Human Behavior and Biology: Fear and the Amygdala
Human Behavior and Biology: Fear and the Amygdala
The definition of psychology is considered to very limited, as specialists from other fields try to prove. The usual notion about psychology is that it exists as a channel of understanding and making some measurements in behavior of humans and other species (Eysenck, 2004). The study of human behavior has been very interesting to many fields of expertise due to its complexity and difficulty. Fields other than psychology: biology, psychiatry, sociology, and many other medical applications are just few of the fields in which discussions regarding the aforementioned topic have been very well explored.
In this regard, the experts combined in their efforts to form more credible results in the explanation of the basis of human behavior. Ethically, socially, and legally, behavior is an important tool to understand and explain such those subject matters (Carson & Rothstein, 1999). Goldsmith (1991), on his book The Biological Roots of Human Nature: Forging Links Between Evolution and Behavior, mentions about the huge involvement of biology into studying the fields of the humanists, social scientists, philosophers, and historians; that they should also include biological principles in the analysis of human behavior.
He emphasizes that there should be two considerations in studying humans’ social behavior, that is, there should be integration of physiology, biochemistry, and the mechanism of behavior in the social aspect. He stressed about the evolution of human behavior to be dissected in biological terms. Anderson (2006) still improves this claim by saying that a criminal behavior for example, maybe is because of the impaired hormonal secretions of the specific body organs.
Motives and the bodily processes should be taken into consideration to understand the individual differences with respect to personality and intellectual differentiation (Eysenck, 2004). A more interesting theory was formulated by Cesare Lombroso, about the facial types, and the way that a criminal can be identified. He based most of his explanations in a biological sense in the same way that the Germans suspected genetics to be effective in identification of people with criminal tendencies at the top of the Nazi’s rulership. It was then that several psychological explanations about criminal behavior have been accepted (Anderson, 2006).
Plato also mentioned that criminality is the effect of the mind being imprisoned by an obscurity of thought which he connected brain being the biological component. It was studied by theorists and researchers in evolutionary biology the patterns regarding the kind of thinking depending on the life stage, whether young or adolescent: including parameters such as their problem-solving capacities and their academic competencies. Other cognitive domains were also associated to this behavioral study: the spatial abilities, mathematical abilities, verbal communication etc. (Lisi & Lisi, 2001).
To be included in this paper are the dissection of the two parts suspected to be working in one direction of behavioral and of biological nature: the explanation of fear and its relation with the amygdala. A Brief background on Fear Fear is the emotion related to the feeling being in a dangerous state, which are actually tangible and realistic. Another definition is given to anxiety, which is often named as fear, because anxiety is the feeling of being in danger but there is no actuality. Watson and Ekman mentioned that fear is no other special feeling. It is just at the same level as joy and anger.
Fear is described as a mechanism of survival, which arrives from exposure to negative things, or the negative stimulus. Fear is usually connected to the disagreement to feel pain (Coan & Allen, 2007). Personal fear can be classified as caution, phobia and paranoia. Fear is manifested when someone feels anxious, worried, frightened, in terror, paranoid and many other negative feelings. Paranoia is achieved when fear is so much heightened. When someone is observed to be in extreme change in behavior, and his attitude has gone extremely changed, one is said to be paranoid.
Caution on the other hand is an interpersonal experience that makes a person feel that he could not trust anyone who is a strange to him. The person feels very different in the presence of the person whom he distrusts and only calms down when that person has gone distance away from his comfortable zone. Terror is a very pronounced classification of fear, which arises from a horrific experience. The person in a state of terror feels always in the vicinity of an immediate danger. The non-typical behavior of the person arises, making him irrational at some point. The subconscious feeling of fear can be extended nightmares.
There are other effects on the person whenever he fears something. Physiologically, the sympathetic and the parasympathetic. The person may be observed to, or feel in himself being hindered from physical movement. Perspiration may also occur as the blood in the body is being forced from the viscera to other peripheral parts of the body. This blood at the periphery carries oxygen, nutrients and heat, which causes the body to feel warm or hot, therefore the body’s mechanism is to perspire, to release the excess heat to cool down the body. Along with this, the body will experience fast heart rate. Phobia
A very interesting topic which deals with the concept of fear is called phobia. Phobia is fear of something. It may be because of a very unwanted experience towards that something that someone fears, or just a transferred rumor that something negative might happen when that object is encountered. Different types of phobia exist depending on the object of fear. In the context of classical conditioning, phobias come from a mixture of internal dispositions and external factors (Lewis & Haviland-Jones, 2000). The experiments of Seligman resulted to his conclusion of objects being feared are genetically predispositioned.
He also mentions that for many cases, traumatic experience triggers phobia. Biology, together with life experiences, can be well explained A malfunctioning amygdale can cause psychological disorders. Patients are not able to classify neutral faces, identifying them as threat. Hyperactivity in the amygdala was observed by researchers when patients are shown frightening situations. Other patients with severe cases of phobia showed a corresponding increase in the amygdale activity. The left amygdala manifested hyperactivity when excitation like fear happened. The book Expression of Emotions in Man and Animals emerged in the 19th century.
Charles Darwin emphasized here that the evolution of species has a counterpart cross culturally and universally. A research conducted by Paul Ekman involved facial expression experiment. Using neuroimaging differences in their evolutionary ancient brain parts were observed for changes, with corresponding changes in potential which was an increase (Doux, 2004). Theories about Emotion and Behavior The Somatic Behaviors William James started the study of emotions and largely argued about that emotional experience is mainly an effect of changes in the body (James, 2007). James, together with Carl Lange created James-Lange theory.
This theory has a biological perspective of viewing the change in emotion as being accompanied next by bodily changes. They emphasize that the change in the state of the body is manifested through the change in emotion. The bodily reactions are considered to be the cause for the change in emotion as felt by a person (Barrett, Niedenthal, & Winkielman, 2005). This theory simply says that we tend to react first in a situation, for example is running because of an event that could make us run, then the emotional manifestation is then felt or executed. In short, we react first before we get to feel the emotion.
Another somatic theory where James-Lane also falls is the Perceptual theory which is known to be a neo-Jamesian theory. The Cognitive Behaviors with Biological Perspective On the other hand, the Cannon-Bard theory nullifies the claims of James-Lange theory and still believes on the previous pattern. This is a cognitive theory that contradicts a somatic theory of emotions. The Two Factor theory, also known as the Singer –Schachter theory rests on the hypothesis that respondents can have different emotional reactions as affected by adrenaline, considering that they have the same initial physiological state.
The respondents were monitored for the emotion they are going to feel, whether happiness or anger, when a person on the same situation felt anger or happiness. The determination of the responses was based on the cognitive aspect or when the situation undergoes appraisal, or the physiological or biological aspect as adrenaline was injected to them. In connection to this, Klaus Scherer made a recent cognitive theory that stresses the connection on different bodily functions in combination to the cognitive components. The Amygdala
Emotionality was discovered because of the bilateral ablation of the temporal lobe responses in the brain (Weiner, 2003). The part of the brain that is responsible for the feeling of fear is the amygdala. It is a tonsil shaped group of neurons situated at the inside portion of the temporal lobe of humans, including other species under the phylum vertebrata. The emotional reaction is being executed by this part of the brain which is also responsible for emotional stimulation (Kadish, 1994; Lewis & Haviland-Jones, 2000; Phelps, O’Connor, Gatenby, Gore, & Davis, 2001).
In the process of fear conditioning, a part of the amygdala, the basolateral complexes help in the mediation of stimuli to the memory. These are brought to the synapses and later on passed to the central nucleus of the nerve, which is involved in the generation of many fear responses that includes immobilization of the body, increased respiration, and release of stress hormones. The type of conditioning called the Pavlovian conditioning may be caused by the damage in this part of the brain.
The functions of the amygdala were looked at to account for the emotional and motivational properties it dictates in the brain. The amygdala is a small structure at the cortex which lies deep within the brain’s temporal lobe. Even small, it possesses a complicated neuroanatomy. It receives a large amount of neural inputs to the many parts of the brain, both the minor and major parts of the cortex. The heterogeneity of the structure of amygdala is due to the evolutionary reason that it comes from different parts of the brain which separated from a common point.
The heterogeneous description is due to the differences in the structures of the neurons as already explained in the previous statement. There were so many description proposed to amygdale regarding its function, and it was by (Johnson, 1923) that the introduction of the description of the amygdale commonly used today. The nuclei of the amygdala should be described as divided into two groups, the primitive group and the recent group (Moore & Oaksford, 2002). A third part was suggested to be occupying the ventricular floor of the cortex (Alheid & Heimer, 1988).
The amygdala is said to be well placed in that position because it is able to gather signals from almost every part of the brain, integrates them all, and is responsible for the processing to arrive at what kind of emotion shall be executed by humans and other species. Research in emotions has been exploiting the amygdala in experimentations. The different types of emotions, fear as example, have different mechanisms in the brain but actually goes to the same pathway which is trying to escape, or of which implies behavioral inhibition (Lewis & Haviland-Jones, 2000).
The impulses sent by the amygdala can have two general effects: first is the modulation of the memory’s retention time for long term responses; second is the influence on attention and perception. The retention of the episodic events is crucial in the emotional response so that the event is not forgotten. In this way we are more likely to be aware of the emotional events compared to the neutral events. Experiments dealing with the delay of fear responses were done to account for the effect of amygdala. Respondents were instructed to use an active emotion regulation strategy to lower conditioned fear responses.
It was found out that doing this lowers the physiological expression of the CR and CS activation of the amygdala. It was deduced from the experiment that cognitive strategies and control mechanisms during fear conditioning and by just viewing negative scenes can disrupt or alter the responses of the amygdala. The studies presented regarding the instructed fear implies that conditioned fear is not necessarily affected by the awareness in cognition and understanding of the emotional properties. It was also found out that there are many things that can affect the amygdala aside from these two.
Dependent responses such as the aversive properties, symbolic communication can also affect the function of the amygdala. Cognitive control mechanisms can be tapped also in the execution of different emotion regulation strategies which can diminish the amygdala responses to strong emotions such as fear. Another study conducted by Phillips and Le Doux (1992) was concerned not just with the contribution of amygdala on the procurement of the conditioned fear responses using a cue, but with the participation of another part of the brain which is the hippocampus.
It was found out that for rats, under the unoperated conditions, faster responses were more susceptible to extinction than those with the responses from conditional stimuli. Lesion experiment on rats’ amygdala reflected an interference on the conditioning of the fear responses to both the cues and the context. On the other hand, hippocampus lesions only affected with the conditioning of the responses, but was found out to be irresponsible for the cues (Phillips & Doux, 1992).
An almost similar experiment was carried out by McKittrick and his colleagues (1996) and Blachard together with this co-researchers (1998) using remodeling of the dendrites and it was found out that this kind of treatment which involves different stress applications to the hippocampus, specifically repeated restraint stress affects the hippocampus the same way with the previous experiment. It was mentioned that amygdala behaved the same (Gazzaniga & Bizzi, 2004). Moore (2002) mentioned a study in his Emotional Cognition: From Brain to Behaviour, which puts a borderline between the functionality of the hippocampus and amygdala.
Le Doux’s theory is often discussed in debates due to its relevance in explaining whether cognitive processes always precede an emotional experience. He said in Moore’s writing that the activation of amygdala by impulses from the neocortex is somewhat consistent with the notion that emotional processing is post cognitive. The hypothesis that emotional processing can be preconscious and precognitive is consistent with the experiment dealing with the thalamic inputs as the amygdale is activated. The two hemispheres of the brain are somewhat different in function with respect to its emotional role.
The emotional stimuli perceived by the brain, together with its processing of emotional expressions are usually processed by the right hemisphere. They were able to prove this as they sent signals only to the right hemisphere of the brain, and it was found out that it produced faster heart rates compared to that of the impulses produced by just showing signals to the left hemisphere (Alheid & Heimer, 1988; Cheng, Knight, Smith, Stein, & Helmstetter, 2003; Davidson, 1998). This was also confirmed this hypothesis to those patients suffering from split-brain disorder.
The corpus callosum, being the bridge between the two hemispheres, is severed during the operation for those who suffer from epileptic disorders. As a result of this experiment, they were able to know that the two hemispheres function independently of each other. Accurate identification or merely detection of the emotional stimuli happens only when the signal flows to the right side of the cortex. It is pointed out that whatever the hemisphere to function depends on the type of emotion that is felt during that time.
The left frontal cortex is more likely to function for pleasant emotions. The right lobe on the other hand functions in the presence of unpleasant emotions. There are people whose only one side of the brain dominates, as proven by Tomarke et al. (1992). People who are dominant in left brain functions are more likely to show positive responses to stimuli, comparing to the other part which remains opposite or negative in reaction. It was further explained by the movement of the muscles of the face which kind of response occurred at the moment of stimulation.
It was explained that a left facial muscle contraction is due to a positive response, whereas the right facial muscle reaction is due to a negative response. Bilateral neurotoxic amygdala lesions in rhesus monkeys (Macaca mulatta): Consistent pattern of behavior across different social contexts – an Example Case Amygdala has always been associated with the behavior of humans, more generally on the primates. Their social behaviors have always been connected to the cases brought about by lesions caused to the amygdala, wherein their behaviors are subjected to studies.
The rhesus monkeys were the non-human primates that are of large importance to the study, since somehow these monkeys represent humans in a more dramatic way than other primates might have. The environments were different for each and every sample monkey, and their physiological characteristics were also different, one is a lesioned or lacerated monkeys and the other monkeys were just normal or unoperated monkeys. In 32 days they were subjected to a 4-monkey group interaction. They were first assessed in pairs (N. J. Emery et al.
, 2001), and were already popular or familiar with each other’s presence to avoid intimidation and possible aggression and depression. As observed, the operated or lesioned monkeys manifested a common or consistent behavior. Obstruction in the amygdala was suspected to be the reason. The operated monkeys were seen to be more sociable; they had better affiliation with other monkeys than with that of the non-operated monkeys. The operated monkeys showed a faster adaptation with their new partners, because of the immediate decrease in their nervous and fearful behavior relative to the controls.
Other possible behaviors such as sexual behavior were not observed among the samples, both the operated and the unoperated, making the authors conclude of that the amygdala may inhibit this the sexual drive of the monkeys, and that there are still other factors that must be considered in looking at other behavioral patterns. References Alheid, G. F. , & Heimer, L. (1988). New perspectives in basal forebrain organization of special relevance for neuropsychiatric disorders: The striatopallidal, amygdaloid, and corticopetal components of substantia innominata. Neuroscience, 27, 1-39.
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C. , & Oaksford, M. (2002). Emotional Cognition: From Brain to Behaviour. PA: John Benjamins Publishing Company. Phelps, E. A. , O’Connor, K. J. , Gatenby, J. C., Gore, J. C. , & Davis, C. G. (2001). Activation of the left amygdala to a cognitive representation of fear. Nature Neuroscience, 4, 437-441. Phillips, R. G. , & Doux, J. E. L. (1992). Differential contribution of amygdala and hippocampus to cued and contextual fear conditioning. Behavioral Neuroscience, 106(2), 274-285. Weiner, I. B. e. a. (2003). Handbook of Psychology. NJ: John Wiley and Sons.
University/College: University of Chicago
Type of paper: Thesis/Dissertation Chapter
Date: 23 November 2016
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