Neuropsychology and biopsychology provide us with a key perspective when exploring the mysteries of the human brain and behavior. These two fields reveal many psychological effects that affect our perception, learning, memory and behavior by studying brain structure, neural mechanisms and physiological processes. This article will introduce in detail three core effects - relying on plasticity effect, compensatory hypertrophy effect and dopamine reward prediction error effect, helping you fully understand these 'invisible forces' that shape the human mind from physiological mechanisms to real-life applications.
Use-dependent plasticity
What is the use-dependent plastic effect?
Use-dependent plastic effect refers to the phenomenon that the brain's neural structure and function will adapt to changes according to the frequency and intensity of use. Simply put, 'the more you use, the stronger your function; the less you use, the weaker your function.' This plasticity runs throughout a person's life, allowing the brain to constantly adapt to environmental changes and learn new skills.
Background source
Early scientists believed that the brain structure will remain unchanged after adulthood. Until the 1960s, neuroscientist Donald Hebb proposed the theory that 'neurons discharge together and connect together', laying the foundation for neuroplasticity. Subsequent research further found that even the brain of adults can strengthen or reorganize neural connections by continuously using specific functional areas. This discovery completely overturns the traditional cognition of 'the brain is fixed and unchanged after adulthood', and the dependence on plasticity effect has also become one of the core contents of neuroplasticity research.
Core Principle
The core principle of relying on plasticity effects is closely related to the connection between neurons - synapses. When we repeatedly use a brain area (such as the motor cortex and auditory cortex used for repeated practice of piano), neurons in that area will frequently discharge, prompting synapses to release more neurotransmitters, while increasing the number of synapses or enhancing synaptic strength. Just as muscle exercises will make muscle fibers thicker, frequent activation of nerve cells will make nerve connections more 'stronger', thereby improving the functional efficiency of the brain area. On the contrary, if a certain brain area is idle for a long time, the synaptic connection will gradually weaken and the function will decrease accordingly.
Experimental basis
Classical experiments provide strong support for the plasticity effect. Scientists have conducted a comparative study of two groups of rats: one was raised in a 'rich environment' full of toys, mazes and companions, and the other was raised in a monotonous 'barren environment'. After a period of time, it was found that the rats in the 'rich environment' had thicker cerebral cortex, significantly more synapses between neurons, and stronger learning and memory abilities. In human studies, brain imaging of musicians shows that the area of the brain area they are responsible for finger movement and auditory processing is larger than that of ordinary people, and the longer the training period, the more obvious the changes in brain area structure, which is the plasticity effect brought about by long-term practice.
Realistic application
The dependence plastic effect is widely used in education, rehabilitation and skill training. In the field of education, through repeated practice and diversified teaching activities, students' brains can strengthen the neural connections related to learning and improve memory and comprehension ability; in the recovery of brain injury, doctors will promote the reorganization and strengthening of peripheral nerves in damaged brain areas through targeted training (such as pronunciation exercises for patients with language disorders), and help restore functions; for ordinary people, continuous learning of new skills (such as musical instruments and languages) can continuously activate brain plasticity and delay cognitive decline.
Critical Analysis
While the reliance on plasticity provides the possibility for brain optimization, it also has limitations. First of all, there are age differences in plasticity. Children's brains are the most plastic. As they age, the difficulty of nerve reorganization will gradually increase. Secondly, excessive use of a certain function may lead to 'nerve fatigue', such as long-term high-intensity use of the brain may cause attention degradation. In addition, plasticity is not unlimited. Without the right training method, simply increasing the frequency of use may not achieve the expected effect, and may even lead to the solidification of wrong neural connections.
Compensatory hypertrophy effect
What is the compensatory hypertrophy effect?
Compensatory hypertrophy effect refers to the phenomenon that when a certain area of the brain is damaged or reduced due to damage or function, other undamaged areas will compensate for the function of the damaged area by enhancing their own functions or expanding the range of neural connections. It is like the brain's 'spare tire mechanism'. When local functions fail, it maintains overall functional stability by mobilizing the 'reserve army'.
Background source
Research on compensatory hypertrophy effect begins with observation of patients with brain injury. In the mid-20th century, neuroscientists discovered that after some stroke patients were damaged in the motor cortex, after rehabilitation training, the limbs that were originally unable to move gradually recovered their function. Through brain imaging technology, it was further found that the undamaged auxiliary motor area and parietal cortex activation intensity of these patients was significantly higher than that of ordinary people, which suggested that there was a compensatory adjustment mechanism in the brain. With the development of neuroimaging technology, scientists have gradually confirmed this 'injury-compensation' neural recombination model, naming it the compensatory hypertrophy effect.
Core Principle
The core of the compensatory hypertrophy effect is the recombination ability of neural networks. The function of the brain relies on collaborative work between different regions to form complex neural networks. When a certain area is damaged, the brain will activate the 'emergency mechanism': on the one hand, neurons in the undamaged area will increase the discharge frequency and improve their functional efficiency; on the other hand, the originally weak neural connections will be strengthened, and even a new connection path will be formed, allowing the undamaged area to take over some of the functions of the damaged area. For example, after the language center (Broca area) is damaged, the brain may strengthen the language-related neural connections in other areas of the temporal lobe or frontal lobe, helping the patient recover some of his or her language skills.
Experimental basis
Rehabilitation studies of stroke patients are typical cases of compensatory hypertrophy effect. The study found that after stroke, patients with motor dysfunction after receiving regular rehabilitation training, the contralateral motor cortex of their damaged brain will increase in volume and increase in activation. It can be seen through functional magnetic resonance imaging (fMRI) that when a patient performs hand movements, the activation intensity of the auxiliary motor area that was not originally involved in motor control is significantly increased and the activation range is expanded. In addition, studies of patients with congenital visual defects (such as congenital cataracts) show that their auditory cortex area is larger than that of ordinary people and have stronger auditory discrimination ability, which is the manifestation of the brain's compensation of visual function with auditory areas.
Realistic application
Compensatory hypertrophy effect provides important ideas for brain injury recovery and neurodegenerative disease intervention. In rehabilitation treatment, doctors will design targeted training based on the patient's injury area, such as allowing stroke patients to repeatedly perform limb activities to promote compensatory activation of undamaged brain areas; for patients with Alzheimer's disease, through memory training, social activities, etc., it can strengthen the compensation of memory function in other areas of the brain and delay cognitive decline. In addition, this effect also guides the development of prosthetic technology, and partial recovery of motor function is achieved by training patients to control prosthetics with other brain areas.
Critical Analysis
Although the compensatory hypertrophy effect brings hope for rehabilitation, it also has obvious limitations. First, there are individual differences in compensation ability, which is closely related to the degree of injury, time of injury and age. Compensation is usually better for young people and patients with less injury, while effective compensation may be difficult for patients with severe injuries or older age. Secondly, excessive compensation may bring side effects. For example, long-term high-intensity activation of a certain brain area may lead to fatigue or functional disorders, and some patients may experience headaches and distractions. In addition, compensation functions often cannot completely replace the original function. For example, compensation after impaired language areas may allow patients to resume simple communication, but complex language expression or writing ability may be permanently impaired.
Dopamine reward prediction error effect: 'regulator' of happiness and addiction
What is the dopamine reward prediction error effect?
The dopamine reward prediction error refers to the phenomenon that dopamine neurons adjust the intensity of activity based on the difference between the 'actual rewards obtained' and the 'expected rewards received', thereby affecting learning and behavioral motivation. Simply put, when the actual reward exceeds expectations, the dopamine release increases, which makes us feel happy and strengthens our behavior; when the actual reward is lower than expected, the dopamine release decreases, prompting us to adjust our behavior.
Background source
The discovery of this effect stems from the study of monkeys by neuroscientist Wolfram Schultz. In the 1990s, Schultz's team recorded the discharge activities of dopamine neurons in monkey brains and found that when monkeys accidentally receive juice rewards, dopamine neurons will discharge violently; when monkeys gradually learn to obtain juice by pressing the lever (forming expectations), dopamine neurons will discharge when the reward is expected, but weaken when the reward is actually received; if there is an expected reward but not obtained, dopamine neuron discharge will significantly reduce. This discovery reveals the central role of dopamine in reward learning.
Core Principle
The core of the prediction error effect of dopamine reward is the 'prediction correction mechanism'. The brain will constantly form expectations for rewards in the environment (such as food, praise, money), and dopamine neurons are like 'error detectors'. By comparing the difference between actual rewards and expected rewards, they adjust the dopamine release amount: when the actual reward > expected reward (positive error), dopamine release increases, strengthening the behavior leading to rewards (such as pressing leverage again); when the actual reward = expected reward (zero error), dopamine release is stable, and the behavior remains unchanged; when the actual reward is < expected reward (negative error), dopamine release decreases, prompting the brain to give up invalid behavior or find new strategies. This mechanism allows us to quickly learn from experience and optimize behavior to get more rewards.
Experimental basis
Schultz's monkey experiment is classic evidence of this effect. In the experiment, when the monkey accidentally obtained juice for the first time, the dopamine neurons discharged violently when they received the reward; after training, the monkey knew that 'pressing the lever after the light was on will get juice.' At this time, the dopamine neurons discharged when the light was on (expected reward), and the discharge weakened when the juice was obtained; if the juice was not given after the light was on, the dopamine neuron discharged significantly decreased at the expected time point. In human studies, brain imaging shows that when people receive unexpected bonuses, the activation of the brain dopamine-related brain regions (such as the nucleus accumbens) is enhanced; and the addict's expectations of drugs will lead to the early release of dopamine. Once drugs are not available, negative errors will trigger a strong sense of thirst, which is the core of the addiction mechanism.
Realistic application
The error effect of dopamine reward prediction is widely used in education, marketing and addiction treatment. In education, teachers create positive errors through 'small surprise rewards' (such as unexpected praise, additional credits) to enhance students' motivation to learn; in the field of marketing, merchants use 'limited-time offers' and 'random gifts' to exceed consumer expectations and stimulate purchasing behavior; in addiction treatment, by gradually adjusting expectations and reducing reward errors, they help addicts reduce their thirst for drugs or alcohol, such as replacing the temporary pleasure brought by regular health rewards.
Critical Analysis
Although this effect can explain the reward learning mechanism, it also has complexity and limitations. First, the subjectivity of the reward will affect the intensity of the effect. The prediction errors caused by the same reward (such as money) vary greatly for different people; second, long-term dependence on external rewards may lead to 'reward fatigue', such as frequent material rewards will increase the brain's expectations, and once the reward stops, negative errors will trigger a decline in motivation; in addition, in addictive behavior, drugs will directly stimulate the large amount of dopamine release, artificially create strong positive errors, break the normal prediction mechanism, and lead to the brain's pathological dependence on drugs, which also shows that this effect may have negative effects in extreme cases.
Conclusion
The plastic-dependent effect reveals the brain's adaptability 'the more you use it, the stronger it becomes', the compensatory hypertrophy effect shows compensatory wisdom after brain injury, and the dopamine reward prediction error effect reveals the neural code of happiness and motivation. These neuropsychological and biopsychological effects not only help us understand the working principles of the brain, but also provide practical guidance in the fields of education, rehabilitation, mental health, etc. By mastering these effects, we can better utilize the brain's plasticity-enhancing ability, use compensation mechanisms to deal with damage, and reasonably regulate reward mechanisms to promote healthy behaviors. In the future, with the development of neuroscience, more 'secret effects' of the brain will be discovered, bringing more possibilities to human mind exploration and healthy life.
Continue to pay attention to the series of articles in 'Complete Psychological Effects' and explore more secret weapons of psychology in depth.
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