Are neurons sensitive to quantum effects?

In summary, the conversation discusses the sensitivity of neurons and chemical receptors to the chemicals that stimulate them, and whether a single molecule or photon can stimulate them. There are two main questions: whether single neurons are affected by quantum mechanics and whether larger nervous systems are affected by it. The answer to the first question is yes, as membrane potential and synaptic events can be affected by quantum fluctuations. The second question is more uncertain, as it is debated whether macroscopic systems like the nervous system can be affected by quantum mechanics. However, it is agreed that randomness does not equal free will and that the brain may have evolved mechanisms to cope with stochastic fluctuations.
  • #1
Iamu
24
2
How sensitive are neurons and chemical receptors like olfactory receptors to the chemicals that stimulate them? Can a single molecule stimulate a nerve? How many photons does it take to stimulate a rod or a cone in the eye?

I ask because I'm curious as to whether or not human thought and behavior is generally sensitive to random quantum effects. If a single photon could stimulate a rod, or a single molecule of a neurotransmitter could cause a neuron to fire, then our behavior might be truly random, because it would depend on truly random quantum events, but if it takes thousands of photons or thousands of molecules of a neurotransmitter, I figure our behavior would probably be governed by more-or-less deterministic classical physics.
 
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  • #2
There are really two questions here.

1. Is the behavior of single neurons ever affected by quantum mechanics?

2. Is the behavior of a larger nervous system affected by quantum mechanics?

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To the first question the answer is certainly yes. Membrane potential is constantly fluctuating due to random openings and closing of ion channels and the like. Mini synaptic events also occur stochastically probably due to quantum fluctuations.

As for the second question. This seems to be untrue. It is likely that just as with any other macroscopic system the basic component parts may feel quantum effects but the assembly as a whole behaves classically. Psychophysicists and behavioral neuroscientists have described and quantified many perceptual behaviors but never encountered one where they could convincingly make the case that something quantum must be going on.

Though, not everyone agrees with me on the above point. See Penrose and Hameroff's work for an opposing view on this.

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Either way, randomness is not the same as free will. I'm not sure anyone has a particularly satisfying answer as to how "free will" gets into a neural system classical or not.
 
  • #3
IIRC, a single photon is enough to alter the membrane potential of a rod cells, so they definitely do have single photon sensitivity. I'm not sure whether olfactory neurons have single molecule sensitivity.

However, also keep in mind that biological systems are very noisy and often the cell employs a variety of mechanisms to cope with that noise. Even though single photon/molecule sensitivity of sensory neurons would lead to stochastic fluctuation in the signals going to the brain, the brain may have evolved control systems to deal with those fluctuations.
 

Related to Are neurons sensitive to quantum effects?

1. What are quantum effects?

Quantum effects are phenomena that occur on a subatomic level, meaning they involve the behavior and interactions of particles such as electrons, protons, and photons. These effects are governed by the principles of quantum mechanics, which is a branch of physics that explains the behavior of matter and energy at a microscopic level.

2. How are neurons relevant to quantum effects?

Neurons are the cells that make up the nervous system and are responsible for transmitting signals throughout the body. While they are typically studied in the context of classical physics, there is growing evidence that suggests they may also be sensitive to quantum effects due to their small size and complex interactions.

3. What evidence supports the idea that neurons are sensitive to quantum effects?

Several studies have shown that certain processes within neurons, such as energy transfers and ion channel dynamics, exhibit behaviors that cannot be fully explained by classical physics. Additionally, some researchers have found quantum-like properties in the brain, such as entanglement between different regions and states of superposition.

4. How could quantum effects impact our understanding of the brain?

If neurons are indeed sensitive to quantum effects, it could have significant implications for our understanding of the brain and its functions. It could help explain some of the mysteries of consciousness and provide insights into neurological disorders. Additionally, it could lead to advancements in fields such as artificial intelligence and quantum computing.

5. What are some potential challenges in studying the effects of quantum mechanics on neurons?

One of the main challenges is that quantum effects are notoriously difficult to observe and measure due to their small scale and fleeting nature. Additionally, the brain is a highly complex and dynamic system, making it challenging to isolate and study specific quantum processes. There is also ongoing debate and skepticism within the scientific community about the role of quantum mechanics in the brain.

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