Amygdala In The Limbic System

The amygdalae (Latin, also corpus amygdaloideum, singular amygdala, from Greek αμυγδαλή, amygdalē, 'almond', 'tonsil', listed in the Gray's Anatomy as the nucleus amygdalæ)[1] are almond-shaped groups of nuclei located deep within the medial temporal lobes of the brain in complex vertebrates, including humans.[2] Shown in research to perform a primary role in the processing and memory of emotional reactions, the amygdalae are considered part of the limbic system.[3].

Those diagnosed with PTSD have shown a reduction in the volume of the hippocampus. The hippocampus helps humans remember new memories and then be able to recall them later, and also helps identify between past and present memories. The amygdala is another section of the brain affected by PTSD, and the amygdala is responsible for processing emotions and fear. The ventromedial prefrontal cortex is shown to have a decreased size in cases. The ventromedial prefrontal cortex regulates negative emotions like stress, anxiety, and fear. The strange behaviours of the patients diagnosed with PTSD can be explained by the damage to the brain. “Researchers believe that the brain changes caused by PTSD increase the tendency of a person developing other psychotic and mood disorders” (brainblogger.com). The brain is like a machine made up of small parts, and if one of these parts break, the machine does not function

Brain imaging studies of posttraumatic stress disorder (PTSD) have identified a few key brain regions whose function appears to be altered in PTSD, most notably the amygdala, the ventromedial prefrontal cortex (vmPFC) and the hippocampus.The amygdala is an almond-shaped region ("amygdala" is greek for almond) that is

This is a brief synoposis of how the brain process trauma. The “DOING” brain called the amygdala, is located in the limbic system, where response to threat, and intense emotion happens (Ferencik, 2010). This is intended to act as a “smoke alarm” that triggers when our brain thinks we are in danger. It is designed to help us respond to possible danger and react accordingly. The “THINKING” brain called the prefrontal cortex helps us plan, solve problems, and organize the world around us. It helps us analyse situations realistically and make logical decisions (Ferencik,

The hippocampus, memory and organization portion of the brain, and the amygdala, the “fight or flight” portion, are both confused by PTSD (“PTSD and The Brain”, 2-3). For example, if an Iraqi soldier hears a helicopter overhead, the hippocampus remembers the sound of the helicopter and works with the amygdala to associate that noise with a traumatic war event. The amygdala then will induct a fight or flight response, causing symptoms of PTSD to initiate. (Ibid, 3) While symptoms can be difficult, the hardest part of having PTSD, is sometimes admitting you have a disorder.

The amygdala appears to be active in dear acquisition, or learning to fear an event, as well as in the early stages of fear extinction or learning to not fear” (Post-Traumatic Stress Disorder). Also researchers have studied and delved into the effects of the prefrontal cortex (PFC). The prefrontal cortex is the area of the brain that is involved in tasks such as decision-making, problem solving, and judgment. “For example, when [the PFC] deems a source of stress controllable, the medial PFC suppresses the amygdala--an alarm center deep in the brainstem that controls the stress response” (Post-Traumatic Stress Disorder). “PTSD is not diagnosed until at least one month has passed since the time a traumatic event has occurred” (Joseph Goldberg, 2014). If the doctors see the symptoms of PTSD they will then go ahead and evaluate the patient by performing a complete medical history form and then physical exam follows. The next step is for the patient to be sent a psychiatrist, psychologist, or another medical health professional to help the patient treat his or her mental illness.

Taking into consideration the range of risk factors that may make an individual more susceptible to PTSD, a biological approach may explain the etiology. This proposal takes into account the anatomical differences in two major brain structures in PTSD patients, the amygdala and the hippocampus. Both of these structures are part of the limbic system, which are responsible for our emotional responses and memory, playing a vital role in fear response and learning. The differences in the function and volumes of these structures manifest in the patient through memory of the traumatic event and stress and its associated emotional responses. In patients with PTSD, MRI scans shows that the amygdala has increased activity compared to individuals without

Being able to understand the many genetic and environmental connections to stress will provide a way to map out the diagnostic and treatment which will show how vulnerable and resilient people are to Posttraumatic Stress Disorder. Also, there are a lot of better ways to study the brain. Scientists are being provided with information about the structures and chemicals of the brain and how the development of PTSD are related to the mind and the brain. There are two brain structures that imaging has placed emphasis on, the amygdala and hippocampus. The amygdala is how we study fear and it is believed that this is involved in people with PTSD. The hippocampus is involved with the memory. There is evidence that there is some memory loss in people with PTSD. It has been discovered that neurochemicals may be involved in PTSD. Medicine can be used to reverse this neurochemical dysfunction. "Ultimately, it may even be possible to predict the development of PTSD based on the early psychological and changes in people who have been exposed to a traumatic event. Continued research also offers the promise of new treatments for PTSD in the future."( Harold Cohen, Ph.D.)

In order to help our brothers and sisters, we must attempt to understand what Post Traumatic Stress disorder actually is. We have to look at what areas of the brain are affected. There are three regions of your brain that become agitated and begin to change due to post traumatic stress, the hippocampus, amygdale, and the medial prefrontal cortex. The region that is affected the most from

The article, Concussive brain injury enhances fear learning and excitatory processes in the amygdala by Maxine L. Reger, Andrew M. Poulos, Floyd Buen, Christopher C. Giza, David A. Hovda, and Michael S Fanselow took a close look into the fears and behaviors generated in rats two days after suffering trauma to the brain. This particular article was discovered by searching the keywords: brain injury and amygdala, in the PubMed database. By searching those keywords, the database was able to pull up numerous articles discussing the two topics, but I felt that Reger et al (2012) demonstrated a clear association between the topics. The article brings about a question of whether or not there is a link between brain injuries, posttraumatic stress disorder, commonly referred to as PTSD, and the changes involved in the excitatory and inhibitory processes involved in the amygdala. In order to examine such a link, the authors performed a number of tests on adult Sprague-Dawley rats to test their hypothesis as well as to investigate the neurobiological correlation between concussion and PTSD. To further assess these correlations, it is imperative to explore the methods used to conduct this study.

Extensive neuroimaging studies on the brains of PTSD patients show that several regions differ structurally and functionally from those of healthy individuals. The amygdala, the hippocampus, and the ventromedial prefrontal cortex play a role in triggering the typical symptoms of PTSD. These regions collectively impact the stress response mechanism in humans, so the PTSD victim, even long after his experiences, continues

5). In contrast, a post-traumatic stress disorder person’s system would seem to be oversensitive. Source says the amygdala may look to be over reactive in PTSD, but it posts a question upon if the amygdala is already over reactive in itself or it could naturally be over reactive responding to trauma (Harvard Women’s Health Watch, 2005). With the help of imaging techniques and its imaging studies, it shows that the hippocampus and the anterior cingulated cortex found to be smaller in PTSD. The two areas of the brain which help maintain the amygdala in check seem to have trouble functioning properly in people with PSTD (Harvard Women’s Health Watch, 2005). Another thought that involves the pathophysiology of PTSD is the role of basal catecholamines. However, the subject is controversial (Miller, 2000). There has been a hypothesis made that cerebrospinal fluid (CSF) corticotrophin-releasing hormone (CRH) concentrations increase in people with PTSD from a study comparing combat veterans and normal volunteers (Miller, 2000). As with any disorder of the brain, the complexities of PTSD are extensive and require a lot of integrating components. Therefore, the pathophysiology of PTSD is unclear.

The limbic system was first recognized due to Franz Josef Gall (LeDoux, J., 1996). Franz Joseph Gall developed the idea of “phrenology” that focused on the study of the different variations of bumps on the human skull to be related to differences in behavioral and emotional functioning. The limbic system’s main function in the brain is to control emotional behaviors and certain forms of memories that are infused with emotion (amygdala). The amygdala is a part of the brain that forms the tail end of the basal ganglia within the rostral temporal lobe and is located near the hippocampus (Lambert, K.G. & Kinsley, C .H., 2005). The amygdala, as defined by the text, is an almond-shaped structure that functions as a part of the limbic system involved in regulation of emotion and sexual urges (Lambert, K.G. & Kinsley, C .H., 2005). In addition, the amygdala is comprised of a dozen or more sub regions that are not all involved in fear conditioning (LeDoux, J., 1996).

The amygdala is known to learn from exposure to fear and store assessment of threat–related stimuli. The prefrontal cortex is involved in extinction and the retention of fear and is connected to the amygdala. Finally, the hippocampus encodes the context during fear learning process and sends it to the amygdala. People with PTSD have hyper-activity in the amygdala, while having hypo-activity in the prefrontal cortex and there is reduction of the hippocampus volume. This reduction may limit proper evaluation and categorization of the experience. A study on Vietnam soldiers revealed that lesions in the amygdala and prefrontal cortex resulted in the absence of PTSD. To get further into the molecular level studies been done on the hormonal system. “Stress is known to contribute to the pathogenesis of a variety of disorders, including the majority of psychiatric like major depression and posttraumatic stress disorder.” (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3825244/pdf/DM30-02-343616.pdf). Research has revealed evidence that a hormonal system known as the hypothalamic-pituitary-adrenal (HPA) axis is the one that gets disrupted in people with PTSD. The hormonal system is involved in normal stress reactions, so the disruption of this system in people with PTSD creates this “false alarm”. It has been suggested by some scientist that the dysfunction of the HPA system results in hippocampal damage in people with PTSD. Damage in the hormones is caused by damage to

As noted in class notes, inside the human brain is an area referred to as the Limbic system. “This system consists of the hypothalamus, hippocampus, and amygdala which are involved in motivation, emotion, learning, and memory.” The hippocampus, being the central area of the brain and associated with creating new memories, corresponds with how children think. As a child, this is important in the growing process. As discussed in class, not only does the “hypothalamus integrate memories into a network of knowledge, but it also consolidates and stores memories within the brain.” The amygdala is also a key point in a child’s development. The amygdala, situated at the tip of each side of the hippocampus, plays a key role in emotional processes, especially