Washing Machine Brains – Advanced yet Vulnerable

February 1, 2019

The Weizmann Institute of Science’s Professor Rony Paz suggests our brains are like modern washing machines – evolved to have the latest sophisticated programming, but more vulnerable to breakdown and prone to develop costly disorders.

He and a group of researchers recently conducted experiments comparing the efficiency of the neural code in non-human and human primates, and found that as the neural code gets more efficient, the robustness that prevents errors is reduced. Their findings, which recently appeared in Cell, may help to explain why disorders as ADHD, anxiety, depression, PTSD and even autism are common in humans.

Paz, in the Institute’s Neurobiology Department, says that anatomical differences between humans and other primates have been described – particularly our large pre-frontal cortex and its extended number of neurons. But differences in the neural code – the ‘software’, in contrast with the ‘hardware’ (the physical structure) – have not been explored.

Raviv Pryluk, a research student in Paz’s group, devised a way to test and compare the efficiency of the neural code in several regions of the brain.

“We defined efficient communication as that which uses the least amount of energy to transmit the maximal information – to pass on as complicated message as possible with the fewest ‘words’,” said Pryluk.

The researchers recorded the electric activity of single neurons both in humans and in macaque monkeys in two regions: the pre-frontal cortex, where higher functions like decision making and rational thinking occur, and the amygdala, a more evolutionarily ancient region that is responsible for the ‘fight or flight’ basic survival functions, as well as emotions.

Paz and his group worked in collaboration with Professor Itzhak Fried of Sourasky Medical Center in Tel Aviv and UCLA Medical School in Los Angeles. Patients with pharmacologically intractable epilepsy come to Fried to have electrodes implanted for diagnostic purposes, and these provide a rare opportunity to record the electric activity of single neurons in the human brain. Also participating in this research were Dr Hagar Gelbard-Sagiv of Tel Aviv University and Dr Yoav Kfir, at that time a research student in Paz’s group.

The research findings research provided support for the ‘washing machine’ theory of brain evolution: The neural code in the ‘more evolved’ pre-frontal cortex is more efficient than the amygdala, both in humans and monkeys. And the neural code of both areas in the human brain was more efficient than its monkey counterpart. But the higher the efficiency of a particular neural code, the less it was robust to errors.

Paz likens the amygdala to the washing machine drum.

“It’s not highly sophisticated, but it is less likely to fail – which is important to animals’ survival,” he said.

“The lower resistance of the human amygdala to errors may play a role in exaggerated survival-like responses in inappropriate contexts, such as those we see in PTSD and other anxiety disorders.”

According to Pryluk evolution works with trade-offs.

“There may be a zero-sum game between efficiency and robustness; and our complex, multidimensional brains have gained one at the price of the other,” he said.

For Fried the comparison between humans and monkeys is key.

“Comparing single-cell recordings from human and monkey brains is a large step forward toward answering the question of what makes the human brain unique,” said Fried.

Paz concluded by saying: “Why, on the one hand, do humans have such superior learning, cognitive and adaptive abilities and, on the other, this tendency to anxiety, depression and other mental diseases? We have shown that these may be two sides of the same coin.”

The research has also been featured in some English written media:

Breaking Israel News

Neuroscience News

 

More Research

A Hundred Million Suns: The Most Complete Portrait of a Supernova

Humankind has long turned to the skies in search of answers. Accounts of supernovae – exploding stars – go back thousands of years, but while we know today that these…

eastRead More

Fungus vs. Fungus: Newly Identified Yeast Might Prevent Life-Threatening Fungal Infections

Researchers at the Weizmann Institute of Science have identified a yeast that might be used to prevent invasive candidiasis, a major cause of death in hospitalised and immunocompromised patients. The…

eastRead More

Toward a Treatment for Huntington’s Disease

Weizmann Institute of Science scientists have discovered two small molecules that can cross the blood-brain barrier in mice, slowing and even reversing the effects of Huntington’s, which is incurable. The…

eastRead More

Proteins without Parents

Using three AI protein prediction tools, a Chinese-Israeli study at the Weizmann Institute of Science uncovered new wrinkles in the folding story of ‘orphan’ proteins. When Weizmann Professors Joel Sussman…

eastRead More

View All