Serious and Sillier


  • Rising concentrations of dopamine could be responsible for pleasurable feelings and falling concentrations for painful feelings.
  • Attraction consists of an initial "liking" phase followed by a "wanting" phase.
  • This may be caused by a rise followed by a fall in dopamine concentration in dopaminergic synapses.

Our feelings and emotions are always in flux. In an instant, let's say, joy might turn to sadness and a short while later sadness might switch back again to joy. But not only what we feel but also the intensity with which we feel something can change. Within an hour or so a headache may turn into a migraine. Peckishness might become hunger. And attraction might develop into love. We could say that our feelings are in continual flux. What kind of system could produce feelings such as these?

A dynamic system for dynamic feelings

About ten years ago it was thought that dopamine was the "pleasure biochemical". The system proposed was a static one.* 1 High concentrations of dopamine were believed to be responsible for feelings of well being. Low concentrations, on the other hand, were the cause of misery and depression.

Recent experiments, however, have shown that even though there is some kind of link between dopamine levels and the state of happiness, there is no direct correlation. (See last post: Dopamine). But although the hypothesis seems to be incorrect, so far nothing convincing has replaced it.

The main problem with the proposed system (apart from the important fact that experiments have shown it not to be true) is that it is static. A static system couldn't produce the continual flux of feelings we experience. Rather, any system has to allow for constant changes. Or, to put it another way, for dynamic feelings we need a dynamic system. But how could such a system work?

The rise and fall of dopamine

Let's assume that dopamine is the biochemical which is principally responsible for our feelings of well-being. If our system is going to be dynamic, there has to be change. So dopamine itself could change. But what kind of change? The simplest kind of change I can think of is a change in concentration. This could make sense: biological systems often use a change in concentration of a substance as a signal to trigger responses. It is quite plausible, then, that changes in dopamine concentration could trigger changes in our feelings.

Instead, then, of high levels of dopamine causing positive feelings, perhaps it's a rise in dopamine concentration which causes them. And instead of low levels of dopamine causing negative feelings, it's a fall in dopamine concentration which causes them. Now, I believe that the only positive feeling is pleasure, and the only negative feeling is pain. (See Pain and pleasure.) This would mean that a rise in dopamine concentration is experienced as pleasure and a fall is experienced as pain. 

Let's think about how such a system might operate. Let's say that I have smelt a pleasant aroma as I walked past a bakery shop. Molecules of aromatic chemicals waft through the air and excite sensory neurones in my nose. From here electrical messages are passed to other neurones until they reach my brain.

Certain neurones in the brain called "dopaminergic neurones" use dopamine as a neurotransmitter. Some of these neurones fire when they receive the messages from my nose. Electrical impulses then pass along them. When an impulse reaches the end of a neurone, a series of chemical changes is initiated. This results in dopamine being released into the synapse. (A synapse is a gap connecting two neurones, across which only chemical signals, and not electrical signals, can be sent.)

So, after receiving messages from my nose, dopaminergic neurones release dopamine into their synapses. This means that shortly after firing, the concentration of dopamine in the synapses increases rapidly.

What happens next? What goes up must come down. After reaching a peak, the concentration of dopamine will begin to drop. If a graph of dopamine concentration against time were to be plotted, it might look something like this:


Eventually, at some time off the graph, dopamine will return to its usual level. This level is the "basal concentration".*2

From the graph above, we can conclude that after firing, the first feeling experienced is pleasure. This corresponds to the rising part of the curve. But the pleasure doesn't last long. Soon the dopamine concentration is in decline, which is represented by the falling part of the curve. This is felt as pain.

Attraction is both pain and pleasure

In other words, there is a short burst of pleasure quickly followed by a slightly longer bout of pain. What, you might wonder, is the use of having such a rapid change in feelings? Actually, it's a lot of use. This swing from pleasure to pain is probably responsible for the feeling of attraction.* 3

Here's how this might work. Let's think about my experiences as I walk past the bakery. First I smell the aroma of fresh pastry. "That's a good smell, " I say to myself. This means my first sensation is pleasure. Then I think to myself: "I would like to eat a croissant." In other words, I feel a want. In Pain and pleasure I argued that a want is a kind of pain. If this is true, my second feeling is pain.

In other words I have felt a burst of pleasure followed by a bout of pain: the same sequence of sensations as predicted by the graph.

So we can say that attraction is not a simple, single feeling. It consists of two phases, one pleasurable and one painful. The pleasurable phase is caused by rising levels of dopamine in synapses, the painful phase is caused by falling levels of dopamine. Only the painful phase motivates. Only the want can make me go into the shop and buy some croissants.

What, then, is the purpose of the pleasurable phase? We can think of pleasure as being a "primer". Without the increase in dopamine, the subsequent decrease wouldn't happen. And the association of both parts with other information, such as of the aromatic chemicals wafting from the bakery, allows the mind to focus on the cause of the pleasure and pain and to explore the concepts needed to get what is wanted.

In the above hypothesis the concentration of dopamine changes dynamically. What I haven't done yet, though, is explain how this dynamism translates into dynamic feelings. How do the fluxes I mentioned in the first paragraph come about? Why, let's say, does the aroma from the bakery smell better when I am hungry than when I am full?

What about other feelings? Could they work in a similar way to attraction? And why do feelings vary in intensity? How are feelings regulated? As always I have left a lot of questions unanswered. I hope to deal with all these questions, and more, in later posts.



* 1. Static in this context means "not changing" or "fixed" . The system is static because a fixed concentration of dopamine is assumed always to produce a specific level of happiness.

* 2. It is important to realise the concentration of dopamine does not decline to zero. This is because dopamine is lost from the synapse through reversible processes - that is, through diffusion and also perhaps metabolism. At the basal concentration, the level of dopamine is in an equilibrium state.

*3. I must make clear what I mean by the word "attraction". The word is sometimes used in the sense of "liking" where "liking" is a pleasurable feeling. So when we say "the town is attractive", we mean that the town gives us some kind of pleasure. Similarly, if we say "we like the food", we mean the taste of the food gives us pleasure.

However, in general the word is used to mean not only "liking" but also the urge or drive towards, or the pull of the object that is liked. That is to say, the word describes a feeling which is both pleasurable and motivating. I use the word "attraction" in this broader sense.

Confusingly, the word "liking" also is used occasionally in the same broader sense. In many situations, too, the word "interest" can be used to mean "attraction". This means the three words are interchangeable in some sentences: I am attracted by dark haired women, I am interested in dark haired women, I like dark haired women.

Where "attraction" and "interest" are used in different senses, the difference in most cases depends on the object of the attraction or interest rather than on the feeling itself. For example, we would usually say "we are interested in football" rather than "we are attracted by football".

What we can say, then, is that the words "interest", "liking" and "attraction" are equivalent when they combine both pleasurable and motivational elements. In this usage these words must represent the same feeling. I have chosen to use the word "attraction" to describe this feeling, but I could have used the words "interest" or "liking" instead.

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