An fMRI study of Anomalous Anticipation of emotional stimuli Dick J. Bierman Universities of...

An fMRI study of Anomalous Anticipation of emotional stimuli

Dick J. Bierman

Universities of Amsterdam & Utrecht (NL)

Toward a science of Consciousness

Tucson, April 10. 2002

What is Presentiment?

Consider the sep. 11 WTC attack. Was there anybody in the general public having some uneasy feeling before the attack?

There are a lot of stories….

Was this just coincidence?

Ed Cox (1960)

Compared train ridership on days with and without a train accident.

He found that on accident days there were significant less people on trains.

(Note: Utts redid the analyses and found a smaller effect after correction for holidays)

1996: Empirical Approach: Presentiment experiment

Presentiment is reported as the apparent psycho-physiological effect of a future emotional ‘cause’.

Procedure

• Subject sits relaxed with electrodes attached• Gets about 40 exposures of randomized

neutral and calm stimuli• Skin conductance is averaged separately for

emotional and neutral stimuli • Before, during and after stimulus• Baseline fixed at ~ -7.5 seconds

Procedure Presentiment ‘trial’

Time

SubjectHitsButton

0 5

OrCalm

Blank screen

baseline

Random!!

Skin C

onductance

Results First Subject (Radin-1)stimulus

Presentiment?

Calm

EmotionalBefore During After

Results all Subjects (Radin-1)

Emotional

Calm

Presentiment!

This should be everywhere!

Main stream emotion research

Measure baseline of dependent varPresent an emotional / calm eventMeasure response of dependent var

baseline event response

time

Mainstream Research questions

R = f ( emotional level of event): Find ‘f’R = Response - BaseLineImplicit assumption: BaseLine is independent of ‘future emotional level’

What did we do?

Search for main stream databases thatMeasure a BaseLine for at least 4 seconds.Use strong emotional eventsFor which Data can be obtained

What did we find?

Hamm group: on the speed with which fear arises in animal phobic patients

Damasio group: on implicit emotional learning during Gambling task

Procedure Animal fear studyS

kin

Con

duct

ance

Fixation stimulus

7000 msec

time

6850 msec

Blank Screen

150 msec

Results re-analysis Hamm’s data

-20

0

20

40

60

80

100

Samplenumber (0.1sec)

calmeroticanimals

STIMULUS

Animal FearStudyALL DATAPOOLED:N = 38 Erotic

Calmpresentiment

Damasio: gambling procedure

• Participant gets initially $2000

• Draws cards from one of 4 different decks

• Card is either winning or losing

time

Preparation

Draws cardFeedback: win or loss

Ski

n C

ondu

ctan

ce

Damasio dataset analyses

• Damasio-analysis P = f (type of deck) !!! Advantageous vs non-advantageous

• Our Re-analysis: P = f(type of Card) Winning vs Losing

Winning vs. Losing Cards:

Quote from: Bechara, Damasio et al, Science, 275, 28 February 97, 1293-1295

: ….. “the players have no way of predicting when a penalty will arise…”

Results re-analysis Gambling experiment

0.500.400.300.200.100.00

0.400.48

SCR before Good and Bad Cards

Pos. Cards

Neg. cards

• t = 1.634; df=117 ; p =0.053

• Presentiment effect : 20%!!!!

So What Next?

• Can we differentiate between different emotions?

• Can we exclude possible artefacts?

• Can we locate the source of this phenomenon?

Event Related Design

• 10 subjects

• 48 pictures (events)

• ~ 16 neutral, ~ 8 erotic, ~ 8 violent

• 4.2 seconds exposure time

• 16.8 seconds for one trial (= 8 volumescans)

• 1 vol: 22 slices, slice resolution: 64 * 64

Analysis procedure (1)

• Dependent var: BOLD signal per voxel (Blood Oxygenation Level Dependent)

• Pre-processing:– Slice time correction– Linear trend removal– 8 mm spatial smooting– No further smoothing in time domain

Analysis Procedure

• General Linear Model – Predictors : neutral stim, erotic stim, violent

stim. Results in:– Regions of Interest with significant fit.

• Event related averaging over stim.condition

• t-test of average BOLD signals in ROI

Brain regions which have a significant fit with emotional stims and neutral stim as predictor

Contrast between emotional and neutral conditon.

Plot for BOLDsignal for the whole experiment

Brain-map with ROI’s

Event related averaging

erotic

neutral

stimulus

Erotic Presentiment effect at time: -4 seconds.

Td = 2.89 df= 39 p < 0.01

-20

0

20

40

60

80

100

Samplenumber (0.1sec)

calmeroticanimals

STIMULUS

Animal FearStudyALL DATAPOOLED:N = 38

ROI:

-51, -78, 1

violent

erotic

ROI:

-1,-80, 37

violent

Amygdala Negative presentiment in neutrals???

Pooling of data

• Mapping in Talairachspace

• Loss of signal due to individual differences

• So:separate male and female

All female:

Erotic & Violent presentiment

(t ~ 1.75, df=158, p<0.05 o.t.)

All male:

Erotic presentiment

(t ~ 2.1, df=226, p<0.01 o.t.)

‘Normal’ explanations

• Chance fluke, weak effects, over analysis• Incorrect Randomization

– With replacement– Subject strategies

• Introduced by software– Hemodynamic curve– smoothing

Conclusion

• This study should be seen as exploratory

• Warrants further research

• Most fmri emotional pictures research sh/could look at this effect if:– Randomization with replacement– Strong stimuli– Reasonable ISI (~ 18 seconds)