Canli Notecards

MRI (Structural; Magnetic Resonance Imaging)
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Terms in this set (26)
MRI (Structural; Magnetic Resonance Imaging)
takes a picture of the structure and parts of the brain -- does not show brain activity
fMRI (Functional Magnetic Resonance Imaging)
measures brain activity by detecting change in blood flow during a task (active state) compared to a baseline (resting state) -- the more active part(s) of the brain correspond to different color displays
Background research discussed in the study
-Studies have shown a positive correlation between the amygdala and emotional experience; the higher the amygdala activation, the higher declarative [hippocampus] memory recall (such as traumatic experiences)
-LaBar and Phelps (1998) suggest that emotional experiences are often better recalled than non-emotional experiences
-Canli (1999) supports the amygdala and emotional memories as well
Purposes of the study
1. to investigate if the amygdala is sensitive varying degrees of emotional intensity
2. to investigate whether the degree of emotional intensity affects the role of the amygdala in aiding memory recall of stimuli categorized as "emotional"
Design of study
repeated measures (Ps exposed to more than one variable)
Strengths of the design of the study
-controls participant variables because every participant is exposed to ALL levels of IV
-requires less Ps because each P serves as their own control group
Weaknesses of the design of the study
-some variables cannot be repeated
-may require replicated equipment or word lists which can lead to increased errors
Hypotheses of the study
1. The amygdala will show sensitivity to varying emotional intensity of stimuli
2. More emotionally-intensive images that produce greater amygdala activation will be recalled at a higher rate compared to stimuli that produce less amygdala activation
IVs of the study
intensity rating of each picture (96 total) on 4pt scale - self-report by Ps through button in the machine
DVs of the study
phase 1: fMRI measurement of amygdala activation for each of the 96 images; accomplished through pixel count for all 11 frames of neural activity captured per image
phase 2: self-report percentages for image memory (forgotten, familiar, or remembered)
Sample of the study (characteristics)10 right-handed, healthy females from self-selecting (volunteer) sample Females chosen because: 1. they are more likely to report intense emotional experiences 2. they are more likely to react physiologically to stimuli of varying emotional degreeApparatuses (materials used) of the studya) fMRI scanner (1.5T General Electric Signa MR imager) b) 96 images from the IAPS (International Affective Picture System); each picture has been normed for emotion based on valence and arousalArousal as used in the studyhow arousing/emotionally affective is the image? (high, mid, low)Valence as used in the studyis it a negative, neutral, or positive image? *positives were not used in this studyPhase 1 data collection summary-Each P would lay down in an fMRI machine under technician supervision; in addition to machine, overhead projector, mirror, and 4 reponse buttons used for data collection; custom-molded bite bar to limit movement of Ps inside machine -Images presented in random order for 2.88 seconds each; fMRI captured 11 frames of amygdala activation for baseline (frames 1, 2, 10, 11) and activation (frames 5-8) -After the image disappeared, a black screen with a single "X" (fixation cross) appeared for 12.96 seconds; Ps rated arousal with button in right handPhase 2 data collection summary-3 weeks later, Ps were tested in an "unexpected recognition test" -The original 96 IAPS pictures plus 48 new foils (144 total - matched for valence and arousal) were presented to Ps -Ps asked whether they had seen each picture before; 1=forgotten, 2=familiar, 3=rememberedCorrelation Mapsmade to show relationship between Ps brain activation and arousal ratings; later used to compare the activation to the memory scores of the imagesComposite Maps (MRI and fMRI slices layered)made of the structure of the amygdala and brain; allowed for fMRI correlation map to be superimposed on top, showing the voxel highlights for activationPixels as used in the studycan be seen as 2d "lighting up" of amygdala imagesVoxels as used in the study(volume pixels) are the 3d equivalent of a pixel when creating computer generated images or models2 results from Phase 11. Ps arousal and valence ratings positively correlated to the pre-determined IAPS image ratings 2. amygdala activation was significantly, bilaterally correlated with higher ratings of individually experienced emotional intensity2 results from Phase 21. memory performance significantly improved for scenes rated as "high" in emotional intensity (3) compared to the 0-2 rated images 2. images rated mild to moderate (0-2) in emotional intensity were not recalled as often, and were not scored as "familiar" by PsMain conclusions of the studya) The amygdala is sensitive to emotional intensity of visual stimuli (H1 supported) b) The more emotionally intense something is, the more likely it will be remembered (H2 supported) c) Moderate to high activation of the LEFT amygdala during encoding helps to determine if a memory is able to be properly recalled later2 methodological strengths of the study1. all Ps were tested in a standardized environment; enabled high control of the situation to exclude extraneous variables 2. the use of an fMRI scanner provided numerous objective and scientific quantitative data; enables statistical analysis of amygdala activation and emotional intensity (phase 1) and amygdala activation to memory of the scene (phase 2)2 methodological weaknesses of the study1. low generalizability - only 10 right-handed females 2. low ecological validity and mundane realismEthics of the study-ethically sound (informed consent, no deception, no harm) -helps to promote research into brain functioning and relationship to emotional stimuli