Looking for pleasure

2011/05/01 Galarraga Aiestaran, Ana - Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Osasuna
• Medikuntza
• Anatomia/Fisiologia

(Photo: iStockphoto.com/Anouchka)

The sources of pleasure are not only to meet the physiological needs of the organism. Proof of this is one of the experiments collected by Dr. Francisco Mora in neurosciences in The labyrinths of pleasure in the human brain.

In this experiment, rats were trained to eat once a day within two hours. At those two hours, the rats could eat what they wanted, the food they had in the same cage, a dry and compact feed. But once a week, and in the same period of two hours, the rats knew that they could cross a long labyrinth of 16 meters and that at the end of it they would have another food waiting. A pleasant, pleasant and attractive meal.

Researchers put cages at a pleasant temperature. On the contrary, in the labyrinth leading to sweet food there were -15C and strong wind currents. Despite being comfortable in the cage, and despite having enough food, they were put to choose another type of food a day, rats abandoned the cage and entered the cold labyrinth in search of sweet food.

That day the rats ate half of what used to cost and on more than one occasion suffered the damage caused by freezing. And yet rats always decided to take the risk and try to get a sweet meal. Just for pleasure. It is more pleasant to get this sweet food than to compensate for hunger with this dry food they have in the cage.

Beyond basic needs

What is observed in rats is even more evident in people. As explained by neurologist Alberto Bergaretxe, "the mechanism of pleasure is very ancient in evolution, equal in all animals, even those from the evolutionary point of view are much simpler than us. It is necessary to survive and ensures that the individual is again a source of pleasure."

So far there is no difference between what people feel and the rest of the animals, and between the basic pleasure and the most elaborate pleasures. However, Bergaretxe considers that there are differences: "Because the mechanism of pleasure is excited by diverse stimuli and the responses they generate are basically the same. But the ways to coordinate and integrate these responses are different when it comes to eating pleasure, listening to music, or remembering something."

According to Bergaretxe, this mechanism also involves the forecasts and expectations, the personal and cultural history of each. "All this modulates the answer, and that's why the pleasures of drinking water and listening to the music you like when you feel like it are different. Although the limbic system deals with the basic mechanism of pleasure (i.e., talculus, hypothalamus, amygdala...), other more complex brain structures also intervene in other pleasures: temporal lobes, frontal lobes, memory... In that they are distinguished."

In fact, the limbic system is the same in all animals, even those that are primitive from the evolutionary point of view. On the contrary, the complex structures mentioned by Bergaretxe are limited to those animals that are considered more developed in evolution.

Alberto Bergaretxe, neurologist at Donostia Hospital and researcher at the Biodonostia Research Institute. Ed. : Ana Galarraga.

On the other hand, just as the evolutionary function of basic pleasures is to guarantee survival, other types of squares also have a function, although less evident. Bergaretxe believes that this type of pleasure is important from the point of view of social cohesion, since they are "useful" to structure groups, create group dynamics, strengthen relationships, etc.

In addition, Bergaretxe believes that there is an intangible aspect, difficult to define, but that explains why we seek that type of pleasure and we do not resign ourselves to meet the basic needs. "I think that passion is at the core of being a person. Also, not everyone needs that. Many people are conservative, that is, they are at ease with what they have and need no more. But there are few who tend to seek innovation. They are called novelty seeking and this trend is partly genetically determined," says Bergaretxe.

In Bergaretxe's view, "probably these are the ones that make the species evolve, so to speak. In my opinion, this includes social pleasure and intellectual pleasure. And animals that don't have the developed cortex, that are evolutionarily more primitive, don't have it."

Coins and genes

In the past, many have understood pleasure as the reverse of pain, as if pain and pleasure were both sides of the same coin. Bergaretxe has nullified this belief: "There is no such dualism, although it is true that pain and pleasure use parts of the same system."

The mechanism of pleasure starts from the neurons that produce dopamine, dopaminergic neurons. Then others come into play, especially noradrenergic and serotonergic neurons. The same as the pain. And some flowing neurotransmitters are the same.

But for Bergaretxe, pain has something that has no pleasure. "On the one hand, it seems useful: you touch the hot iron and you burn; you drink too much alcohol and your head hurts. Those pains are good because you learn that you don't have to do it again. And we understand it easily. But what does chronic pain make sense? What is the evolutionary cause of this pain? What benefit does it have for the individual or society that a person with cancer or arthritis has severe pain? ".

In pleasure he does not see it that way, although it can also have negative side effects, "for example in the case of drugs. And that's what we've studied most, especially cocaine."

Playing is essential in the learning process. However, children do not play to learn, but only with pleasure. Ed. : Nagy-Bagoly Arpad/350RF.

According to Bergaretxe, once a dose of cocaine is taken, all people begin to have a similar reaction. However, in the long run there are people who tend to develop dependence and others who do not. "Because their genetic base is known," says Bergaretxe. "And, probably, the conclusions of these studies can be extrapolated well to other stimuli."

Therefore, consider that the key to long-term variations of other stimuli can also be genetic: "Of course, previous experiences, culture... influence the response to stimuli, modulate it, but I think genetics also has something to say."

Pleasure Research

In addition to studies related to drugs and genetics, other research is carried out to deepen the knowledge of pleasure. For example, Bergaretxe has mentioned a recent study conducted in the United States with university students: "The study used PET (positron emission tomography) to see which areas of the brain were activated during intercourse. Of course, it can't be the same as you feel involved and participating in an experiment than what you feel in a quiet and pleasant place."

However, the results of the study seem useful to know sexual pleasure better: "For example, it looks great how certain areas are lit and how others are inhibited. And that inhibition is necessary to lose control at that time, and in that study they have shown that the frontal lobe, which makes the censor, goes out."

Bergaretxe loves to see them. "Magnetic resonance research is also underway and as technology advances, we will go deeper into knowledge. I, for example, have a special interest in the Connectome project. The goal is to see where neurons go. It seems fascinating to me."

Music as sex and drugs

In the 1970s the expression sex, drugs and rock roll was born. But the relationship between sex, drugs and music is, on the one hand, broader, since it is not limited to rock, and on the other, much more previous. All this has now been tested by neurologists from the Canadian University of McGill, who have published their results in the specialized journal Nature Neuroscience.

In fact, researchers have found that hearing favorite music increases dopamine production and activates the remuneration mechanism. Just like when hunger is satisfied, the desire to have sex or the need to take a dose of drug.

Two techniques have been used: positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). With the first one you can see if dopamine production increases and with the second, where and how much it is released.

(Photo: Shai Tan/Creative Commons/acknowledge and share under the same authorization)

Thus, they have shown that listening to music at ease, whatever type it is, generates dopamine and, in addition, they have discovered that the response of the brain advances. In fact, dopamine emission begins a few seconds before hearing the favorite musical part, in a certain area of the brain (praised core). Then, when the most exciting part comes to oneself, it flows elsewhere (sharp core). The first field is related to cognitive system and motor and the other to emotions.

In addition, they have confirmed that the observed changes in the brain correspond to those shown by physiological parameter measurements. Thus, in the most exciting moments of musical composition, researchers detected significant changes in participating organisms, such as increased heart rate, temperature change and electrical conductivity of the skin, respiratory acceleration, etc.

According to researchers, the experiment helps to understand why music influences people so much. Dopamine emission can explain the effectiveness of music in rituals, marketing or therapy. On the other hand, they have pointed out that it is the starting point for analyzing abstract or intellectual sources of pleasure.