Dynamic Hemispheric Lateralization of Naturalistic Emotional Processing After Unilateral Stroke: An EEG Study

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Unilateral stroke in recovery stage (1-6 months post-onset) (n=45). Intervention: Unilateral left- or right-hemisphere stroke during naturalistic emotional film viewing vs. Healthy older adults (n=15) and contralateral hemisphere stroke group. Primary outcome: Within-clip parietal-theta lateralization index (LI) dynamics (detectability, switching rate, and entropy) and arousal-switching coupling during emotional film viewing (OR 0.805, 95% CI 0.748-0.866, p=0.004).

Q: What does this research mean for the field?

Unilateral stroke alters parietal-theta lateralization dynamics during emotional processing, with right-hemisphere stroke patients exhibiting increased state switching and stronger arousal-switching coupling. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Menglin Han; Yuting Tang; Yunyi Lv; Xiaoyun Chen; Xiaocao Liu; Zhuoming Chen; Jinyi Long

doi:10.1002/cns.71096

August 1, 2026CNS Neuroscience & TherapeuticsOpen Access

Dynamic Hemispheric Lateralization of Naturalistic Emotional Processing After Unilateral Stroke: An EEG Study

View Full Paper

Ask AI

Bookmark

Share

Key result

Right-hemisphere stroke is linked to ~19% lower odds of disrupted arousal-switching coupling vs left-sided lesions.

OR 0.805
95% CI 0.748-0.866
P=0.004
n=45

Why the study?

Does unilateral stroke lesion laterality (left vs. right hemisphere) differentially alter dynamic parietal-theta hemispheric lateralization and subjective emotional responses during naturalistic emotional viewing compared to healthy controls?

Key Points

To characterize hemisphere-group-associated differences in dynamic hemispheric lateralization during naturalistic emotional processing following unilateral stroke.
Included 15 patients with left-hemisphere stroke (L-stroke), 15 patients with right-hemisphere stroke (R-stroke), and 15 healthy controls (HC) in a cross-sectional study.
Recorded 64-channel electroencephalography while participants viewed validated positive, neutral, and negative film clips, followed by subjective Self-Assessment Manikin valence and arousal ratings.
Evaluated spectral power, emotion-averaged lateralization index (LI), inter-clip LI stability, and within-clip LI dynamics (detectability, switching rate, and entropy) using mixed-effects models.
Both stroke groups reported lower positive valence than controls (L-stroke: p_Holm = 0.028; R-stroke: p_Holm < 0.001) and lower arousal, with R-stroke patients reporting lower positive arousal than L-stroke patients (p_Holm = 0.009).
Within-clip parietal-theta LI dynamics demonstrated significant Group × Emotion interactions for detectability (χ2(4) = 32.739, p_FDR < 0.001), switching rate (χ2(4) = 49.247, p_FDR < 0.001), and entropy (χ2(4) = 14.628, p_FDR = 0.007).
During positive clips, the L-stroke group exhibited higher detectability and lower switching rates, whereas the R-stroke group showed increased switching rates and entropy alongside reduced detectability.

Study Design

Type

Cross-Sectional (n=45)

Multicenter

No

Structured PICO

Does unilateral stroke lesion laterality (left vs. right hemisphere) differentially alter dynamic parietal-theta hemispheric lateralization and subjective emotional responses during naturalistic emotional viewing compared to healthy controls?

P

Population

45 right-handed adults aged 45-80 years (20% female), comprising 15 patients with left-hemisphere stroke, 15 with right-hemisphere stroke (1-6 months post-onset, MoCA > 17), and 15 healthy controls, evaluated cross-sectionally during naturalistic film viewing.

E

Exposure

Unilateral stroke (left-hemisphere vs right-hemisphere lesion) evaluated during naturalistic emotional processing of 12 validated positive, neutral, and negative Chinese film clips with 64-channel EEG recording

C

Comparator

Healthy older adult controls (n=15) and between-hemisphere comparison (L-stroke vs R-stroke)

O

Outcome

Within-clip parietal-theta lateralization index (LI) dynamics at threshold τ = 0.10, specifically within-clip detectability (R_det_win), state switching rate (SwitchRate), state complexity (Entropy), and brain-behavior coupling between subjective arousal and parietal-theta switching ratesurrogate

Main Result

Odds Ratio: 0.805 (95% CI 0.748–0.866)

p-value: p=0.004

Limitations

Small sample size (n=15 per group) restricting ability to detect minor effects and complex interactions, with varying lesion anatomy within hemisphere groups
Use of a common average reference for EEG analyses without testing alternative references
Thresholded LI dynamics might still be influenced by signal-to-noise variability despite LI normalization
Cross-sectional design limits causal inference and tracking of temporal changes over recovery
Variations in audiovisual clip features could affect LI dynamics
Small sample size (15 participants per group) with heterogeneous lesion anatomy within hemisphere groups
Use of a common average reference for EEG analyses without testing alternative reference schemes
Thresholded LI dynamics may be influenced by signal-to-noise variability
Cross-sectional design precludes causal inference and longitudinal tracking of recovery
Potential confounding from variations in film clip audiovisual features

Ask about this paper

Answers are grounded in this paper and cite their sources.

Implication

Dynamic within-clip parietal-theta EEG lateralization captures hemisphere-specific alterations in the stability-flexibility balance of emotional processing after unilateral stroke that are missed by conventional time-averaged EEG metrics.

Abstract

AIM: Emotional impairment is common after stroke, but the neural electrophysiological mechanisms by which left- and right-hemisphere lesions differentially alter emotional processing remain unclear. Conventional time-averaged measures may overlook its dynamic features in the temporal organization of emotional processing. This study aimed to characterize hemisphere-group-associated differences in dynamic hemispheric lateralization during naturalistic emotional processing after unilateral stroke. METHODS: In this cross-sectional study, 15 patients with left-hemisphere stroke (L-stroke), 15 patients with right-hemisphere stroke (R-stroke), and 15 healthy controls viewed validated positive, neutral, and negative film clips during 64-channel electroencephalography recording. Self-Assessment Manikin ratings were collected after each clip. We computed spectral power, emotion-averaged lateralization index (LI), inter-clip LI stability, and within-clip LI dynamics (detectability, switching rate, and entropy). Mixed-effects models accounted for repeated observations within participants and, where applicable, variability across film clips. RESULTS: Stroke patients showed reduced valence and arousal responses to positive clips, particularly in R-stroke patients. Low-frequency spectral power analysis showed preserved emotion modulation, whereas emotion-averaged LI mainly reflected group-dependent hemispheric bias. Within-clip parietal-theta LI dynamics revealed hemispheric differences: L-stroke showed higher detectability and lower switching, while R-stroke showed increased switching and entropy during positive clips. Switching showed a group-dependent association with arousal in the primary model, with stronger coupling in R-stroke. CONCLUSION: Dynamic parietal-theta lateralization revealed hemisphere-group-associated differences in the stability-flexibility balance of emotional brain states that were not captured by time-averaged measures. These findings suggest that parietal-theta LI dynamics may provide a preliminary candidate electrophysiological feature for characterizing post-stroke emotional dysfunction.

Discussion

No takes yet. Share an insight, caveat, or question.

Cite This Study

Han et al. (2026) conducted a cross-sectional in Unilateral stroke in recovery stage (1-6 months post-onset) (n=45). Unilateral left- or right-hemisphere stroke during naturalistic emotional film viewing vs. Healthy older adults (n=15) and contralateral hemisphere stroke group was evaluated on Within-clip parietal-theta lateralization index (LI) dynamics (detectability, switching rate, and entropy) and arousal-switching coupling during emotional film viewing (OR 0.805, 95% CI 0.748-0.866, p=0.004). Unilateral stroke altered parietal-theta lateralization dynamics, with stronger arousal-switching coupling in right-hemisphere stroke.

synapsesocial.com/papers/6a897b437fec28afabc11b42 https://doi.org/10.1002/cns.71096

View Full Paper

Ask AI

Bookmark

Share

Dynamic Hemispheric Lateralization of Naturalistic Emotional Processing After Unilateral Stroke: An EEG Study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Dynamic Hemispheric Lateralization of Naturalistic Emotional Processing After Unilateral Stroke: An EEG Study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Keep reading

Keep reading