Critical Neuroscience of Pleasure - Amadeus Magrabi Critical Neuroscience University of Osnabrueck April 2010
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Critical Neuroscience of
Pleasure
Amadeus Magrabi
Critical Neuroscience
University of Osnabrueck
April 2010
Critical Neuroscience of
Pleasure
Amadeus Magrabi
Critical Neuroscience
University of Osnabrueck
April 2010
Inferring Phenomenology from fMRI-Data:
Justified or Premature?
Critical Assessment of the
Development in Pleasure Research.
Amadeus Magrabi
Critical Neuroscience
University of Osnabrueck
April 2010
A Rough Sketch of what I am going to do
1. Describe a certain strategy
in fMRI-research
2. Check whether it is widespread
3. Analyze what‘s wrong with it
Knowledge Construction in
Cognitive Neuroscience
What can we do to learn something about mental state x?
Step 1
Mental State x correlates with Brain Region y
Step 2
Brain Region y
was active
suggests that must have
?
Mental State x
been present
Is step 2 already justified?
Knowledge Construction in
Cognitive Neuroscience
Question is too general to be answered, so I focussed on pleasure research.
Step 1
fMRI
Pleasure correlates with Ventral Striatum
Step 2
Ventral striatum
was active
fMRI
suggests that
Participant
must have felt
?
good
Research questions:
(1) Is there a trend towards doing step 2 in pleasure research? Is step 2 justified?
Why is step 2 attractive for pleasure research?
• Measuring how much participants like something is a
powerful experimental tool
• Alternatives are often unreliable
– subjective rating scale: didn‘t like it at all liked it a lot
– preference judgements:
or ?
vulnerable to social desirability
biases, bad introspection, ...
• In contrast, fMRI can be seen as a
more direct, objective measurement
An example of step 2 research:
Singer et al. (2004)
Theory (simplified!):
Social fairness is important for human behavior.
Approach:
Have participants play a social game (iterated prisoner‘s dilemma)
against cooperative or uncooperative players in an fMRI scanner.
Conclusions:
„*...+ the observation of task-specific reward-related
[brain] activation suggests that social fairness is experienced as
rewarding per se.“
Another example of step 2 research:
Stice et al. (2008)
Theory:
Obese people get more pleasure from the consumption and
anticipation of food than lean people.
Approach:
Have participants consume chocolate milkshake
or a tasteless solution in an fMRI scanner.
Conclusions:
„Given that the insula and overlying operculum have been
associated with subjective reward from food intake, these findings
may imply that obese individuals experience greater food reward
relative to lean individuals.“
Is step 2 justified?
• Experimental designs to find neural correlates of pleasure:
– Wait until participants are hungry/thirsty and
then let them eat/drink in the scanner
– Imagine or watch pictures of favorite food or sexual scenes
– Smell pleasant odors
– Reward a certain performance with money
– Let male participants watch videos of soccer goals
– Invasive recordings in animal studies
• There are definitely some “hotspots” for pleasure in the brain,
like the orbitofrontal cortex, the striatum, the amygdala,
the cingulate cortex, and the insular cortex.
(some reviews: Smith et al. 2010; Berridge & Kringelbach 2008;
Haber 2009; Delgado 2008; O’Doherty 2002)
• There are even experiments which suggest that the magnitude
of the experienced pleasure is correlated with the activity of
certain brain areas. (Small et al. 2003; Volkow et al. 1999)Is step 2 justified?
• But if we are being honest, the literature is a mess.
• Some shortcomings in a dogmatic list:
– The literature is fundamentally contradicting in many respects.
– What exactly the hotspots are strongly depends on the author.
• Example of the striatum: Ventral striatum? Dorsal striatum? Both?
Only nucleus accumbens? Only the shell of the nucleus
accumbens?
– All hotspots seem to play a role, but they
seem to be neither necessary nor sufficient.
– What exactly is represented?
• Liking (experience of pleasure)? Wanting (motivation)?
The prediction of a pleasant event?Is step 2 justified?
• But if we are being honest, the literature is a mess.
• Some shortcomings in a dogmatic list:
– ...
– Typical problems of fMRI: indirect, bad temporal resolution.
– There are various kinds of pleasures (eating a burger vs. watching a
romantic sundown)
– Do the brain areas cause or code pleasure?
– „there is strong evidence to implicate the ventral striatum in aversive
as well as reward processing” (O’Doherty 2002)
– Paraphrasing Stice et al (2008):
• Why use the fMRI-paradigm instead of rating scales? Because
rating scales are unreliable whereas fMRI is direct and objective.
• Is the fMRI-paradigm valid? Yes, because the data correlate with
rating scales.Is step 2 justified? It seems to be too soon for step 2. Pleasure research is in need of more step 1 research.
Is there a trend torwards
doing step 2 research?
• So far, I found these studies:
– Stice et al. 2008
– Singer et al. 2004
– De Quervain et al. 2004
– Gatze-Kopp et al. 2009
– Fliessbach et al. 2007
• In general, the abstracts say that they wanted to find neural
correlates (step 1), but deeply hidden in the text are subtle
step 2 conclusions. But in most papers, the step 2 conclusions
are phrased very weak.
• I can‘t say that I found the strong trend that I was suspecting.A Warning Sign
Another Warning Sign
Science
playing
Critique aroundThe End Science
playing
Critique around
• Can you point me to some other studies
which go into the same direction?
• How do you see this „trend“ of
overinterpreting fMRI-data?
• Fear=amygdala, insula=disgustYou can also read
