Spatial distribution and hemispheric asymmetry of electrically evoked experiential phenomena in the human brain
Search for other papers by Michal M. Andelman-Gur in
Current site
Google Scholar
PubMed
Search for other papers by Tomer Gazit in
Current site
Google Scholar
PubMed
Search for other papers by Fani Andelman in
Current site
Google Scholar
PubMed
Epilepsy and EEG Unit, and
Search for other papers by Svetlana Kipervasser in
Current site
Google Scholar
PubMed
Pediatric Epilepsy Unit, Tel Aviv Medical Center, Tel Aviv, Israel; and
Search for other papers by Uri Kramer in
Current site
Google Scholar
PubMed
Epilepsy and EEG Unit, and
Search for other papers by Miri Y. Neufeld in
Current site
Google Scholar
PubMed
Functional Neurosurgery Unit,
Department of Neurosurgery, University of California, Los Angeles, California
Search for other papers by Itzhak Fried in
Current site
Google Scholar
PubMed
Epilepsy and EEG Unit, and
Search for other papers by Firas Fahoum in
Current site
Google Scholar
PubMed
OBJECTIVE
Experiential phenomena (EP), such as illusions and complex hallucinations, are vivid experiences created in one’s mind. They can occur spontaneously as epileptic auras or can be elicited by electrical brain stimulation (EBS) in patients undergoing presurgical evaluation for drug-resistant epilepsy. Previous work suggests that EP arise from activation of different nodes within interconnected neural networks mainly in the temporal lobes. Yet, the anatomical extent of these neural networks has not been described and the question of lateralization of EP has not been fully addressed. To this end, an extended number of brain regions in which electrical stimulation elicited EP were studied to test whether there is a lateralization propensity to EP phenomena.
METHODS
A total of 19 drug-resistant focal epilepsy patients who underwent EBS as part of invasive presurgical evaluation and who experienced EP during the stimulation were included. Spatial dispersion of visual and auditory illusions and complex hallucinations in each hemisphere was determined by calculation of Euclidean distances between electrodes and their centroid in common space, based on (x, y, z) Cartesian coordinates of electrode locations.
RESULTS
In total, 5857 stimulation epochs were analyzed; 917 stimulations elicited responses, out of which 130 elicited EP. Complex visual hallucinations were found to be widely dispersed in the right hemisphere, while they were tightly clustered in the occipital lobe of the left hemisphere. Visual illusions were elicited mostly in the occipital lobes bilaterally. Auditory illusions and hallucinations were evoked symmetrically in the temporal lobes.
CONCLUSIONS
These findings suggest that complex visual hallucinations arise from wider spread in the right compared to the left hemisphere, possibly mirroring the asymmetry in the white matter organization of the two hemispheres. These results offer some insights into lateralized differences in functional organization and connectivity that may be important for functional mapping and planning of surgical resections in patients with epilepsy.
ABBREVIATIONS
DTI = diffusion tensor imaging; EBS = electrical brain stimulation; ED = Euclidean distance; EP = experiential phenomena; fMRI = functional MRI; IFG = inferior frontal gyrus; MNI = Montreal Neurological Institute; TLVMC = Tel Aviv Medical Center.Supplementary Materials
- Supplementary Tables 1 and 2 (PDF 434 KB)
Diagram from Kondziolka et al. (pp 1–2).
© Copyright 1944-2023 American Association of Neurological Surgeons