Sensation: Are all senses addictive?
Stare at this color pattern, without blinking, and slowly count to ten. Then shift your eyes to a blank sheet of paper. What happens?
In your retina, each of your cone cells (color receptors) adapts–loses the ability to see the color. Now white light can only be perceived as the opposite color. This is called adaptation.
Adaptation is a fundamental part of any stimulus-response. Why? Why do we have five senses, anyhow? All senses provide response to a changing environment–they tell us to run away from a chasing tiger, or follow the smell of food. But our senses must adapt, in order to allow future response: If the tiger is gone, quit running. For the same reason, our sense of hearing adapts. That is why we keep needing to hear music louder; we keep turning up the headphones.
If you were to stare long enough, the cones would burn out, and could no longer respond. If you hear loud music and leaf blowers long enough, you lose hearing early, as many of us already do. Adaptation becomes permanent.
What does adaptation have to do with addiction? Adaptation explains why you keep needing to increase your dose of coffee, of alcohol, of cocaine, to achieve the same effect. When adaptation becomes permanent–when you can’t ever “feel good” without the stimulus–that’s addiction. (Or habituation; I don’t care to argue this supposed distinction.)
So what’s the problem in Brain Plague–why are the intelligent microbes dangerous? They control the brain’s senses; and they’re addictive. What could be more dangerous than an addictive thing that knows what it’s doing?
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Ultraphyte 
Isn’t addiction the basis for modern consumer culture anyway?
I don’t think your premise is logical.
1. As your eyes adapt, they do not permanently adapt. While the cones in your eyes are adapting, adding more light doesn’t improve vision. This is different from addition.
2. Addiction is tied to the reward pathways in the brain. AFAIK, sight and hearing are not (directly).
3. Sight may be tied to addiction via post processing content. Pornography may be addictive, but most content is not.
Thus I think that senses are not addictive, but the mental states for particular content/patterns may be.
The unifying principle is adaptation–at all levels, from molecule to cell to organ system.
(1) Your eyes do adapt–your cones and rods, and your eyes as a whole. That is why when you go from indoors to outside at noon, when the sun is high, your eyes overexpose at first, until they adapt. Then when you come indoors, or go into a dark room, you have to adapt downward. Eyes are a good case of reversible adaptation–for overall light exposure, and for individual primary colors.
(2) Addiction is tied to the reward pathway–which is different circuitry from the light perception pathway, but they both involve sensory molecules. I was using the light adaptation pathway as a model or analogy for the reward pathway. There is a deep similarity, in that both cases involve down-regulation of a sensor.
The other point is that true addiction involves overexposure, where adaptation becomes permanent. This can happen too with vision and hearing. These are not the same as mental addiction, but at the molecular level similar molecular processes occur. And the overall principle is the same–sensory adaptation.
(3) My main point is that addiction to a pleasure stimulus involves a molecular mechanism and a principle of sensory adaptation comparable to other kinds of positive stimuli.
Interestingly, negative stimuli (pain) do not adapt to the same extent as positive senses. So pain can persist without adaptation; that is why long term chronic pain is a problem.
If sensory stimuli, including vision, are addictive, what are you positing as the withdrawal systems from the addiction? If you become addicted to opiates, as you adapt, you require more of the opiate to satisfy the reward circuits. Add more light to your eyes, they adapt, but they do not create withdrawal systems when the light is removed.
The similarity in surface effects between light adaptation and addiction has no mechanism similarity, AFAICS.
Worse, applying the word addiction to adaptation could be twisted to imply that neural synapse connection strengths are becoming addicted as they learn. This would imply that learning has the same addictive mechanism. While I accept that consuming information can be addictive, I don’t see the mechanism in the same light at all.
I see this as part of the ‘everything is relative’ aspect of existence. Like Yin and Yang, each ‘creates’ the other by being its opposite. It also contains aspects of the ‘all things must end’ part of existence. If we feel too much, we stop feeling—if we stop feeling, we begin to feel again. Our bodies and minds need renewal, of a sort. Sleep, in this sense, is also addictive. And food. And oxygen.
Many have tried to characterize the function of sleep. My two cents is: we spend our waking hours receiving and decoding sensory input; when we sleep, we ‘transmit’ our results—kinda like a body-builder exercising the opposing muscle as well as the targeted muscle. But that’s just my one theory among hundreds. But mine is based on the quirky nature of sleep—we can (and do) rest our bodies simply by lying down—but if we go without sleep, we go mad. Thus I suspect that dreaming is an ‘exhalation’ of all that has been mentally inhaled.
I read somewhere that fruits and vegetables all have complex molecules that affect our minds—not as strongly as peyote, mescaline or psilocybin mushrooms, but in the same sense of sending unique ‘perception-biasing’ molecules to the brain. I think this is one of the reasons for the varieties of herbal teas—and our chocolate obsession.
When the Olympics are held in high-altitude locations, the oxygen content of a lungful is reduced, giving the advantage to those native to such places, those who haven’t built up their ‘oxygen jones’ to the same degree as lowlanders.
When you get right down to it, Life is addictive. Think about it—for many people, life is difficult, even painful—how easy it would be to opt out. Yet our minds and bodies instinctively veto this urge—our DNA didn’t get where it is today by giving up—it wants immortality and will most likely achieve it some day.
If you apply the term “addictive” to all feedback mechanisms, you explain nothing, but are just co-opting the term.
Addiction has a defined meaning. Trying to extend it to cover many more phenomena does not help explain anything, and certainly not the phenomena being encompassed.
I think the ‘addictive/adaptive’ aspect of senses exists and is a necessary part of self-protection and survival. We need a mechanism to alert us of potential “new” threats. Any stimulus that endures eventually fades because it has/would have been addressed. Louder is ‘new’ in that it’s an increase along the dimension of quantity — more predators or a larger predator would probably make more noise.
“If sensory stimuli, including vision, are addictive, what are you positing as the withdrawal systems from the addiction?”
“If you apply the term “addictive” to all feedback mechanisms, you explain nothing, but are just co-opting the term. ”
To clarify: *Reversible* adaptation of senses (as SFreader points out) is necessary for survival. The phenomenon of adaptation and reversion has a molecular mechanism–and the molecular mechanism (of a sensor molecule requiring greater signal for response) is similar, whether the stimulus is light, sound, cocaine, or caffeine. The difference is in how quickly one adapts, and how difficult is the reversion. Ultimately, increased stimulus can lead to *irreversible* adaptation. Whether you call it addiction (cocaine) or deafness (hearing loss) the biological basis is similar.
We call it “addiction” when the reversion is uncomfortable (withdrawal) leading someone to seek greater stimulus. For example, it is well known that people using headphones tend to keep “turning up” the volume as their ears adapt. I consider this addiction to sound volume. I realize that’s not a popular opinion 😉 but it reflects medical reality.
About vision–it will be interesting to see if people lose vision at earlier ages, as we all grow up staring at glowing screens. I haven’t seen a study of that; has anyone?
I’m wondering how one can distinguish between sensory-pollution related injury and addiction, and how treatment would differ between the two causes as I think we’re likely to see increases in both.
Below is a link to the Incidence of Age-Related Cataract (Baseline study 1998) — the follow-up study (whenever that happens to be) should be interesting.
http://archopht.ama-assn.org/cgi/content/abstract/116/2/219
IMHO the difference between sensory-pollution injury and addiction has to do with how much control a person has over stopping the behavior. Then, Alex is right, it gets much more complicated than the sensory molecules.
A fascinating study tries to map the behavior of addicts and see which parts of their environment actually trigger the behaviors:
http://www.npr.org/2011/11/20/142554574/in-baltimore-mapping-the-world-of-addiction
Obviously this gets a lot more complicated than the basic physiology of stimulus-response.
In my book, Brain Plague, something similar happens, in that different microbial populations affect people differently–but have to stop there, avoid spoilers.
The sight loss issue has to tease apart physical degradation (e.g. cataracts) and adaptation.
Consider “sensory deprivation”. We know there are “adrenaline junkies” and clearly the raw sensory stimulus taht induces fear/excitement is addictive. However, I personally cannot stand not being mentally stimulated. I always have a book or some means to read with me. While one might think that the changing visual patterns associated with reading might be considered visual stimulus, we know that simple visual stimuli is not sufficient. Real information is needed. The addiction is the need for mental stimulus that is post-sensory.
Almost certainly reading stimulates my reward system as an infovore and that is what causes the withdrawal symptoms of this form of addiction.
Surely the adaption mechanism in iris dilation as a response to changing light levels is fundamentally different to a physiological addiction to a chemical? Unless you look at something so bright as to cause rods and cones to burn out (eg the Sun through a telescope) the dilation occurs with the same benefits (perceiving similar levels of “scene brightness” over a range of illumination levels) in response to different levels of change in both directions.
Similarly, listening to REALLY LOUD music actually damages the sound receptors in the ears, hence why UK law requires workers in noisy environments to wear ear protection.
How different? Aside from the piezoelectric activity of the CNS (which, admittedly, includes the optic nerve, but still) all human function is chemical based. Even outside of a fine-tuned life-form like humans, chemical and enzymatic reactions and processes always exhibit a pattern of going from one imbalance to another. Plus, we are completely overlooking the psychological component of addictions–no addiction is solely due to the chemical reactions taking place–an element of bias or tropism reinforces dependencies–even in cases where there is no physical addiction.