Canli et al. Brain Scans and Emotions Flashcards
Title
Event related activation in the human amygdala associates with later memory for individual emotional experiences
fMRI
functional magnetic resonance imaging
functions of fMRI
- non-invasive brain scanning technique that uses radio waves and strong magnetic field
- measures brain activity by detecting changes associated with blood flow
procedure fMRI
- scanner traces the journey of strong oxygenated blood around the brain
- maps activity
- picture is color coded to show intensity of activity
Amygdala
- almond shaped
- in the brain’s medial temporal lobe
- key role in processing emotions: fear/ pleasure/ anger
Background
- amygdala activation correlates with emotional memory
- emotional experiences are better recalled than non–emotional ones
- amygdala is responsive in dynamic/ phasic ways to moment to moment indi emotional experience
- amygdala activation would reflect flexible, rapidly changing emotional response
Aim
- to investigate whether the amygdala is sensitive to varying degrees of individually experienced emotional intensity
- whether the degree of emotional intensity affects the role of the amygdala in enhancing memory for emotional stimuli
Materials
- fMRI scanning machine
- scenes
- screen projector
- mirror
Research Method
Laboratory Experiment
Experimental design
repeated measures design
Sample
10 right handed females
why were only females selected for this experiment?
because women are more likely to report intense emotional experiences (Shields) and show more physiological reactivity in concordance with valence judgments than men (Lang et al)
Sampling Technique
Volunteer Sampling
Independent Variable
intensity rating of each stimulus on a 4 point scale (0-3)
Dependent Variable
- the self report % of familiar, forgotten and remembered with certainty
- functional images of 11 frames per trial resulting in a pixel count
Procedure
MRI and Behavioral
Behavioral Procedure
- shown 96 scenes through a mirror directed at a back projection screen
- view each scene for the entire time it was shown
- when the fixation cross appeared, they had to rate the scene by pressing the relevant button with their right hand
How many scenes were shown?
96 scenes
Description of Scenes
- had a normative rating for arousal and valence from the International Affective Picture System stimuli set
- were shown in random order
Valence rating of scenes (normative rating)
1.17 (highly negative) - 5.44 (neutral)
Arousal rating of scenes (normative rating)
1.97 (tranquil) - 7.63 (highly arousing)
How long was each scene shown?
2.88 seconds
How long was the internal stimulus interval?
- 96 seconds
during this time, they had to view a fixation cross
Rating scale for emotional arousal
0-3
0: not emotionally intense at all
3: extremely emotional intense
What occurred after the scene rating and scan procedure?
participants were tested in an unexpected recognition test
viewed all the previously seen scenes and 48 new ones (foils)
What were the foils?
scenes that matched the valence and arousal characteristics of the previously shown scenes
Valence rating of foils (normative rating)
1.31 (highly negative) - 5.78 (neutral)
Arousal rating of foils (normative rating)
2.74 (tranquil) - 7.22 (highly arousing)
What were the participants asked during the recognition test?
if they remembered the scene
and if they remembered it with certainty, less certain or not remembered
What was the coding of the labels during the recognition test?
certainty - remembered
less certain - familiar
-all three trials (remem 3, forgo 1, fami 2) were encoded in numerical format to construct a correlational map
MRI Procedure
- data acquisition
- imaging
- correlational map
What was used to gather data?
- 1.5 T General Electric Signa MR imager
- used to measure BOLD contrast (blood oxygen level dependent signal)
Correlation map
created to correlate brain activity with participants arousal ratings and memory scores
How was head movement minimised?
using a bite bar which was formed by using the ppt’s dental imprints
Results
- ppt’s exp of emotional intensity in the present study correlated well with average rating of emotional valence and arousal
- amygdala activation was bilaterally and significantly correlated with higher ratings of individually experienced emotional intensity
Results of Memory Recall
- better for scenes rated as emotionally intense
- 0-2: mild to moderate emotional intensity/ similar distribution of percentage of F, F, R
- 3: highly emotionally intense / was more remembered and recalled // higher freq
Result of Correlation Coefficient
- between intensity ratings and normative ratings
- .66 and .68
What were the controls in the study?
- headmovement was reduced due to the use of a bite bar formed with each participant’s dental impression
- images were chosen from standardised sets of known emotional valence
- ppts fixated on a cross so that they would be looking in the right place to ensure that they would not miss the next image
- the duration of the image shown/ cross fixation
What did the use of repeated measures design ensure?
that indi differences in emotional responses, brain activity or recall ability could not affect the results
PROCEDURE
- during scanning, ppts were shown a series of 96 scenes presented via an overhead projector and mirror to allow them to see it while in the fMRI scanner
- scenes were shown in random order (2.88 sec per image // 12.96 sec per fixation cross)
- during the cross, they had to indicate their emotional arousal on a 0-3 scale
- 3 weeks later, they were tested in an unexpected recognition test in the lab
- the recognition test involved viewing of the prev 96 scenes and 48 new scenes
- asked whether they had seen each scene before and for images judged as prev seen, they had to say whether they remembered with certainty (remember), or familiarity (know)
applicability
It has helped us understand better the emotional memory of negative experiences, which can be useful in therapy that attempts to help people with trauma to forget such experiences.
nature vs nurture
strengths: it explains the impact of natural human inheritance on human emotions.
weaknesses: it fails to account for the differences people might show in their emotional experiences as a result of the different environments in which they were brought up.
situational vs individual
strengths: it explains why different memories in a person’s lifetime maybe remembered with different intensity.
weaknesses: it fails to account for the fact that some memories may be remembered as strongly as others even if lesser in emotional impact.
psychology being investigated
The connection between activity in the amygdala, and a person’s experience of emotional events and their long-term memory for those events is being investigated in the present study
