This paper is my second assignment for physiological psychology. The first section of this paper critiques an article entitled “Ecstasy and Agony: Activation of the Human Amygdala in Positive and Negative Emotion”. This sections main point is to show that there is enough evidence indicating that the amygdala plays a critical role in negative human emotions. And the instrument of choice was PET. The second section of this paper critique’s an article entitled “Overactive Action Monitoring in Obsessive-Compulsive Disorder: Evidence from Functional Magnetic Resonance Imaging”.
This section includes the discussion on how the anterior cingulate cortex has been found to be hyperactive in those with OCD. Testing for this study was using FMRI’S. The main interest for the article “Ecstasy and Agony: Activation of the Human Amygdala in Positive and Negative Emotion” was the roles that the amygdala plays on humans positive and negative emotions. The amygdala plays a more extensive role in negative emotion than in positive emotion. The research was done using PET scanning focusing on the amygdala.
The research was done on ten, right-handed male participants averaging the age of 22. They used only heterosexual males for this study because of the pictures they have used for the pleasant images they were to be shown. During the PET scans, the participants viewed pictures and were told to “pay attention and experience whatever thoughts or feelings the pictures may elicit you. ” There were two different groups of pictures they were shown to view the positive and negative effects.
The first group was of pleasant images such as sexually arousing images, appetizing food, and appealing animals ad infants. And the unpleasant photographic stimuli which consisted of mutilated and diseased bodies, frightening animals, and graphic violence. There were twelve PET scans done on each participant. During the scans, the participants must view pictures on the monitor and after had to rate each picture they saw by a 5-point scale on emotional arousal, emotional valence, and degree of interest. In order to assess physiological reactions, SCR and heartrate we measured.
Three different sets of data were collected, Behavioral Data, Physiological Data, and Imaging Data. For the behavioral data, the ratings were confirmed the intended emotional and cognitive states had been elicited. The positive and negative stimuli were rated as more emotionally arousing and more pleasant or unpleasant than the low-interest and high-interest neutral stimuli. They were paired as ts(9) > 4. 75, ps <. 001. The physiological data collected was heart rate decelerated more during viewing of the pleasant pictures as opposed to the more neutral pictures.
The SCR were elevated in the high-interest condition due to the fact that skin conductance is affected by the response to interesting stimuli. Imaging data collected was done by PET scanning in which every image from the participants were aligned and resliced. SPM99 was used to create statistical parametric maps calculated from contrasts between activation images. Two different analyses were used in order to categorize stimulus-related activations. The first analysis used a region-of-interest (ROI) in order to directly probe the bilateral amygdalar region for activation.
The second analysis examined the entire brain. It used standard statistical thresholding procedures to identify regions of elevated activity. The amygdala ROI was defined as a sphere. This testing found that positive emotion was associated with activation in the left-amygdala ROI. It was found that viewing appetite, positive stimuli elicited significant amygdala activation in the left hemisphere.
The left hemisphere lateralization of amygdala activation is consistent with the predominantly left ateralization of amygdala activation associated with negative emotion, it was found that the amygdala participates in more areas that are involved in positive emotional states and compared with the positive emotions, negative emotions were associated with fewer areas outside the amygdala. And unlike the positive emotions the negative emotions showed no activation of reward related areas in the frontal cortex and the ventral striatum. High-interest conditions focal activation was o in the left amygdala.
Since the spatial resolution of PET IS limited, it would not be possible to determine that different regions pf the amygdala mediate the different roles or if the same regions perform many functions. Both negative and positive emotional arousal have been associated with the amygdala, and lesions to the amygdala region have yet to be reported that there may be an effect of reducing positive or negative reactions to visual stimuli. Although the amygdala has been known to participate with the emotional reactions, it is viewed to not be so critical for those reactions.
The findings in this article have been consistent to the introduction of this article. In the very introduction it does state that the positive and negative emotions are from the amygdala and the findings have proven the work they have put forth and matched to was introduced in the introduction. Over all, the research of this paper has been valuable because of the fact that there has been previous research to this aspect and it has proven and added more information to what was already known.
Throughout the research they learned more about the amygdala and other funtions it may be associated with. The greatest strengths of this article is it followed previous research and extended the study for more results. Another strength would be that the research was done with several different categories of pictures that stimulate the same type of emotions, such as every stimuli would differ in the type of arousal but still cause a negative or a positive emotion.
The weakness was that they used PET as their choice not giving them enough spatial resolution and being able o determine if different regions of the amygdala mediate the different fuctional roles or if the same regions may perform many different functions. The second article “Overactive Action Monitoring in Obsessive-Compulsive Disorder: Evidence from Functional Magnetic Resonance Imaging” focuses on the anterior cingulate cortex (ACC) in patients with obsessivecompulsive disorder that seems to be hyperactive. During rest periods, symptom provocation, and after commission of errors in cognitive tasks is when it seems to by hyperactive.
It was also researched to test the hypothesis that the ACC was more involved in the pathophysiology of OCD than previously thought. To obtain the data for this research there were a total of thirty participants. Fifteen were healthy adults and the other fifteen were adults whom had OCD. Both groups were screened for lifetime psychotic symptoms. They were also screened for substance abuse and history of neurological disorders, including head trauma. These participants were scanned while performing AX-CPT. The participants were asked to perform as quickly and accurately as possible.
For this research, the participants were tested with FMRI image. There were more results found using FMRI as a tool compared to previous research where ERP was used. To test the first hypothesis the FMRI was used to compare the ACC activity in OCD patients by using a type of continuous-performance task. The tasks were those which produced increased levels of response conflict and increased error rates. Into the research they noticed their results were correlating with the results of previous research done with the ERP.
All the results of this research suggested that the ACC is involved in OCD than it was previously hypothesized. The results confirm that the ACC is very informative as a source of error-related activity in subjects. The information throughout the research is consistent with the information given in the introduction. All the previous studies and this new research do correlate and prove to show that FMRI is a good choice for the testing. The research on this article is valuable because it further nhances what was already known and helped prove past research as true.
Like all researches there are slight adjustments to be made. In the article I read more about the use of ERP scanning compared to FMRI. The test were done with FMRI, but ore data of past research was used as the data from past ERP exams. A great strength in the research was the fact that the results correlated with past results extremely well and further enhanced the past research by proving that it was correct. In these two articles they have used PET and FMRI.
There is a difference between the two options but every test suits a different research. Positron Emission Tomography (PET) scans detect changes of blood flow in the specific brain regions. PET scans are not the greatest on temporal resolution. The purpose of a PET scan is to correlate the changes in blood flow patterns during specific activities. The blood flow is able to be measured by injecting the patient with a radioactive substance and followed by monitoring the substance as the blood is absorbing it and it passes the blood brain barrier into the brain.
The radioactive substance that was injected is picked up by the PET scan and is photographed. PET is based the assumption that blood flow will increase in areas of the brain that are in heavy use. The radioactive isotopes that were injected will end up in the active part of the brain. These gamma rays that are from the radioactive substance are picked up by the PET scanner and the PET scan image then determines where they came from in the brain. Functional Magnetic Resonance Imaging (FMRI) monitors the change of blood flow in the brain just as PET does.
FMRI IS the best at spatial resolution compared to PET. EMRI scans require really strong magnets that are not available at most hospitals. Oxygen atoms are what controls the results of this scan. Oxygen atoms that are inside and around blood vessels in the brain change in accordance to blood flow in the vessel. The FMRI picks up the transitory surplus of oxygen in the blood vessels. Unlike the PET scan, nothing is injected into the blood stream. It is tested on the oxygen that is naturally in the system.