Authors :
Presenting Author: Kanako Tsuchimoto, Medical Student – Kagoshima University
Kotaro Saito, DDS, PhD – Department of Neurosurgery – Kagoshima University; Naoto Kuroda, MD – Research associate, Department of Pediatrics, Wayne State University; Kazuki Sakakura, MD – Research associate, Department of Pediatrics, Wayne State University; Aya Kanno, MD, PhD – Research associate, Department of Pediatrics, Wayne State University; Takumi Mitsuhashi, MD,PhD – Department of Neurosurgery – Juntendo University; Masaki Sonoda, MD, PhD – Department of Neurosurgery – Yokohama City University; Ryosuke Hanaya, MD, PhD – Professor, Chairman, Department of Neurosurgery, Kagoshima University; Eishi Asano, MD, PhD, MS – Professor, Department of Pediatrics, Wayne State University
Rationale:
The present study aimed to investigate the network dynamics between the anterior nucleus of the thalamus and the cerebral cortex. To achieve this, we measured intracranially-recorded cortical responses induced by single-pulse electrical stimulation (SPES) of the anterior thalamic nucleus, as well as the thalamic responses elicited by cortical stimulation.
Methods:
This study included patients with drug-resistant focal epilepsy who underwent stereotactic electroencephalography (sEEG) recording from both the anterior thalamic nucleus and cerebral cortex. As part of our routine presurgical evaluation to understand brain network dynamics, we delivered SPES to all adjacent pairs of sEEG electrodes (at 5 mA, 1 Hz, for a total of 40 stimuli). We quantified the latency and amplitude of gamma-band responses occurring within 10-50 ms after SPES, specifically in the spectral frequency range of 30-40 Hz, and compared them to the baseline period before SPES.
Results:
A total of 163 sEEG electrode contacts were included in the study, with 66 contacts located in the left hemisphere. Among these, 96 contacts were localized in the cerebral cortex, with 38 in the left hemisphere, while three contacts were specifically located in the anterior thalamic nucleus, including one in the left hemisphere. No adverse events were obse
rved following SPES. The analysis of thalamo-cortical spectral responses revealed the involvement of the middle temporal and cingulate gyri, along with extensive frontal lobe sites within 50 ms. In contrast, cortico-thalamic spectral responses were observed following SPES of the hippocampus, as well as extensive frontal lobe sites within 50 ms.Conclusions:
This study elucidated the network dynamics between the anterior thalamic nucleus and the cerebral cortex, shedding light on their reciprocal interactions. Furthermore, our findings provide compelling electrophysiological evidence that supports the existence of the Papez circuit within the human brain. This neural circuit, recognized for its pivotal role in memory processing, encompasses connections extending from the hippocampus to the anterior thalamic nucleus and from the anterior thalamic nucleus to the cingulate gyrus. Our observation of neural responses in the middle temporal gyrus and extensive frontal lobe sites subsequent to the stimulation of the anterior thalamic nucleus implies that this nucleus not only forms connections with the limbic cortex but also exhibits a network relationship with the frontal-temporal neocortex.
Funding: