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Despite promising advancements, closed-loop neurostimulation for drug-resistant epilepsy (DRE) still relies on manual tuning and produces variable outcomes, while automated predictable algorithms remain an aspiration. As a fundamental step towards addressing this gap, here we study predictive dynamical models of human intracranial EEG (iEEG) response under parametrically rich neurostimulation. Using data from n = 13 DRE patients, we find that stimulation-triggered switched-linear models with ~300 ms of causal historical dependence best explain evoked iEEG dynamics. These models are highly consistent across different stimulation amplitudes and frequencies, allowing for learning a generalizable model from abundant STIM OFF and limited STIM ON data. Further, evoked iEEG in nearly all subjects exhibited a distance-dependent pattern, whereby stimulation directly impacts the actuation site and nearby regions (≲ 20 mm), affects medium-distance regions (20 ~ 100 mm) through network interactions, and hardly reaches more distal areas (≳ 100 mm). Peak network interaction occurs at 60 ~ 80 mm from the stimulation site. Due to their predictive accuracy and mechanistic interpretability, these models hold significant potential for model-based seizure forecasting and closed-loop neurostimulation design.

Functional mapping during brain surgery is applied to define brain areas that control critical functions and cannot be removed. Currently, these procedures rely on verbal interactions between the neurosurgeon and electrophysiologist, which can be time-consuming. In addition, the electrode grids that are used to measure brain activity and to identify the boundaries of pathological versus functional brain regions have low resolution and limited conformity to the brain surface. Here, we present the development of an intracranial electroencephalogram (iEEG)-microdisplay that consists of freestanding arrays of 2048 GaN light-emitting diodes laminated on the back of micro-electrocorticography electrode grids. With a series of proof-of-concept experiments in rats and pigs, we demonstrate that these iEEG-microdisplays allowed us to perform real-time iEEG recordings and display cortical activities by spatially corresponding light patterns on the surface of the brain in the surgical field. Furthermore, iEEG-microdisplays allowed us to identify and display cortical landmarks and pathological activities from rat and pig models. Using a dual-color iEEG-microdisplay, we demonstrated coregistration of the functional cortical boundaries with one color and displayed the evolution of electrical potentials associated with epileptiform activity with another color. The iEEG-microdisplay holds promise to facilitate monitoring of pathological brain activity in clinical settings.

This study explored illness experiences and decision-making among patients with epilepsy who underwent two different types of surgical interventions: resection versus implantation of the NeuroPace Responsive Neurostimulation System (RNS). We recruited 31 participants from a level four epilepsy center in an academic medical institution. We observed 22 patient clinic visits (resection: n = 10, RNS: n = 12) and conducted 18 in-depth patient interviews (resection: n = seven, RNS: n = 11); most visits and interviews included patient caregivers. Using an applied ethnographic approach, we identified three major themes in the experiences of resection versus RNS patients. First, for patients in both cohorts, the therapeutic journey was circuitous in ways that defied standardized first-, second-, and third- line of care models. Second, in conceptualizing risk, resection patients emphasized the permanent loss of taking out brain tissue whereas RNS patients highlighted the reversibility of putting in a device. Lastly, in considering benefit, resection patients perceived their surgery as potentially curative while RNS patients understood implantation as primarily palliative with possible additional diagnostic benefit from chronic electrocorticography. Insight into the perspectives of patients and caregivers may help identify key topics for counseling and exploration by clinicians.

OBJECTIVE: The study objective was to evaluate intraoperative experience with newly developed high-spatial-resolution microelectrode grids composed of poly(3,4-ethylenedioxythiophene) with polystyrene sulfonate (PEDOT:PSS), and those composed of platinum nanorods (PtNRs). METHODS: A cohort of patients who underwent craniotomy for pathological tissue resection and who had high-spatial-resolution microelectrode grids placed intraoperatively were evaluated. Patient demographic and baseline clinical variables as well as relevant microelectrode grid characteristic data were collected. The primary and secondary outcome measures of interest were successful microelectrode grid utilization with usable resting-state or task-related data, and grid-related adverse intraoperative events and/or grid dysfunction. RESULTS: Included in the analysis were 89 cases of patients who underwent a craniotomy for resection of neoplasms (n = 58) or epileptogenic tissue (n = 31). These cases accounted for 94 grids: 58 PEDOT:PSS and 36 PtNR grids. Of these 94 grids, 86 were functional and used successfully to obtain cortical recordings from 82 patients. The mean cortical grid recording duration was 15.3 ± 1.15 minutes. Most recordings in patients were obtained during experimental tasks (n = 52, 58.4%), involving language and sensorimotor testing paradigms, or were obtained passively during resting state (n = 32, 36.0%). There were no intraoperative adverse events related to grid placement. However, there were instances of PtNR grid dysfunction (n = 8) related to damage incurred by suboptimal preoperative sterilization (n = 7) and improper handling (n = 1); intraoperative recordings were not performed. Vaporized peroxide sterilization was the most optimal sterilization method for PtNR grids, providing a significantly greater number of usable channels poststerilization than did steam-based sterilization techniques (median 905.0 [IQR 650.8-935.5] vs 356.0 [IQR 18.0-597.8], p = 0.0031). CONCLUSIONS: High-spatial-resolution microelectrode grids can be readily incorporated into appropriately selected craniotomy cases for clinical and research purposes. Grids are reliable when preoperative handling and sterilization considerations are accounted for. Future investigations should compare the diagnostic utility of these high-resolution grids to commercially available counterparts and assess whether diagnostic discrepancies relate to clinical outcomes.

Sleep disturbance is a prevalent and disabling comorbidity in Parkinsons disease (PD). We performed multi-night (n = 57) at-home intracranial recordings from electrocorticography and subcortical electrodes using sensing-enabled Deep Brain Stimulation (DBS), paired with portable polysomnography in four PD participants and one with cervical dystonia (clinical trial: NCT03582891). Cortico-basal activity in delta increased and in beta decreased during NREM (N2 + N3) versus wakefulness in PD. DBS caused further elevation in cortical delta and decrease in alpha and low-beta compared to DBS OFF state. Our primary outcome demonstrated an inverse interaction between subcortical beta and cortical slow-wave during NREM. Our secondary outcome revealed subcortical beta increases prior to spontaneous awakenings in PD. We classified NREM vs. wakefulness with high accuracy in both traditional (30 s: 92.6 ± 1.7%) and rapid (5 s: 88.3 ± 2.1%) data epochs of intracranial signals. Our findings elucidate sleep neurophysiology and impacts of DBS on sleep in PD informing adaptive DBS for sleep dysfunction.

Context: Primary central nervous system tumours have poor survival outcomes. Surgery, the first-line treatment, presents technical limitations, such as visualising the whole tumour border. Intracranial impedance monitoring and electrocorticography techniques provide insights into the local field potential characteristics, resistance and capacitance properties of brain tissue. We hypothesised that measurements obtained by either modality can distinguish between tumour and healthy brain tissue intraoperatively. Methods: A "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA)-compliant systematic review was conducted, searching PubMed, Ovid, Scopus, Cochrane and Web of Science. Studies on electrocorticography and impedance monitoring in patients with brain tumours were included. Data on patient demographics, technical details, obtained results and safety were extracted and analysed in Excel. Results: Eighteen studies involving 286 patients in total were identified. Ten impedance studies showed that brain tumour tissue has significantly different values than healthy tissue, while its resistivity varies, being either higher or lower. Eight electrocorticography studies indicated increased high gamma power and altered connectivity in tumour tissue. No studies integrated impedance monitoring and electrocorticography in one device. Conclusion: Impedance and electrocorticography measurements have the potential of differentiating between tumour and unaffected issues intra-operatively. Larger studies with standardised protocols are needed to validate these findings. Additionally, the combination of these two modalities has the potential for improved specificity with a single device. Future research should explore the role of these modalities in enhancing tumour margin identification across different tumour subtypes and in improving survival outcomes. [ABSTRACT FROM AUTHOR]

Spreading depolarizations (SD) contribute to lesion progression after experimental focal cerebral ischemia while such correlation has never been shown in stroke patients. In this prospective, diagnostic study, we investigate the association of SDs and secondary infarct progression after malignant hemispheric stroke. SDs were continuously monitored for 3–9 days with electrocorticography after decompressive hemicraniectomy for malignant hemispheric stroke. To ensure valid detection and analysis of SDs, a threshold based on the electrocorticographic baseline activity was calculated to identify valid electrocorticographic recordings. Subsequently SD characteristics were analyzed in association to infarct progression based on serial MRI. Overall, 62 patients with a mean stroke volume of 289.6 ± 68 cm3 were included. Valid electrocorticographic recordings were found in 44/62 patients with a mean recording duration of 139.6 ± 26.5 hours and 52.5 ± 39.5 SDs per patient. Infarct progression of more than 5% was found in 21/44 patients. While the number of SDs was similar between patients with and without infarct progression, the SD-induced depression duration per day was significantly longer in patients with infarct progression (593.8 vs. 314.1 minutes; *p = 0.046). Therefore, infarct progression is associated with a prolonged SD-induced depression duration. Real-time analysis of electrocorticographic recordings may identify secondary stroke progression and help implementing targeted management strategies. [ABSTRACT FROM AUTHOR]

Selective attention relies on neural mechanisms that facilitate processing of behaviorally relevant sensory information while suppressing irrelevant information, consistently linked to alpha-band oscillations in human M/EEG studies. We analyzed cortical alpha responses from intracranial electrodes implanted in eight epilepsy patients, who performed a visual spatial attention task. Electrocorticographic data revealed a spatiotemporal dissociation between attention-modulated alpha desynchronization, associated with the enhancement of sensory processing, and alpha synchronization, associated with the suppression of sensory processing, during the cue-target interval. Dorsal intraparietal areas contralateral to the attended hemifield primarily exhibited a delayed and sustained alpha desynchronization, while ventrolateral extrastriatal areas ipsilateral to the attended hemifield primarily exhibited an earlier and sustained alpha synchronization. Analyses of cross-frequency coupling between alpha phase and broadband high-frequency activity (HFA) further revealed cross-frequency interactions along the visual hierarchy contralateral to the attended locations. Directionality analyses indicate that alpha phase in early and extrastriatal visual areas modulated HFA power in downstream visual areas, thus potentially facilitating the feedforward processing of an upcoming, spatially predictable target. In contrast, in areas ipsilateral to the attended locations, HFA power modulated local alpha phase in early and extrastriatal visual areas, with suppressed interareal interactions, potentially attenuating the processing of distractors. Our findings reveal divergent alpha-mediated neural mechanisms underlying target enhancement and distractor suppression during the deployment of spatial attention, reflecting enhanced functional connectivity at attended locations, while suppressed functional connectivity at unattended locations. The collective dynamics of these alpha-mediated neural mechanisms play complementary roles in the efficient gating of sensory information. [ABSTRACT FROM AUTHOR]

One of the flavonoids found in some fruits and plants such as pomegranates, nuts, and apples is ellagic acid (EA). This compound has antidepressant, anxiolytic, antioxidant, and anti-inflammatory effects. Aim of this study was to investigate the effects of EA on experimental penicillin-induced epilepsy model electrophysiologically in rats. In this study, 70 adult male Wistar rats were divided into acute and chronic main groups. Only EA, and 10, 50 and 100 mg/kg doses of EA were the subgroups of the study. Sham and control groups were used as common groups for acute and chronic main groups. Substances were given to the acute group 30 min before the epileptiform activity started but for 21 days to the chronic group. Rats were anaesthetized with urethane. Electrodes were placed on the left somatomotor area. Electrocorticography (ECoG) recording was started and then penicillin was injected into the rats to induce epileptiform activity. 120 min more ECoG recordings were taken after penicillin was injected. In sham and only EA groups there was no epileptiform activity. Both acute and chronic groups of EA significantly increased the latency time to onset of the first spike-wave (P<0.05) and decreased the frequency and amplitude except for some time periods (P<0.05). Consequently, the administration of EA has an antiepileptic effect in penicillin-induced epilepsy in rats. Therefore it may be a potential anti-epileptogenic drug in the future. [ABSTRACT FROM AUTHOR]

• N1 amplitude increases with intensity of bipolar stimulation but is not affected by interelectrode distance. • N1 delay is not significantly affected by stimulation intensity or interelectrode distance. • Axonal stimulation generates earlier and more evoked potentials than cortical stimulation. To identify optimal bipolar stimulation parameters for robust generation of brain evoked potentials (BEPs), namely the interelectrode distance (IED) and the intensity of stimulation (IS), in cortical and axonal stimulation. In 15 patients who underwent awake surgery for brain tumor removal, BEPs were elicited at different values of IED and IS, respectively: 5 mm-5 mA, 5 mm-10 mA, and 10 mm-10 mA. The number of BEPs elicited by stimulation, as well as the delays and amplitudes of the N1 waves were compared between the different groups of stimulation parameters and according to the stimulated brain structure (cortical vs. axonal). The amplitudes of N1 increased with the intensity of bipolar stimulation, either in cortical or axonal stimulation, while N1 peak delays were not affected by the stimulation parameters. Furthermore, axonal stimulation produced more N1s than cortical stimulation, with lower latencies. Understanding the relationship between stimulation parameters and BEP is of utmost importance to determine whether the generated N1 waves accurately reflect the underlying structural anatomy. Other factors, such as stimulation frequency or pulse width and shape, may also play a role and warrant further investigation. This study represents the first step in describing the influence of common bipolar stimulation parameters on robustness of BEPs by examining the impact of IED and IS on the N1 wave. [ABSTRACT FROM AUTHOR]

Introduction: Sleep disorders are common in the general population, necessitating the search for new strategies to address this public health challenge. The study aims to describe the electrocorticographic and behavioral changes in sleep deprived Wistar rats exposed to varying doses of camphor, to assess its effects on sleep and its potential as a sleep-inducing drug. Materials and Methods: For the electrocorticographic evaluation, seventy-two rats were randomly assigned to distinct groups: a control group, a sleep-deprived group, three sleep-deprived groups receiving 10, 20, and 30 mg/kg i.p. of camphor respectively, and three groups that received these doses without sleep deprivation. For the behavioral analysis, twenty-seven rats were divided into three groups, each receiving the same doses as the previous test. Results and Discussion: Our results showed that there was a decrease in the frequency of brain oscillatory patterns when camphor was administered at 10 mg/kg i.p. whereas there was a dose-dependent increase in the spectral power and distribution following the administration of 20 and 30 mg/kg i.p., with the emergence of Delta, Theta, Alpha, and Beta waves. As for the behavioral analysis, it was demonstrated that testicular relaxation, decreased motility, and light sleep induction also occurred in a dose-dependent manner. Thus, we conclude that camphor administration intensifies occipital electrocorticographic patterns in sleep-deprived rats, and its electrocorticographic and behavioral analysis could indicate a potential as a supporting agent in the insomnia treatment. [ABSTRACT FROM AUTHOR]

AbstractPurposeMaterials and MethodsResults and ConclusionsAwake craniotomy (AC) is a procedure often performed concomitantly with direct electrical cortical stimulation (DES) and electrocorticography (ECoG) during functional brain mapping. Patients undergoing AC are at risk of acute symptomatic seizures, including intraoperative (IS) and early postoperative seizures (EPS) which can lead to higher risk of morbidity. Predicting those who are at risk of IS and EPS could alert clinicians and provide the ability to closely monitor and consider management changes in the acute setting to prevent seizures.This is a narrative review of previous studies on IS and EPS during awake craniotomy, including a summary of studies from our center using a novel circular grid electrode.There are a number of clinical features with variable association with a higher risk of EPS and IS. Surgeries involving the anterior and central head regions are a risk factor for IS. EPS is more likely to occur in patients with perioperative intracranial hemorrhage. Improving grid/electrode technology for ECoG can allow for better sensitivity of detecting epileptiform activity which can help to diagnose and predict perioperative seizures. [ABSTRACT FROM AUTHOR]

The ability to initiate volitional action is fundamental to human behaviour. Loss of dopaminergic neurons in Parkinson's disease is associated with impaired action initiation, also termed akinesia. Both dopamine and subthalamic deep brain stimulation (DBS) can alleviate akinesia, but the underlying mechanisms are unknown. An important question is whether dopamine and DBS facilitate de novo build-up of neural dynamics for motor execution or accelerate existing cortical movement initiation signals through shared modulatory circuit effects. Answering these questions can provide the foundation for new closed-loop neurotherapies with adaptive DBS, but the objectification of neural processing delays prior to performance of volitional action remains a significant challenge. To overcome this challenge, we studied readiness potentials and trained brain signal decoders on invasive neurophysiology signals in 25 DBS patients (12 female) with Parkinson's disease during performance of self-initiated movements. Combined sensorimotor cortex electrocorticography and subthalamic local field potential recordings were performed OFF therapy (n = 22), ON dopaminergic medication (n = 18) and on subthalamic deep brain stimulation (n = 8). This allowed us to compare their therapeutic effects on neural latencies between the earliest cortical representation of movement intention as decoded by linear discriminant analysis classifiers and onset of muscle activation recorded with electromyography. In the hypodopaminergic OFF state, we observed long latencies between motor intention and motor execution for readiness potentials and machine learning classifications. Both, dopamine and DBS significantly shortened these latencies, hinting towards a shared therapeutic mechanism for alleviation of akinesia. To investigate this further, we analysed directional cortico-subthalamic oscillatory communication with multivariate granger causality. Strikingly, we found that both therapies independently shifted cortico-subthalamic oscillatory information flow from antikinetic beta (13–35 Hz) to prokinetic theta (4–10 Hz) rhythms, which was correlated with latencies in motor execution. Our study reveals a shared brain network modulation pattern of dopamine and DBS that may underlie the acceleration of neural dynamics for augmentation of movement initiation in Parkinson's disease. Instead of producing or increasing preparatory brain signals, both therapies modulate oscillatory communication. These insights provide a link between the pathophysiology of akinesia and its' therapeutic alleviation with oscillatory network changes in other non-motor and motor domains, e.g. related to hyperkinesia or effort and reward perception. In the future, our study may inspire the development of clinical brain computer interfaces based on brain signal decoders to provide temporally precise support for action initiation in patients with brain disorders. [ABSTRACT FROM AUTHOR]

Executive control of movement enables inhibiting impulsive responses critical for successful navigation of the environment. Circuits mediating stop commands involve prefrontal and basal ganglia structures with fMRI evidence demonstrating increased activity during response inhibition in the dorsolateral prefrontal cortex (dlPFC)—often ascribed to maintaining task attentional demands. Using direct intraoperative cortical recordings in male and female human subjects, we investigated oscillatory dynamics along the rostral-caudal axis of dlPFC during a modified Go/No-go task, probing components of both proactive and reactive motor control. We assessed whether cognitive control is topographically organized along this axis and observed that low-frequency power increased prominently in mid-rostral dlPFC when inhibiting and delaying responses. These findings provide evidence for a key role for mid-rostral dlPFC low-frequency oscillations in sculpting motor control. [ABSTRACT FROM AUTHOR]

Subdural electrocorticography (ECoG) is a valuable technique for neuroscientific research and for emerging neurotechnological clinical applications. As ECoG grids accommodate increasing numbers of electrodes and higher densities with new manufacturing methods, the question arises at what point the benefit of higher density ECoG is outweighed by spatial oversampling. To clarify the optimal spacing between ECoG electrodes, in the current study we evaluate how ECoG grid density relates to the amount of non-shared neurophysiological information between electrode pairs, focusing on the sensorimotor cortex. We simultaneously recorded high-density (HD, 3 mm pitch) and ultra-high-density (UHD, 0.9 mm pitch) ECoG, obtained intraoperatively from six participants. We developed a new metric, the normalized differential root mean square (ndRMS), to quantify the information that is not shared between electrode pairs. The ndRMS increases with inter-electrode center-to-center distance up to 15 mm, after which it plateaus. We observed differences in ndRMS between frequency bands, which we interpret in terms of oscillations in frequencies below 32 Hz with phase differences between pairs, versus (un)correlated signal fluctuations in the frequency range above 64 Hz. The finding that UHD recordings yield significantly higher ndRMS than HD recordings is attributed to the amount of tissue sampled by each electrode. These results suggest that ECoG densities with submillimeter electrode distances are likely justified. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of different effect compartment concentrations of propofol on the ste-reotactic electroencephalography (SEEG) of the left cerebral neocortex and limbic system in adult patients with epilepsy. Methods Fourteen patients undergoing elective electrode removal following robot-guided stereotactic implantation of left intracerebral electrodes in the Department of Epilepsy Surgery at our hospital from January 2021 to December 2022 were selected. Patients were divided into neocortex group and limbic system group according to the location of electrodes in the brain. The power range and percentage of δ, θ, α, β, and γ waves on SEEG at the intraoperative effect compartment concentrations of propofol of 0, 2, 3, 4, and 5 mg/L (concentrations of D1-D5) as well as the modulation index (MI) of phase-amplitude coupling (PAC) in the wave bands of δ-γ, θ-γ, α-γ, and β-γ were recorded and compared between the two groups. Results The power ranges of γ wave on SEEG of the left limbic system and cerebral neocortex were significantly lower at the concentrations of D2-D5 than at the concentration of D1 (F=15.13,20.33,t=4.33-8.72,P

Sharing human brain data can yield scientific benefits, but because of various disincentives, only a fraction of these data is currently shared. We profile three successful data-sharing experiences from the NIH BRAIN Initiative Research Opportunities in Humans (ROH) Consortium and demonstrate benefits to data producers and to users.

Delay Differential Analysis (DDA) is a nonlinear method for analyzing time series based on principles from nonlinear dynamical systems. DDA is extended here to incorporate network aspects to improve the dynamical characterization of complex systems. To demonstrate its effectiveness, DDA with network capabilities was first applied to the well-known Rössler system under different parameter regimes and noise conditions. Network-motif DDA, based on cortical regions, was then applied to invasive intracranial electroencephalographic data from drug-resistant epilepsy patients undergoing presurgical monitoring. The directional network motifs between brain areas that emerge from this analysis change dramatically before, during, and after seizures. Neural systems provide a rich source of complex data, arising from varying internal states generated by network interactions.

• Electrical stimulation in white matter induces delays in the evoked response due to slow conduction velocity. • The waveforms from white matter and cortical stimulation remain generally identical. • Responses to white matter and cortical stimulation differ on response times. • The relaxation of the N1 component is longer during cortical stimulations. • There is probable activation of intra-cortical axons during cortical stimulation. Direct cortical responses (DCR) and axono-cortical evoked potentials (ACEP) are generated by electrically stimulating the cortex either directly or indirectly through white matter pathways, potentially leading to different electrogenic processes. For ACEP, the slow conduction velocity of axons (median ≈ 4 m.s−1) is anticipated to induce a delay. For DCR, direct electrical stimulation (DES) of the cortex is expected to elicit additional cortical activity involving smaller and slower non-myelinated axons. We tried to validate these hypotheses. DES was administered either directly on the cortex or to white matter fascicles within the resection cavity, while recording DCR or ACEP at the cortical level in nine patients. Short but significant delays (≈ 2 ms) were measurable for ACEP immediately following the initial component (≈ 7 ms). Subsequent activities (≈ 40 ms) exhibited notable differences between DCR and ACEP, suggesting the presence of additional cortical activities for DCR. Distinctions between ACEPs and DCRs can be made based on a delay at the onset of early components and the dissimilarity in the shape of the later components (>40 ms after the DES artifact). The comparison of different types of evoked potentials allows to better understand the effects of DES. [ABSTRACT FROM AUTHOR]

Abstract Methods to quantify cortical hyperexcitability are of enormous interest for mapping epileptic networks in patients with focal epilepsy. We hypothesize that, in the resting state, cortical hyperexcitability increases firing-rate correlations between neuronal populations within seizure onset zones (SOZs). This hypothesis predicts that in the gamma frequency band (40–200 Hz), amplitude envelope correlations (AECs), a relatively straightforward measure of functional connectivity, should be elevated within SOZs compared to other areas. To test this prediction, we analyzed archived samples of interictal electrocorticographic (ECoG) signals recorded from patients who became seizure-free after surgery targeting SOZs identified by multiday intracranial recordings. We show that in the gamma band, AECs between nodes within SOZs are markedly elevated relative to those elsewhere. AEC-based node strength, eigencentrality, and clustering coefficient are also robustly increased within the SOZ with maxima in the low-gamma band (permutation test Z-scores > 8) and yield moderate discriminability of the SOZ using ROC analysis (maximal mean AUC ~ 0.73). By contrast to AECs, phase locking values (PLVs), a measure of narrow-band phase coupling across sites, and PLV-based graph metrics discriminate the seizure onset nodes weakly. Our results suggest that gamma band AECs may provide a clinically useful marker of cortical hyperexcitability in focal epilepsy.

Background: During epilepsy surgery, it is equally important to record electrocorticography (ECoG) for detecting epileptogenic activity and guiding brain resection, and to evaluate neuromonitoring data, particularly motor evoked potentials (MEP), for avoidance of postoperative neurological complications. However, sevoflurane, which is commonly used during recording of ECoG, may attenuate the MEP response. It enforces anesthesiologists and neurosurgeons to select one anesthetic agent over another, facilitating either ECoG or MEP monitoring. Case presentation: In the presented case of a 20-year-old man, who underwent surgery for temporal lobe epilepsy, a novel technique of neuroanesthesia was introduced, integrating initial induction of the total intravenous anesthesia (TIVA) with propofol (effect-site concentration, 2.3–3.0 μg/ml), its subsequent switching to sevoflurane (end-tidal concentration, 2.5%) for ECoG recording, and further change back to TIVA for MEP monitoring during brain resection. Conclusions: Intraoperative switch of anesthetic agents according to specific intraoperative requirements may be useful for cases of brain surgery requiring both ECoG recordings and MEP monitoring. [ABSTRACT FROM AUTHOR]

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Electrophysiological methods of research are widely used in neurobiology. To assess the bioelectrical activity of the brain in small laboratory animals, electrocorticography (ECoG) is most often used, which allows the recording of signals directly from the cerebral cortex. To date, a number of methodological approaches to the manufacture and implantation of ECoG electrodes have been proposed, the complexity of which is determined by experimental tasks and logistical capabilities. Existing methods for analyzing bioelectrical signals are used to assess the functional state of the nervous system in test animals, as well as to identify correlates of pathological changes or pharmacological effects. The review presents current areas of applications of ECoG in neuropharmacological studies in small laboratory animals. Traditionally, this method is actively used to study the antiepileptic activity of new molecules. However, the possibility of using ECoG to assess the neuroprotective activity of drugs in models of traumatic, vascular, metabolic, or neurodegenerative CNS damage remains clearly underestimated. Despite the fact that ECoG has a number of disadvantages and methodological difficulties, the recorded data can be a useful addition to traditional molecular and behavioral research methods. An analysis of the works in recent years indicates a growing interest in the method as a tool for assessing the pharmacological activity of psychoactive drugs, especially in combination with classification and prediction algorithms. [ABSTRACT FROM AUTHOR]

Methods to quantify cortical hyperexcitability are of enormous interest for mapping epileptic networks in patients with focal epilepsy. We hypothesize that, in the resting state, cortical hyperexcitability increases firing-rate correlations between neuronal populations within seizure onset zones (SOZs). This hypothesis predicts that in the gamma frequency band (40–200 Hz), amplitude envelope correlations (AECs), a relatively straightforward measure of functional connectivity, should be elevated within SOZs compared to other areas. To test this prediction, we analyzed archived samples of interictal electrocorticographic (ECoG) signals recorded from patients who became seizure-free after surgery targeting SOZs identified by multiday intracranial recordings. We show that in the gamma band, AECs between nodes within SOZs are markedly elevated relative to those elsewhere. AEC-based node strength, eigencentrality, and clustering coefficient are also robustly increased within the SOZ with maxima in the low-gamma band (permutation test Z-scores > 8) and yield moderate discriminability of the SOZ using ROC analysis (maximal mean AUC ~ 0.73). By contrast to AECs, phase locking values (PLVs), a measure of narrow-band phase coupling across sites, and PLV-based graph metrics discriminate the seizure onset nodes weakly. Our results suggest that gamma band AECs may provide a clinically useful marker of cortical hyperexcitability in focal epilepsy. [ABSTRACT FROM AUTHOR]

Direct neural recordings from human auditory cortex have demonstrated encoding for acoustic-phonetic features of consonants and vowels. Neural responses also encode distinct acoustic amplitude cues related to timing, such as those that occur at the onset of a sentence after a silent period or the onset of the vowel in each syllable. Here, we used a group reduced rank regression model to show that distributed cortical responses support a low-dimensional latent state representation of temporal context in speech. The timing cues each capture more unique variance than all other phonetic features and exhibit rotational or cyclical dynamics in latent space from activity that is widespread over the superior temporal gyrus. We propose that these spatially distributed timing signals could serve to provide temporal context for, and possibly bind across time, the concurrent processing of individual phonetic features, to compose higher-order phonological (e.g. word-level) representations.

Animacy perception, the ability to discern living from non-living entities, is crucial for survival and social interaction, as it includes recognizing abstract concepts such as movement, purpose, and intentions. This process involves interpreting cues that may suggest the intentions or actions of others. It engages the temporal cortex (TC), particularly the superior temporal sulcus (STS) and the adjacent region of the inferior temporal cortex (ITC), as well as the dorsomedial prefrontal cortex (dmPFC). However, it remains unclear how animacy is dynamically encoded over time in these brain areas and whether its processing is distributed or localized. In this study, we addressed these questions by employing a symbolic categorization task involving animate and inanimate objects using natural movie stimuli. Simultaneously, electrocorticography were conducted in both the TC and dmPFC. Time-frequency analysis revealed region-specific frequency representations throughout the observation of the movies. Spatial searchlight decoding analysis demonstrated that animacy processing is represented in a distributed manner. Regions encoding animacy information were found to be dispersed across the fundus and lip of the STS, as well as in the ITC. Next, we examined whether these dispersed regions form functional networks. Independent component analysis revealed that the spatial distribution of the component with the most significant animacy information corresponded with the dispersed regions identified by the spatial decoding analysis. Furthermore, Granger causality analysis indicated that these regions exhibit frequency-specific directional functional connectivity, with a general trend of causal influence from the ITC to STS across multiple frequency bands. Notably, a prominent feedback flow in the alpha band from the ITC to both the ventral bank and fundus of the STS was identified. These findings suggest a distributed and functionally interconnected neural substrate for animacy processing across the STS and ITC.

Background: The rapid development of neurosurgical techniques, such as awake craniotomy, has increased opportunities to explore the mysteries of the brain. This is crucial for deepening our understanding of motor control and imagination processes, especially in developing brain–computer interface (BCI) technologies and improving neurorehabilitation strategies for neurological disorders. Objective: This study aimed to analyze brain activity patterns in patients undergoing awake craniotomy during actual movements and motor imagery, mainly focusing on the motor control processes of the bilateral limbs. Methods: We conducted detailed observations of patients undergoing awake craniotomies. The experimenter requested participants to perform and imagine a series of motor tasks involving their hands and tongues. Brain activity during these tasks was recorded using functional magnetic resonance imaging (fMRI) and intraoperative electrocorticography (ECoG). The study included left and right finger tapping, tongue protrusion, hand clenching, and imagined movements corresponding to these actions. Results: fMRI revealed significant activation in the brain's motor areas during task performance, mainly involving bilateral brain regions during imagined movement. ECoG data demonstrated a marked desynchronization pattern in the ipsilateral motor cortex during bilateral motor imagination, especially in bilateral coordination tasks. This finding suggests a potential controlling role of the unilateral cerebral cortex in bilateral motor imagination. Conclusion: Our study highlights the unilateral cerebral cortex's significance in controlling bilateral limb motor imagination, offering new insights into future brain network remodeling in patients with hemiplegia. Additionally, these findings provide important insights into understanding motor imagination and its impact on BCI and neurorehabilitation.

IntroductionSleep disorders are common in the general population, necessitating the search for new strategies to address this public health challenge. The study aims to describe the electrocorticographic and behavioral changes in sleep deprived Wistar rats exposed to varying doses of camphor, to assess its effects on sleep and its potential as a sleep-inducing drug.Materials and MethodsFor the electrocorticographic evaluation, seventy-two rats were randomly assigned to distinct groups: a control group, a sleep-deprived group, three sleep-deprived groups receiving 10, 20, and 30 mg/kg i.p. of camphor respectively, and three groups that received these doses without sleep deprivation. For the behavioral analysis, twenty-seven rats were divided into three groups, each receiving the same doses as the previous test.Results and DiscussionOur results showed that there was a decrease in the frequency of brain oscillatory patterns when camphor was administered at 10 mg/kg i.p. whereas there was a dose-dependent increase in the spectral power and distribution following the administration of 20 and 30 mg/kg i.p., with the emergence of Delta, Theta, Alpha, and Beta waves. As for the behavioral analysis, it was demonstrated that testicular relaxation, decreased motility, and light sleep induction also occurred in a dose-dependent manner. Thus, we conclude that camphor administration intensifies occipital electrocorticographic patterns in sleep-deprived rats, and its electrocorticographic and behavioral analysis could indicate a potential as a supporting agent in the insomnia treatment.

Broadly congruent mirror neurons, responding to any grasp movement, and strictly congruent mirror neurons, responding only to specific grasp movements, have been reported in single-cell studies with primates. Delineating grasp properties in humans is essential to understand the human mirror neuron system with implications for behavior and social cognition. We analyzed electrocorticography data from a natural reach-and-grasp movement observation and delayed imitation task with 3 different natural grasp types of everyday objects. We focused on the classification of grasp types from high-frequency broadband mirror activation patterns found in classic mirror system areas, including sensorimotor, supplementary motor, inferior frontal, and parietal cortices. Classification of grasp types was successful during movement observation and execution intervals but not during movement retention. Our grasp type classification from combined and single mirror electrodes provides evidence for grasp-congruent activity in the human mirror neuron system potentially arising from strictly congruent mirror neurons.

Electrophysiological recording and stimulation are the gold standard for functional mapping during surgical and therapeutic interventions as well as capturing cellular activity in the intact human brain. A critical component probing human brain activity is the interface material at the electrode contact that electrochemically transduces brain signals to and from free charge carriers in the measurement system. Here, we summarize state-of-the-art electrode array systems in the context of translation for use in recording and stimulating human brain activity. We leverage parametric studies with multiple electrode materials to shed light on the varied levels of suitability to enable high signal-to-noise electrophysiological recordings as well as safe electrophysiological stimulation delivery. We discuss the effects of electrode scaling for recording and stimulation in pursuit of high spatial resolution, channel count electrode interfaces, delineating the electrode-tissue circuit components that dictate the electrode performance. Finally, we summarize recent efforts in the connectorization and packaging for high channel count electrode arrays and provide a brief account of efforts toward wireless neuronal monitoring systems.

Objective.Intracranial electroencephalogram (iEEG) plays a critical role in the treatment of neurological diseases, such as epilepsy and Parkinsons disease, as well as the development of neural prostheses and brain computer interfaces. While electrode geometries vary widely across these applications, the impact of electrode size on iEEG features and morphology is not well understood. Some insight has been gained from computer simulations, as well as experiments in which signals are recorded using electrodes of different sizes concurrently in different brain regions. Here, we introduce a novel method to record from electrodes of different sizes in the exact same location by changing the size of iEEG electrodes after implantation in the brain.Approach.We first present a theoretical model and anin vitrovalidation of the method. We then report the results of anin vivoimplementation in three human subjects with refractory epilepsy. We recorded iEEG data from three different electrode sizes and compared the amplitudes, power spectra, inter-channel correlations, and signal-to-noise ratio (SNR) of interictal epileptiform discharges, i.e. epileptic spikes.Main Results.We found that iEEG amplitude and power decreased as electrode size increased, while inter-channel correlation did not change significantly with electrode size. The SNR of epileptic spikes was generally highest in the smallest electrodes, but 39% of spikes had maximal SNR in larger electrodes. This likely depends on the precise location and spatial spread of each spike.Significance.Overall, this new method enables multi-scale measurements of electrical activity in the human brain that can facilitate our understanding of neurophysiology, treatment of neurological disease, and development of novel technologies.

BACKGROUND: Sleep dysfunction is disabling in people with Parkinsons disease and is linked to worse motor and non-motor outcomes. Sleep-specific adaptive Deep Brain Stimulation has the potential to target pathophysiologies of sleep. OBJECTIVE: Develop an adaptive Deep Brain Stimulation algorithm that modulates stimulation parameters in response to intracranially classified sleep stages. METHODS: We performed at-home, multi-night intracranial electrocorticography and polysomnogram recordings to train personalized linear classifiers for discriminating the N3 NREM sleep stage. Classifiers were embedded into investigational Deep Brain Stimulators for N3 specific adaptive DBS. RESULTS: We report high specificity of embedded, autonomous, intracranial electrocorticography N3 sleep stage classification across two participants and provide proof-of-principle of successful sleep stage specific adaptive Deep Brain Stimulation. CONCLUSION: Multi-night cortico-basal recordings and sleep specific adaptive Deep Brain Stimulation provide an experimental framework to investigate sleep pathophysiology and mechanistic interactions with stimulation, towards the development of therapeutic neurostimulation paradigms directly targeting sleep dysfunction.

INTRODUCTION: Stepping and arm swing are stereotyped movements that require coordination across multiple muscle groups. It is not known whether the encoding of these stereotyped movements in the human primary motor cortex is confined to the limbs respective somatotopy. METHODS: We recorded subdural electrocorticography activities from the hand/arm area in the primary motor cortex of 6 subjects undergoing deep brain stimulation surgery for essential tremor and Parkinsons disease who performed stepping (all patients) and arm swing (n = 3 patients) tasks. RESULTS: We show stepping-related low frequency oscillations over the arm area. Furthermore, we show that this oscillatory activity is separable, both in frequency and spatial domains, from gamma band activity changes that occur during arm swing. DISCUSSION: Our study contributes to the growing body of evidence that lower extremity movement may be more broadly represented in the motor cortex, and suggest that it may represent a way to coordinate stereotyped movements across the upper and lower extremities.

Objective: Preterm neonates encounter hyperoxia relatively early, and are more exposed to hyperoxic stress due to their insufficient antioxidant defense mechanisms. This study was planned around the hypothesis that this hyperoxic effect may cause a disposition to future acute seizures. Methods: This study was composed of two main groups Hyperoxy and Control (Room air with normal O2 levels) Groups. Group 1 – hyperoxia (Study): The experimental group consisted of premature newborn rats exposed to hyperoxia with their dams from birth to postnatal day 5. Group 2 – room air (Control): The group was not exposed to hyperoxia and housed the same room air and temperature as their dams. Female, Acute Epilepsy Female, Male, Acute Epilepsy Male, and a total of eight subgroups were formed in both the control and hyperoxia groups. When the rats were two months old, intracranial electrodes were attached to obtain electrocorticography (ECoG) recordings. Pre-model recordings were taken, after which an acute pentylenetetrazole (PTZ) model of absence seizure was induced by the intraperitoneal administration of PTZ at 50 mg/kg. ECoG records were examined using the PowerLab system for 180 min. Spike wave number and duration, Spike wave frequency and amplitude data were evaluated.Results: Seven female and three male rats were exposed to hyperoxia, and a control group of five female and three male rats were included in the study. The median interquartile range for spike wave latency in the hyperoxia and control groups were 1112 (644–1545) and 654 (408–1152), frequency 4476 (3120–7421) and 3934 (2264–4704), and amplitude data 0.68 (0.59–0.79) and 0.52 (0.37–0.67), respectively. Although a difference was observed in median values capable of constituting susceptibility to epilepsy, the difference was not statistically significant (p > 0.05). In terms of gender, spike-wave counts were significantly higher in female rats (p < 0.05). Females exposed to hyperoxia were more susceptible to epilepsy than both males and females in the control group (p < 0.05).Conclusion: Exposure to hyperoxia in the first days of life of premature neonates due to their susceptibility to oxidative stress and insufficient antioxidant mechanisms, can cause a disposition to acute seizures. As a result, females exposed to hyperoxia during the neonatal period may be prone to epilepsy in maturity. [ABSTRACT FROM AUTHOR]

Substance P (SP) is a peptide neurotransmitter that plays a role in pain transmission, stress, inflammation, and emesis through neurokinin-1 receptor (NK-1R). Previous studies of NK-1R antagonists suggest that SP can have either convulsant or anticonvulsant effects. Aprepitant, an NK-1R antagonist, is clinically used to prevent nausea and vomiting in chemotherapy and post-operative patients. However, the effects of aprepitant on epilepsy have not been studied yet. Therefore, the objective of this study was to explore the influence of aprepitant on epileptiform activity in a rat model of epilepsy induced by penicillin. Male Wistar rats, aged 2.5 to 3 months, were divided into 5 groups (n=6): Control, Vehicle, Aprepitant, Substance P, and Aprepitant+Substance P. Aprepitant was administered intragastrically (30 mg/kg) 24 hours and 3 hours before surgery. Substance P (10 pmol) was administered intraventricularly during the surgical procedure. Induction of epileptiform activity was achieved by the injection of penicillin G (500 IU) into the cortex. Electrocorticography (ECoG) recording was conducted online using the PowerLab data acquisition system for over 3 hours. The disparity in spike frequency and amplitude among groups for each 10-minute interval was assessed through One-Way ANOVA and subsequent Tukey post-hoc tests, utilizing the SPSS 15.0 software package. Epileptiform activity was observed in all rats within 3 minutes after the injection of penicillin into the cortex. No significant difference was found between groups in terms of spike frequency and amplitude. When the percentage changes in mean spike frequency and amplitude values were calculated, no significant difference was shown between the groups. Using a penicillin-induced epilepsy model, the present study showed that aprepitant does not affect epileptiform activity in the presence or absence of exogenous SP. Further studies are needed to understand possible anticonvulsant or proconvulsant properties of aprepitant. [ABSTRACT FROM AUTHOR]

Intraoperative neurophysiological monitoring (IONM) is a crucial advancement in neurosurgery, enhancing procedural safety and precision. This technique involves continuous real-time assessment of neurophysiological signals, aiding surgeons in timely interventions to protect neural structures. In addition to inherent limitations, IONM necessitates a detailed anesthetic plan for accurate signal recording. Given the growing importance of IONM in neurosurgery, we conducted a narrative review including the most relevant studies about the modalities and their application in different fields of neurosurgery. In particular, this review provides insights for all physicians and healthcare professionals unfamiliar with IONM, elucidating commonly used techniques in neurosurgery. In particular, it discusses the roles of IONM in various neurosurgical settings such as tumoral brain resection, neurovascular surgery, epilepsy surgery, spinal surgery, and peripheral nerve surgery. Furthermore, it offers an overview of the anesthesiologic strategies and limitations of techniques essential for the effective implementation of IONM. [ABSTRACT FROM AUTHOR]

• The number of corticocortical evoked potentials decreases under anesthesia compared to the awake state. • The N1-peak latency is increased under propofol-anesthesia. • The topology of effective networks in awake patients is preserved under anesthesia. We compared the effective networks derived from Single Pulse Electrical Stimulation (SPES) in intracranial electrocorticography (ECoG) of awake epilepsy patients and while under general propofol-anesthesia to investigate the effect of propofol on these brain networks. We included nine patients who underwent ECoG for epilepsy surgery evaluation. We performed SPES when the patient was awake (SPES-clinical) and repeated this under propofol-anesthesia during the surgery in which the ECoG grids were removed (SPES-propofol). We detected the cortico-cortical evoked potentials (CCEPs) with an automatic detector. We constructed two effective networks derived from SPES-clinical and SPES-propofol. We compared three network measures (indegree, outdegree and betweenness centrality), the N1-peak-latency and amplitude of CCEPs between the two effective networks. Fewer CCEPs were observed during SPES-propofol (median: 6.0, range: 0–29) compared to SPES-clinical (median: 10.0, range: 0–36). We found a significant correlation for the indegree, outdegree and betweenness centrality between SPES-clinical and SPES-propofol (respectively r s = 0.77, r s = 0.70, r s = 0.55, p < 0.001). The median N1-peak-latency increased from 22.0 ms during SPES-clinical to 26.4 ms during SPES-propofol. Our findings suggest that the number of effective network connections decreases, but network measures are only marginally affected. The primary network topology is preserved under propofol. [ABSTRACT FROM AUTHOR]

Previous neuroimaging studies have offered unique insights about the spatial organization of activations and deactivations across the brain; however, these were not powered to explore the exact timing of events at the subsecond scale combined with a precise anatomical source of information at the level of individual brains. As a result, we know little about the order of engagement across different brain regions during a given cognitive task. Using experimental arithmetic tasks as a prototype for human-unique symbolic processing, we recorded directly across 10,076 brain sites in 85 human subjects (52% female) using the intracranial electroencephalography. Our data revealed a remarkably distributed change of activity in almost half of the sampled sites. In each activated brain region, we found juxtaposed neuronal populations preferentially responsive to either the target or control conditions, arranged in an anatomically orderly manner. Notably, an orderly successive activation of a set of brain regions--anatomically consistent across subjects--was observed in individual brains. The temporal order of activations across these sites was replicable across subjects and trials. Moreover, the degree of functional connectivity between the sites decreased as a function of temporal distance between regions, suggesting that the information is partially leaked or transformed along the processing chain. Our study complements prior imaging studies by providing hitherto unknown information about the timing of events in the brain during arithmetic processing. Such findings can be a basis for developing mechanistic computational models of human-specific cognitive symbolic systems. [ABSTRACT FROM AUTHOR]

Light is an electromagnetic radiation that has visible and invisible wavelength spectrums. Visible light can only be detected by the eyes through the optic pathways. With the presence of the scalp, cranium, and meninges, the brain is seen as being protected from direct exposure to light. For that reason, the brain can be viewed as a black body lying inside a black box. In physics, a black body tends to be in thermal equilibrium with its environment and can tightly regulate its temperature via thermodynamic principles. Therefore, a healthy brain inside a black box should not be exposed to light. On the contrary, photobiomodulation, a form of light therapy for the brain, has been shown to have beneficial effects on some neurological conditions. The proposed underlying mechanisms are multiple. Herein, we present our intraoperative findings of rapid electrocorticographic brainwave changes when the brain was shone directly with different wavelengths of light during awake brain surgery. Our findings provide literature evidence for light's ability to influence human brain energy and function. Our proposed mechanism for these rapid changes is the presence of plasma-like energy inside the brain, which causes fast brain activities that are akin to lightning strikes. [ABSTRACT FROM AUTHOR]

Summary: In an era of ‘big data’, we propose that a collaborative network approach will drive a better understanding of the mechanisms of delirium, and more rapid development of therapies. We have formed the International Delirium Pathophysiology & Electrophysiology Network for Data sharing (iDEPEND) group with a key aim to ‘facilitate the study of delirium pathogenesis with electrophysiology, imaging, and biomarkers including data acquisition, analysis, and interpretation’. Our initial focus is on studies of electrophysiology as we anticipate this methodology has great potential to enhance our understanding of delirium. Our article describes this principle and is used to highlight the endeavour to the wider community as we establish key stakeholders and partnerships.

Declarative memory encoding, consolidation, and retrieval require the integration of elements encoded in widespread cortical locations. The mechanism whereby such "binding" of different components of mental events into unified representations occurs is unknown. The "binding-by-synchrony" theory proposes that distributed encoding areas are bound by synchronous oscillations enabling enhanced communication. However, evidence for such oscillations is sparse. Brief high-frequency oscillations ("ripples") occur in the hippocampus and cortex and help organize memory recall and consolidation. Here, using intracranial recordings in humans, we report that these ∼70-ms-duration, 90-Hz ripples often couple (within ±500 ms), co-occur (≥ 25-ms overlap), and, crucially, phase-lock (have consistent phase lags) between widely distributed focal cortical locations during both sleep and waking, even between hemispheres. Cortical ripple co-occurrence is facilitated through activation across multiple sites, and phase locking increases with more cortical sites corippling. Ripples in all cortical areas co-occur with hippocampal ripples but do not phase-lock with them, further suggesting that cortico-cortical synchrony is mediated by cortico-cortical connections. Ripple phase lags vary across sleep nights, consistent with participation in different networks. During waking, we show that hippocampo-cortical and cortico-cortical coripples increase preceding successful delayed memory recall, when binding between the cue and response is essential. Ripples increase and phase-modulate unit firing, and coripples increase high-frequency correlations between areas, suggesting synchronized unit spiking facilitating information exchange. co-occurrence, phase synchrony, and high-frequency correlation are maintained with little decrement over very long distances (25 cm). Hippocampo-cortico-cortical coripples appear to possess the essential properties necessary to support binding by synchrony during memory retrieval and perhaps generally in cognition.

Electrode grids are used in neuroscience research and clinical practice to record electrical activity from the surface of the brain. However, existing passive electrocorticography (ECoG) technologies are unable to offer both high spatial resolution and wide cortical coverage, while ensuring a compact acquisition system. The electrode count and density are restricted by the fact that each electrode must be individually wired. This work presents an active micro‐electrocorticography (µECoG) implant that tackles this limitation by incorporating metal oxide thin‐film transistors (TFTs) into a flexible electrode array, allowing to address multiple electrodes through a single shared readout line. By combining the array with an incremental‐ΔΣ readout integrated circuit (ROIC), the system is capable of recording from up to 256 electrodes virtually simultaneously, thanks to the implemented 16:1 time‐division multiplexing scheme, offering lower noise levels than existing active µECoG arrays. In vivo validation is demonstrated acutely in mice by recording spontaneous activity and somatosensory evoked potentials over a cortical surface of ≈8×8 mm2. The proposed neural interface overcomes the wiring bottleneck limiting ECoG arrays, holding promise as a powerful tool for improved mapping of the cerebral cortex and as an enabling technology for future brain‐machine interfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • Usefulness of trapezoid-shaped electrode in temporal lobe epilepsy was evaluated. • Seizure freedom in 73% & 50% patients with mTLE & extra-mTLE, respectively. • Significant risk factors are > 64 electrode contacts and male sex, not TSE placement. • TSE is useful for evaluating mTLE in patients undergoing ICE placement. • TSE placement has low complication rate and can be safely used in patients with TLE. A trapezoid-shaped electrode (TSE) is used for detecting epileptogenicity in patients with temporal lobe epilepsy (TLE). However, the utility and safety associated with TSE placement have not been reported. In this study, we evaluated the safety and usefulness of TSE by analyzing the seizure detection, surgical outcomes and complications in patients with TLE who underwent intracranial electrodes (ICE) placement. Between April 2000 and August 2019, 50 patients with TLE who underwent 51 ICE placement procedures were examined. A TSE with eight contacts covering the parahippocampal gyrus and basal temporal lobe was used. Among the 37 patients who underwent TSE placement, 26 and 11 patients were diagnosed with mesial TLE (mTLE) and extra-mTLE, respectively. The 14 remaining patients without TSE placement were diagnosed with extra-mTLE. Seizure freedom was achieved in 73% (19/26) of mTLE patients detected by TSE and 50% (14/24) of extra-mTLE patients.Good seizure outcomes (Engel class I and II) were observed in 81% (21/26) patients with mTLE and 67% (16/24) patients with extra-mTLE. Radiographic complications were observed in 20% (10/50) patients who underwent ICE placement. Although 6% (3/50) patients showed transient neurological deficits, none were permanent. The electrodes responsible for the occurrence of complications included nine grid electrodes and one TSE. The complication rate after TSE placement was 3% (1/37). More than 64 electrode contacts and male sex, not TSE placement, were identified as significant risk factors for developing complications. This study demonstrated the usefulness and safety of TSE for evaluating mTLE in patients undergoing ICE placement. [ABSTRACT FROM AUTHOR]

Electroencephalography (EEG) microstates are short successive periods of stable scalp field potentials representing spontaneous activation of brain resting-state networks. EEG microstates are assumed to mediate local activity patterns. To test this hypothesis, we correlated momentary global EEG microstate dynamics with the local temporo-spectral evolution of electrocorticography (ECoG) and stereotactic EEG (SEEG) depth electrode recordings. We hypothesized that these correlations involve the gamma band. We also hypothesized that the anatomical locations of these correlations would converge with those of previous studies using either combined functional magnetic resonance imaging (fMRI)-EEG or EEG source localization. We analyzed resting-state data (5 min) of simultaneous noninvasive scalp EEG and invasive ECoG and SEEG recordings of two participants. Data were recorded during the presurgical evaluation of pharmacoresistant epilepsy using subdural and intracranial electrodes. After standard preprocessing, we fitted a set of normative microstate template maps to the scalp EEG data. Using covariance mapping with EEG microstate timelines and ECoG/SEEG temporo-spectral evolutions as inputs, we identified systematic changes in the activation of ECoG/SEEG local field potentials in different frequency bands (theta, alpha, beta, and high-gamma) based on the presence of particular microstate classes. We found significant covariation of ECoG/SEEG spectral amplitudes with microstate timelines in all four frequency bands (p = 0.001, permutation test). The covariance patterns of the ECoG/SEEG electrodes during the different microstates of both participants were similar. To our knowledge, this is the first study to demonstrate distinct activation/deactivation patterns of frequency-domain ECoG local field potentials associated with simultaneous EEG microstates. [ABSTRACT FROM AUTHOR]

Purpose: Epilepsy is a set of chronic neurological disorders characterized by seizures associated with abnormal and uncontrolled neuronal activity of the brain. Glutamate is the main excitatory neurotransmitter in the central nervous system. Excitatory amino acid transporter-2 (EAAT2), one of the major glutamate transporters, is responsible for total glutamate intake. Ceftriaxone is a β-lactam antibiotic that increases EAAT-2 expression and functional activity. This study aims to investigate the effects of ceftriaxone on penicillin-induced epileptiform activity by using electrocorticography (ECoG) in anesthetized rats. Method: In this study, 35 Wistar male rats were used. The rats were divided into five groups of 7. In group 1, 2.5 μL 500 IU of penicillin intracranially (i.c.) and 1 ml saline solution and intraperitoneally (i.p.) were given, respectively. In group 2, 200 mg/kg, i.p. of ceftriaxone was administered 30 minutes after penicillin. In group 3, 400 mg/kg of ceftriaxone was administered i.p. 30 minutes after penicillin. 500 mg/kg of sodium valproate was administered i.p. following 30 minutes of penicillin in group 4. In group 5, 400 mg/kg, i.p. of ceftriaxone and 500 mg/kg, i.p. of sodium valproate were administered 30 minutes after penicillin. After the surgical procedure the rats were placed in a stereotaxic device and electrocorticogram recordings were captured for 210 minutes. Results: The acute treatment of ceftriaxone reduced spike-wave frequency and spike-wave amplitude of penicillin-induced epileptiform activity in the rats. Conclusion: These findings suggest that acute ceftriaxone had an anticonvulsant effect on penicillin-induced focal onset epileptic activity. Ceftriaxone may have an anti-epileptogenic potential. [ABSTRACT FROM AUTHOR]

Background Electrocorticography (ECoG) language mapping is often performed extraoperatively, frequently involves offline processing, and relationships with direct cortical stimulation (DCS) remain variable. We sought to determine the feasibility and preliminary utility of an intraoperative language mapping approach guided by real-time visualization of electrocorticograms. Methods A patient with astrocytoma underwent awake craniotomy with intraoperative language mapping, utilizing a dual iPad stimulus presentation system coupled to a real-time neural signal processing platform capable of both ECoG recording and delivery of DCS. Gamma band modulations in response to 4 language tasks at each electrode were visualized in real-time. Next, DCS was conducted for each neighboring electrode pair during language tasks. Results All language tasks resulted in strongest heat map activation at an electrode pair in the anterior to mid superior temporal gyrus. Consistent speech arrest during DCS was observed for Object and Action naming tasks at these same electrodes, indicating good correspondence with ECoG heat map recordings. This region corresponded well with posterior language representation via preoperative functional MRI. Conclusions Intraoperative real-time visualization of language task-based ECoG gamma band modulation is feasible and may help identify targets for DCS. If validated, this may improve the efficiency and accuracy of intraoperative language mapping. [ABSTRACT FROM AUTHOR]

• Direct stimulation affected the subregions responsible for cognitive processes. • Cognitive processes were linked to changes in gamma power. • Direct cortical stimulation has the potential to enhance cognitive processes. This study aims to investigate the potential of direct cortical stimulation (DCS) to modulate tactile categorization and decision-making, as well as to identify the specific locations where these cognitive functions occur. We analyzed behavioral changes in three epilepsy patients with implanted electrodes using electrocorticography (ECoG) and a vibrotactile discrimination task. DCS was applied to investigate its impact on tactile categorization and decision-making processes. We determined the precise location of the electrodes where each cognitive function was modulated. This functional discrimination was related with gamma band activity from ECoG. DCS selectively affected either tactile categorization or decision-making processes. Tactile categorization was modulated by stimulating the rostral part of the supramarginal gyrus, while decision-making was modulated by stimulating the caudal part. DCS can enhance cognitive processes and map brain regions responsible for tactile categorization and decision-making within the supramarginal gyrus. This study also demonstrates that DCS and the gamma activity of ECoG can concordantly identify the detailed brain mapping in a tactile process compared to other functional neuroimaging. The combination of DCS and ECoG gamma activity provides a more nuanced and detailed understanding of brain function than traditional neuroimaging techniques alone. [ABSTRACT FROM AUTHOR]

Awake craniotomy with electrocorticography (ECoG) and direct electrical stimulation (DES) facilitates lesionectomy while avoiding adverse effects. Early postoperative seizures (EPS), occurring within 7 days following surgery, can lead to morbidity. However, risk factors for EPS after awake craniotomy including clinical and ECoG data are not well defined. We retrospectively studied the incidence and risk factors of EPS following awake craniotomy for lesionectomy, and report short-term outcomes between January 1, 2020, and December 31, 2022. We included 138 patients (56 female) who underwent 142 awake craniotomies, average age was 50.78 ± 15.97 years. Eighty-eight (63.7%) patients had a preoperative history of tumor-related epilepsy treated with antiseizure medication (ASM), 12 (13.6%) with drug-resistance. All others (36.3%) received ASM prophylaxis with levetiracetam perioperatively and continued for 14 days. An equal number of cases (71) each utilized a novel circle grid or strip electrodes for ECoG. There were 31 (21.8%) cases of intraoperative seizures, 16 with EPS (11.3%). Acute abnormality on early postoperative neuroimaging (P = 0.01), subarachnoid hemorrhage (P = 0.01), young age (P = 0.01), and persistent postoperative neurologic deficits (P = 0.013) were associated with EPS. Acute abnormality on neuroimaging remained significant in multivariate analysis. Outcomes during hospitalization and early outpatient follow up were worse with EPS. We report novel findings using ECoG and clinical features to predict EPS, including acute perioperative brain injury, persistent postoperative deficits and young age. Given worse outcomes with EPS, clinical indicators for EPS should alert clinicians of potential need for early postoperative EEG monitoring and perioperative ASM adjustment. [ABSTRACT FROM AUTHOR]