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First-Person Neuroscience of Pain: Puzzles, Methods and Data. Simon Peter van Rysewyk Graduate Institute of Medical Humanities, Taipei Medical University Brain and Consciousness Research Center, Taipei Medical University-Shuang Ho Hospital. my focus today. - PowerPoint PPT Presentation
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First-Person Neuroscience of Pain: Puzzles, Methods and Data
Simon Peter van RysewykGraduate Institute of Medical Humanities,
Taipei Medical University Brain and Consciousness Research Center,
Taipei Medical University-Shuang Ho Hospital
Simon van Rysewyk 2
my focus today
a puzzle about introspection and the limits of pain science
researcher-subjects
“experiential-phenomenological method”
Simon van Rysewyk 3
a seeming puzzle for pain science
P1 pains seem knowable via introspection
P2 introspection is subjective
P3 science is intersubjective
∴ pains cannot be a scientific object
Simon van Rysewyk 4
a seeming puzzle for pain science
P1 experiences seem knowable via introspection
introspection is a way of learning about one's own ongoing, or very recently past, experiences
targets conscious experiences, beliefs, intentions
produces beliefs, judgments, knowledge
requires proximity in time
Simon van Rysewyk 5
a seeming puzzle for pain science
P2 introspection is subjective
I have a uniquely privileged position about my experiences that no one else can have
I can directly and immediately access my own experiences in a way you cannot
Simon van Rysewyk 6
a seeming puzzle for pain science
P3 science is intersubjective
no one is epistemically privileged with regard to gathering evidence about the object of a study
Simon van Rysewyk 7
a seeming puzzle for pain science
P1 experiences seem knowable via introspection
P2 introspection is subjective
P3 science is intersubjective
∴ experiences cannot be a scientific object
∴ experiences are non-physical
Simon van Rysewyk 8
a seeming puzzle for pain science
P1 pains seem knowable via introspection
P2 introspection is subjective
P3 science is intersubjective
∴ pains cannot be a scientific object
∴ pains are non-physical
Simon van Rysewyk 9
cartesian dualism
PAIN begins in the PNSascends in specific pathwaysends in a specific brain centerintrospection of pain by the non-physical “soul”
Rene DescartesTreatise of man(1662)
Simon van Rysewyk 10
property dualism
imagine you are blind and you know all physical facts about vision
you have neurosurgery which enables you to see
you know all physical facts about vision, but on seeing for the first time you learn a new fact
the fact you learn is non-physical: what it is like to see
Simon van Rysewyk 11
understanding the seeming puzzle
“pain cannot be a scientific object”?
false – pain science objectively studies the brain
pain dualist: does pain science study pain itself or the brain correlates of pain?
pain depends on brain activity, but experiences of pain are only knowable via subjective introspection
Simon van Rysewyk 12
understanding the seeming puzzle
∴ pain experience and brain activity are distinct
pain science studies brain correlates of pain, not pain itself (“what it is like”)
“pain cannot be a scientific object”
Simon van Rysewyk 13
understanding the seeming puzzle
“pain science studies brain correlates of pain, not pain itself”
not quite right – the object of pain science is brain activity as related to introspected pain
pain psychophysics and neuroimaging rely on introspective report
animal studies await introspective confirmation
Simon van Rysewyk 14
challenging property dualism
“pain science cannot know what it is like to have a pain”
scientific explanations of experiences do not cause the experiences to occur (e.g., to feel pain)
if I learn all physical facts about pregnancy, would I thereby become pregnant?
Simon van Rysewyk 15
introspection might be physical
what science knows about experience may prove to be identical with what we know via introspection – specific brain activity
there are not two distinct activities (cartesian dualism)
there is only one kind of activity: brain activity with only physical properties
Simon van Rysewyk 16
introspection might be physical
direct introspection is beneficial for survival
introspection accesses brain activity in a direct way without telling us what the complex physical properties of such brain activity are
neuroscience tells us what those physical properties are
Simon van Rysewyk 17
introspection might be physical
we have color experiences without knowing what the physical surface properties are
color neuroscience tells us what the physical surface properties
our visual system responds to such physically complex properties without informing us about their properties: we simply perceive colors
Simon van Rysewyk 18
epistemological dualism of pain
replace cartesian dualism of pain with epistemological dualism of pain
two forms of access to one and the same phenomena – to the brain activity underlying pain experiences
∴ pains are physical
Simon van Rysewyk 19
summary
first- and third-person access to pain is essential in pain science and historical fact
dualism is consistent with pain science, but epistemological dualism of pain is preferred
epistemological dualism does not entail cartesian dualism
Simon van Rysewyk 20
two scientific uses of introspection
non-researcher-subject report (verbal/written)researcher-subject report (verbal/written)
double-paincatastrophizing and sensitization
Simon van Rysewyk 21
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 22
double pain
Simon van Rysewyk 23
double pain
Lewis & Pochin 1938
independently mapped body regions wherein they introspected double pain
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 24
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 25
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 26
catastrophizing and sensitization
von Baeyer 2014
“When I walked on my treadmill for progressively shorter periods of time, a powerful aversive sensation would build up in the soles of my feet. I would rate the pain intensity at 3/10 and the unpleasantness at 8/10. The pain would stop a few minutes after I stopped walking on the treadmill, but would return quicker and stronger each time I resumed … the problem never occurred during ordinary walking.”
Simon van Rysewyk 27
von Baeyer 2014
“I told myself, ‘I wasted $1200. I'll never be able to use this treadmill. I'll have to go back to sitting at a desk. So much for my fitness plan,’ and similar discouraged thoughts. When I did attempt to walk on the treadmill while working, I could not concentrate on the work at all: my mind was almost fully occupied with the sensation in my feet and with those catastrophizing thoughts. Realizing this led to a vicious cycle of increased catastrophizing: ‘What an idiot – I ought to be able to focus on my work!’
Simon van Rysewyk 28
von Baeyer 2014
von Baeyer then realized his pain was caused by central sensitization due to repetition of identical physical stimuli (treadmill walking):
•allodynia (feeling a normal touch as painful)•windup (progressively stronger pain to the exact same stimulus)
Simon van Rysewyk 29
von Baeyer 2014
“With this insight, the cure was obvious: I had to vary the stimulus. When the sharp gravel sensation starts, I kick off my shoes and continue walking in my socks or bare feet; if I am already barefoot when the sensitization begins, I put my socks and shoes back on.”
changing catastrophizing can change central sensitization: pain 1/10, unpleasantness 3/10
Simon van Rysewyk 30
von Baeyer 2014
“Reduction in secondary hyperalgesia was associated with reduced pain catastrophizing, suggesting that changes in central sensitization are related to changes in pain-related cognitions. Thus, we demonstrate that central sensitization can be modified volitionally by altering pain-related thoughts.”
Salomons et al. 2014. PAIN.
Simon van Rysewyk 31
researcher-subjects?
1. the results were obtained through researchers introspecting personal 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 32
bias and researcher-subjects
the participation of researcher-subjects may minimize and eliminate bias
preferable for formulating hypotheses and designing experiments than relying on published accounts or the imagination of others
multiple researcher-subjects likely optimal
Simon van Rysewyk 33
a first-person neuroscientific method of pain
“experiential-phenomenological method”
Price DD, Aydede, M (2006) Pain: New Essays on its Nature and the Methodology of its Study, M Aydede (Ed.), Cambridge, Mass: MIT Press.
Simon van Rysewyk 34
overview
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 35
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 36
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 37
horizontal phase
2. describing pain from the first-personverbal/written self-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 38
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 39
horizontal phase
‘Feel bothered by this and distressed’can reduce to‘I have a feeling of intrusion related to this pain’
Simon van Rysewyk 40
horizontal phase
definitional hypotheses: experiential factors commonly present during a pain
functional hypotheses: common factor interrelationships
Simon van Rysewyk 41
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 42
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 43
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 44
vertical phase
correlate horizontal results with brain activity to establish possible causal relationships
patterns of brain activity that co-vary with different factors of pain could be identified
Simon van Rysewyk 45
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 46
Rainville et al. 1997
↑ unpleasantness increased magnitudes of pain-unpleasantness ratings and neural activity in ACC
no change in ACC for ↓ unpleasantness
no change in S1 activity and magnitude ratings of pain sensation intensity in both conditions
Simon van Rysewyk 47
Rainville et al. 1997
Simon van Rysewyk 48
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 49
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 50
significance of pain-brain relations
changes in experience and brain activity cannot be predicted only by stimulus properties
the neural activity sufficient for a given pain quality of pain does not prove it exists within one brain region
Simon van Rysewyk 51
future issues
less well-known introspective methods should be used in the study of pain
relate pain and brain activity in real-time using neurofeedback techniques
promote first-person neuroscience of pain within pain associations (SIGs)
Simon van Rysewyk 52
acknowledgements
NSC 102-2811-H-038-001
Brain and Consciousness Research Centerhttp://consciousbrain.tmu.edu.tw/main.php