At all times we are bombarded by a collection of visual, auditory, tactile, taste and olfactory information. They bring us loads of emotional, cognitive and sensory content that can be discarded in a short time, stored for a long time or for a lifetime. In this blog, we will understand a little more about the neural basis of memory and learning.
The neurobiology of memory was studied in 1920 by the American psychologist Karl Lashley (1890-1958). Through laboratory experiments, Lashley compared healthy rats with animals subjected to brain damage, his main objective was to understand where the brain stores information, a region that the researcher called Engram. Lashley subjected the animals to maze testing and found that healthy animals learn to exit the maze as they are exposed to the same training environment. However, brain-injured rats could not learn independently of the affected brain region. With this, Lashley concluded that memory was stored in various cortical regions. However, Lashley did wrong analyzes, because the animals did not complete the tests due to visual, auditory and synesthetic deficits caused by the injury. Later, in 1940, Donald Hebb showed in his studies that memory was a distributed property, just as Lashley predicted. However, it was associated with specific areas that would be evoked. For Hebb, an event could be perceived by a person and could activate visual, auditory, motor neural networks, and when evoked (remembered) could reactivate these same nerve pathways. Therefore, Hebb concluded that when neural networks are frequently stimulated and engaged in tasks, they become more easily activated which facilitates the learning process, the same happens when it stops being stimulated, which becomes atrophied. To understand how the physiological process of the neural bases of memory occurs, it is necessary to understand its concept. Therefore, memory is understood as the ability to retain information. The first mnemonic process is the acquisition of information, that is, the perception of an event, which is characterized as any information that is perceived by us. Events can be related to the external world (objects, music, scents, situations, people) or to the internal world (thoughts and emotions). The second mnemonic process is retention, which is classified in different ways; memory, when related to information retention time, can be: ultra-fast or immediate, short term or long term. Ultra-fast memory is retained for seconds only, short-term or short-term memory is only retained for minutes or hours, and long-term memory can be retained for months or years. In a way, some information will always be lost, which characterizes forgetfulness. This is also a natural physiological process that avoids information overload. However, constant forgetting is called amnesia, which may be suggestive of neurodegenerative disorders, such as Alzheimer's, and exacerbated retention is hypermnesia. Memory can also be classified by nature into explicit memory (declarative), implicit memory (non-declarative) and working memory (working). Explicit memory is evoked through symbols or phrases, implicit memory is evoked by everyday situations, and working memory that is temporary and fundamental to performing everyday tasks. It is currently known that the prefrontal cortex is related to working memory, it is responsible for higher cognitive activities. The third mnemonic process is consolidation, characterized by prolonged retention of information or permanently. The last process is evocation, also called remembrance. It occurs mainly when we activate already consolidated neural circuits. The evocation of memory is an important process for the human being. It allows us to relive emotions and feelings. It is also what characterizes our learning process. In this sense, learning is understood as the process of retaining information that will be stored in memory. Learning differs from memory in that it shapes our behavior, our actions, and our thoughts. Memory, however, consists only of information retention. Learning can be classified as associative and non-associative. Associative learning was studied by Russian physiologist Ivan Pavlov in the mid-20th century, who demonstrated through dog experiments the classical conditioning through visual stimuli. In this type of learning, dogs associated the presence of a light stimulus with food and began to salivary. In addition, other studies have also shown another type of associative learning called operant conditioning, characterized by the association between stimulus and behavioral action that may be related to a positive experience (reward or reinforcement) or a negative experience (punishment).
To memory and learning study, methods as microelectrode implant and EEG are so efficient techniques. For more information about access to our Hub "Learning & Memory".
References:
Roberto Lente. Cem bilhões de neurônios. Conceitos Fundamentais de neurociência. Kandel. Princípios da Neurociência
Eric R. Kandel, James H. Schwartz, Thomas M. Jessell, Steven A. Siegelbaum, A. J. Hudspeth. Princípios de Neurociências. edição.
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