It shouldn't be too surprising given its role in fear processing that the amygdala might also play a role in anxiety. While fear is considered a response to a threat that is present, anxiety involves the dread that accompanies thinking about a potential threat—one that may or may not ever materialize. A number of studies suggest that the amygdala is involved in experiencing anxiety, and that it may be overactive in people with anxiety disorders. Although the amygdala is well-known for its role in fear responses, there is now a great deal of evidence that suggests its contribution to behavior is much more complex.
For example, the amygdala seems to be involved with the formation of positive memories, like earning a reward in an experiment.
And damage to the amygdala can impair the ability to form these positive memories , just like it can affect the ability to form memories about negative events like the foot shock mentioned above. One popular perspective suggests that the amygdala is involved with evaluating things in the environment to determine their importance—whether their value is positive or negative—and generating emotional responses to those stimuli that are considered important.
It also may be involved in the consolidation of memories that have some strong emotional component, regardless of whether the associated emotions are pleasant or unpleasant. Thus, our understanding of the function of the amygdala is still evolving, and we likely have much more to learn before we can fully catalog the activities of this complex structure.
The amygdala: Beyond fear. We experience these things every day, but how do our brains create them? Your Brain, Explained is a personal tour around your gray matter. Damage to the hippocampus could lead to deficits in being able to learn anything new, as well as affecting memory.
Hypothalamus damage can affect the production of certain hormones, including those which can affect mood and emotion. A potential treatment for limbic impairments is deep brain stimulation. Successful treatment of some cognitive disorders such as anxiety and posttraumatic stress disorder has come from DBS of the amygdala. DBS has also shown to be useful in targeting the nucleus accumbens in relation to drug addiction. Similarly, the use of antidepressant medications has shown links with restoring the underlying physiological differences in the limbic system in major depressive disorder.
Two sets of blood vessels supply blood and oxygen to the brain: the vertebral arteries and the carotid arteries. The external carotid arteries extend up the sides of your neck, and are where you can feel your pulse when you touch the area with your fingertips.
The internal carotid arteries branch into the skull and circulate blood to the front part of the brain. The vertebral arteries follow the spinal column into the skull, where they join together at the brainstem and form the basilar artery , which supplies blood to the rear portions of the brain.
The circle of Willis , a loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood from the front of the brain to the back and helps the arterial systems communicate with one another. The hippocampus is located in the internal zone of the temporal lobe of the brain and according to the anatomy it is related to the hypothalamus and the amygdala, therefore they work together in the composition of the limbic system.
The hippocampal formation is a curved and recurve sheet of cortex, located on the medial surface of the temporal lobe. Cross sections show that the hippocampal formation is made up of three distinct areas: the dentate gyrus, the hippocampus, and the subiculum.
In these types of sections, the dentate gyrus and hippocampus are shaped like two interlocking Cs. The subiculum is a transition zone that continues with the hippocampus at one end and the parahippocampal cortex at the other. The three components are organized as anterior to posterior bands within the temporal lobe, which together form a cylinder.
The hippocampus is an important part of the brain since, thanks to research, we know that it has functions related to declarative, non-declarative and long-term memory and to maintain memories depending on what the person experiences emotionally at the moment it is created, what which indicates that it is related to the ability to learn.
Likewise, it is a brain structure capable of intervening in spatial visual processes, which is why it is considered a necessary area to remember, locate ourselves in space and memorize.
The basolateral complex is the largest of the amygdaloid clusters, located roughly within the lateral and middle parts of the amygdala, and includes the lateral and basal nuclei, while the cortical and medial nuclei comprise the cortico-medial amygdaloid group.
Interestingly, the basolateral amygdala has been implicated in both mediating the formation of memories related to emotional events and fear extinction through interaction with the prefrontal cortex.
By Olivia Guy-Evans , published May 09, The amygdala is a complex structure of cells nestled in the middle of the brain, adjacent to the hippocampus. The amygdala is primarily involved in the processing of emotions and memories associated with fear. The amygdala is considered to be a part of the limbic system within the brain and is key to how we process strong emotions like fear or pleasure.
This allows the amygdala to organize physiological responses based on the cognitive information available. The most well-known example of this is the fight-or-flight response. There are two amygdalae in each hemisphere of the brain and there are three known functionally distinct parts:. The midbrain is comprised of structures located deep within the brain, between the forebrain and the hindbrain.
The reticular formation is centered in the midbrain, but it actually extends up into the forebrain and down into the hindbrain. The substantia nigra and the ventral tegmental area are also located in the midbrain. Both regions contain cell bodies that produce the neurotransmitter dopamine, and both are critical for movement. Degeneration of the substantia nigra and VTA is involved in Parkinsons disease.
In addition, these structures are involved in mood, reward, and addiction. Figure 3. The substantia nigra and ventral tegmental area are located in the midbrain. The hindbrain is located at the back of the head and looks like an extension of the spinal cord.
It contains the medulla, pons, and cerebellum. For instance, we may make a decision which is based off our own personal emotions, or we may pay more attention to something if we believe it will make us feel positive emotions towards it. An area in which the amygdala is most prominent is within the formation of memories, especially those which are emotional. As the amygdala is remarkably close to, and forms connections with the hippocampus a memory structure of the brain , these two often work together to make memories more memorable.
The amygdala can attribute emotions onto memories. Essentially, the more emotive the memory, the more likely it is to be remembered. For instance, the birth of a child is typically a highly emotive positive memory, as so is likely to be retained.
Some emotional memories can be permanent, whereas those memories which are mundane, having little to no emotional attachment, are often forgotten. The amygdala acts as a store for good and bad memories, but especially for emotional traumas. This is when the amygdala can be detrimental as these traumas will be especially difficult to overcome, due to it being a highly emotional memory.
Individuals who have experienced emotional trauma may also find that their trauma can affect other cognitive functions as a result, due to the amygdala being connected to many other regions of the brain. Fear memories are thought to be embedded within the neuronal connections of the amygdala.
The amygdala is the most important part of the limbic system for many emotions, including aggression. The reactivity of the amygdala is a good predictor of aggression. Groves and Schlesinger , found that surgical removal of the amygdala reduces aggression in previously violent individuals. In animal studies, stimulation of the amygdala produces aggressive behavior.
Removal of the amygdala from monkeys, rats and humans reduces aggression. Many neuroimaging studies have investigated the structural and functional connectivity of the amygdala. Sexual orientation has suggested to be linked to structural differences in the amygdala. Homosexual males tend to show patterns in their amygdala alike to those of heterosexual females.
Likewise, homosexual females tend to show patterns alike to heterosexual men and have more widespread right amygdala connections Swaab, A variety of research has shown that the amygdala, especially on the left side, are associated with mental health conditions such as social anxiety , obsessive compulsive disorder OCD , generalized anxiety disorder, and posttraumatic stress disorder Arehart-Treichel, Also, those who have more neural pathways from their amygdala to their prefrontal cortex are more likely to experience nervousness and anxiety as these pathways allow the frontal cortex to be flooded with more alerts of threat from their amygdala.
Individuals who are diagnosed with depression have been shown to have over hyperactivity in their left amygdala, especially when interpreting emotions from faces, mainly fearful faces Sheline et al.
Similar findings were discovered in another study with those who had PTSD. When they were shown pictures of faces with fearful expressions, their amygdalae tended to display high activation Carlson,
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