Francesca Fardo
@francescafardo.bsky.social
Neuroscientist • brain • spinal cord • pain and temperature perception
Lab website: https://body-pain-perception-lab.github.io/
Lab website: https://body-pain-perception-lab.github.io/
We were intrigued to find that R2* in bilateral, basolateral amygdala was related to the uncertainty modulation of the thermal grill index. This region is important for affect and pain conditioning, and could help explain how we infer pain sensations from harmless inputs.
April 16, 2024 at 7:36 AM
We were intrigued to find that R2* in bilateral, basolateral amygdala was related to the uncertainty modulation of the thermal grill index. This region is important for affect and pain conditioning, and could help explain how we infer pain sensations from harmless inputs.
We find that individual variance in thermosensory computations (e.g., decision temperature and hierarchical uncertainty) index the microstructural features of the somatosensory cortex, insula, amygdala, and the brainstem Subnucleus Reticularis Dorsalis (SRD).
April 16, 2024 at 7:35 AM
We find that individual variance in thermosensory computations (e.g., decision temperature and hierarchical uncertainty) index the microstructural features of the somatosensory cortex, insula, amygdala, and the brainstem Subnucleus Reticularis Dorsalis (SRD).
Next, leveraging our large sample, we conducted a whole brain quantitative MRI analysis using the MPM sequences developed collaborators at UCL, relating individual fingerprints of thermosensory computations to brain maps indexing cortical myelination and iron.
April 16, 2024 at 7:35 AM
Next, leveraging our large sample, we conducted a whole brain quantitative MRI analysis using the MPM sequences developed collaborators at UCL, relating individual fingerprints of thermosensory computations to brain maps indexing cortical myelination and iron.
Clinically, responsiveness to the TGI is often used as an indicator of thermo-nociceptive function. We calculated an uncertainty modulation of thermal grill illusion index (UMTI), and found that it was highly correlated with individual differences in TGI response.
April 16, 2024 at 7:34 AM
Clinically, responsiveness to the TGI is often used as an indicator of thermo-nociceptive function. We calculated an uncertainty modulation of thermal grill illusion index (UMTI), and found that it was highly correlated with individual differences in TGI response.
So cool and warm percepts are precision-weighted, but what about the illusion? Remarkably, we find that the intensity of the TGI is specifically increased by estimation uncertainty. When we are unable to make reliable thermal predictions, we infer greater pain.
April 16, 2024 at 7:34 AM
So cool and warm percepts are precision-weighted, but what about the illusion? Remarkably, we find that the intensity of the TGI is specifically increased by estimation uncertainty. When we are unable to make reliable thermal predictions, we infer greater pain.
Next, using our hierarchical ZOIB regression approach, we predicted VAS ratings using trial by trial variance in prediction and estimation uncertainty. We find that the precision (i.e., inverse uncertainty) of thermosensory predictions increases felt cold and warm sensations.
April 16, 2024 at 7:34 AM
Next, using our hierarchical ZOIB regression approach, we predicted VAS ratings using trial by trial variance in prediction and estimation uncertainty. We find that the precision (i.e., inverse uncertainty) of thermosensory predictions increases felt cold and warm sensations.
The model does an excellent job of explaining trial by trial learning, where the 1st level encodes thermal prediction uncertainty (e.g., probability of warm vs cold stimuli) and the 2nd encodes estimation uncertainty (e.g., uncertainty about cue-stimulus associations).
April 16, 2024 at 7:33 AM
The model does an excellent job of explaining trial by trial learning, where the 1st level encodes thermal prediction uncertainty (e.g., probability of warm vs cold stimuli) and the 2nd encodes estimation uncertainty (e.g., uncertainty about cue-stimulus associations).
To develop a precision-weighted predictive coding model of thermosensation, we adapted the hierarchical gaussian filter (HGF) to our task. Bayesian model comparison, posterior predictive checks, and cross-validation all supported a 2-level learning model.
April 16, 2024 at 7:33 AM
To develop a precision-weighted predictive coding model of thermosensation, we adapted the hierarchical gaussian filter (HGF) to our task. Bayesian model comparison, posterior predictive checks, and cross-validation all supported a 2-level learning model.
So how did TGI trials influence thermal learning? We hypothesized that TGI would reinforce associations depending on if they were perceived as predominately warm or cold. We found participants were highly stable in this tendency, which significantly explained post TGI errors.
April 16, 2024 at 7:32 AM
So how did TGI trials influence thermal learning? We hypothesized that TGI would reinforce associations depending on if they were perceived as predominately warm or cold. We found participants were highly stable in this tendency, which significantly explained post TGI errors.
Positive control 3): Do predictions influence subjective ratings? Hierarchical zero one inflated beta regression (ZOIB) of VAS ratings revealed that cold and warm ratings are increased when stimuli matched predictions. Participants expectations shifted their felt sensations!
April 16, 2024 at 7:31 AM
Positive control 3): Do predictions influence subjective ratings? Hierarchical zero one inflated beta regression (ZOIB) of VAS ratings revealed that cold and warm ratings are increased when stimuli matched predictions. Participants expectations shifted their felt sensations!
Positive control 2): Did catch trials successfully elicit the TGI? Yes! Catch trials were rated as significantly more warm and burning, characteristic of the TGI, than innocuous cold and warm trials. Same temperatures, but participants feel more pain!
April 16, 2024 at 7:30 AM
Positive control 2): Did catch trials successfully elicit the TGI? Yes! Catch trials were rated as significantly more warm and burning, characteristic of the TGI, than innocuous cold and warm trials. Same temperatures, but participants feel more pain!
Positive control 1): does cue validity (predictive, nonpredictive, antipredictive) influence participants' predictions and reactions times? Yes! Participants successfully learned the cue-stimulus associations. Responses to TGI trials resembled veridical prediction error trials.
April 16, 2024 at 7:30 AM
Positive control 1): does cue validity (predictive, nonpredictive, antipredictive) influence participants' predictions and reactions times? Yes! Participants successfully learned the cue-stimulus associations. Responses to TGI trials resembled veridical prediction error trials.
Across blocks, the relationship between cues and stimuli underwent probablistic reversals, requiring associative learning. However, unbeknownst to the participants, within this sequence we embedded combinations of the same innocuous temperatures, creating a thermal grill.
April 16, 2024 at 7:29 AM
Across blocks, the relationship between cues and stimuli underwent probablistic reversals, requiring associative learning. However, unbeknownst to the participants, within this sequence we embedded combinations of the same innocuous temperatures, creating a thermal grill.
To study how expectations & uncertainty influence feeling cool vs warm, we designed a novel probalistic thermal learning (PTL) task. 267 healthy participants heard auditory cues, predicted if the next stimulus would be cool or warm, and then rated felt cold, warm, and burning.
April 16, 2024 at 7:29 AM
To study how expectations & uncertainty influence feeling cool vs warm, we designed a novel probalistic thermal learning (PTL) task. 267 healthy participants heard auditory cues, predicted if the next stimulus would be cool or warm, and then rated felt cold, warm, and burning.
Thermosensory predictive coding underpins an illusion of pain! Our new study reveals how perceptions of pain can emerge from the interplay between thermal sensations, expectations, and uncertainty. Check out our thread for all the details! www.biorxiv.org/content/10.1... #neuroskyence #psychology 🧪
April 16, 2024 at 7:27 AM
Thermosensory predictive coding underpins an illusion of pain! Our new study reveals how perceptions of pain can emerge from the interplay between thermal sensations, expectations, and uncertainty. Check out our thread for all the details! www.biorxiv.org/content/10.1... #neuroskyence #psychology 🧪
This was particularly surprising, as we found that pain symptom scores (measured by the PHQ-15), were highly correlated with depression scores. This suggests that experiencing systematic pain is a factor in mental health, even if laboratory measures of acute pain are unrelated.
January 11, 2024 at 10:34 AM
This was particularly surprising, as we found that pain symptom scores (measured by the PHQ-15), were highly correlated with depression scores. This suggests that experiencing systematic pain is a factor in mental health, even if laboratory measures of acute pain are unrelated.
We then estimated correlations between these factors and pain sensitivity profiles. To our surprise, we did not replicate previous findings, finding no link between pain sensitivity and symptoms. Bayesian analyses indicated strong to moderate evidence for the null correlation.
January 11, 2024 at 10:33 AM
We then estimated correlations between these factors and pain sensitivity profiles. To our surprise, we did not replicate previous findings, finding no link between pain sensitivity and symptoms. Bayesian analyses indicated strong to moderate evidence for the null correlation.
To measure mental health symptoms, participants completed validated inventories, spanning depression, anxiety, well-being, and pain symptoms. Using factor analysis, we found a three-factor structure which indexed general distress, fatigue, and bodily distress.
January 11, 2024 at 10:33 AM
To measure mental health symptoms, participants completed validated inventories, spanning depression, anxiety, well-being, and pain symptoms. Using factor analysis, we found a three-factor structure which indexed general distress, fatigue, and bodily distress.
To assess individual pain sensitivity, we measured participants' cold ❄️, warm 🔥, and thermal grill ❄️ & 🔥 pain threshold using a special thermode. This enabled us to construct a thermal pain profile for each participant, spanning veridical and illusory pain sensitivity.
January 11, 2024 at 10:32 AM
To assess individual pain sensitivity, we measured participants' cold ❄️, warm 🔥, and thermal grill ❄️ & 🔥 pain threshold using a special thermode. This enabled us to construct a thermal pain profile for each participant, spanning veridical and illusory pain sensitivity.
We addressed these issues in a new study of mental health symptoms and sensitivity to cold ❄️ and warm 🔥 pain in 260 individuals 👥. Our sample was recruited from Aarhus University and the surrounding community and reflected a wide range of mental health symptoms and pain sensitivity profiles.
January 11, 2024 at 10:31 AM
We addressed these issues in a new study of mental health symptoms and sensitivity to cold ❄️ and warm 🔥 pain in 260 individuals 👥. Our sample was recruited from Aarhus University and the surrounding community and reflected a wide range of mental health symptoms and pain sensitivity profiles.
Studies suggest mental health and pain are closely linked. Chronic pain is a major risk factor for depression, which is also known to reduce acute pain sensitivity. However, this link is obscured by a preponderance of underpowered studies, which have led to conflicting results.
January 11, 2024 at 10:30 AM
Studies suggest mental health and pain are closely linked. Chronic pain is a major risk factor for depression, which is also known to reduce acute pain sensitivity. However, this link is obscured by a preponderance of underpowered studies, which have led to conflicting results.
📄 Our new preprint is out! In a new study of more than 250 individuals, we investigated the link between mental health and sensitivity to acute thermal pain 🌡️😣. Check out the thread below for surprising findings, as well as links to all study materials and code! osf.io/preprints/ps... 🧠📈 #psychology
January 11, 2024 at 10:28 AM
📄 Our new preprint is out! In a new study of more than 250 individuals, we investigated the link between mental health and sensitivity to acute thermal pain 🌡️😣. Check out the thread below for surprising findings, as well as links to all study materials and code! osf.io/preprints/ps... 🧠📈 #psychology