MARCH 20 Flashcards
recap of an affective module
an affective module should be dedicated to a SINGLE AFFECTIVE FUNCTION and this must be STABLE across a wide range of conditions
recap of an affective mode
operation of an affective mode can be inferred if an AFFECTIVE MODULE SWITCHES its AFFECTIVE FUNCTIONS under particular conditions
paper: “brain representations of affective _______ and ________ in sustained ________ and _______”
brain representations of affective VALENCE and INTENSITY in sustained PLEASURE and PAIN
pleasure and pain have opposite what?
valence
(pleasure is positive, pain is negative)
pleasure and pain interact in what?
in our SUBJECTIVE INTERPRETATION of our CURRENT HEDONIC STATE
examples of how pleasure and pain interact
- giving flowers to a sick friend
- a massage
- getting a lollipop after a shot
- experiencing pain can dull ability to experience pleasure
- relieving pain can itself be a pleasurable experience
what do we know about how pleasure and pain interact in the brain?
painful and pleasant sensations are PROCESSED in DISTINCT SPINAL and PERIPHERAL CIRCUITS
(but less is known about how these signals are integrated centrally in the brain in affective experience)
T/F: large overlap in brain regions that process pleasure & pain
true
many brain regions are involved in processing both pleasure and pain
gap this paper tries to fill
most of the evidence on pleasure and pain comes from studies that have looked at EITHER pain or pleasure,
but NOT BOTH in the SAME INDIVIDUAL
how do brain regions that are activated both by both pain and pleasure encode these experiences?
pain pleasure continuum possibility
it’s possible that brain regions could represent affective valence ranging from positive to negative on a continuum with PAIN and PLEASURE at OPPOSITE ENDS
populations of neurons that respond to BOTH positive and negative valence in the same way may be representing WHAT?
may be representing AROUSAL or SALIENCE
this can be thought of as AFFECTIVE INTENSITY
what did the study examine?
how the brain represents VALENCE and INTENSITY across PLEASURE and PAIN
used fMRI in human participants
imaged while tasting PLEASANT or PAINFUL substances
to determine which brain regions represent pleasure and pain
used brain scans to identify brain regions that encode which stimuli were presented, as well as to predict the Ps subjective ratings of intensity of pain and pleasure
specific research questions
- which BRAIN REGIONS contain info about pleasure and pain?
- can we identify PREDICTIVE MODELS of AFFECTIVE VALENCE and INTENSITY within the overlapping brain regions?
- which LARGE-SCALE BRAIN NETWORKS are CORRELATED With these predicate models?
their axiomatic approach
AXIOM 1:
^ brain regions encoding information for sustained pain or pleasure must SIGNIFICANTLY PREDICT RATINGS of subjective pain or pleasure
AXIOM 2:
^ of the brain regions identified in axiom 1, those encoding AFFECTIVE INTENSITY should predict both pain and pleasure ratings, IRRESPECTIVE of the POLARITY of the rating
AXIOM 3:
^ of the brain regions identified in axiom 1, those encoding AFFECTIVE VALENCE should predict the DIRECTIONAL SIGN of both PAIN and PLEASURE ratings
study design
fMRI with 58 Ps in study 1, 62 Ps in study 2
Ps CONTINUOUSLY RATE subjective pleasantness/unpleasantness while experiencing SUSTAINED PLEASURE and PAIN
pleasure and pain = induced by delivering CHOCOLATE or CAPSAICIN liquid to the mouth
study 1: data used to make the predictive models
study 2: data used to test the predictive models
continuous pleasantness/unpleasantness rating
from “strongest imaginable unpleasantness of any kind” to “strongest imaginable pleasantness of any kind”
difference in timing between chocolate and capsaicin delivery
capsaicin delivery was shorter than chocolate delivery
but the subjective experience of unpleasantness was still MORE INTENSE and MORE SUSTAINED than the subjective experience of the chocolate
what brain regions did they look at?
limited it to 48 brain regions of interest (ROIs)
based on prior literature to increase statistical power
(to minimize ‘false positives’, they’re only looking at brain regions where they expect to see a signal)
how did they identify brain regions that encode info about pleasure and pain?
by using fMRI data to train pattern-based models to predict the PLEASANTNESS-UNPLEASANTNESS RATINGS SEPARATELY for pain and pleasure conditions
brain regions - do some predict only pain? others only pleasure? what about both?
- some regions significantly predict ONLY PAIN ratings
- some regions predict ONLY PLEASURE ratings
- some regions predict BOTH
they developed predictive models of INTENSITY and VALENCE based on what hypothesis?
hypothesis that INTENSITY and VALENCE are 2 fundamental affective dimensions SHARED ACROSS PAIN AND PLEASURE
details of their model
MULTIPLE-REGION BASED MODEL
^ leads to better prediction than models based on single regions
how did they train the model?
used COMBINED DATA from CAPSAICIN, CHOCOLATE and CONTROL Conditions
and fMRI data from the 7 OVERLAPPING brain regions
was their model able to predict affective valence and intensity in the data?
yes
correlations between model predictions and actual behavioural data were ALL SIGNIFICANT
for both VALENCE and AROUSAL
