Curiosity is one of the most common observations in healthy children and is even an established biomarker in diagnosing conditions such as autism, schizophrenia, depression, dementia, etc. Curiosity is known to be very low or even non-existent in older and/or chronically ill people, who are very novelty/curiosity averse and can even become violent when faced with a continuous stream of novel experiences. In other words, healthy people naturally prefer and seek novelty while older/sick people prefer routine and lack of change, and are averse to open-mindedness. Ray mentioned this in several of his articles in the context of energy production, since curiosity/learning is a very energy-intensive process and can be used as a reliable biomarker of overall health in people of all ages. The study below now confirms officially that the active thyroid hormone T3 is the direct driver of curiosity and novelty-seeking behavior, and the steady decline of T3 in aging and chronic diseases would explain the lack of curiosity and open-mindedness in such people. Once again, something even as abstract and seemingly brain-specific as curiosity turns out to be directly controlled by metabolism.
http://dx.doi.org/10.1016/j.cell.2024.07.041
https://www.sciencedaily.com/releases/2024/08/240822125859.htm
“…Thyroid hormone plays a key role in regulating a range of physiologic functions, including metabolism, temperature, heart rate, and growth. It accomplishes this impressive array of activities by interacting with almost every organ system in the body. Yet despite a long history of research on how thyroid hormone influences different organs, its effects on arguably the most crucial organ — the brain — have remained shrouded in mystery. Now, scientists at Harvard Medical School have gained new insights into thyroid hormone’s effects on the brain. The work, conducted in mice and published Aug. 22 in Cell, shows that thyroid hormone changes the wiring of brain circuits in a manner that drives animals to engage in exploratory behavior. By simultaneously changing brain wiring and altering metabolic rate, the researchers concluded that thyroid hormone coordinates the brain and body to produce exploratory behavior when it is most needed — for example, during seasons when animals need to find mates or stockpile resources. “It’s well known that thyroid hormone modulates metabolism, and now we’ve shown that it also modulates exploratory behaviors through direct action on the brain,” said lead author Daniel Hochbaum, research fellow in neurobiology in the Blavatnik Institute at HMS. The findings also help elucidate how low levels of the hormone could lead to depressive states marked by a low desire to explore, while too much could precipitate manic states characterized by an extreme desire for exploration. Thus, the researchers see their work as an important step toward understanding how aberrant levels of thyroid hormone could contribute to certain psychiatric conditions.”
“…Moreover, when researchers induced higher levels of thyroid hormone in the cortex, mice became more willing to explore the environment and take risks. Conversely, when researchers blocked the hormone’s action in only the cortex, the animals no longer changed how much they explored based on thyroid hormone levels. “This told us that thyroid hormone is doing important things directly in the cortex,” Hochbaum said.”
