Brain Activation of High and Low Self-Esteem Individuals - Essay Example

BRAIN ACTIVATION OF HIGH AND LOW SELF-ESTEEM INDIVIDUALS DURING THE ENCODING OF VALENCE STIMULI This research proposal aims to investigate how self-esteem plays a role in memory recognition and whether or not low and high self-esteem individuals show different patterns in brain activation, especially in the hippocampus and amygdala. To address this hypothesis, participants selected for mass testing will undergo a functional magnetic resonance imaging (fMRI) scan while viewing pairs of words: a neutral word paired with either positive, negative, or neutral word. After a filler task, they will perform a subsequent recognition test outside of the fMRI scan. If the predicted result is correct, individuals with low self-esteem will remember more words paired with negative words than the ones paired with positive or neutral words. High self-esteem individuals, however, will remember more words paired with positive words than the ones paired with negative or neutral words. The results from the fMRI study should show significant activation in the right amygdala for low self-esteem individuals and the converse for high self-esteem individuals. The left hippocampus should be activated regardless of the type of stimuli. The findings from this proposal would be evidence for the relationship between valence memory, brain activation, and personality, and provide a better understanding of depressed and suicidal individuals. Brain Activation of High and Low Self-Esteem Individuals During the Encoding of Valence Stimuli Have you ever wonder why some people seem to remember only negative things that happen in their lives, while others seem to recall only the wonderful events they encounter? This may be due to differences in self-esteem. Research has increasingly shown a connection between self-esteem and memory recall depending on valence. Story (1998) suggested that memory accuracy varies on an individual’s level of self-esteem and favorability of feedback. High self-esteem individuals remembered feedback more accurately when feedback reflects favorably on their personality, whereas low self-esteem individuals remembered feedback more accurately when it puts them in an unfavorable light (Story, 1998). This research indicated that individuals with low self-esteem tend to associate themselves with negative stimuli as opposed to individuals with high self-esteem who associate themselves with positive stimuli. Moreover, people with depression, correlated with low self-esteem, showed preferential recall of negative words. This factor is associated with increased activation in the left hippocampus and parahippocampal gyrus during memory encoding (Thomaes et al., 2009). As technology becomes more advanced, researchers are able to investigate how the encoding of valence stimuli corresponds to brain activation. Mneimne et al. (2010) suggested that there might be hemispheric lateralization in memory for valence words such that RH systems mediate responses to negative emotional stimuli and LH systems mediate responses to positive emotional stimuli. Their finding contradicts Thomaes et al. who argued that there is an increase in left hippocampal activation during encoding of negative stimuli. Therefore, there might be other areas of the brain that facilitate valence memory. Fortunately, other researches have shown that the amygdala is associated with memory. Cahill et al. (1997), for example, reported that the generally improved recall of affectively valenced over neutral information is greatly reduced in patients with amygdala lesions. Furthermore, with functional magnetic resonance imaging (fMRI), Canli et al. (2000) found amygdala responsivity predicted subsequent memory performance for affective stimuli across both individuals and across trials. Thus, several investigators have posited that the amygdala facilitates memory for emotional stimuli through modulation of the hippocampus, a structure crucial for episodic memory encoding (Steinvorth, 2005). Overall, self-esteem is associated with how much each type of valence is encoded in memory, as this affects memory recognition. This should also lead to different patterns of activation in the brain. Thus, this research proposal aims to address how self-esteem plays a role in subsequent memory recognition and investigates whether or not low and high self-esteem individuals show different patterns in brain activation at the encoding stage, especially in the hippocampus and amygdala. Method Participants 40 female undergraduate students from the University of Toronto will be selected on a basis of their pretest score on the Rosenberg Self-Esteem Scale (Rosenberg, 1965) as participants for the proposed study. All participants will receive monetary compensation or course credit for their participation. Males were excluded from this study based on research that suggests that asymmetries for emotional processing differ between men and women (Proverbio et al., 2006). All participants gave informed consent for the experiment and denied having had a traumatic brain injury. Materials The materials were adapted from those described in Mneimne (2010). Stimuli included 34 pairs of words, 10 negative, 14 neutral, and 10 positive. Each pair consisted of a neutral word with either a negative, a positive, or a neutral word. All words of different valence are equated in terms of concreteness, imagery, frequency, and word length. Consistent with the practice of researchers studying affective modulation of startle, and with conceptualizations of most emotional stimuli and experiences as having a level of arousal that is ordinarily higher than the level of arousal associated with non-emotional stimuli or experiences (e.g., Barrett et al., 2007), positive and negative words were chosen. These words were equated on an arousal level and were higher than the arousal level of the neutral words. Words ranged from three to six letters in length. Four of the neutral word pairs served as fillers to control for primacy and recency effects (two presented at the beginning of the list and two at the end), and the remaining thirty pairs were used in the analyses. An additional 30 neutral words were selected from the ANEW (Bradley & Lang, 1999) database and served as foils on the recognition test. These words were equated with the target words with regard to word length and valence, arousal, and frequency ratings. Procedure During the PSY100H class session, participants completed a pretest questionnaire that included the Rosenberg Self-Esteem Scale (Rosenberg, 1965) and Beck Depression Inventory (BDI; Beck, 1967). Participants will later be contacted individually to participate in this experiment and will be asked to undergo an fMRI scan in order to investigate the relationship between personality and brain activation. Upon entering the laboratory, the selected participants will be seated at a desk where they will be asked to read and sign a consent form. Participants will then be asked to place their chins upon a chin rest and be told that they will view words on the screen. Participants will be asked to pay attention to the screen at all times and to memorize the words on the screen, as they will be asked about them later. Participants viewed 34 pairs of words for two seconds each while undergoing a functional magnetic resonance imaging (fMRI) scan. Following this, participants will engage in a verbal attention task outside of fMRI scanner to prevent any lingering effect from viewing word pairs. Participants will then perform a recognition memory task where they will be presented with 30 words that they had viewed in the scanner intermixed with 30 new words. Participants will be asked to indicate if they recognized the word as “old” or if it was “new.” If the participant recognized the word as “old,” they will be asked to identify whether the word was paired with a negative, positive, or neutral word. Predicted Results Result of fMRI I predict that the right amygdala will be more activated in low self-esteem individuals while the left amygdala will be more activated in high self-esteem individuals. This is because the right amygdala is responsible for the encoding of negative stimuli (Hamilton & Gotlib, 2008). The activation in both negative and positive words will be stronger than in neutral words. Hippocampus activation, however, will show no difference in individuals with high and low self-esteem. Hippocampus will only be activated on the left side during encoding of all stimuli according to the hemisphere lateralization model, which states that the left hemisphere is more oriented towards verbal information, whereas the right hemisphere is oriented toward spatial information (Iidaka et al., 2003). Result of Recognition test People with low self-esteem will recognize more words associated with negative words than the ones paired with positive or neutral words (See Figure 1). In contrast, people with high self-esteem will recognize more words associated with positive words than the ones paired with negative or neutral words (See figure 2). Figure 1: Expected scores of recognition test as a function of memory for words associated with negative words Figure 2: Expected scores of recognition test as a function of memory for words associated with positive words Discussion This proposed research offers a potential insight into the area of personality and memory. Self-esteem is often a measure in personality studies. It provides a basis for making predictions about individuals’ traits and their behaviors. This study can be generalized to socially prescribed perfectionism described as the need to meet the perceived expectations and standards of others, and is measured by statements such as “People will probably think less of me if I make a mistake” in the Multidimensional Perfectionism Scale (Rasmussen et al., 2008). These kind of perfectionists tend to think lowly of themselves and if my predicted result is true, their amygdala will show significant activation during the encoding of negative word pairs. In support of this finding of amygdala facilitation of hippocampal-dependent learning, outside research contains neuroimaging studies of humans reporting a significant correlation between activation of the amygdala and hippocampus during the successful encoding of affective stimuli (Hamilton & Gotib, 2008). In addition, the amygdala seems to associate with areas of the brain other than the hippocampus during information processing. An evidence of an fMRI study in emotional memory network showed arousal also increased the strength of amygdala connections to the inferior frontal gyrus and the middle occipital gyrus for negative information; positive information arousal decreased the strength of these amygdala efferents. Furthermore, while the effect of arousal on memory for positive information was restricted to amygdala efferents, arousal had a more widespread effect for negative items, enhancing connectivity between other nodes of the emotional memory network (Mickley Steinmetz et al., 2010). The emotional memory network may be able to explain why the suicide rate is very high in depressed and low self-esteem individuals. Since negative valence is more accessible than positive valence, these individuals constantly activate negative thoughts. It is probably difficult to break away from these thoughts (Mickley Steinmetz et al., 2010). For example, Lee et al. (2011) found that those with higher levels of perfectionism experienced more distress as a result of intrusive mental imagery, found it harder to dismiss the imagery, and experienced a more negative impact as compared with those with lower levels of perfectionism. It is important for researchers to understand the relationship between valence in memory and personality in order to intervene and help prone-to-suicide individuals. The study on expressive facial recognition indicated a specific engagement of the left hippocampal regions in conscious recollection and identification of facial features. The activity in the right hippocampus increased under both the identity and emotion conditions. The present results may relate with the functional model of face recognition in which the left hemisphere contributes to the processing of detailed features and the right hemisphere is efficient in the processing of global features (Iidaka et al., 2003). Following this discovery, potential future research can investigate whether the left hippocampus activates more frequently than the right hippocampus in perfectionists during memory tasks. A person identified as a perfectionist is quite detailed-oriented and may process information locally rather than globally. Ultimately, the human brain is a complicated and dynamic machine. There is still a lot to understand about different functions within the brain. Nevertheless, researchers have managed to study memory and brain activation extensively. In the next decade society will witness many fascinating discoveries of brain functions that will offer explanations for of variety of things that happen in our lives. References Adolphs, R., Cahill, L., Schul, R., & Babinsky, R. (1997). Impaired declarative memory for emotional material following bilateral amygdala damage in humans. Learning & Memory, 4, 291–300. Barrett, L. F., Mesquita, B., Ochsner, K. N., & Gross, J. J. (2007). The experience of emotion. Annual Review of Psychology, 58, 373–403. Beck, A.T. (1976). Cognitive therapy and the emotional disorders. New York: International Universities Press. Bradley, M. M., & Lang, P. J. (1999). Affective norms for English words (ANEW). Gainesville, FL: The NIMH Center for the Study of Emotion and Attention, University of Florida. Canli, T., Zhao, Z., Brewer, J., Gabrieli, J.D.E., & Cahill, L. (2000). Event-related activation in the human amygdala associates with later memory for individual emotional experience. Journal of Neuroscience, 20, RC99 Hamilton, J.P., & Gotlib, I.H. (2008). Neural Substrates of Increased Memory Sensitivity for Negative Stimuli in Major Depression. BIOL PSYCHIATRY, 63, 1155–1162. Iidaka, T., Terashima, S., Yamashita, K., Okada, T., Sadato, N., &Yonekura, Y. (2003). Dissociable Neural Responses in the Hippocampus to the Retrieval of Facial Identity and Emotion: An Event- Related fMRI Study. HIPPOCAMPUS, 13, 429– 436. Lee, M., Roberts-Collins, C., Coughtrey, A., Phillips, L., & Shafran, R. (2011). Behavioural Expressions, Imagery and Perfectionism. 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