Mechanisms of Psychedelics in Neurovascular Coupling: A Latest Research Interpretation

1. Academic Background and Research Motivation

In the past decade, psychedelics such as psilocybin and lysergic acid diethylamide (LSD) have regained high attention in the scientific community due to their rapid and significant efficacy in clinical fields such as depression and substance dependence. An increasing number of clinical trials have indicated that psychedelics can significantly alleviate mood disorders and addiction-related diseases, making the exploration of their mechanisms a new hotspot in psychiatry and neuroscience.

Currently, research on the neural mechanisms of psychedelics mostly focuses on their regulation of neurons, especially the activation of the 5-hydroxytryptamine 2A receptor (5-HT2A receptor, 5-HT2AR) in the brain. Numerous functional magnetic resonance imaging (fMRI) studies have shown that psychedelics cause dramatic reorganization of brain functional networks, such as changes in the default mode network (DMN) and enhanced whole brain resting-state functional connectivity (RSFC). These findings have led scholars to commonly interpret fMRI signal changes as direct regulation of neuronal activity by psychedelics.

However, it is noteworthy that serotonin itself has strong vasoactive effects, which can directly modulate cerebral microcirculation. At the same time, changes in blood flow detected in fMRI are interpreted as neural activity, but may actually reflect the effects of psychedelics on vasculature or neurovascular coupling (NVC), rather than solely neuronal changes. Therefore, how to distinguish the sources of neuronal and vascular signals under the action of psychedelics, and to avoid misinterpreting vascular effects as neural activity, is a major scientific issue in the study of psychedelic brain mechanisms.

2. Paper Information and Authors

This research paper, titled “psychedelic 5-ht2a receptor agonism alters neurovascular coupling and differentially affects neuronal and hemodynamic measures of brain function”, was published in the top international journal Nature Neuroscience (Volume 28, November 2025). The work was jointly completed by scholars Jonah A. Padawer-Curry, Oliver J. Krentzman, Chao-Cheng Kuo, Xiaodan Wang, Annie R. Bice, Ginger E. Nicol, Abraham Z. Snyder, Joshua S. Siegel, Jordan G. McCall, and Adam Q. Bauer, mainly from Washington University and other leading research institutions in the United States.

3. Detailed Description of Research Work and Workflow

1. Study Design and Methodological Innovation

To thoroughly answer whether the effects of psychedelics on brain function originate from changes in neurovascular coupling, the authors conducted a multi-level, multi-modal research:

(1) Reanalysis of Human fMRI Data

First, the authors reanalyzed published human fMRI data involving different subjects under conditions of receiving the psychedelic psilocybin, methylphenidate (as a drug control), or no compound, while performing an auditory-visual matching task. Using a “double gamma function” model, the authors modeled and compared the key parameters of the hemodynamic response functions (HRF) in different brain regions, including peak, dispersion, and time to peak (TTP). The results revealed that psychedelics significantly altered HRF parameters in most brain regions, suggesting that the information transfer relationship between neurons and vessels was affected under psychedelic intervention, and that the NVC mechanism may be disrupted.

(2) Mouse Wide-Field Optical Imaging (WFOI)

To further clarify the mechanism by which psychedelics affect NVC, the researchers developed an innovative mouse wide-field optical imaging platform (WFOI). This method enables simultaneous, high spatiotemporal resolution acquisition of cortical excitatory neuronal activity and hemodynamic signals by expressing the red-shifted genetically encoded calcium indicator JRGECO1a in the mouse cortex (primarily reporting transient calcium activity of excitatory neurons, i.e., action potential-induced calcium signals), combined with hemoglobin absorption spectra monitoring. The experimental subjects were Thy1-JRGECO1a transgenic mice in an awake state after behavioral acclimation, with a total of 8 mice.

The experimental process included: - Cortical imaging behavioral acclimation (7 days, 45 minutes per day); - Each mouse randomly received injections of the following compounds and was imaged: saline (control), DOI (2,5-dimethoxy-4-iodoamphetamine, a psychedelic), MDL100907 (selective 5-HT2AR antagonist), DOI+MDL100907; additionally, groups with Lisuride (non-hallucinogenic 5-HT2AR agonist) were included; - After injection, cortical calcium signals and hemodynamic signals were recorded for up to 30 minutes in both stimulation experiments (whisker stimulation) and resting states.

The experiment employed motion tracking and pupillometry to control for animal movement, with custom algorithms to correct the influence of hemoglobin absorption on fluorescence signals, and analyzed the time-frequency dynamics of neurovascular coupling.

(3) Pharmacological Validation and Algorithmic Analysis

The authors used induced head-twitch response (HTR) in mice to confirm the hallucinogenic dosage of DOI, and verified the specificity of JRGECO1a calcium signals using ex vivo electrophysiology and high-frequency filtering methods (excluding interference of DOI-induced slow intracellular calcium increase on calcium signals), ensuring that comparative analysis truly reflects action-potential-related responses of excitatory neurons.

For data analysis, weighted least squares deconvolution was used to establish a causal and linear system model between neuronal activity (calcium signals) and hemodynamic signals, analyzing features of HRFs, frequency domain transfer characteristics, and key parameters such as peak, TTP, full-width at half maximum (FWHM). For functional connectivity (RSFC), community detection analysis and correlation statistics were used to comprehensively compare calcium signals and hemodynamic signals in different brain regions’ resting-state network structures.

2. Detailed Interpretation of Major Research Results

(1) Acute Effects of Psychedelics Alter Hemodynamic Responses in Human Subjects’ Brain Regions

Analysis showed that psilocybin led to a reduction in HRF time to peak in multiple brain regions (except the right visual area), as well as reductions in response dispersion and peak in some regions, reflecting a significant shift in the correspondence between hemodynamics and neuronal activity under psychedelic exposure.

(2) DOI-Induced Spatiotemporal Decoupling Between Cortical Neuronal and Hemodynamic Signals in Mice

In whisker stimulation experiments, DOI significantly weakened action-potential-related calcium signals in certain brain regions (such as retrosplenial and motor areas), while hemodynamic signals showed contrasting changes (such as enhancement in auditory cortex and reduction in motor cortex), indicating DOI caused spatial decoupling between calcium and hemodynamic signals. DOI increased peak and sustained calcium response of excitatory neurons, but the corresponding hemodynamic response was markedly decreased and even became negative (reflected by decreased oxygenation and increased deoxygenation).

(3) DOI Significantly Alters Neurovascular Coupling Model and Response Function Morphology

Deconvolution analysis showed that DOI caused stimulus-evoked HRF to narrow significantly (FWHM reduction) and enhanced the transfer of neuronal activity above 0.5 Hz into subsequent hemodynamics. At rest, DOI led to the emergence of an “acausal peak” in whole brain HRFs (i.e., hemodynamic activity seemed to precede neuronal activity), suggesting a new neurovascular/vasculoneural coupling mechanism with non-classical causality.

(4) Calcium Signal and Hemodynamic Signal “Measurement Uncertainty” in RSFC Network Structure

In resting-state analysis, DOI caused cortical calcium signal power in different regions to exhibit interval increases and decreases in low and high frequency bands, but the distribution of changes in hemodynamic signals was markedly different. For example, DOI increased low-frequency calcium fluctuations in the prefrontal and cingulate cortex, while promoting hemodynamic signal enhancement in the somatosensory cortex. The two showed distinct opposition and separation in topographical distribution.

Further community analysis revealed that DOI not only led to functional connectivity strength (such as between prefrontal cortex and cingulate cortex) reported by hemodynamics and calcium signal being “completely different”, but also displayed decoupling in network boundaries and modular scores (calcium signals showed modularity enhancement in certain regions, while hemodynamic signals did not exhibit corresponding changes).

(5) Most DOI Effects Can Be Reversed by 5-HT2AR Antagonist MDL100907

In the DOI with MDL co-administration group, most changes in neurovascular coupling and signal decoupling induced by DOI were restored, further confirming that these effects mainly depend on the 5-HT2AR pathway. However, some DOI effects were not completely reversed, suggesting possible involvement of other receptors and pathways.

(6) Non-Hallucinogenic Lisuride and Low-Dose DOI Do Not Change NVC or Network Structure

Lisuride, as a partial agonist, has limited influence on 5-HT2AR signaling and blood flow, and low-dose DOI does not significantly change NVC and RSFC structure in brain regions, highlighting a dose-effect relationship between hallucinogenic intensity and vascular mechanism modulation.

(7) DOI May Induce Brain Region-Specific Vasculoneural Coupling (VNC)

In some brain areas, DOI rendered HRF to exhibit characteristics of hemodynamic activity leading calcium signal, suggesting the existence of specific mechanisms for blood flow to retrogradely regulate neuronal activity, such as nitric oxide (NO)-mediated vasodilation/constriction, stretch-sensitive ion channel activation, etc. This offers new biological hypotheses and experimental approaches for understanding psychedelic regulation of brain function.

3. Research Conclusions and Scientific & Applied Value

This work systematically confirms for the first time that the acute effects of psychedelics not only directly regulate neuronal activity, but fundamentally reshape neurovascular coupling mechanisms, making conventional interpretations of neuronal activity through hemodynamic indicators (like fMRI) more complex and “uncertain.” This finding has paradigm-shifting significance for cognitive understanding of psychedelic neural mechanisms, reminding related fields to seriously consider vascular and neurovascular factors when interpreting psychedelic brain imaging results.

On the application level, the research also provides scientific foundation for future psychiatric treatments, clinical applications of psychedelics, and innovations in imaging analysis methods. For example, using multimodal synchronous detection (such as simultaneous EEG-MRI acquisition) and high temporal resolution optical imaging in human fMRI studies can better separate sources of neuronal and vascular signals, avoid misinterpretation and clinical decision errors.

4. Research Highlights and Innovations

• Achieved, for the first time, simultaneous, high-resolution adaptive imaging of cortical neuronal and blood flow signals, opening a new technical direction for dynamic quantification of neurovascular coupling in animal models;
• Systematically explained the region-specific and frequency-specific regulatory mechanisms of psychedelics on neurovascular coupling, revealing new patterns of nonlinear and acausal coupling induced by psychedelics;
• Through pharmacological intervention experiments (combined MDL antagonist and non-hallucinogenic Lisuride), finely differentiated the independent role of the 5-HT2AR pathway in NVC regulation;
• Established a new paradigm for vascular signal interpretation and network function analysis in psychedelic-related research, providing methodological recommendations for future brain mechanism and clinical studies.

5. Other Important Information and Outlook

The study also discussed experimental limitations, such as cell-type restrictions due to genetic indicator expression, effects of animal movement stress, and that current NVC models make causality and linearity assumptions which simplify actual complexity.

For future directions, the authors suggest introducing indicatiors for more cell types, multimodal imaging, synchronous EEG-optical acquisition, etc., to comprehensively reveal the interaction between psychedelics, brain microcirculation, and neural information processing. At the same time, more comprehensive pharmacological intervention tests, multi-dose group design, and consideration of sex and compound diversity will enrich the understanding of psychedelic mechanisms.

5. Research Significance and Scientific Value Summary

This study advances both basic mechanisms and technological innovation, providing new perspectives and theoretical foundations for the scientific mechanisms of psychedelics acting on the brain. It expands the methodological boundaries of psychedelic brain research, inspires new therapeutic approaches and imaging tool development for related diseases in the future, and prompts the broader neuropsychiatric field to more comprehensively understand the complex neurovascular coupling and information flow dynamics of the brain.