Behavior is the result of the interaction of genes and the environment. Changes in genes (such as transgenes, knockouts, or down-regulations) ultimately manifest as behavioral changes associated with genes; changes in the environment (such as sound, light, electrical stimulation, and drug treatment) not only directly affect animal behavior. And can change the behavior of animals by affecting related genes. Learning and memory are a form of behavioral behavior of this related gene interacting with the environment. Learning is a process of obtaining information about the external environment (for animals) or about world knowledge (for humans); memory is the process of encoding, storage, and reproduction of such information or knowledge. the process of. Human memory is complex, including blurring of explicit or declarative memory of events and objects, and learning-independent (such as adaptability and sensitivity) or related (such as operational techniques and habit formation). Implicit memory or nondeclarative memory. Animal memory is relatively simple, including short-term memory and long-term memory; the former typically lasts from a few minutes to a few hours, while the latter lasts for 24 hours to several days, weeks or even longer. Corresponding to this is working memory and reference memory. Working memory is the process of processing and storing the information for a short period of time, thus representing short-term memory. Reference memory refers to the process of processing and storing information that is useful throughout the experiment (any day of testing), thus representing long-term memory.
The brain mechanism of memory is very complicated and remains unclear. As early as the late 1940s, the famous neurosurgeon Wilder Penfield was the first to obtain evidence that the processing of memory may be carried out at specific parts of the human brain. He observed from thousands of patients that electrically stimulating patients' temporal lobes produced a series of memories of early experience, which the patient called an "experiential response." A few years later, in an accidental opportunity, in order to perform a brain surgery on a patient with epilepsy for 10 years, Penfield removed the bilateral hippocampal amygdala and part of the temporal cortex. Postoperatively, the patient's epileptic symptoms were greatly improved. Unexpectedly, the patient's memory is simultaneously devastatingly damaged. Although the patient retained short-term memory for a few seconds to a few minutes and had very good "long-term memory" of pre-operative events, he could not convert short-term memory into long-term memory. Keep information such as people, places or objects for no more than one minute. Moreover, his spatial positioning ability has been greatly weakened, and it took even a year to learn to take a road around a new house without getting lost. In fact, all patients with extensive damage to the marginal structure of the medial temporal lobe due to surgery or disease have similar memory deficits. These results suggest that the limbic system plays an important role in memory regulation.
Subsequent research for nearly half a century has shown that there are at least five different structural systems in the brain that are relatively specifically involved in the regulation of learning and memory, including the hippocampus, amygdala, cortex (especially the perirhinal cortex), cerebellum and back. Lateral striatum. Aiming at these brain structures, a corresponding behavioral measurement method with certain specific learning and memory was established. The hippocampus is the most important regulatory brain area of ​​spatial memory, and it is also involved in the regulation of emotional memory. Destruction of the hippocampus leads to complete loss of spatial memory, and emotional memory will also weaken, but will not completely disappear. This is because emotional memory is mainly regulated by the amygdala. The determination of amygdala-dependent memory is mainly based on the conditional fear method; the animal behavior test methods are reviewed, and there are many methods for determining hippocampal-dependent memory, including various labyrinths and inhibitory avoidance experiments. The periorbital cortex is a specific area for regulating visual object memory, which is commonly detected by object recognition. The cerebellum is a specific brain structure that regulates classical reflexes associated with skeletal muscle responses, and the eyeblink conditioning model has high specificity for cerebellar-dependent memory. The striatum plays an important role in the learning and memory process of the stimulus-response habit, and mainly regulates learning and memory related to drug abuse. There are few methods for measuring striatum memory, and currently the win-stay radial arm maze method is mainly used. Striatum damage can lead to memory manipulation disorders in this model, and damage to the hippocampus or amygdala has no significant effect on this memory. Explain that the win-leave arm maze method is specific to striatal memory.
Although the mechanism of memory is still unclear, there is increasing evidence that the cyclic AMP-protein kinase A (Camp-PKA) signaling system plays an important regulatory role in memory. Activation of receptors coupled to stimulatory G protein (Gs) stimulates adenylate-enzyme activity, thereby increasing cAMP formation and activating PKA.PKA to cAMP-responsive-element-binding protein (cAMP-responsive-element-binding protein) , CREB) phosphorylates and activates, thereby promoting memory-related gene expression and ultimately enhancing memory. In addition, the mitogen-activated protein kinase (MAPK/extracellular signal-regulated kinase (ERK) signaling pathway regulates the activity of CREB in a similar phosphorylation manner, thereby regulating memory. Therefore, in addition to the anatomically removing the regulation function of a particular brain structure on memory by the method of brain structure damage, any drug that can affect the function of the above signaling pathway (such as NMDA receptor antagonist MK-801 and MEK inhibition) Agent U0126 attenuates memory; type 4 phosphodiesterase (PDE4) inhibitors enhance memory) or related treatments (such as transgenic or gene knockout or down-regulation) can affect learning and memory processes.
Learning and memory research is one of the hottest areas in the biomedical world today. The development in this area can be described as ever-changing. New or improved research methods and methods are emerging. Therefore, this chapter cannot describe all the research methods related to learning and memory one by one, but choose some representative common methods to introduce them. In addition, the equipment used is not limited to what is described in this chapter. In the same experiment, the instruments used in different laboratories will be different, but the experimental results should be consistent. A review of experimental methods of animal behavior Â
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