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How to activate the brain's reward system through electrical stimulation? Unlock the brain's secret of pleasure!
Brain Stimulation reward (BSR) is a pleasant phenomenon caused by directly stimulating a specific brain area. This phenomenon was originally discovered by James Olds and Peter Milner. BSR serves as a powerful operant reinforcement tool that activates neural circuits in the brain's reward system, forming response habits similar to those established through natural rewards such as food and sexual intercourse. Early experiments showed that stimulating the outer hypothalamus and other brain areas related to nature reward can have a sense of rewards and motivation. This phenomenon has been found not only in all vertebrates tested, but also in humans, providing a useful tool for understanding how natural rewards are processed in specific brain regions and neural circuits.
“Electrical brain stimulation and intracerebral drug injections can significantly produce feelings of reward due to their relatively direct activation of reward circuits.”
In an experimental environment, BSR is produced through intracerebral self-stimulation (ICSS). Subjects had permanent electrodes implanted in multiple brain regions known to produce BSR and were trained to continuously respond to electrical stimulation of that brain region. ICSS studies are particularly useful for examining the effects of various drug manipulations on reward sensitivity. At the same time, ICSS is also used as an important means to assess the addictiveness of many types of drugs. Data from these studies are highly relevant to findings regarding the addictive properties of self-administered drugs.
History
In 1953, James Olds and Peter Milner at McGill University observed that rats were more likely to return to areas of experimental equipment that received direct electrical stimulation. From this, they inferred that the stimulation was rewarding, and subsequently confirmed experimentally that mice could be trained to perform new behaviors such as lever pressing to obtain short bursts of brain stimulation. Through these experiments, Olds and Milner uncovered the reward mechanisms in the brain associated with positive reinforcement and concluded that electrical stimulation could serve as an operant reinforcement tool.
“The discovery of electrical stimulation allowed motivation and reinforcement to be understood in terms of their physiological basis.”
The strengthening mechanism of brain stimulation
Early research on the motivational effects of brain stimulation addressed two main questions: 1. Which brain areas can be stimulated to produce the perception of reward? 2. Which drugs can affect the stimulation response and its mechanism? Research has found that natural drives in brain circuits reach reward circuits in a transsynaptic manner through the peripheral senses of sight, hearing, taste, smell, or touch. However, experimentally induced BSR activates the reward circuitry in a more direct manner, bypassing the process of transmission through peripheral senses. Electrical stimulation tools provide a means to identify central nervous system reward circuits with some anatomical and neurochemical specificity.
Relationship to natural rewards and drives
The relationship between BSR and natural rewards such as food, water, and mating has been a hotly debated topic, and many early studies focused on their similarities and differences. Due to its more direct effect, BSR can strongly activate the central reward mechanism. Unlike natural rewards, BSR has no built-in assistance in meeting survival needs, which makes BSR less responsive in the early stages of a series of experiments.
"The properties of BSR allow animals to self-stimulate to exhaustion."
Addiction
Addiction is a chronic brain disorder characterized by impulsive drug intake and pursuit behaviors that persist despite adverse effects on health, relationships, and work life. Laboratory procedures can establish compulsive self-administration habits to obtain drugs, which are highly similar to the self-administration behavior of BSR. Many studies have shown that the effective mechanism of BSR makes it effective in establishing compulsive habits because it directly activates the reward pathway and skips the external sensory transmission of natural rewards.
Anatomy of Reward
Through mapping and lesion studies, scientists are able to identify the locations of reward-related neurons and the signaling pathways directly affected by electrical stimulation of the brain, thereby gaining insights into the role of BSR in neural mechanisms. Various parts such as the lateral hypothalamus, medial forebrain bundle (MFB), and mesolimbic system provide different behavioral characteristics and reward effects for BSR stimulation.
"MFB is considered to be the most commonly used brain stimulus reward site, and its main transmission of dopamine fibers."
Conclusion
Research on electrical brain stimulation of rewards has given us a deeper understanding of how pleasure is achieved by directly activating the brain's reward system. However, as knowledge about BSR accumulates, related ethical and social issues begin to emerge. We should seriously think about how to maintain respect and responsibility for ourselves and others while pursuing happiness.
