P11.06.A NEUROPLASTIC CHANGES IN VISUAL NETWORK CONNECTIVITY AND VISUAL COGNITIVE FUNCTIONING IN BRAIN TUMOR PATIENTS WITH LESIONS IN THE OPTIC RADIATION
Authors: Rosengarth K , Hense K , Deuter D , Bumes E , Lenglinger M , Doenitz C , Hau P , Schmidt N 
Published: October 2024

Abstract

BACKGROUND
The influence of brain tumors along important structures of the visual pathway on the overall organization of the visual system and visual cognitive functioning is not fully understood. To address this, the influence of a brain tumor infiltrating the optic radiation (OR) on the functional connectivity in the visual network and on specific visual cognitive functions was investigated.

MATERIAL AND METHODS
fMRI data of 145 patients (69 female, M = 54.15 y) with brain tumors (96 left hemisphere, 49 right hemisphere) were included in this study. Patients were either assigned to a group with tumors inside (69 patients) or outside (76 patients) the area of the OR. A word generation task served as fMRI paradigm, as this reliably addresses the visual system through the visual presentation of stimuli in written form. Based on these data, seed-to-voxel functional connectivity was calculated using the CONN toolbox. Seed regions of interest were located in the bilateral calcarine cortex (CC), occipital poles (OP), and lateral occipital cortex (LOC). Neuropsychological testing included Rey-Osterrieth Complex Figure - Copy and 30min Recall, Trail Making Test A and Digit Symbol Coding, and Corsi Block Span task.

RESULTS
The results showed that patients with tumors distant from the OR had significant higher connectivity regarding all four ROIs compared to patients with tumors located in the projection zone of the OR. Significant connectivity clusters included parts of the left planum temporal, Heschl’s gyrus, parietal operculum, and central opercular cortex for the CC (p =.013), OP (p &lt;.001), and LOCR (p &lt;.001) seed ROIs. Also, the left lateral occipital cortex was included in the significant connectivity clusters of the OP and LOCR seeds, while the same area of the right hemisphere was significant for the LOCL ROI (p =.045). To evaluate hemispheric effects, the patients were subdivided according to their tumor-affected hemisphere. The results yieled comparable significant connectivity profiles as the entire patient sample. Additionally, patients with tumors in the projection zone of the OR showed lower percentile ranks in the Rey-Osterrieth Complex Figure - Copy (p =.048) and Rey-Osterrieth Complex Figure - 30min Recall (p =.005) tests. There was also a trend in the Digit Symbol Coding test (p =.081), while both patient groups showed comparable results in the Trail Making Test A and Corsi Block Span task.

CONCLUSION
This study showed differences in functional connectivity within the visual network and visual cognitive functioning suggesting not only primary visual areas but also higher visual areas appear to be affected in patients with tumors in the OR. These patients also showed reduced performance in visuo-constructive functions, visual memory, and visuo-motor speed. The results indicate that deficits can exist throughout different domains, which emphasizes the complexity of the visual system.