The amygdala ( ; plural: amygdalae ; also corpus amygdaloideum ; Latin from the Greek, ???????? , amygdal? , 'Almond', 'tonsil') is one of two nucleic groups in the form of a nucleus that lies deep and medial in the temporal lobes of the brain in complex vertebrates, including humans. Shown in research to perform a major role in memory processing, decision making and emotional response, the amygdala is considered part of the limbic system.
Video Amygdala
Structure
Areas described as the amygdala nucleus include several structures with different connective and functional characteristics in humans and other animals. Among these cores are the basolateral complexes, the cortical nucleus, the medial nucleus, the central nucleus, and the intercalated cell groups. The basolateral complex can be subdivided into lateral, basal, and basal core accessories.
Anatomically, the amygdala, and especially its central and medial nuclei, are sometimes classified as part of the basal ganglia.
Specialization of the world
There is a functional difference between the right and left amygdala. In one study, electrical stimulation of the right amygdala induces negative emotions, especially fear and sadness. On the contrary, left amygdala stimulation can cause pleasant (happy) or unpleasant emotions (fear, anxiety, sadness). Other evidence suggests that the left amygdala plays a role in the brain reward system.
Each side has a specific function in the way we understand and process emotions. The right and left sides of the amygdala have independent memory systems, but work together to store, encode, and interpret emotions.
The right hemisphere is associated with negative emotions. It plays a role in the expression of fear and in the processing of stimuli that encourage fear. The fear of conditioning, which occurs when a neutral stimulus obtains hostility, occurs in the right hemisphere. When an individual is confronted with a negated and negative stimulus, it is processed in the right amygdala, resulting in an unpleasant or frightening response. This emotional response conditions the individual to avoid the stimuli that encourage fear.
The right hemisphere is also associated with the declarative memory, which consists of facts and information from previous events and must be consciously recalled. It also plays an important role in episodic memory retention. The episodic memory consists of aspects of autobiographical memory, allowing you to remember your personal emotional and sensory experiences of an event. This type of memory does not require conscious memory. The amygdala rightly plays a role in time and place associations with emotional traits.
Maps Amygdala
Development
There is considerable growth in the first few years of structural development in both the male and female amygdala. In this early period, the limbic structure of women grew at a faster pace than that of men. Among female subjects, the amygdala reaches full growth potential about 1.5 years before the peak of male development. The structural development of the male amygdala occurs over a longer period than in women. Despite the early development of the female amygdala, they achieve their growth potential faster than men, whose amygdala continues to grow. The larger relative size of the male amygdala can be attributed to this extended period of progression.
In addition to longer developmental periods, other neurological and hormonal factors may contribute to differences in the development of sex. The amygdala is rich in androgen receptors - nuclear receptors that bind testosterone. The androgen receptors play a role in the DNA bonds that regulate gene expression. Although testosterone is present in the female hormone system, women have lower testosterone levels than men. The amount of testosterone in the male hormonal system can contribute to the development. In addition, the gray matter volume in the amygdala is estimated by the level of testosterone, which can also contribute to the increase in the mass of the male amygdala.
In addition to gender differences, there is a developmental difference that can be observed between the right and left amygdala in both men and women. The left amygdala reaches its development peak about 1.5-2 years before the right amygdala. Despite initial growth of the left amygdala, an increase in volume is appropriate for a longer period of time. The right amygdala is associated with a response to frightening stimuli and facial recognition. It was concluded that early development of left amygdala function provides the ability to detect danger in infants. In childhood, the amygdala is found to react differently to same sex versus the opposite sex. This reactivity decreases until a person enters adolescence, where it increases dramatically at puberty.
Gender differences
The amygdala is one of the most understandable brain regions associated with differences between the sexes. The amygdala is larger in males than females in children aged 7-11 years, in adult humans, and in adult rats.
In addition to size, other functional and structural differences between the male and female amygdala have been observed. Activation of the subject's amygdala is observed when watching horror movies and subliminal stimuli. The results showed different lateralizations of the amygdala in men and women. The increase in memory for the film is associated with an increase in left activity, but not the right, amygdala in women, whereas it is associated with an increase in the right activity, but not the left, amygdala in men. One study found evidence that the average woman tends to maintain a stronger memory for emotional events than men.
The right amygdala is also associated with taking action as well as being associated with negative emotions, which can help explain why men tend to respond to emotionally stressful emotional stimuli. The left amygdala makes it possible to remember details, but also produces more thought than action in response to emotional stress stimuli, which may explain the absence of a physical response in women.
Function
Connection
The amygdala sends projection to the hypothalamus, dorsomedial thalamus, reticular thalamic nucleus, trigeminal nerve nuclei and facial nerve, ventral tegmental area, coeruleus locus, and laterodorsal tegmental nucleus. The basolateral amygdala project to the nucleus accumbens, including the medial shell.
The medial core is involved in the sense of smell and processing of pheromones. It receives input from olfactory bulb and olfactory cortex. The lateral amygdalae, which sends impulses throughout the basolateral complex and to the centromedial nucleus, receives input from the sensory system. The centromedial core is the main output for the basolateral complex, and is involved in the emotional arousal in mice and cats.
Emotional learning
In complex vertebrates, including humans, the amygdala performs a major role in the formation and retention of memories associated with emotional events. Research shows that, during fear conditioning, sensory stimuli reach the basolateral amygdala complex, especially lateral nuclei, where they form associations with memory stimuli. The relationship between the stimuli and the hostile events they predict may be mediated by long-term potentiation, a continuous improvement of signaling between affected neurons. There have been studies showing that damage to the amygdala can disrupt emotionally reinforced memories. One study examined a patient with bilateral amygdala degeneration. He was given a story of violence accompanied by a suitable image and was observed based on how much he could remember from the story. Patients have less memory of the story than patients with functional amygdala, suggesting that the amygdala has a strong relationship with emotional learning.
Emotional memories are thought to be stored in synapses throughout the brain. Memory fears, for example, are thought to be stored in neural connections from the lateral nucleus to the central nucleus of the amygdala and the stria terminalis bed core (part of the extended amygdala). Of course, this connection is not the only location of frightened memories given that the amygdala nucleus receives and sends information to other areas of the brain that are important for memories such as the hippocampus. Some sensory neurons project the axon terminal to the central core. The central core is involved in the genesis of many fear responses such as defensive behavior (freezing or escape reactions), autonomic nervous system responses (changes in blood pressure and heart rate/tachycardia), neuroendocrine responses (hormone-stress release) Damage to the amygdalae destroys Pavlovian's acquisition and expression of fears, a form of conditioning of classical emotional responses.
The amygdala is also involved in positive (positive) conditioning. It appears that different neurons respond to both positive and negative stimuli, but no clustering of these different neurons becomes a clear anatomical nucleus. However, central central lesions in the amygdala have been shown to reduce learning in mice. Lesions in the basolateral region do not show the same effect. Research like this shows that the different nuclei in the amygdala have different functions in appetite conditioning. Nevertheless, the researchers found an example of an interesting emotional learning that shows an important role for the basolateral amygdala: naïve female mice are innately attracted to the non-volatile pheromones contained in dirty beds, but not by the volatiles derived from male- to be attractive when associated with the non-volatile attractive pheromone, which acts as a conditioned stimulus in the case of Pavlov's associative learning. In vomeronasal, olfactory and emotional systems, Fos proteins show that non-volatile pheromones stimulate vomeronasal systems, whereas volatiles generated by air only activate the olfactory system. Thus, the preference gained for male-derived volatiles reveals the associative-olomeric vomeronasal learning. In addition, the reward system is activated differently by the main pheromones and smells of secondary interest. Exploring the fascinating main pheromones activates the basolateral amygdala and the nucleus accumbens shell but not the ventral tegmental area or the orbitofrontal cortex. Instead, exploring aromas derived from men of interest both involve activation of circuits that include the basolateral amygdala, the prefrontal cortex and the ventral tegmental area. Therefore, the basolateral amygdala stands out as a major center for associative vomeronasal-olfactory learning.
Gift
The glutaminergic neuron in the basolateral amygdala sends a projection to the nucleus accumbens nucleus (NAc). Activation of this projection promotes the importance of motivation. This projection ability to drive the significance of incentives depends on the dopamine receptor D1.
Memory Modulation
The amygdala is also involved in memory consolidation modulation. Following each learning event, long-term memories for the event are not instantly formed. Instead, information about the event is slowly assimilated to long-term (potentially life-long) storage over time, possibly through long-term potentiation. Recent studies show that the amygdala regulates memory consolidation in other brain regions. In addition, fear conditioning, a type of memory disturbed by amygdala damage, is mediated in part by long-term potential.
During the consolidation period, memory can be modulated. In particular, it appears that the emotional passion following the learning events affects the next memory force for that event. Larger emotional excitement after a learning event increases a person's retention of the event. Experiments have shown that stress hormone administration to rats as soon as they learn something that increases their retention when they are tested two days later.
The amygdala, especially basolateral nuclei, are involved in mediating the effects of emotional arousal on memory power for the event, as demonstrated by many laboratories including from James McGaugh. These laboratories have trained animals on various learning tasks and found that the drugs injected into the amygdala after training affected the subsequent retention of the animal duties. These tasks include basic classical conditioning tasks such as inhibition avoidance, in which mice learn to associate light footshocks with special equipment compartments, and more complex tasks such as spatial or water mazes, in which rats learn to swim onto a platform to escape from the water. If drugs that activate the amygdala are injected into the amygdala, the animals have better memory for training in the task. If a drug that inactivates the amygdala is injected, the animals have memory impairment for the task.
Monks who practice compassionate meditation have been shown to modulate their amygdala, along with their intersection and temporoparietal insulation, during their practice. In an fMRI study, more intensive insula activity was found in expert meditators than in beginners. Increased activity in the amygdala following compassion-oriented meditation can contribute to social connectedness.
The amygdala activity at the time of encoding information correlates with retention for that information. However, this correlation depends on the relative "emotionality" of the information. The more emotionally evocative information increases the amygdalar activity, and the activity is correlated with retention. The amygdala neurons show different types of oscillations during emotional arousal, such as theta activity. This synchronized neuronal event can increase synaptic plasticity (which is involved in memory retention) by increasing the interaction between the neocortical storage and the temporal lobe structures involved in declarative memory.
Research using Rorschach test blot 03 found that the number of unique responses in this random image led to larger amygdala. The researchers note, "Because previous reports have shown that unique responses are observed at higher frequencies in the artistic population than in normal nonartistic populations, this positive correlation suggests that amygdalar enlargement in normal populations may be related to creative mental activity."
Neuropsychological correlations of amygdala activity
Initial research on primates provides an explanation of the amygdala function, as well as the basis for further research. In early 1888, rhesus monkeys with temporal cortex lesions (including the amygdala) were observed to have significant social and emotional deficits. Heinrich KlÃÆ'¼ver and Paul Bucy then expanded this same observation by showing that large lesions in the anterior temporal lobe produce noticeable changes, including overreaction to all objects, hypoemotionality, fear loss, hypersexuality, and hyperorality, a condition in which objects are not appropriately placed. in the mouth. Some monkeys also showed an inability to recognize familiar objects and would approach living things and die indiscriminately, indicating a loss of fear to the researchers. This behavioral disorder is then named KlÃÆ'¼ver-Bucy syndrome, and then research proves it specifically because of amygdala lesions. Monkey mothers who have amygdala damage show a decreased maternal behavior toward their baby, often physically abusing or ignoring them. In 1981, the researchers found that selective radio frequency lesions from the entire amygdala were due to the KlÃÆ'¼ver-Bucy syndrome.
With advances in neuroimaging technology such as MRI, neurologists have made significant findings about the amygdala in the human brain. Various data show the amygdala has a substantial role in the mental state, and is associated with many psychological disorders. Some studies show children with anxiety disorders tend to have smaller left amygdala. In most cases, there is a relationship between increasing the size of the left amygdala with the use of SSRIs (antidepressant drugs) or psychotherapy. The left amygdala has been linked to social anxiety, obsessive and compulsive disorder, and post traumatic stress, as well as wider to general separation and anxiety. In a 2003 study, subjects with a threshold personality disorder showed significantly greater left amygdala activity than normal control subjects. Some borderline patients even have difficulty classifying neutral faces or seeing them as a threat. Individuals with psychopathy show less autonomic response to instruct fear cues than healthy individuals. In 2006, researchers observed hyperactivity in the amygdala when patients were presented with a threatening face or confronted with a frightening situation. Patients with severe social phobia showed a correlation with increased responses to the amygdala. Similarly, depressed patients exhibit excessive left amygdala activity when interpreting emotions for all faces, and especially for fearful faces. This hyperactivity is normalized when the patient is given an antidepressant. In contrast, the amygdala has been observed to respond differently in people with bipolar disorder. A 2003 study found that adult and adult bipolar patients tend to have much smaller amygdala volumes and smaller hippocampal volumes. Many studies focus on the relationship between the amygdala and autism.
Studies in 2004 and 2006 show that normal subjects exposed to facial images or faces of frightened people from other races will show increased amygdala activity, even if the exposure is not real. However, the amygdala is not required to process fear-related stimuli, because people with bilateral damage exhibit a rapid reaction to a scary face, even without functional amygdala.
Recent research has shown that parasites, especially toxoplasma, form cysts in the brains of rats, often occupying homes in the amygdala. This may provide clues as to how specific parasites can contribute to the development of disorders, including paranoia.
Future studies have been proposed to address the role of the amygdala in positive emotions, and the ways in which the amygdala tissues with other brain regions.
Sexual orientation
Recent studies have suggested possible correlations between brain structures, including differences in hemispheric ratios and connection patterns in the amygdala, and sexual orientation. Homosexual men tend to exhibit a more feminine pattern in the amygdala than heterosexual men, just as homosexual women tend to exhibit a more masculine pattern in the amygdala than in heterosexual women. It is observed that the amygdala connection is wider than the left amygdala in homosexual men, as is also found in heterosexual women. Amygdala connections are broader than the right amygdala in homosexual women, as in heterosexual men.
Social interactions
The Amygdala volume is positively correlated with the size (number of contacts a person has) and the complexity (number of different groups in which a person is) of the social network. Individuals with larger amygdala have larger and more complex social networks. They are also better able to make accurate social judgments about the faces of others. The role of the amygdala in the analysis of social situations derives primarily from its ability to identify and process changes in facial features. However, he does not process the gaze of the perceived person.
The amygdala is also considered a determinant of one's emotional intelligence level. In particular it is hypothesized that the larger amygdala allows greater emotional intelligence, enabling greater integration and social cooperation with others.
The amygdala processes reactions to privacy-related violations. These reactions do not exist in people where the amygdala is bilaterally damaged. Furthermore, the amygdala is found to be activated in fMRI when people observe that other people are physically close to them, as when someone who is scanned knows that the experiment is standing right next to the scanner, rather than standing in the distance.
Aggression
Animal studies have shown that stimulating the amygdala appears to increase sexual and aggressive behavior. Likewise, studies using brain lesions suggest that damage to the amygdala may produce the opposite effect. Thus, it appears that this part of the brain can play a role in the appearance and modulation of aggression.
Fear
There are several cases of human patients with bilateral fossal amygdala ligaments, due to the rare genetic condition of Urbach-Wiethe disease. Such patients fail to exhibit fear-related behavior, leading one, 'Patient S.M.', to be nicknamed "women without fear". These findings reinforce the conclusion that the amygdala "plays an important role in triggering a state of fear".
Alcoholism_and_binge_drinking Alcoholism and binge
The amygdala seems to play a role in a liquor party, marred by episodes of poisoning and repeated withdrawal. Alcoholism is associated with wetted activation in the brain tissue responsible for emotional processing, including the amygdala. Protein kinase C-epsilon in the amygdala is important to regulate the behavioral response to morphine, ethanol, and control behavior such as anxiety. Proteins are involved in controlling the function of other proteins and play a role in the development of the ability to consume large amounts of ethanol.
Anxiety
There may also be a connection between the amygdala and the anxiety. In particular, there is a higher prevalence of women who are affected by anxiety disorders. In an experiment, the children were excited from their mother but allowed to hear her call. In response, men produce serotonin receptors that increase in the amygdala but women lose them. This causes men to become less affected by stressful situations.
The amygdala group is activated when one expresses feelings of fear or aggression. This happens because the amygdala is the main brain structure responsible for fighting or escaping. Anxiety and panic attacks can occur when the amygdala feels environmental stress that stimulates a fight or flight response.
The amygdala is directly related to conditioned fears. A conditioned fear is the frame used to describe the behavior generated when the initial neutral stimulus is consistently paired with a stimulus that evokes fear. The amygdala represents the core fear system in the human body, which is involved in the expression of conditioned fears. Fears are measured by changes in autonomic activity including increased heart rate, increased blood pressure, as well as simple reflexes such as flashing or flashing.
The central core of the amygdala has a direct correlation with the hypothalamus and brainstem - an area directly related to fear and anxiety. This association is evident from animal studies that have undergone amygdalae removal. Such research shows that animals that lack the amygdala have less fearful expressions and enjoy behavior that does not resemble species. Many areas of amygdala projection are involved critically in specific signs used to measure fear and anxiety.
Mammals have a very similar way of processing and responding to hazards. Scientists have observed similar areas of the brain - especially in the amygdala - illuminating or becoming more active when mammals are threatened or begin to experience anxiety. Similar parts of the brain are activated when rodents and when humans observe dangerous situations, the amygdala plays an important role in this assessment. By observing the function of the amygdala, one can determine why a rodent can be much more anxious than others. There is a direct relationship between amygdala activation and anxiety level perceived by the subject.
Anxiety begins with catalysts - a stressful environmental stimulus. This can include various smells, sights, and internal feelings that lead to anxiety. The amygdala reacts to this stimulation by preparing to stand and fight or to turn and run. This response is triggered by the release of adrenaline into the bloodstream. As a result, blood sugar rises, becoming immediately available to muscles for quick energy. Shaking can occur in an effort to restore blood throughout the body. A better understanding of the amygdala and its various functions can lead to new ways of treating clinical anxiety.
Posttraumatic stress disorder
There seems to be a connection with amygdalae and how the brain processes post-traumatic stress disorder. Several studies have found that amygdalae may be responsible for the emotional reactions of PTSD patients. One study found that when PTSD patients were shown facial images with fear expression, their amygdala tended to have higher activation than a person without PTSD.
Bipolar disorder
Amygdala dysfunction during facial emotional processes is well documented in bipolar disorder. Individuals with bipolar disorder exhibit greater amygdala activity (especially the amygdala/medial-prefrontal-cortex circuits).
Political orientation
The size of the amygdala has been correlated with the cognitive style associated with political thought. One study found that "greater liberalism is associated with increased gray matter volumes in the anterior cingulate cortex, whereas greater conservatism is associated with an increase in the volume of the right amygdala." These findings suggest that the amygdala and anterior cingulate gyrus volumes can be attributed to an individual's ability to tolerate uncertainty and conflict.
See also
- The amygdala hijack
- BELBIC
- List of areas in the human brain
- Trie brain
- The intercalation cells of the amygdala
Further reading
- Amygdala Joseph E. LeDoux, Scholarpedia, 3 (4): 2698. doi: 10.4249/scholarpedia.2698
References
External links
- Media related to the amygdala on Wikimedia Commons
- Stained slice brain image that includes "amygdala" in BrainMaps project
- international committee for the amygdala and health studies
Source of the article : Wikipedia
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