Strip Electrodes Research Articles

Ictal onset zone localization by using ECOG signals

The diagnosis of seizure onset zone is crucial in epilepsy surgery for patients having pharmacoresistant, that the localization of ictal onset zone (IOZ) is associated with epileptiform activity region, by using intracranial strip and grid electrodes of electrocorticography (ECOG). Thus, these ECOG signals determine areas of the brain which can be surgically removed by visual inspection, especially in partial epilepsy named focal seizure. However, this paper investigates recent automatic IOZ localization, based on recurrent neural network (RNN) to improve the performance of identification of IOZ. Therefore, statistical patterns in time-frequency domains are extracted after applying hybrid empirical mode decomposition (EMD) and variational mode decomposition (VMD) methods. In addition, the evaluation of this work is performed by implementation of several indicators to distinct between focal and non focal ECOG signals. Moreover, the experiment results using Bern– Barcelona dataset indicated the effectiveness of using hybrid EMD-VMD method and RNN, that the proposed model achieve better classification performance reached 100% of accuracy. Hence, by comparison with other studies in the literature review, ECoG recordings provide best localization of IOZ by using this system. Finally, this developed method shows accurate results to help clinical experts in seizure resection, and indicates localization of IOZ which can be removed from brain area.

РОЗРАХУНОК ПОХИБКИ ЄМНІСНОГО СЕНСОРА ПОВІТРЯНОГО ПРОМІЖКУ В ГІДРОГЕНЕРАТОРАХ З СИСТЕМОЮ КОМПЛАНАРНИХ ЕЛЕКТРОДІВ, ЗУМОВЛЕНОЇ ПЕРЕКОСОМ

In this paper calculating the technological errors that arise when using capacitive sensors to measure the air gap (AG) in hydrogen generators, in particular, those caused by the inaccuracy of their installation on the machine. The results of the analysis of the error caused by the skew of the plane of the sensor electrodes relative to the constructive boring of the stator core are given. It was found that the skew of the electrodes could significantly affect the accuracy of the measurements, which in turn affects the efficiency and reliability of the hydrogen generator. A detailed assessment of the influence of this skew on the measurement results was carried out using a sensor consisting of a system of N coplanar parallel strip electrodes located perpendicular to the core boring. A calculation scheme has been developed for the quantitative assessment of the error, which allows determining the value of the error taking into account analytical dependencies. Numerical methods were used to assess the influence of skew on the accuracy of measurements, and the results were obtained for a sensor designed for a capsule hydrogen generator of the SGK538/160-70M type. Based on the obtained results, practical recommendations have been developed to reduce the impact of skew error on measurement accuracy. Ref. 11, fig. 6.

Analysis of skin and corneal fiber electrodes for electroretinogram assessments in patients with major depressive disorder.

Electroretinograms (ERG) are usually recorded with non-invasive corneal electrodes, requiring direct contact with the ocular surface. However, corneal electrode application is not tolerated by some individuals. The advent of handheld ERG devices has facilitated the use of skin electrodes for ERG measurements. Skin electrodes do not require corneal contact and thus enhance patient comfort, simplify the attachment process, and reduce preparation time, which is particularly beneficial for clinical psychiatric research. Nevertheless, due to the different attachment methods, ERG amplitudes recorded with skin compared to corneal electrodes are considerably smaller. However, comparative data on ERGs recorded with skin vs. corneal electrodes in psychiatric populations are currently lacking. We recorded flash electroretinograms of 57 healthy controls (HC) and 30 patients with a major depressive disorder (MDD) using both sensor strip skin and corneal electrodes with the handheld RETeval® device. The significant reduction in both the amplitude and peak time of the a-wave in MDD when using sensor strip skin electrodes could not be replicated with corneal electrodes. Comparing both electrode types in HC revealed a fair correlation between sensor strip and corneal electrodes for a- and b-wave amplitudes and a moderate correlation for a- and b-wave peak times. In addition to being better tolerated, sensor strip skin electrodes appear to be more effective than corneal electrodes in detecting ERG alterations in patients with MDD when using the RETeval® device, making them a promising alternative to traditional corneal electrodes.

Epilepsy-surgery for fronto-basal lesions: Management, outcome, and review of literature

BackgroundIn this study, we isolated a cohort of patients who have refractory epilepsy who underwent surgery with frontobasal focus. This work aimed to develop prognostic factors associated with a better seizure outcome and identify risk factors determining postoperative morbidity. MethodsWe identified all patients with frontobasal epilepsy who underwent surgery due to refractory epilepsy at the University Hospital Bonn over 22 years. Although this is a retrospective study, all data sets were collected prospectively. We evaluated both surgical and functional outcomes. ResultsIn total, 32 patients were identified for inclusion in this study. With a long and stable postoperative seizure outcome averaging 109 months, we were able to show that patients with frontobasal epilepsy can achieve a better outcome (53 % seizure-free, ILAE1) than patients with frontal epilepsy. In contrast to other brain regions, the resection size (isolated or extended) did not influence the outcome. Low-grade tumors, on the other hand, were associated with a better seizure outcome, and gliosis or non-specific histological findings with a worse seizure outcome. Stereo-EEG with depth electrodes is more suitable for invasive diagnostics at the frontal base than strip or grid electrodes. Patients who did not become seizure-free after surgery and underwent a second surgery did not profit significantly concerning seizure outcome. ConclusionPatients with frontobasal epilepsy who are operated on early in the course of the disease, are MRI-positive, and have a tumor as an epileptogenic pathology have the best chance of seizure freedom.

Performance Investigations of Two Channel Readout Configurations on the Cross-Strip Cadmium Zinc Telluride Detector.

In a detector system where the number of channels exceeds the number of channels available on an application-specific integrated circuit (ASIC), there is a need to configure channels among multiple ASICs to achieve the lowest electronic noise and highest count rate. In this work, two board configurations were designed to experimentally assess which one provides the more favorable performance. In the half-half configuration, contiguous channels from one edge to the center of CZT detector are read by one ASIC, and the other half are read by the other ASIC. In the alternate configuration, the CZT channels are read by alternating ASICs. A lower electronic noise level, better FWHM energy resolution performance (5.35% ± 1.08% compared to 7.84% ± 0.98%), and higher count rate was found for the anode electrode strips with half-half configuration. Cross-talk between ASICs and deadtime play a role in the different performances, and the total count rate of the half-half configuration has a count rate 18.1% higher than that of the alternate configuration.

Local Orientation Transitions to a Lying Helix State in Negative Dielectric Anisotropy Cholesteric Liquid Crystal

Orientation transitions in a cholesteric liquid crystal (CLC) layer with negative dielectric anisotropy, under the influence of a non-uniform spatially periodic electric field created using a planar system of interdigitated electrodes, were studied experimentally and numerically. In the interelectrode space, transitions are observed from a planar Grandjean texture, with the helix axis perpendicular to the layer plane, to states with a lying helix, when the helix axis is parallel to the layer plane and perpendicular to the electrode stripes. It was found that the relaxation time of the induced state in the Grandjean zones, corresponding to two or more half-turns of the helix, significantly exceeded the relaxation time for the first Grandjean zone with one half-turn. An analysis of experimentally observed and numerically simulated textures shows that slow relaxation to the initial state in the second Grandjean zone, as well as in higher-order zones, is associated with the formation of local topologically equivalent states. In these states, the helix has a reduced integer number of helix half-turns throughout the layer thickness or unwound into the planar alignment state.

Subject-Agnostic Transformer-Based Neural Speech Decoding from Surface and Depth Electrode Signals.

This study investigates speech decoding from neural signals captured by intracranial electrodes. Most prior works can only work with electrodes on a 2D grid (i.e., Electrocorticographic or ECoG array) and data from a single patient. We aim to design a deep-learning model architecture that can accommodate both surface (ECoG) and depth (stereotactic EEG or sEEG) electrodes. The architecture should allow training on data from multiple participants with large variability in electrode placements and the trained model should perform well on participants unseen during training. We propose a novel transformer-based model architecture named SwinTW that can work with arbitrarily positioned electrodes by leveraging their 3D locations on the cortex rather than their positions on a 2D grid. We train subject-specific models using data from a single participant and multi-patient models exploiting data from multiple participants. The subject-specific models using only low-density 8x8 ECoG data achieved high decoding Pearson Correlation Coefficient with ground truth spectrogram (PCC=0.817), over N=43 participants, outperforming our prior convolutional ResNet model and the 3D Swin transformer model. Incorporating additional strip, depth, and grid electrodes available in each participant (N=39) led to further improvement (PCC=0.838). For participants with only sEEG electrodes (N=9), subject-specific models still enjoy comparable performance with an average PCC=0.798. The multi-subject models achieved high performance on unseen participants, with an average PCC=0.765 in leave-one-out cross-validation. The proposed SwinTW decoder enables future speech neuroprostheses to utilize any electrode placement that is clinically optimal or feasible for a particular participant, including using only depth electrodes, which are more routinely implanted in chronic neurosurgical procedures. Importantly, the generalizability of the multi-patient models suggests that such a model can be applied to new patients that do not have paired acoustic and neural data, providing an advance in neuroprostheses for people with speech disability, where acoustic-neural training data is not feasible.

A novel single-sided dual-period liquid crystal phase grating with high phase difference and fast-response

The liquid crystal (LC) phase grating is highly sought-after in a myriad of applications, ranging from telecommunications to sensing technologies. However, achieving both rapid response times and high phase differences simultaneously remains a formidable challenge. Here, a novel single-sided dual-period LC phase grating structure with high phase difference and fast-response is proposed. The grating's substrate is comprised of a composite electrode, incorporating strip electrodes and a common electrode. By applying varied voltages across different electrode modules, distinct periods and diffraction angles are attained. Simulation results indicate that this approach yields phase differences of 1.61π for large-period LC phase grating and 1.17π for small-period ones. Moreover, the measured rise and decay time for the former is 8.15 ms and 4.10 ms, and for the latter is 8.84 ms and 4.12 ms, respectively. The proposed LC phase grating, with its simplicity and ease of operation, holds substantial potential for application across a broad spectrum of fields, highlighting its considerable room for development.

Intraoperative Neuromonitoring for the Lower-Extremity Region Using Motor-Evoked Potential With Direct Cortical Stimulation in Brain Tumor Surgeries.

To evaluate the motor function of the lower extremity (LE), we used direct cortical stimulation motor-evoked potential (D-MEP) monitoring with a single six-contact subdural strip electrode placed in the interhemispheric fissure. Intraoperative neuromonitoring using D-MEPs in the LE was performed in 18 cases (16 patients) for brain tumor surgery from December 2018 to April 2023 with a follow-up period of at least 3 months. After dural opening, a single six-contact subdural strip electrode was placed inside the interhemispheric fissure. To identify the central sulcus, phase reversal was recorded using somatosensory evoked potentials. Next, direct cortical stimulation was applied to the primary motor cortex. The baseline waveform was defined as a reproducible waveform of 30 µV or higher, and a significant decrease of ≥50% in the amplitude resulted in a warning during surgery. The success rate of central sulcus identification in the LE was 66.7% (12/18 cases). Direct cortical stimulation motor-evoked potential monitoring could record stable contralateral motor-evoked potentials of the tibialis anterior, gastrocnemius, and abductor hallucis in 16 of 18 cases (88.9%). The mean intensity of stimulation for D-MEPs was 20.5 ± 9.9 mA, and the 16 cases showed no significant reduction in amplitude. Seventeen cases showed no deterioration of motor function of the LE at 1 and 3 months postoperatively. In the remaining case with unsuccessful D-MEP, paralysis of the LE worsened at 1 and 3 months postoperatively. The placement of electrodes in the interhemispheric fissure on the primary motor cortex of the LE enabled motor-function monitoring in the LE with D-MEPs, suggesting that D-MEP-based monitoring may be a reliable approach.

Cortical and subcortical intraoperative-monitoring of the visual pathway under general anesthesia in epilepsy surgery

ObjectiveThe purpose of this study was to evaluate the applicability of visual evoked potentials (VEP) for intraoperative visual pathway monitoring in epilepsy surgery of the posterior hemispheric quadrant (PHQ) and to correlate it with post-operative visual field status. MethodsVEP monitoring was performed in 16 patients (12 females, 7 children). Flash-induced VEP were recorded with strip electrodes from the banks of the calcarine cortex. Latency and amplitude of the first component of VEP (V1-lat, V1-amp) were monitored. Evaluation of the visual field was performed pre- and post-operatively in all patients. ResultsAll procedures were successfully completed without adverse events.In 10 patients the strip covered both the inferior and superior calcarine banks, while only one bank was sampled in 6 cases (inferior in 4, superior in 2). Considering one of the two calcarine banks, at the end of the resection VEP had disappeared in 4 patients, whereas a decrease >33.3% in 4 and <20% of V1-amp was recorded in 5 and in 4 cases respectively. The percentage of V1-amp reduction was significantly higher for the patients who experienced a post-operative visual field reduction (p < 0.001). Post-operative visual field deficits were found in patients presenting a reduction >33.3% of V1-amp. ConclusionsVEP monitoring is possible and safe in epilepsy surgery under general anesthesia. SignificanceIntraoperative recording of VEP from the banks of the calcarine cortex allows monitoring the integrity of post-geniculate visual pathways during PHQ resections for epilepsy and it is pivotal to prevent disabling visual field defects, including hemianopia and inferior quadrantanopia.

Return of intracranial beta oscillations and traveling waves with recovery from traumatic brain injury.

Traumatic brain injury (TBI) remains a pervasive clinical problem associated with significant morbidity and mortality. However, TBI remains clinically and biophysically ill-defined, and prognosis remains difficult even with the standardization of clinical guidelines and advent of multimodality monitoring. Here we leverage a unique data set from TBI patients implanted with either intracranial strip electrodes during craniotomy or quad-lumen intracranial bolts with depth electrodes as part of routine clinical practice. By extracting spectral profiles of this data, we found that the presence of narrow-band oscillatory activity in the beta band (12-30 Hz) closely corresponds with the neurological exam as quantified with the standard Glasgow Coma Scale (GCS). Further, beta oscillations were distributed over the cortical surface as traveling waves, and the evolution of these waves corresponded to recovery from coma, consistent with the putative role of waves in perception and cognitive activity. We consequently propose that beta oscillations and traveling waves are potential biomarkers of recovery from TBI. In a broader sense, our findings suggest that emergence from coma results from recovery of thalamo-cortical interactions that coordinate cortical beta rhythms.

A Novel Technique for Intraoperative Mapping of the Somatosensory Cortex

Intraoperative mapping of the nervous system is used to identify "eloquent" cortical areas. In this technical report, we describe a novel way of mapping the somatosensory cortex so that injury to those critical pathways can be avoided. An 8-year-old female with drug resistant epilepsy presented for resection of a right posterior parietal focal cortical dysplasia. Left median nerve stimulation was used to record somatosensory evoked potentials (SEPs) directly from the somatosensory cortex with a strip electrode. A handheld monopolar electrode was also used to record both the median and tibial SEP. Total intravenous anesthesia with propofol and remifentanil was used. SEP recordings were obtained from a 4-contact strip electrode placed across the central sulcus. A phase reversal was identified and the most likely post central gyrus was noted. With the strip electrode left in place, a monopolar handheld electrode was used to record the median nerve SEPs from different locations on the postcentral gyrus. The tibial nerve was also stimulated to record where the highest amplitude tibial nerve SEP was present. This map was used delineate functionally "eloquent" areas to avoid during surgery. During resection, the median nerve SEP was recorded from the strip electrode continuously. No significant change in the SEP was noted, and the patient awoke without any sensory deficits. Sensory mapping of the cortex is possible with a handheld monopolar electrode. This technique is easy to perform and can help reduce neurological morbidity.

Smartphone based wearable sweat glucose sensing device correlated with machine learning for real-time diabetes screening

BackgroundDiabetes is a significant health threat, with its prevalence and burden increasing worldwide indicating its challenge for global healthcare management. To decrease the disease severity, the diabetic patients are recommended to regularly check their blood glucose levels. The conventional finger-pricking test possesses some drawbacks, including painfulness and infection risk. Nowadays, smartphone has become a part of our lives offering an important benefit in self-health monitoring. Thus, non-invasive wearable sweat glucose sensor connected with a smartphone readout is of interest for real-time glucose detection. ResultsWearable sweat glucose sensing device is fabricated for self-monitoring of diabetes. This device is designed as a body strap consisting of a sensing strip and a portable potentiostat connected with a smartphone readout via Bluetooth. The sensing strip is modified by carbon nanotubes (CNTs)-cellulose nanofibers (CNFs), followed by electrodeposition of Prussian blue. To preserve the activity of glucose oxidase (GOx) immobilized on the modified sensing strip, chitosan is coated on the top layer of the electrode strip. Herein, machine learning is implemented to correlate between the electrochemical results and the nanomaterial content along with deposition cycle of prussian blue, which provide the highest current response signal. The optimized regression models provide an insight, establishing a robust framework for design of high-performance glucose sensor. SignificanceThis wearable glucose sensing device connected with a smartphone readout offers a user-friendly platform for real-time sweat glucose monitoring. This device provides a linear range of 0.1–1.5 mM with a detection limit of 0.1 mM that is sufficient enough for distinguishing between normal and diabetes patient with a cut-off level of 0.3 mM. This platform might be an alternative tool for improving health management for diabetes patients.

Stereoscopic Monitoring Technique for Motor Area Tumors

The balance between comprehensive intraoperative neurophysiological monitoring (IONM) for both upper and lower limbs while ensuring the reliability of motor evoked potentials (MEPs) is paramount in motor area surgery. It is commonly difficult to obtain good simultaneous stimulation of both upper and lower limbs. A series of factors can bias MEP accuracy, and inappropriate stimulation intensity can result in unreliable monitoring. The presented IONM technique is based on the concurrent use of both transcranial and cortical strip electrodes to facilitate simultaneous monitoring of both upper and lower limbs at optimized stimulation intensities to increase IONM accuracy during motor area surgery. Ten nonconsecutive motor area tumors were studied. Good visualization of both limbs was observed in the series at a low amperage (1.2 mA from thestrip electrode and 165.3 mA from the transcranial electrode). Our analysis confirms concordance between the IONM data and postoperative outcomes. An MEP reduction >20% and >50% correlated with postoperative modified Rankin scale score changes without false-negative IONM findings. The technique was demonstrated to be accurate in providing a good simultaneous neurophysiological evaluation of both upper and lower limbs with an optimized and stimulation amplitude. The technique results in a low encumbrance of electrodes in the surgical field. Our results have confirmed the "proof of concept," its reliability and feasibility.

A portable and integrated traveling-wave electroosmosis microfluidic pumping system driven by triboelectric nanogenerator

The lab-on-a-chip system can simultaneously complete the preparation, reaction, separation, and detection of samples on a centi-scale platform by manipulating trace fluids. Traveling-wave electroosmosis (TWEO) technology, with the merit of electric signal-based flexible control over the fluid behavior, can achieve precise driving of fluids, which is an important requirement of the lab-on-a-chip system. However, the peripheral power equipment such as the function generator required for TWEO limits the application in some occasions lacking power supply facilities, due to its large size and high cost. In this paper, we have developed a brand-new portable and integrated TWEO microfluidic pumping system, wherein a front-end module of triboelectric nanogenerator (TENG) is in serial connection with the back-end microfluidic pumping chip, which greatly improves portability and reduces costs. The TENG can output stable four consecutively 90°-phase-shifted alternating current voltage signals in a continuous rotational motion originated by its novel electrode structure. And the four-phase traveling potential waves are applied to four sets of electrode strips alternately distributed in the microchannel, thereby inducing nonlinear electroosmotic slip on the electrode surface, achieving stable pumping of fluids in the microchannel. Compared with traditional fluid-driven methods, this system features high safety for the operator and chip but also realizes the almost instantaneous start, stop, and directional switching in response to a turn on, turn off, and turn in reverse of TENG, respectively. Finally, this system is integrated into a droplet microfluidic chip for the efficient generation of single emulsion droplets. This study presents a promising solution for the miniaturization, integration, and commercialization of lab-on-a-chip system.

Parallel-plate avalanche counters for heavy-ion beam tracking: History and mysteries

Despite being an old detector concept, position-sensitive parallel-plate avalanche counters (PPACs) remain widely used today for heavy-ion position and timing measurements. In modern rare isotope beam facilities and large-acceptance fragment separators, PPACs are used to characterize beam properties (diagnostics), facilitate beam delivery (tuning), and provide event-by-event beam tracking for particle identification (PID). Most popular particle localization methods in PPAC detectors are based on strip electrodes electrically connected to resistive-chain circuits or delay lines. More exotic systems include optical readouts based on recording electroluminescence light with high-granularity photodetector arrays or high-resolution resistive anode electrodes. PPACs with conventional resistive-chain or delay-line readouts achieve typical position and time resolutions of below 1 mm (σ) and around 150 ps (σ), respectively. In addition, delay-line systems are capable of counting rates above several hundred kHz for beam areas of a few millimeters square, and around 1 MHz for larger beam sizes. Resistive-chain readouts have limited rates of a few tens of kHz. A review of the operation principles and performance of PPAC detectors is presented in this paper. We will discuss decades-long experience building and operating PPACs developed at the National Superconducting Cyclotron Laboratory, and then refined at the Facility for Rare Isotope Beams (FRIB), mostly focusing on the delay-line readout technique (DLPPAC). We will also discuss problems that arise due to electric discharges at high rates and briefly describe ongoing developments at FRIB. Published by the American Physical Society 2024

Interactive driving of electrostatic film actuator by proximity motion of human body

AbstractA built-in capacitive proximity sensing method for a charge-induction electrostatic film actuator is proposed. This actuator consists of two thin sheets that function as a stator and a slider. A stator is an insulating sheet with many strips of electrodes in it, whereas a slider is a dielectric sheet that has slight conductivity on its surface. By applying actuation voltage on stator electrodes, the slider that is placed on the stator is driven by electrostatic force. This research realized the simultaneous actuation and proximity sensing using the same electrodes by integrating a resonance-based capacitance measurement circuit into a driving circuit. The study investigated the impact of having a slider on sensing performance, confirming the feasibility of simultaneous sensing and driving. The implemented system achieved an interactive actuation that changed driving velocity according to the proximity distance of the human hand.

Simultaneous Electrochemical Detection of Cu2+ and Zn2+ in Pig Farm Wastewater.

In recent years, the rapid development of pig farming has led to a large quantity of heavy metal-polluted wastewater. Thus, it was desirable to develop a simple heavy metal detection method for fast monitoring of the wastewater from the pig farms. Therefore, there was an urgent need to develop a simple method for rapidly detecting heavy metal ions in pig farm wastewater. Herein, a simple electrochemical method for simultaneous detection of Cu2+ and Zn2+ was developed and applied to pig farm wastewater. With a glassy carbon electrode and anodic stripping voltammetry, simultaneous detection of Cu2+ and Zn2+ in water was achieved without the need for complicated electrode modification. Furthermore, it was found that the addition of Cd2+ can enhance the response current of the electrode to Zn2+, which increased the signal by eight times. After systematic optimization, the limit of detection (LOD) of 9.3 μg/L for Cu2+ and 45.3 μg/L for Zn2+ was obtained. Finally, it was successfully applied for the quantification of Cu2+ and Zn2+ with high accuracy in pig farm wastewater. This work provided a new and simple solution for fast monitoring of the wastewater from pig farms and demonstrated the potential of electrochemical measurement for application in modern animal husbandry.

253 Tissue Partial Pressure of Oxygen During Spreading Depolarization in Malignant Stroke is Associated With Outcome

INTRODUCTION: Spreading depolarization (SD) describes a propagating neuronal mass depolarization within the cerebral cortex that likely represents a relevant mechanism of secondary lesion progression. METHODS: This prospective observational study included 25 patients with MHS that underwent decompressive hemicraniectomy (DC) followed by subdural placement of an electrocorticography (ECoG) strip electrode and cortical implantation of a PtiO2 probe within in the periinfarct tissue. Continuous ECoG and PtiO2 recordings were obtained at bedside for five days and analyzed for the occurrence of SD and SD-associated PtiO2 changes, as well as their association with clinical outcome at 6 months. RESULTS: The overall simultaneous ECoG and PtiO2 recording time was 2603 hours, during which 796 SDs were detected. The overall SD duration and SD frequency did not correlate with outcome. During the observation period, the overall PtiO2baseline changed significantly with an almost linear increase that reached a peak around 100 hours (*p=0.0055), followed by a PtiO2 drop until the end of the monitoring period (*p = 0.0048). Accordingly, low baseline PtiO2 (&lt;15 mmHg) was mainly noted during the first 24 hours but did not correlate with outcome (p = 0.916). Conversely, 20 out of 25 patients showed SD-associated PtiO2 changes in 363 out of 796 SDs (45.6%), which were categorized as biphasic (222), hypoxic (119) and hyperoxic (22). Among these SD-associated PtiO2 responses, a high occurrence rate, biphasic response pattern and high amplitude correlated significantly with favorable outcome (mRS 1-3) at 6 months. CONCLUSIONS: SD-associated PtiO2 coupling in patients suffering hemispheric stroke appears to be associated with clinical outcome and could reflect the presence of viable and metabolically less impaired peri-infarct tissue.

482 Identification of Candidate Neural Biomarkers of Obsessive-compulsive Symptom Intensity and Response to DBS

INTRODUCTION: Despite the success of DBS for the treatment of refractory OCD, there are currently no robust neural signatures for obsessive-compulsive (OC) symptoms or initial mood and energy improvements associated with DBS. This gap may be due to limited opportunities available for conducting intracranial electrophysiological recordings during natural symptom fluctuations. Recently available DBS platforms offer a way over this hurdle, allowing for streaming of intracranial local field potentials (LFP) at home and in the clinic. METHODS: We conducted longitudinal intracranial recordings in 10 patients with refractory OCD implanted with recording-capable DBS devices targeted to ventral capsule/ventral striatum (VC/VS). Five of the 10 were additionally implanted with ECoG strip electrodes over the orbitofrontal cortex (OFC). We captured LFP at home during naturalistic exposures to OCD triggers and in the clinic during variations in stimulation amplitude. RESULTS: All 5 participants who have completed the study so far are clinical responders to DBS therapy. Using the intracranial data collected during OCD exposures, we identified low delta-band power as a candidate neural biomarker of OC symptom intensity during symptom provocations (left VC/VS: R = -0.59, p = 0.01; right VC/VS: R = -0.56, p = 0.04). Electrophysiological analysis of acute response to stimulation revealed a narrow band increase in 30 Hz power specific to lateral OFC that was associated with increased talkativeness and approach behaviors that are typical harbingers of clinical response CONCLUSIONS: These signals have potential utility for classification of symptom intensity and increased mood and energy to enable adaptive DBS systems for OCD. Our data suggest that the neural biomarkers of these two clinical features might be separable, thus possibly allowing for simultaneous optimization of both.