Naturalistic Visual Search After Childhood Hemispherectomy
Abstract number :
3.085
Submission category :
11. Behavior/Neuropsychology/Language / 11B. Pediatrics
Year :
2025
Submission ID :
1165
Source :
www.aesnet.org
Presentation date :
12/8/2025 12:00:00 AM
Published date :
Authors :
Presenting Author: Maria Chroneos, BA – Carnegie Mellon University and University of Pittsburgh
J. Patrick Mayo, PhD – University of Pittsburgh School of Medicine
Marlene Behrmann, PhD – University of Pittsburgh School of Medicine
Rationale: Smooth pursuit (slow motion tracking) and saccades (fast fixation shifts) bridge the sensorimotor and cognitive components of the visual system, integrating incoming information for use in higher-order cognition. Childhood hemispherectomy patients have persistent deficits in these eye movements and show differences in visuo-cognitive tasks (Troost 1972, Chroneos et al, under revision, Pinabiaux 2022, Granovetter 2024). While visual-cognitive abilities rely on eye movements, the consequences of basic oculomotor deficits for atypical visual behaviors are rarely considered. Furthermore, how eye movement differences impact behavior in more naturalistic contexts is also not understood. Investigating these relationships is crucial for improved understanding of the functional outcomes of epilepsy, surgery, and developing interventions. Here, using a naturalistic paradigm, we measured visual search behavior in childhood hemispherectomy patients.
Methods: We tested 17 patients with left (n = 9) or right (n = 8) childhood hemispherectomy to treat intractable seizures (Mean Test Age: 15.8 years, Mean Surgery Age: 5.1 years). In twelve 12-second videos of computer characters walking in a school hallway (Pamir, 2024), repeated 1-4 times, patients tracked the target (“the principal”) walking right or left. Patients indicated detecting her with a button press. Eye movements were measured with an Eyelink 1000 Plus and patients’ heads stabilized with a chinrest.
Results: While participants reported seeing the target on 90% of trials, preliminary results suggest they fixated only minimally directly on the target. The eyes were continuously on target for 150 milliseconds or more in only 54% of trials, despite moving in tandem with target motion. We thus calculated average time spent leading or lagging the target when it was visible. Patients spent significantly less time leading (42.5%) than lagging (57.5%) (Wilcoxon signed rank test: V = 140, p = 0.001). Both surgery groups showed this difference (both p > 0.025), but neither target direction showed a leading versus lagging time difference (both p > 0.05).
Conclusions: Prior studies of pursuit of simple targets show that hemispherectomy patients lag targets, especially toward the side of surgery. Here, patients’ eyes lagging the target may reflect this oculomotor deficit. The lack of differences for pursuit direction here, however, might indicate that patients rely on different strategies in more realistic tasks. Future directions include quantifying gaze error, characterizing the pursuit nature (smooth vs saccadic) by direction, and comparison to controls. To our knowledge, this is the first study of visual search after hemispherectomy using a more naturalistic task. Our results have implications for the functional consequences of epilepsy and epilepsy surgery on visual behavior.
Funding: MZC: 1F30EY035942 from NIH NEI, T32GM144300 NIH NIGMS, Rita Levi Montalcini Scholarship, Dompe Foundation. MB, JPM: P30 CORE award EY08098, NEI. Funds from The Research to Prevent Blindness Inc, NY, and the Eye & Ear Foundation of Pittsburgh. MB: R01EY027018, NIH NEI
Behavior