterior insular cortex is a small brain region that plays a crucial role in human self-awareness and in related neuropsychiatric disorders.
An exclusive cell type – the Von Economo Neuron (VEN) – is located there.
For a long time, the VEN was understood to be unique to humans, great apes, whales and elephants.
However, Henry Evrard, neuroanatomist at the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, has now discovered that the VEN also occurs in the insula of macaque monkeys.
The morphology, size and distribution of the monkey VEN hint that it is at least a primal anatomical homolog of the human VEN.
This finding offers new and much-needed opportunity to examine in detail the connections and functions of a cell and brain region that could have a key role in human self-awareness and in mental disorders which include autism and specific forms of dementia.
The insular cortex, or simply insula, is basically a hidden cortical region folded and tucked away deep in the brain – an island within the cortex.
Within the last decade, the insula has emerged from darkness as having a key role in varied functions usually linked to our internal bodily states, to our emotions, to our self-awareness, and to our social interactions.
The very frontal part of the insula, in particular, is where humans consciously sense subjective emotions, such as love, hate, resentment, self-confidence or embarrassment.
In relation to these feelings, the anterior insula is concerned with various psychopathologies.
Damage of the insula leads to apathy and the inability to tell as to what feelings humans experience.
These inabilities and alteration of the insula are also encountered in autism and in other highly detrimental neuropsychiatric disorders including the behavioural variant of frontotemporal dementia (bvFTD).
The Von Economo Neuron (VEN) occurs almost solely in the anterior insula and anterior cingulate cortex.
In contrast to the typical neighbouring pyramidal neuron that is present in all mammals and all brain regions, the VEN has a odd spindle shape and is about three times as large.
Their numeral density is selectively altered in autism and bvFTD.
Now, Evrard`s present work has provided compelling evidence that monkeys possess at least a primitive form of the human VEN although they do not have the ability to recognize themselves in a mirror, a behavioural hallmark of self-awareness.
“This means, other than previously believed, that highly concentrated VEN populations are not an exclusivity of hominids, but also occurs in other primate species.
“The VEN phylogeny needs to be reexamined. Most importantly, the very much-needed analysis of the connections and physiology of these specific neurons is now possible,” said Evrard”
Now having known the functions of the VEN and its connections to other regions of the brain in monkeys, it could give us clues on the evolution of the anatomical substrate of self-awareness in humans.
Besides this, the finding also may help us in better understanding of serious neuropsychiatric disabilities including autism, or even addictions such as to drugs or smoking.