Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.08.23.554467

Conditioned pain modulation of pressure pain is associated with reduced activation in the parietal operculum and posterior insula

Ojala, K. E.·Chu, Y.·Finsterbusch, J.·Büchel, C.
View original source ↗Export metadata ↓

Abstract

Conditioned pain modulation (CPM) is the phenomenon of pain inhibiting further pain. CPM is impaired in patients suffering from various chronic pain conditions and may resemble a pro-nociceptive profile. A possible neural mechanism for CPM is descending control from cortical regions via brainstem that modulates neural activity at the level of the dorsal horn of the spinal cord where noxious input first arrives. We studied the involvement of the descending pain modulatory pathway by simultaneous functional imaging of the brain, brainstem, rostral medulla, and cervical spinal cord during CPM with pressure cuff algometry in 42 healthy human participants. Subjective CPM as measured by decreased pain ratings developed over the experiment with application of repeated short test stimuli for long conditioning pain compared with non-painful conditioning. Test stimuli paired with painful conditioning were associated with decreased BOLD fMRI activity in the parietal operculum (secondary somatosensory cortex) and posterior insula, as well as increased responses in bilateral primary somatosensory cortices. Subjective CPM reflected in pain ratings was associated with decreased test stimulus responses in somatosensory and pain-responsive brain regions such as the anterior and posterior insula and the parietal operculum. Conditioning pain and test pain were associated with increased neural activity in stimulus-ipsilateral spinal cord dorsal horn at segment C6 and C4, respectively. No evidence for neural correlates of CPM or associations with subjective CPM was observed in the spinal cord. Functional connectivity between the brain and spinal cord was altered during both conditioning and test pain but did not depend on conditioning intensity. Taken together, we observed neural activity associated with both negative (CPM) and positive modulation of pain in different somatosensory and pain-associated brain regions, and an association of these and other neural responses with subjective CPM. While we found that painful stimuli altered the connectivity along the descending pain modulatory pathway, we did not find evidence for a modulation by conditioning intensity nor neural correlates of CPM in the spinal cord.

Explore related subjects

neurosciencePreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ojala, K. E., Chu, Y., Finsterbusch, J., Büchel, C.. 2023-08-24. Conditioned pain modulation of pressure pain is associated with reduced activation in the parietal operculum and posterior insula. https://doi.org/10.1101/2023.08.23.554467

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

The Unreasonable Effectiveness of Cell Types in Describing Neuronal Physiological Features

Single-cell RNA sequencing (scRNA-seq) captures detailed gene expression profiles at scale, while patch-clamp recordings measure intrinsic neuronal electrophysiological properties. Modeling the relations between these two modalities remains a challenge. Here, we compare how well electrophysiological features can be predicted by traditional transcriptomic cell type classification, representations derived from a foundational model (scGPT) pretrained on large-scale scRNA-seq datasets, ion channel-coding genes, and highly variable genes. Using paired transcriptomic and electrophysiological patch-sequencing data from 495 human neurons from neurosurgical tissue, we find that cluster-level cell type representations consistently outperform highly variable gene selection, ion channel gene selection, and context-enriched scGPT embeddings. Notably, performance varies across model architectures and initializations, and the best results are obtained by combining the outputs of separate cell type and scGPT-based models. Together, these findings suggest that traditional discrete cellular classification is highly effective in predicting physiological features. For maximum performance it can be complemented by pretrained transformer models.

neuroscience↗
bioRxiv2026

A nonlinear inhibition pathway underlying cortical responses to tuned holographic optogenetic perturbations

Optogenetics enables causal manipulation of cortical activity. Perturbation responses can be counterintuitive due to network interactions, making theory essential for predicting them. Existing approaches often rely on linear approximations, which fail for many biologically relevant perturbations. Here we develop a nonlinear theory of responses to holographic perturbations in cell-type-specific recurrent networks with structured connectivity. We fit a nonlinear model to mouse V1 data, which shows cotuned-ensemble suppression: perturbing spatially clustered neurons with similar preferred orientations yields markedly stronger short-range suppression than perturbing untuned ensembles. We show that cotuned-ensemble suppression arises from a feature-tuned, nonlinear inhibition pathway implicating somatostatin-positive (SST) interneurons. The theory predicts that cotuned ensembles suppress parvalbumin-positive (PV) neurons but facilitate SST neurons, and links the degree of cotuned-ensemble suppression or facilitation to the variance of the SST response. This framework identifies mechanisms by which nonlinear inhibition sculpts cortical dynamics and establishes a predictive basis for targeted optogenetic interventions.

neuroscience↗
bioRxiv2026

Proteomic signatures of APOE ε4 across human tissues and cell types in Alzheimers disease

The apolipoprotein E {varepsilon}4 (APOE {varepsilon}4) allele is the strongest genetic risk factor for late-onset Alzheimers disease (AD). However, the underlying molecular mechanisms remain unclear. This study included 1691 participants from the Religious Orders Study and Rush Memory and Aging Project (ROSMAP), 1226 participants from the Accelerating Medicines Partnership - Alzheimers Disease (AMP-AD) Diverse Cohorts Study, and 735 participants from the Alzheimers Disease Neuroimaging Initiative (ADNI). To characterise APOE {varepsilon}4 molecular effects, we analysed proteomic data from plasma, cerebrospinal fluid (CSF), and induced pluripotent stem cell (iPSC)-derived astrocytes and neurons, as well as transcriptomic and proteomic data from multiple brain regions. The association of APOE {varepsilon}4 with AD neuropathology was also examined. APOE {varepsilon}4 carriers shared a plasma proteomic signature enriched for immune processes, irrespective of AD diagnosis. A machine learning classifier trained on this signature discriminated APOE {varepsilon}4 carriers from non-carriers in an independent cohort using CSF proteomics. APOE {varepsilon}4 carriage was associated with higher Braak stages and Consortium to Establish a Registry for Alzheimers Disease (CERAD) score. However, only limited APOE {varepsilon}4-associated transcriptomic and proteomic changes were observed in bulk brain tissue, with poor cross-layer concordance. Proteomic analyses of iPSC-derived astrocytes and neurons further revealed cell-type-specific APOE {varepsilon}4-associated changes. APOE {varepsilon}4 is associated with a consistent proteomic signature across plasma and CSF. Its molecular effects in the brain differ across cell types, brain regions and molecular layers. These findings support the need for cell-type-resolved multi-omic studies to elucidate how APOE {varepsilon}4 confers AD risk.

neuroscience↗