Deviations in effective connectivity explain different hallucination subtypes in Parkinson's disease psychosis.
The 6 matches · 2 of them tie a paragraph to a whole file, not to given lines: weak matches, whose lines are not tinted
- [1] § Methods › Exploratory receptor binding atlases and MMN source-reconstructed signal analysis ↔ eeg-pet_extracting.m, the whole file · a weak match · score 0.89 · NIfTI, receptor density, MMN maps, PET map, alignment, imcalc
- [2] § Methods › Statistical analysis › Linear regressions and LMM for exploratory receptor binding atlases and MMN source-reconstructed signal analysis ↔ eeg-pet_extracting.m, the whole file · a weak match · score 0.69 · NIfTI, receptor density, variable, regional, atlas, MMN
- [3] § Methods › Statistical analysis › Leave one out multiple regression models by hallucination subtype ↔ loocvd-regress_example.r, lines 1–45 · score 0.63 · cross validation, complex VH, regression, predicting, severity, connection
- [4] § Methods › Statistical analysis › Second-level analysis with PEB ↔ pdp_peb_recursive_final_Bmatexample.m, lines 127–139 · score 0.56 · spm_dcm_peb, winning model, bmr
- [5] § Results › vMMN differences correlate with decreased top-down connectivity in PD-VH ↔ pdp_peb_recursive_final_Bmatexample.m, lines 1–43 · score 0.51 · parametrical empirical, Recursive PEB, connected
- [6] § Methods › Statistical analysis › Second-level analysis with PEB ↔ pdp_peb_recursive_final_Bmatexample.m, lines 100–124 · score 0.51 · free energy, recursive PEB, model
Paper
Loaded from Europe PMC by your browser, not stored by OSCR: doi.org · Europe PMC
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The authors' code
MATLAB · 143 lines · 4.7 KB · no license · 3 matches
- %--------------------------------------------------------------------------
- % SECOND-LEVEL ANALYSIS: PARAMETRICAL EMPIRICAL BAYES PEB
- %--------------------------------------------------------------------------
- clear all;
- %--------------------------------------------------------------------------
- % Setup a group DCM
- %-------------------------------------------------------------------------
- % Select all DCM files
- dcms = spm_select ();
- %if cannot find headmodel give path:
- %headmodel = ft_read_headmodel ('/PATH/single_subj_T1_EEG_BEM.mat');
- % turn character array in cell array
- GCM = cellstr ( dcms );
- % DCM filenames -> DCM structures
- GCM = spm_dcm_load (GCM);
- %--------------------------------------------------------------------------
- %if needed load GCM and dm
- load('design_matrix3.mat');
- load('GCM_full3.mat');
- %--------------------------------------------------------------------------
- % Setup of the design matrix
- %--------------------------------------------------------------------------
- %M.Q - choice of precision components: all', the between-subject
- %variability for each DCM connection will be individually estimated.
- M = struct ();
- M.Q = 'all ';
- M.X = X;
- M. Xnames = X_labels;
- %--------------------------------------------------------------------------
- %________________________________ RECURSIVE PEB __________________________%
- %________________________________ MATRIX B _______________________________%
- %--------------------------------------------------------------------------
- clear C PEB F Ep labels fam_idx families
- %% basics for recursive peb
- C_fwd = {'B{1}(3,1)','B{1}(4,2)','B{1}(5,3)','B{1}(6,4)','B{1}(5,1)','B{1}(6,2)'}; % forward conns
- C_bwd = {'B{1}(1,3)','B{1}(2,4)','B{1}(3,5)','B{1}(4,6)','B{1}(1,5)','B{1}(2,6)'}; % backward conns
- C_self = {'B{1}(1,1)','B{1}(2,2)','B{1}(3,3)','B{1}(4,4)','B{1}(5,5)','B{1}(6,6)'}; % self conns (diagonal elements)
- C_lateral = {'B{1}(1,2)','B{1}(2,1)','B{1}(3,4)','B{1}(4,3)','B{1}(5,6)','B{1}(6,5)'}; %lateral/crosshemi
- %% --- Parameter groups definitions (names + sets; no lateral) ---
- %% comment in and out whatever you want, this system does not have issues
- % with N of models used and labels like the previous version
- families = {
- 'B(full extrinsic+self)', [C_fwd, C_bwd, C_self]
- 'B(full)', [C_fwd, C_bwd]
- 'B(forward)', C_fwd
- 'B(backward)', C_bwd
- 'B(forward+self)', [C_fwd, C_self]
- 'B(backward+self)', [C_bwd, C_self]
- 'B(self)', C_self
- 'B(forward+s)', [C_fwd, {'S'}]
- 'B(back+s)', [C_bwd, {'S'}]
- % 'B (cross-hemi)', C_lateral
- 'B(bwd)+G', [[C_bwd], {'S'}]
- 'B(fwd)+G', [[C_fwd], {'S'}]
- 'B(full)+G', [[C_fwd, C_bwd], {'S'}]
- % 'S', {'S'}
- 'G', {'G'}
- 'T', {'T'}
- % 'G+S', {'G','S'}
- };
- K = size(families,1);
- % Normalise labels to a 1xK cell array of char
- raw_labels = families(:,1); % Kx1 (cell or string)
- if isstring(raw_labels) % string array -> cellstr
- labels = cellstr(raw_labels);
- elseif iscell(raw_labels)
- labels = raw_labels;
- else % char array fallback
- labels = cellstr(raw_labels);
- end
- labels = labels(:)';
- %% --- Run PEB for each family ---
- F = nan(K,1);
- PEB = cell(K,1);
- for k = 1:K
- Cset = families{k,2};
- PEB{k} = spm_dcm_peb(GCM, M, Cset);
- F(k) = PEB{k}.F;
- end
- %% --- Winner and plots (Free Energy: bigger is better) ---
- [~, order] = sort(F,'descend');
- best_idx = order(1); second_idx = order(2);
- dF = F(best_idx) - F(second_idx);
- save ('/..../recursive_PEB.mat','PEB');
- figure;
- % Panel 1: ΔF (winner at 0)
- subplot(2,1,1);
- bar(F - max(F));
- ylabel('\DeltaF (model - best)');
- title(sprintf('Family BMC: winner = %s, \\DeltaF_{best-second}=%.2f', ...
- labels{best_idx}, F(best_idx)-F(order(2)))); % <-- single { }
- set(gca,'XTick',1:K,'XTickLabel',labels); xtickangle(45);
- % Panel 2: softmax posteriors
- model_post = spm_softmax(F - max(F));
- subplot(2,1,2);
- bar(model_post);
- ylabel('Model posterior (approx.)');
- title('Family posteriors from Free Energy');
- set(gca,'XTick',1:K,'XTickLabel',labels); xtickangle(45);
- set(gcf,'color','w');
- %% Repeat PEB in the winning model and run BMR
- %--------------------------------------------------------------------------
- [REB, RCM] = spm_dcm_peb(GCM,M, MODEL);
- RMA = spm_dcm_peb_bmc(REB);
- spm_dcm_peb_review (RMA ,GCM);
- % example for other type of model, like second best
- [REB, RCM] = spm_dcm_peb(GCM,M, {'B(full)'});
- RMA = spm_dcm_peb_bmc(REB);
- spm_dcm_peb_review (RMA ,GCM);
pdp_peb_recursive_final_Bmatexample.m at commit e66cacd, no license · at the source
Overview
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
- Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
- Department of Psychology, University of Southampton, Southampton, UK
- Department of Psychology, University of Exeter, Exeter, UK
- Department of Clinical Neurosciences, Herchel Smith Building, University of Cambridge, Cambridge, UK
- University of London, London, UK
- Imperial College London, Faculty of Medicine, Department of Brain Sciences, The Hammersmith Hospital, London, UK
- Parkinson Foundation Centre of Excellence, King’s College Hospital NHS Foundation Trust, London, UK
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Department of Clinical Neurosciences, Parkinson and Movement Disorders Unit, Milan, Italy
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge/Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
Abstract
Psychosis and visual hallucinations (VH) in Parkinson’s disease (PD) substantially impact patient outcomes, yet the underlying neural mechanisms remain unclear, limiting effective treatments. Here we used dynamic causal modeling to leverage the fast temporal dynamics captured with electroencephalography data during a visual mismatch negativity task in people with PD with (N = 20) and without (N = 18) VH to examine effective connectivity. We found reduced top-down and enhanced bottom-up connectivity in ventral visual and prefrontal regions during task performance in PD-VH, suggesting deficits in sensory prediction updating and an overreliance on visual input. Connectivity patterns differed with hallucination complexity, with complex VH being associated with altered top-down and bottom-up right-hemisphere connectivity, and multimodal hallucinations to more widespread bilateral disruption. Increased task activity, as computed with source reconstruction, correlated positively with normative serotonergic 5-HT2A receptor distribution. These findings highlight specific neural targets for early therapeutic interventions, supporting a transdiagnostic computational architecture of hallucinations.
Reproduced under the paper's license (CC BY), from the paper cited above.
Repositories
Its files are read in the Code ↔ Paper reader above, with 6 matches between paragraphs and lines of code.
VMiri/visual-MMN-DCM-
e66cacd71aaa880e0cd8ba74b8926ca369522c40, 3 June 2026Availability: 1 check, the latest on 27 September 2026: the link answers
- 27 September 2026: the link answers
5 files
- brainsmash_code.py, Python, 75 lines
- eeg-pet_extracting.m, MATLAB, 134 lines, 2 matches
- loocvd-regress_example.r
, R, 118 lines, 1 match - pdp_peb_recursive_final_
Bmatexample.m , MATLAB, 143 lines, 3 matches - README.md, Text, 19 lines
OSF umd89
Availability: 1 check, the latest on 27 September 2026: the link answers (HTTP 200)
- 27 September 2026: the link answers (HTTP 200)
3 files
- DCM article code/
brainsmash_code (1).py , Python, 75 lines - DCM article code/
eeg-pet_extracting (1).m , MATLAB, 134 lines - DCM article code/
loocvd-regress_example (1).r , R, 118 lines
Code availability
All the code used in the study is available via GitHub at https://
Reproduced under the paper's license (CC BY), from the paper cited above.
Tracing map
Proposed by the machine: these links were found in the paper and verified at the source, without human review. The map will receive a Zenodo DOI once one of the paper's authors has validated it with their ORCID.
What the map holds:
- 2 repositories of the authors' code, each at its verified commit, with its license and how the link was found in the paper;
- 7 scripts, each with its path and the digest of its content;
- 6 matches between paragraphs of the paper and lines of the code (method lexical-v1);
- neither the text of the paper nor the code itself.
Its JSON (tracing-map.json) is deposited on Zenodo with its DOI once the map is validated.
Data
No dataset and no data link were found in the paper.
Data Availability Statement
The data supporting the analyses presented in the main text is openly available from the King’s College London research data repository, KORDS, at 10.18742/
All the code used in the study is available via GitHub at https://
Reproduced under the paper's license (CC BY), from the paper cited above.
Versions
The history of this record: each version stored by the harvester or made by a correction of its authors or of the maintainers of its code, and what changed in its facts. The texts of the paper (its abstract, its availability statements) are not part of it; versions that changed only those are not listed.
Version 2, 28 September 2026
- Publisher: n/a → Springer Science+Business Media
- Funding: added National Institute for Health and Care Research: (NIHR203312; Department of Health and Social Care; King's College London; University College London; Alzheimer’s Research UK: ARUK-RF2022B-002; NIHR Maudsley Biomedical Research Centre; Medical Research Council: MR/R005931/1, NIHR203312, MR/W029235/1; NIHR Cambridge Biomedical Research Centre: NIHR 203312
Version 1, 27 September 2026: the first record
Recorded: type, language, journal, volume, issue, pages, dates, 13 authors, 3 keywords, 78 references.
Cite
This paper
Vignando, M., Ffytche, D., Mazibuko, N., Palma, G., Bhat, A., Montagnese, M., Dave, S., Tai, Y. F., Batzu, L., Leta, V., Chaudhuri, K. R., Williams Gray, C. H., & Mehta, M. A. (2026). Deviations in effective connectivity explain different hallucination subtypes in Parkinson's disease psychosis. Nature. Mental health, 4(6), 994-1009. https://
BibTeX
@article{vignando2026dev
author = {Vignando, Miriam and Ffytche, Dominic and Mazibuko, Ndabezinhle and Palma, Giulio and Bhat, Anjali and Montagnese, Marcella and Dave, Sonali and Tai, Yen F and Batzu, Lucia and Leta, Valentina and Chaudhuri, K Ray and Williams Gray, Caroline H and Mehta, Mitul A},
title = {{Deviations in effective connectivity explain different hallucination subtypes in Parkinson's disease psychosis}},
journal = {Nature. Mental health},
year = {2026},
month = jun,
volume = {4},
number = {6},
pages = {994--1009},
publisher = {Springer Science+Business Media},
issn = {2731-6076},
doi = {10.1038/
url = {https://
pmid = {42291779},
pmcid = {PMC13259922}
}
RIS
TY - JOUR
AU - Vignando, Miriam
AU - Ffytche, Dominic
AU - Mazibuko, Ndabezinhle
AU - Palma, Giulio
AU - Bhat, Anjali
AU - Montagnese, Marcella
AU - Dave, Sonali
AU - Tai, Yen F
AU - Batzu, Lucia
AU - Leta, Valentina
AU - Chaudhuri, K Ray
AU - Williams Gray, Caroline H
AU - Mehta, Mitul A
TI - Deviations in effective connectivity explain different hallucination subtypes in Parkinson's disease psychosis
T2 - Nature. Mental health
J2 - Nat Ment Health
PY - 2026
DA - 2026/
VL - 4
IS - 6
SP - 994
EP - 1009
SN - 2731-6076
PB - Springer Science+Business Media
DO - 10.1038/
UR - https://
LA - en
ER -
CSL-JSON
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