Encoding valence

What is the goal of Lee et al’s study?

Want to see how brain represents valence/intensity across pain/pleasure using fMRI

What are some of the primary research questions of Lee et al’s study?

1. Which brain regions contain info abt pleasure/pain?

2. Can we identify predictive models of affective valence and intensity within overlapping brain regions?

3. Which large-scale brain networks are correlated with these predictive model

What is meant by Lee et al’s ‘axiomatic approach’?

1. Axiom 1: brain regions encoding info for sustained pain/pleasure must significantly predict ratings of subjective pain/pleasure

2. Axiom 2: of brain regions identified, those encoding ‘affective intensity’ shld predict both pain + pleasure ratings

3. Axiom 3: of brain regions identified in axiom 1, those encoding ‘affective valence’ should predict the directional sign of both pain/pleasure readings

What was the study design of Lee et al’s paper?

1. Participants continuously rate subjective pleasantness/unpleasantness while experiencing sustained pleasure and pain

2. Pleasure and pain are induced by delivering chocolate or capsaicin liquid to the mouth

Which brain regions significantly predict pain based on Lee et. al’s study?

Anterior OFC

Midcingulate cortex

Frontal pole

Presupplementary motor area

Which regions predict pleasure based on Lee et al’s 2024 study?

1. Insula anterior & posterior long gyri

2. Dorsal midcingulate cortex

3. Supplementary motor area

Which regions predict pleasure AND pain based on Lee et al’s findings?

1. Amygdala

2. Anterior insola

3. Ventromedial mPFC

4. Posterior OFC

5. Ventro to dorso lateral PFC (includes 3 regions)

Could Lee et al identify predictive models of affective valence and intensity within overlapping brain regions?

Yes

Affective intensity and valence can be decoded from activity of 7 regions that represent both pleasure and pain

Affective intensity & valence seem to be represented by distinct sub-populations of voxels

• Insula predicts intensity

• Ventromedial PFC predicts valence

What was the intensity model signficantly correlated with according to Lee et al’s study?

Insula, anterior midcingulate cortex

Part of the ventral attention (salience) network

What was the valence model signficantly correlated with according to Lee et al’s study?

Ventromedial PFC and posterior cingulate cortex

Part of default network

What were the conclusions of Lee et al’s study?

1. fMRI analyses identified a subset of brain regions activated by both pleasure and pain

2. Predictive models using brain activity from these regions independently predict valence and intensity

   1. Intensity is primarily associated with the ventral attention network

   2. Valence is primarily associated with the default mode network

3. Valence and intensity are encoded in brain regions that process both pleasure and pain BUT the evidence suggest that the specific sub-regions as well as the broader functional connectivity networks are distinct

4. This suggests that intensity and valence are processed in distinct brain circuits and so it should be possible to dissociate these processes

What are some of the limitations of Lee et al’s study?

1. The predictive models didn’t take into account functional connectivity and used only brain activation patterns

2. Affective experience may induce global and enduring changes suggesting that there may be additional information carried in functional connectivity patterns

3. Pain and pleasure experiences were unbalanced- pain was overall more intense

4. Using different stimuli (different modalities?) will be important to test the generalizability of these results.