Newsletter #196 Our brains are capable of mind-boggling feats, yet we still know very little about how they pull it off
Newsletter about nature and science
Our brains are capable of mind-boggling feats, yet we still know very little about how they pull it off
At least 86 billion nerve cells are active in our brains. They form approximately 500 billion connections with each other. And perhaps there are many, many more.
We know a little about how nerve cells process and store information. First in short-term memory, and then in long-term storage, which, under certain circumstances, we can still consult decades later. We have learned a great deal from the learning behavior of a sea slug, Aplysia (the sea hare), which has only 20,000 neurons. This hefty, algae-eating slug exhibits complex behavior, avoids touch and pain, and can defend itself against enemies with clouds of purple ink.
We understand how their nerve cells transmit information thanks to the work of neurobiologist Eric Kandel. In 2000, he received the Nobel Prize in Physiology or Medicine for his contribution to our knowledge of learning and memory. This was due to his crucial decision to abandon his work on memory storage in rats in New York—animals with nearly 200 million neurons—to work on such a “primitive” animal in France instead
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In his nearly 1,000-page textbook, “Principles of Neural Science” (co-authored with James Schwartz), Kandel described what he considered the five essential questions about how our brains work: How do adult brains develop? How do brain cells talk to each other? How do connections between nerve cells influence our behavior and perception? How, in turn, do our experiences influence the connections between nerve cells and different brain areas? And how do diseased brains differ from healthy ones?
Research has found answers to many of these questions. But always in small parts, and many major questions remain unanswered.
Thanks to new techniques, we know that localization—the specific place in the brain—is important for much of what happens in our heads. But simultaneously, we have increasingly discovered that the contacts between brain cells and brain regions are essential. This often happens in rapid networks where information is circulated. We owe such insights to new technologies, such as three-dimensional X-rays in a computed tomography (CT) scanner. We can track our metabolism through positron emission tomography (PET), where a radioactive substance is injected for an activity scan. Magnetic resonance imaging (MRI) uses a magnetic field and radio waves to track the presence of chemical elements like hydrogen, carbon, nitrogen, and phosphorus in our brains. When this is measured during specific brain activities, it is called functional MRI (fMRI). And finally, we can track electrical activity in brain regions with increasing precision using electroencephalography (EEG) measurements.
Small electrical currents in the membranes of our nerve cells, called action potentials, play a major role in communication between brain cells. This is often combined with the release of chemical messengers, known as neurotransmitters, into the synaptic cleft between cells. Information exchange between nerve cells occurs in other ways too, such as via direct small gap-junctions, and the role of glia (support cells) is gaining increasing attention. The timing of brain activity also matters. Simultaneous activity of nerve cells strengthens the connection between those cells—a form of learning reflected in anatomy. Brains turn out to be much more flexible and changeable than we previously thought.
We gain new insights into the working of our brains almost daily. It is becoming increasingly difficult to oversee the entire field of neuroscience. Of the 114 Nobel Prizes in Physiology or Medicine, 30 have gone to neurosciences.
Within chronobiology, the influence of light on emotional centers and the distinct clock functions of our brains have recently played a role. Therapeutically, the ability to intervene with electrical currents in conditions like Parkinson’s tremors has recently been expanded to treat tinnitus (ringing in the ears), to name just a few examples.
It is becoming increasingly clear that we can learn a lot from the other animals on Earth. In many functions, they are far better than us, sometimes with much smaller brains than ours (compare the sea slug). A phenomenon once considered mysterious and unique to humans, such as (self-)consciousness, appears to be distinctly present in many animals.
Many great questions remain open, such as how exactly our experiences are stored, how logical reasoning is structured, the influence of our perception of the environment, and the role of sleep. regarding diseases, we struggle with the increasing problem of Alzheimer’s and Parkinson’s, despite all the research. It is beautiful, yet barely understood, how much recovery and adaptive capacity lies hidden in our healthy brains. Anyone who thinks they must fall back on a “collective, external consciousness” (for which convincing proof has yet to be provided) to understand our brains is unfairly underestimating their own minds.
Tips to keep a brain healthy:
Ensure sufficient sleep and good sleeping conditions.
Stay mentally active: learn an extra language, read, or learn to play a new musical instrument.
Stay physically active: participate in sports, or in any case, ensure sufficient movement.
Eat a healthy and varied diet; avoid fast food and the pre-fabricated products super-markets are full of.
Continue to be amazed by what is happening around you; actively capture light, images, sounds, smells, and touches, and enjoy what pleases you.
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