‘The Observer is the Observed: Towards Integrating Pain Phenomenology with Third-Person Scientific...
-
Upload
simonvanrysewyk -
Category
Health & Medicine
-
view
677 -
download
0
description
Transcript of ‘The Observer is the Observed: Towards Integrating Pain Phenomenology with Third-Person Scientific...
The Observer is the Observed: Towards Integrating Pain Phenomenology and
Third-Person Methods in the Scientific Study of Pain
Simon van RysewykTaiwan National Science Council Postdoctoral Fellow
Taipei Medical University
Simon van Rysewyk 2
my focus today
a puzzle for pain science about introspection
pain studies in which researcher-subjects use introspection
experiential method that integrates first and third-person methods to study pain
Simon van Rysewyk 3
a seeming puzzle for pain science
1 experiences seem knowable via introspection
2 introspection is subjective
3 science is intersubjective
∴ experiences cannot be a scientific object
(experiential science is not objective)
Simon van Rysewyk 4
a seeming puzzle for pain science
like vision, pain has an object of perception (tissue damage)
unlike vision, pain itself is an experience only knowable by introspection
‘An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’ (IASP)
Simon van Rysewyk 5
a seeming puzzle for pain science
1 pain seems knowable via introspection
2 introspection is subjective
3 science is intersubjective
∴ pain cannot be a scientific object
(pain science is not objective)
Simon van Rysewyk 6
the puzzle’s impact on pain science
conclusion false – pain science studies the brain
pain experience and brain activity must be distinct (cartesian dualism)
pain science studies brain correlates of pain, not pain itself
Simon van Rysewyk 7
dualism is true of pain science
cartesian dualism implies that the subject matter of pain is brain activity related to pain
pain science is committed to introspection
pain-neuroimaging was established by robust correlation of neuroimages with pain self-report
cartesian dualism and pain science are historically consistent
Simon van Rysewyk 8
dualism is true of pain science
metaphysical dualism is not convincing
pain science can assert epistemological dualism and mind-brain identity theory
identity is advantageous: brain activity is identical to pain without revealing complex physical features of the brain
Simon van Rysewyk 9
two scientific uses of introspection
researcher-subject verbal/written reportnon-researcher-subject verbal/written report
intuitive notion of introspection:inner perception yielding knowledge of immediate personal statesintersubjectively available to researcherstaken to indicate sensory qualities
Simon van Rysewyk 10
researcher-subjects: double pain
first and second pain results from a sudden noxious stimulus to a distal part of the body
0.5 to 1.5 second delay between the two pains
impulses in thinly myelinated A axons (6–30 meters/sec) travel much faster than those in C axons (0.5–1.5 meters/sec)
Simon van Rysewyk 11
researcher-subjects: double pain
Simon van Rysewyk 12
researcher-subjects: double pain
Lewis & Pochin 1938
independently mapped body regions wherein they introspected double pain
near the elbow but not the lower trunk although both sites are about the same distance from the brain
C fibers that supply the trunk have a short conduction distance to the spinal cord
Simon van Rysewyk 13
Lewis & Pochin 1938
C fibers that supply the skin near the elbow have a long conduction distance
once these C fibers enter the spinal cord, they synapse on A neurons
differences in peripheral conduction distance and time mean that double pain can be discriminated at the elbow but not the trunk
Simon van Rysewyk 14
researcher-subjects: double pain
Landau & Bishop 1953
first pain sharp or stinging, well localized, and brief (A fibers)
second pain diffuse, less well localized, dull, aching, throbbing, burning (C fibers)
second pain longer lasting than first pain, vague unpleasantness
Simon van Rysewyk 15
researcher-subjects: double pain
1. the results were obtained through researchers introspecting their own pain
2. observations about specific pain experiences3. the observations have been integrated into
our knowledge of pain4. the observations have been replicated in
studies using standard experimental designs and methods
Simon van Rysewyk 16
relating introspection and brain activity to pain sensation and emotion
Rainville et al. 1997
subjects rated pain sensation intensity and pain unpleasantness of immersion of the left hand in a 47° C water bath for 60 s
condition hypnotic suggestion sensation1 ↑ pain unpleasantness no
change2 ↓ pain unpleasantness
Simon van Rysewyk 17
Rainville et al. 1997
↑ unpleasantness increased magnitudes of pain-unpleasantness ratings and neural activity in ACC (area 24)
no change in ACC for ↓ unpleasantness
no change in S1 activity and magnitude ratings of pain sensation intensity in both conditions
Simon van Rysewyk 18
Rainville et al. 1997
Simon van Rysewyk 19
Hofbauer et al. 2001
subjects rated pain sensation intensity and pain unpleasantness of immersion of the left hand in a 47° C water bath for 60 s
condition hypnotic suggestion unpleasantness1 ↑ sensation intensity
no change2 ↓ sensation intensity
Simon van Rysewyk 20
Hofbauer et al. 2001
↑ intensity increased magnitudes of pain-intensity ratings and neural activity in S1
no change in S1 for ↓ intensity
no change in ACC activity and magnitude ratings of pain unpleasantness in both conditions
Simon van Rysewyk 21
the significance of brain-pain phenomenology parallels
changes in experience and brain activity cannot be predicted only by stimulus properties
changes in experience and brain activity can be explained by analysis of experience and brain activity
the neural activity sufficient for a given pain quality of pain does not prove it exists within one brain region
Simon van Rysewyk 22
an experiential approach to pain
Barrell & Barrell 1975, Price & Barrell 1980
experimental tasks phase
identify common factors within pain experiences horizontal (first-person)
‘phenomenal structure’identify common factor interrelationships
identify common factor-brain relationships
vertical (third-person)‘brain structure’
Simon van Rysewyk 23
horizontal phasehorizontal phase stages experimental subjects
1 question and observe
researcher-subjects2 describe from a first-person perspective
3 find common factors and their interrelationships
4 use psychophysical methods to test generality and functional relationships between common factors
non-researcher-subjects
Simon van Rysewyk 24
horizontal phase
1. questioning and observing
‘What is it like to experience the unpleasantness of laboratory pain, such as immersion of the hand in a heated water bath?’
how of pain (sensations, thoughts, feelings) not why pain occurs (stimulus conditions)
‘passive attention’, ‘being with pain’, immediate retrospective attention
Simon van Rysewyk 25
horizontal phase
2. describing pain from the first-personverbal/written reports of immediate pain:
‘My hand was immersed in a 47° C water bath when intense burning and throbbing occurred in my hand. Feel bothered by this and distressed. Is it going to get stronger? Concern. Hope my hand isn't going to be scalded’
Simon van Rysewyk 26
horizontal phase
3. finding common factors and interrelationships
‘phenomenological reduction’‘Is it going to get stronger? Concern. I hope my hand isn't going to be scalded” can reduce to‘I think and feel concern for future consequences related to this pain’
Simon van Rysewyk 27
horizontal phase
‘Feel bothered by this and distressed’can reduce to‘I have a feeling of intrusion related to this pain’
Simon van Rysewyk 28
horizontal phase
definitional hypotheses: experiential factors commonly present during a pain-type
functional hypotheses: common factor interrelationships
Simon van Rysewyk 29
horizontal phase
sample definitional hypotheses:1. an intense burning throbbing sensation in
the hand 2. an experienced intrusion or threat associated
with this sensation3. a feeling of unpleasantness associated with
this felt intrusion or threat
Simon van Rysewyk 30
horizontal phase
when the factors of intrusion or threat are present, there is a felt sense of pain
felt sense of pain is pain-aversion
pain-aversion seems about felt bodily integrity
Simon van Rysewyk 31
horizontal phase
sample functional hypotheses:1. felt unpleasantness should increase as a
function of experienced intrusion or threat 2. experienced intrusion should increase as a
function of the intensity of burning, throbbing sensation
Simon van Rysewyk 32
horizontal phase
4. applying psychophysical methods
controlled observation of ratings of experiential factors (pain aversion) or sub-factors (concern)
rating scale methods (ratio scales)
subjects are not researchers
Simon van Rysewyk 33
vertical phase
correlate horizontal results with brain activity to establish possible causal relationships
patterns of cerebral cortical activity that co-vary with different factors of pain could be identified
Simon van Rysewyk 34
future questions
can less well-known introspective methods be used in the study of pain?
are there experiential and neural similarities and differences between sub-types of acute and chronic pain?
can there be a ‘neural signature’ of pain?