Amygdala In Rhesus Monkeys

Due to its primary role in processing memory and emotional reactions, over the last decade and a half psychologists have been linking the amygdala to psychopathy. It is involved in aversive conditioning and instrumental learning and is thus involved in all the processes that, when impaired, produce the same functional impairments displayed by psychopaths. Two famous studies conducted by Tiihonen and Kiehl respectively have confirmed this. Tiihonen used a volumetric MRI to test and confirm the positive correlation between low amygdaloid volume and a high degree of psychopathy in violent criminals (measured by the Hare checklist-revised) while Kiehl used a functional MRI to prove reduced amygdala response during an emotional memory task in individuals who scored high on the Hare checklist-revised. However, both these studies along with numerous others were conducted using violent offenders as subjects rather than individuals with psychopathy. Although many psychopaths do exhibit violent tendencies, not all violent offenders are necessarily psychopaths. A study conducted by Raine is one of the few that did focus only on individuals exhibiting psychopathy. In his study Raine was able to show reduced prefrontal grey matter in his test subjects. Unfortunately though, he was unable to differentiate between grey matter in different regions of the prefrontal cortex. It is however clear that there is one region of the frontal cortex that could be

Signal processing within the amygdala is further regulated by interactions with a network of external structures. In particular, the dMT and its projections to the CeL have been demonstrated to play a role in fear memory retrieval. Notably, the dMT is assumed to be extensively modulated by opioids considering its innervation with opioidergic fibers and the high expression levels of MORs. Previous studies have reported the MOR system in the PVT, as part of the dMT, to be involved in managing physical pain. Moreover, social pain, which describes social rejection, being excluded or not being liked by others and which is associated with symptoms of anxiety and depression, appears to involve the MOR system in the PVT (Hsu et al). However, so far a direct implication of

The experiment shows reductionism. The intricate idea of ‘aggression’ and ‘generosity’ are studied and a cause and effect relationship is established between them and testosterone. The amygdala and hypothalamus play an important role in emotions (aggression). However, there was no mention of their role in the body nor how it may affect the results in different ways.

Magnetic Resonance Imaging (or an MRI) has been used to look into the minds of these psychopaths, which allows scientist to evaluate the brains of serial killers and take note of the things that are not quite normal. Sean Martin discusses in his article that neuroimages “found diminished activity in areas of the brain are linked to self-awareness.” Self-awareness is the processing of emotions and sensitivity to violence. (Sean Martin). The article tells us that the findings on these scans propose that several people who are being punished for their crimes at the moment cannot control their behaviors. This shows these people are experiencing different disorders that need treatment. Also in the article, Graeme Fairchild states that he found adolescents with violent tendencies had a shrunken amygdala, which is the part of the brain that controls emotions and morality. These brain scans simply show that people with disorders are not actually killing others to be harmful and horrific human beings, but because they can not actually control themselves or the way they feel when performing these actions. According to bestcouncelingdegrees.net, Jim Fallon, a neurologist, also studied brain scans and compared them to his sons brain, as well as his own. These scans showed

In “The Anatomy of a Violent Brain”, Wall Street Journal correspondent Jason Bellini covers some of the recent discoveries in neuropsychological research, particularly the role of the prefrontal cortex and how its activity relates to acts of violence.

It is believed that a mutation in the prefrontal cortex predisposes some people to violence. The frontal lobe is what we use to make decisions and, when fully developed, allows us to think carefully about our actions before we take them. An alteration in the prefrontal cortex may make us susceptible to impulsive and rash behaviors. For example, teens tend to be more reckless than adults. The teen frontal lobe is not fully formed, which is the reason for this outcome. Teens also tend to rely on their amygdalas to make decision. The amygdala is the center for powerful emotions, such as anger, jealousy, and guilt. For example, psychopaths have been found to be void of guilt and regret as a result of “the amygdala [being] less activated when they

The term ‘amygdala’ was first used by Burdach (1819) and referred to a set of nuclei in the brain (Aggleton & Saunders, 2000). In 1939, researchers Klüver & Bucy inflicted bilateral lesions of the inferior temporal lobe of monkeys in a laboratory in an attempt to reduce aggression. These lesions affected the cortical areas, amygdala, and the hippocampus. Later this became known as Klüver-Bucy syndrome, and consisted of symptoms such as psychic blindness, hypermetamorphsis, oral tendencies, and changes in emotional and sexual behaviors. Lesions of the amygdala made monkeys fearless of e.g. humans or snakes, and affectively flat, tame. This research brought recognition to the notion that the amygdala plays a significant role in the

From neurobiological point of view, Impulsive aggression is seen as a consequence of a failure in the regulation of negative emotions, such as anger, for example. This thinking of Disinhibition and hostility was found and documented by Grafman et al. (1996) in TBI patients with frontal lobe damage involving subcortical limbic structures. According to Davidson et al (2000), threatening environmental stimuli are transmitted to the amygdala, which makes projections to the basal ganglia, where they are integrated with information of the social context that comes from the orbitofrontal cortex. Appropriate behavioral responses can, therefore, be initiated through projections toward other cortical regions, hypothalamus or brain stem. Consequently, the orbitofrontal cortex and adjacent areas such as the dorsolateral prefrontal

Throughout this day in age, all over several media outlets, different acts of crime are shown on display for anyone, of all ages, to review. One thing that lacks from the plentiful amounts of these reports on various atrocities, ranging from theft to cold-blood murder, is a motive. However, what if a motive does not play a role in a crime? Yes, there a bounteous reasons as to why some commit crimes, but something may possibly lay deeper within the mind that one cannot see without a series of invasive research of psychological and neurological testing. Within his findings, documented in The Anatomy of Violence, Adrian Raine takes a look into the anatomical and biological roots as to why people execute felonies; wanting readers to gain and

Studying parts of the brain that are involved in dealing with fear and stress also helps researchers understand possible causes of PTSD to begin formulating a plan to treat PTSD. The amygdala is known for its role in emotion, learning, and memory. The amygdala appears active in learning to fear an event as well as in the early stages of fear extinction. In storing extinction memories and dampening an existing fear the prefrontal cortex, which is involved in problem solving, decision making, and judgement, is seemingly

They stated that murderers that plead not guilty by the reason of insanity (NGRI) have brain dysfunction. So they obtained a group of individuals who had been charged with murder but pleaded NGRI, in which some of these individuals had mental illnesses including schizophrenia, some had personality disorders such as Multiple Personality Disorder and some had brain injuries. To compare, there was also a control group involved who had schizophrenia but had not committed a crime. This study examined brain activity in the individuals who had committed the offence when completing a task. The results that were found showed that there is a link between criminal behaviour and the activity and structure of the brain. Although this could only mean that the brain activity could be a contributing factor towards such behaviours, so it doesn’t mean that it’s the main cause for the violent

Best, Williams and Coccaro (2002) defined premeditated aggression as the sort of aggression one uses to try and control their external environment, like mugging someone. Impulsive aggression results from the inability to control your impulses and emotions, leading to things like temper tantrums or road rage. It is ths impulsive aggression that appears to present itself more readily in those with prefrontal injuries. This study sought to examine exactly where that dysfunction might be. In order to this they recruited twenty-four patients diagnosed with Intermittent Explosive Disorder (IED). IED tends to exhibit itself in the form of chronic impulsive aggression. 22 control subjects were also recruited. Interestingly, exclusion criteria included any past neurological illness or traumatic brain injury. Multiple neuropsychological tests of frontal lobe functioning were administered to the participants. On working memory tasks, there was no impairment suggesting that the dorsolateral prefrontal cortex was in working order. However, in all tests related to the Orbitomedial Prefrontal Cortex Circuit there was statistically significant impairment in the IED group when compared to controls. This included poor problem solving, as evidenced by the Iowa Gambling Task, and impaired recognition of facial emotion, particularly negative emotions such as disgust or anger. Interestingly, they found that the most common

The importance of the amygdala in social cognitions has been examined in both primate and human studies. Use of primates to study the social brain suggests that the amygdala contributes to social cognition. Kluver and Bucy made large bilateral lesions in monkey brains made across the amygdala, temporal neocortex, and surrounding structure. After the lesion, the animals engaged in hypersexual behaviors, unusual tameness, and a lack of knowledge about emotional stimuli. Lesions exclusively targeting the monkey’s amygdala resulted in similar, but more subtle impairments. This suggest that the amygdala may play a role in emotions elicited by social cues. Studies of the amygdala’s role in human social cognition suggest that the temporal lobes process socially relevant facial information from humans. Emotions from facial expressions, in particular fear are projected to the amygdala. Studies using FMRI to examine typical subjects and subjects with amygdala damage support this theory. Individuals with amygdala damage have difficulty recognizing facial expressions, specifically negative emotions such as fear.

Through encephalon imagining studies, belligerent deportment has been shown to be a concomitant factor of structural and functional deficits in the prefrontal cortex. Evidence suggests both structural and functional abnormalities in violent or anti-social individuals and theories have been bestowed that has linked violent and anti-social behaviour to deficits as quoted by (Yang Y, Raine A. 2009) ‘’in the prefrontal cortex, temporal cortex, insula, amygdala, hippocampus/parahippocampus, and anterior/posterior cingulate gyrus’’ (Blair, 2001; Kiehl, 2006; Raine and Yang, 2006).

This area is called the hypothalamus. Its function is to coordinate responses like anger. (3 Diamond) The relationship between anger, rage, and violence, and psychopathology that is abnormal or unnatural in human behavior and experience. People demonstrate their anger reactions in different ways. Similar to most human behavior, violence has a meaning that it only seems "senseless" or "meaningless" to the extent that we are unable to understand it. Most violence starts the fiery human emotions of anger and rage. Not all-violent behavior has its origins in anger and rage; some of it is learned, as mentioned before. Some violence is driven primarily something that Friedrich Nietzsche referred to as "the will to power". In other words, rage. (3. Diamond) Rage is an instinctual and defensive reaction to severe stress, or physical threat. This is an automatic reflex that people share with animals. Walter Cannon as the "fight or flight" response refers to this response to serious threat. It's the first defense for the survival of the species. Any other threat to the continued physical existence, a person would have the instinct to try to leave, or if they can't, then physically defend them by attacking the source of the threat. (7 . Hawkins, Fredman ) Relating to the fact that men are more aggressive than women are, studies shown in several cases those testosterone levels in young men especially are. The high levels of endogenous testosterone seem to encourage behavior