User:Abdulaziz Alhumud/sandbox

"Over the past decade, interest in the human amygdala has grown considerably, spurred on by the progress in animal studies and by the development of functional imaging technique." The amygdala is a large complicated structure in the brain which plays a main role in several normal behavioral functions, and it has a huge effect on mental situations. The amygdala is a relatively 'silent' area of the brain, and it contains a strong inhibitory network that keeps spontaneous cellular activity low and that prevents calls from firing action potentials to irrelevant stimuli. The amygdala is located on the dorsomedial portion of the temporal lobe, its volume is almost 1700 mm which was measure by MRI and its name is coming from the Greek or Latin language.

Amygdala Functions
The amygdala has different aspects in the modulation of cognitive functions such as attention, memory, and perception. Furthermore, a research shows that the amygdala is involved in processing of rewards to encourage keeping behaviors. Facial expression has a main role in communication, so the amygdala gets stimulated with expression, especially with the fearful expression, and it has a negative effect. Several researchers has decided that the amygdala have an effective role in fear. Moreover, "One long- standing idea is the amygdala consists of an evolutionarily primitive division associated with the olfactory system ( the cortico-medial redion) and an evolutionarily newer division addociated with the neocortex ( the basolateral region)."

Amygdala Lesions
In 1930, researchers noticed that damaging the temporal lobe has direct effect on emotional process, aggression, feeding and sexual behavior. Any change in the structure or the function of the amygdala cause different psychological conditions such as different kinds of anxiety, depression, schizophrenia, and autism. When the human amygdala gets damaged, that will make collision between functional activities and fear conditionings in daily life. Some of the psychological disorders and mental conditions which are related to the amygdala might be occurred because of the amygdala’s role in anxiety. A recent study of the relationship between the volume of the amygdala with depression and anxiety in Cushing syndrome shows that a correlation between amygdala and depression and anxiety in patients who have CS, so the volume of the right amygdala is smaller than the normal size, and the left amygdala had a negative correlation with depression and anxiety levels. An experiment on awake human patients who had severe epilepsy shows that electrical stimulation evokes fear, feelings, anxiety, and fear’s reactions in the amygdala. One of the most common causes for the lesions is the injuries which some patients had in the bilateral lobe. An obvious finding reflects that deficits in the perception of the emotional meaning of faces, especially fearful faces, have been found in patients with selective bilateral amygdala damage because of an unusual inheritable disorder. In additions, a clear evidence by one study shows that the amygdala plays a role in consolidation of memories of emotional experience. However, going through a rough experience during childhood influences negatively the functional emotional development of the amygdala, and it leads children to have different kinds of anxiety. One study of the effect of the amygdala shows that children who live separately from their mothers in the first two years of their life have a weak and a different degree of responding to any subject in the amygdala, and that makes a prediction to have the severity of separation anxiety symptoms. Different studies had an evidence which shows the effect of the volume of the amygdala on patients to have PTSD. Another study of veterans who were under dangers during wars demonstrated that the volume of the amygdala increased with PTSD. A previous study of fear and panic attack shows that the volume of the inhalation of CO2 triggers the fear and panic among people. Moreover, a recent study in mice which were used as model to explain a clinical condition demonstrated that the amygdala reveals CO2 and acidosis to produce fear behaviors. One study found that the possibility of occurring panic attack and fear happens by the effectiveness of the CO2, and that influences negatively the amygdala function which is a reason for the development of all the two disorders. In addition, One of the studies which examined the response of the amygdala to terrifying faces in schizophrenia patients shows that the amygdala has inability in reactivity to negative faces which is caused by fear. Furthermore, several studies mentioned that sports which make concussion have a negative effect on mood states, structural brain, and neuropsychological functions. A previous study which examined the effect of concussion on amygdala in collegiate football plyers found a strong evidence between amygdala shape and causing, anger, and TMD, and only the left laterobasal amygdala was correlated with negative mood. A study of the social anxiety by using a novel social referencing test demonstrated that the amygdala in people who had social anxiety had increased its activities to objects which are related to others’ fearful reactions with a high oxygen level. A study, its goal to find out whether the rate of the amygdala growth is not normal in the brain in children who had Autism, showed that the growth of the amygdala in autistic children is more than the normal children. Another study in young people who had autism found out that the functional connectivity of the amygdala decreased was decreased comparing with the normal development of other people. A comprehensive study of the amygdala in rats showed that damaging the amygdala in early age have a high possibility to predict having neurodevelopmental and psychological problems in the future. A study, its purpose to investigate whether the left amygdala or the left has a main role in aggressive and escape behavior in the middle of awake surgery, showed that in all the cases of the study patients had aggressive behaviors in the two sides of the amygdala. Finally, the amygdala does not cause any disorder, it simply that in people who have any disorder alteration occur in the amygdala.