As of 2018, is it possible to induce pleasure in humans by some intervention like sending electrical signals? I've read that it's been done on mice. If not, it's quite imaginable that it will become possible in the near future. What would be the neurological implications of such intervention, other than addiction? I mean what would happen to the brain if we force the brain to stay in an orgasm-like or ecstasy state for several minutes? What are the possible adverse effects or damages? Of course that we know very little yet, but I appreciate to get some insights on how pleasure works, and if there really are pleasure centers in the brain that can be easily manipulated.
As of 2018, is it possible to induce pleasure in humans by some intervention like sending electrical signals?
Yes, it is possible and has been done, typically as DBS (Deep Brain Stimulation) for various disorders: OCD and depression are a few examples where the brain are stimulated induced pleasure. (Synofzik, Schlaepfer & Fins 2012)
Regarding "How much"... How much until what? Death? Brain damage? Subjective "that's enough"? Habituation? Realize that most of what you ask is definitely unethical as an experiment (on humans, which is your focus) in this century.
For an ethics discussion I stronly suggest the aforementiond paper paper by Synofzik, Schlaepfer & Fins "How Happy Is Too Happy? Euphoria, Neuroethics, and Deep Brain Stimulation of the Nucleus Accumbens" which has been the subject of interest for popsci press (e.g. article in The Atlantic).
A few points paraphrased from the paper:
- the euphoria was a result of deep brain stimulation (DBS) treatment for OCD (obsessive-compulsive disorder) performed in the anterior limb of the internal capsule and the nucleus accumbens region (ALIC-NA).
- The pleasure experienced is voltage dependant. However, patients also reported being overstimulated when the voltage was too high and expressed that as some kind of discomfort either somewhat physical "that's too much", or more psychological concern such as that they felt "unrealistically good”.
- Habituation to the pleasure elicited by this type of DBS reportedly does occur, and pretty quickly, on the order of minutes. This is somewhat surprising given that they also mention the classic experiment of Olds (1958), in which mice kept engaging thousands of times in behavior that rewarded them with brief shocks to the brain's "pleasure center". I'm guessing there's something either in the biology or in the protocol that causes faster habituation in humans, but the paper is not clear on what that is.
Luckily there are not one but several brain areas that when stimulated call for repeat stimulation. That is a way how one can define pleasure, by the way. If stimulation of an area makes animal to want more it is pleasurable. If not - the animal will avoid the mechanism that triggers the stimulus - that defines an aversive stimulus.
In the 7 affective system model (where the areas in mammalian brain have been identified) the systems producing wanting repeat stimulation would be SEEKING, PLAY, LUST, CARE and those of avoidance would be FEAR, RAGE, SEPARATION ANXIETY.
As to what happens to animals whose brain sites are overstimulated - they certainly can die and have died in experiments. Brain is a delicate biological system and overstimulating an area electrically is no better than doing this with street drugs. Brain needs to maintain its own balance in order to enable us to make sense of the world. The first problem would be 'cheating the brain' in addition to the second problem - damaging the brain physically through effects of drugs or electrodes.
Lastly your query is about 'ease' of manipulation. Not easy at all. The said brain areas have been identified in humans (who are another kind of mammals) needing surgery for epilepsy when it is often necessary to map brain areas by brief stimulation. Then there are experimental treatments using deep brain stimulation - for Parkinson's disease and rarely treatment resistant depression. They are complex and involved procedures, way more complicated than stimulating an 'ecstasy' centre.
The best way of interacting with the brain remains through it's natural interface - language, visual and other sensory stimuli. IMHO this will stay so for a long time. I hope that one can see a dose of optimism in this state of affairs though ;)
- Burgdorf, Jeffrey, and Jaak Panksepp. ‘The Neurobiology of Positive Emotions’. Neuroscience & Biobehavioral Reviews 30, no. 2 (2006): 173–187.
- J. Panksepp. Affective Neuroscience: The Foundations of Human and Animal Emotions. Oxford University Press, 1998.
- Panksepp, Jaak. ‘Affective Neuroscience of the Emotional BrainMind: Evolutionary Perspectives and Implications for Understanding Depression’. Dialogues in Clinical Neuroscience 12, no. 4 (December 2010): 533–45.
- Berridge, Kent C. ‘Pleasures of the Brain’. Brain and Cognition 52, no. 1 (June 2003): 106–28.
- ‘Psychotherapy Is The Biological Treatment’. Medscape. April 2018. http://www.medscape.com/viewarticle/893720.