Page 69 - MEGIN Book Of Abstracts - 2023

Language Neuroplasticity in Brain Tumor Patients with the right hemisphere performing similar computa-
Revealed by Magnetoencephalography (2020) tions as the left hemisphere typically performs.

Piai, Vitória; De Witte, Elke; Sierpowska, Joanna; Zheng, Journal of cognitive neuroscience (2020), Vol. 32, No. 8
Xiaochen; Hinkley, Leighton B; Mizuiri, Danielle; Knight, (32286133) (7 citations)
Robert T; Berger, Mitchel S; Nagarajan, Srikantan S

Radboud University Medical Center, Nijmegen, the Neth- The impact of high functional connectivity network
erlands; University of California, San Francisco; Radboud hub resection on language task performance in
University, Nijmegen, the Netherlands; University of Califor- adult low- and high-grade glioma (2020)
nia, Berkeley
Lee, Anthony T; Faltermeier, Claire; Morshed, Ramin
ABSTRACT Little is known about language impairment A; Young, Jacob S; Kakaizada, Sofia; Valdivia, Claudia;
in brain tumor patients, especially in the presurgical Findlay, Anne M; Tarapore, Phiroz E; Nagarajan,
phase. Impairment in this population may be missed Srikantan S; Hervey-Jumper, Shawn L; Berger, Mitchel S
because standardized tests fail to capture mild deficits.
Additionally, neuroplasticity may also contribute to Department of Neurological Surgery and; Biomagnetic Imag-
minimizing language impairments. We examined 14 ing Laboratory, Department of Radiology and Biomedical
presurgical patients with brain tumors in the language- Imaging, University of California, San Francisco, California
dominant hemisphere using magnetoencephalogra-
phy (MEG) while they performed a demanding picture- OBJECTIVE Gliomas are intrinsic brain tumors with the
word interference task, that is, participants name hallmark of diffuse white matter infiltration, resulting
pictures while ignoring distractor words. Brain tumor in short- and long-range network dysfunction. Preop-
patients had behavioral picture-naming effects typi- erative magnetoencephalography (MEG) can assist in
cally observed in healthy controls. The MEG responses maximizing the extent of resection while minimizing
also showed the expected pattern in its timing and morbidity. While MEG has been validated in motor
amplitude modulation typical of controls, but with an mapping, its role in speech mapping remains less well
altered spatial distribution of right hemisphere sources, studied. The authors assessed how the resection of
in contrast to the classic left hemisphere source found intraoperative electrical stimulation (IES)-negative, high
in healthy individuals. This finding supports tumor- functional connectivity (HFC) network sites, as identi-
induced neural reorganization of language before fied by MEG, impacts language performance.
surgery. Crucially, the use of electrophysiology allowed
us to show the "same" neuronal response in terms of its METHODS Resting-state, whole-brain MEG recordings
timing and amplitude modulation in the right hemi- were obtained from 26 patients who underwent peri-
sphere, supporting the hypothesis that the processes operative language evaluation and glioma resection
performed by the right hemisphere following reorga- that was guided by awake language and IES mapping.
nization are similar in nature to those (previously) per- The functional connectivity of an individual voxel was
formed by the left hemisphere. We also identified one determined by the imaginary coherence between the
participant with a fast-growing tumor affecting large index voxel and the rest of the brain, referenced to its
parts of critical language areas and underlying ventral contralesional pair. The percentage of resected HFC
and dorsal white matter tracts who showed a deviant voxels was correlated with postoperative language out-
pattern in behavior and in the MEG event-related re- comes in tasks of increasing complexity: text reading,
sponses. In conclusion, our results attest to the validity 4-syllable repetition, picture naming, syntax (SYN), and
of using a demanding picture-naming task in presurgi- auditory stimulus naming (AN).
cal patients and provide evidence for neuroplasticity,

 ontents  Index 48
C