Describing intracortical laminar organization of interictal epileptiform discharges (IED) and high frequency oscillations (HFOs), also known as ripples. Defining the frequency limits of slow and fast ripples. We recorded potential gradients with laminar multielectrode arrays (LME) for current source density (CSD) and multi-unit activity (MUA) analysis of interictal epileptiform discharges IEDs and HFOs in the neocortex and mesial temporal lobe of focal epilepsy patients. IEDs were observed in 20/29, while ripples only in 9/29 patients. Ripples were all detected within the seizure onset zone (SOZ). Compared to hippocampal HFOs, neocortical ripples proved to be longer, lower in frequency and amplitude, and presented non-uniform cycles. A subset of ripples (≈ 50%) co-occurred with IEDs, while IEDs were shown to contain variable high-frequency activity, even below HFO detection threshold. The limit between slow and fast ripples was defined at 150 Hz, while IEDs’ high frequency components form clusters separated at 185 Hz. CSD analysis of IEDs and ripples revealed an alternating sink-source pair in the supragranular cortical layers, although fast ripple CSD appeared lower and engaged a wider cortical domain than slow ripples MUA analysis suggested a possible role of infragranularly located neural populations in ripple and IED generation. Laminar distribution of peak frequencies derived from HFOs and IEDs, respectively, showed that supragranular layers were dominated by slower (< 150 Hz) components. Our findings suggest that cortical slow ripples are generated primarily in upper layers while fast ripples and associated MUA in deeper layers. The dissociation of macro- and microdomains suggests that microelectrode recordings may be more selective for SOZ-linked ripples. We found a complex interplay between neural activity in the neocortical laminae during ripple and IED formation. We observed a potential leading role of cortical neurons in deeper layers, suggesting a refined utilization of LMEs in SOZ localization.
Neurological emergencies, such as acute stroke, are especially challenging during the current Coronavirus disease-2019 (COVID-19) pandemic. Symptoms as aphasia or dysarthria are severely impacting cooperation and communication with patients. During physical examination, both the patient and the medical team are fitted routinely with surgical masks to minimize potential exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, such a practice can lead to concealment of particularly relevant physical signs. We report a case series of four acute stroke patients who were transferred for endovascular mechanical thrombectomy to our institute after intravenous thrombolysis was initiated at primary stroke centers. Upon arrival, after removing their masks, we observed oral angioedema, as a reaction to thrombolytic agent alteplase. Symptoms remained obscured by face masks through patient care at the referring stroke unit and during transportation, nevertheless they resolved after treatment. Most probably, there are a number of similar cases encountered at emergency departments and acute stroke units. To improve patient safety, a compromise between ensuring protection against the novel coronavirus and facilitating detection of potentially life-threatening physical signs must be found.
Objective:Describing intracortical laminar organization of high frequency oscillations (HFOs).Methods:We recorded potential gradients with laminar microelectrode arrays (LME) for current source density (CSD) and multi-unit activity (MUA) analysis of interictal discharges (IID) and HFOs in the neocortex and mesial temporal lobe of focal epilepsy patients. Results:Ripples were only observed in 9/29 patients, all within the seizure onset zone (SOZ). Ripples variably (≈50%) coincided with IIDs. CSD analysis revealed slow ripples (<150Hz) to exhibit an alternating sink-source pair in the upper cortical layers. In contrast, fast ripples (>150Hz) were biased to the lower layers, tending to precede the superficial activity (10-30ms).Conclusion: Our findings suggest that cortical slow ripples are generated primarily in upper layers while fast ripples and associated MUA in deeper layers. The dissociation of macro- and microdomains suggests that microelectrode recordings may be more selective for SOZ-linked ripples.Significance:We found a complex interplay between neural activity in the neocortical laminae during ripple formation. We observed a potential leading role of cortical neurons in deeper layers, suggesting a refined utilization of LMEs in SOZ localization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.