We report our experience regarding evaluation, surgical treatment and outcomes in a population of 21 children with histopathologically confirmed developmental tumours [nine dysembryoplastic neuroepithelial tumours (DNET), ten gangliogliomas (GG) and two gangliocytomas (GC)] and related epilepsy, analyzing video-EEG, MRI and neuropsychological data, before and after surgery. Most children had focal epilepsy correlating well with lesion location. One patient had epileptic spasms and generalized discharges. Tumours were located in the temporal lobe in 13 patients. Mean age at surgery was 11.16 years. Postsurgical MRI showed residual tumour growth in one DNET. One child had a recurrent ganglioglioma with anaplastic transformation. At latest follow-up (mean 4.68 years) 95.2% of patients were seizure-free and no significant neuropsychological declines were observed. Evidence from our study suggests that, in this setting, surgery should be performed before criteria for refractory epilepsy are met, particularly in cases with early seizure onset, in order to optimize cognitive outcome.
Adaptive memory recall requires a rapid and flexible switch from external perceptual reminders to internal mnemonic representations. However, owing to the limited temporal or spatial resolution of brain imaging modalities used in isolation, the hippocampal–cortical dynamics supporting this process remain unknown. We thus employed an object-scene cued recall paradigm across two studies, including intracranial electroencephalography (iEEG) and high-density scalp EEG. First, a sustained increase in hippocampal high gamma power (55 to 110 Hz) emerged 500 ms after cue onset and distinguished successful vs. unsuccessful recall. This increase in gamma power for successful recall was followed by a decrease in hippocampal alpha power (8 to 12 Hz). Intriguingly, the hippocampal gamma power increase marked the moment at which extrahippocampal activation patterns shifted from perceptual cue toward mnemonic target representations. In parallel, source-localized EEG alpha power revealed that the recall signal progresses from hippocampus to posterior parietal cortex and then to medial prefrontal cortex. Together, these results identify the hippocampus as the switchboard between perception and memory and elucidate the ensuing hippocampal–cortical dynamics supporting the recall process.
Adaptive memory recall requires a rapid and flexible switch from external perceptual reminders to internal mnemonic representations. However, owing to the limited temporal or spatial resolution of brain imaging modalities used in isolation, the hippocampal-cortical dynamics supporting this process remain unknown. We thus employed an object/scene cued recall paradigm across three studies, spanning single neuron recordings, intracranial as well as high-density EEG and fMRI. First, a hippocampal gamma power/spike rate increase distinguishing successful vs. unsuccessful recall emerged 500 ms after cue onset. Intriguingly, hippocampal gamma peaks marked the moments at which extrahippocampal activation patterns shifted from perceptual cue towards mnemonic target representations. In parallel, source-localised EEG (corroborated by fMRI) revealed a recall signal progressing from hippocampus to posterior parietal cortex and then to medial prefrontal cortex. These results identify the hippocampus as the switchboard between perception and memory and elucidate the ensuing hippocampal-cortical dynamics supporting the recall process.
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