Multi-modal connectivity of the brain underlying visual hallucinations evoked by high-frequency intracranial stimulations
Background: Visual hallucinations are a common symptom in patients with epilepsy. To the best of our knowledge, there are no studies evidencing the functional and effective networks responsible for different characteristics of these manifestations. Objective/hypothesis: In this study we aim to perfo...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-07-01
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| Series: | Brain Stimulation |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1935861X25002505 |
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| Summary: | Background: Visual hallucinations are a common symptom in patients with epilepsy. To the best of our knowledge, there are no studies evidencing the functional and effective networks responsible for different characteristics of these manifestations. Objective/hypothesis: In this study we aim to perform a multi-modal characterization of the networks underlying visual hallucinations that could be used for clinical purposes. Methods: Patients suffering from drug-resistant epilepsy in whom visual hallucinations were elicited by alternating polarity high frequency stimulation (AP-HFS) during stereo-EEG were included. The responses were further classified in 14 clinical categories. We used three methods to characterize functional (FC) and effective connectivity (EC) underlying these clinical responses: non-linear regression analysis using h2 correlation coefficient (FC), magnitude of evoked responses (high-frequency activation – HFA) and phase-locking value (PLV) during stimulation (EC). Results: We selected 64 consecutive patients in which we applied the AP-HFS and in 22 patients we elicited 130 visual hallucinations. The majority of visual hallucinations were elementary (n = 112), plus (n = 111), static (n = 82), continuous (n = 83) and non-color (n = 74). HFA method shows the highest magnitude of evoked responses in the primary visual cortex and lingual gyrus. PLV analysis reveals a posterior-anterior gradient of connectivity involving both dorsal and ventral stream. The h2 FC highlights the remote prefrontal networks involved in cognitive processing of visual information. Conclusions: We evidenced the networks underlying visual hallucinations with different clinical characteristics. These networks are particularly important for planning stereo-EEG explorations in patients with drug-resistant epilepsy and for functional prognosis in posterior acquired lesions and after surgical resections. |
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| ISSN: | 1935-861X |