- Email: [email protected]
S10. Clinical and electroencephalographic correlates of ictal spitting
Abstracts / Clinical Neurophysiology 129 (2018) e142–e212
inaccessible to subdural electrodes. Our case demonstrates the utility of Stereotactic EEG in localizing seizure onset zone and mapping the function of both cortical and subcortical structures in a patient with drug resistant focal epilepsy. Methods: The patient is a 58 year old right handed woman with a history of drug resistant epilepsy since age 18. Her seizures were predominantly nocturnal and arose out of sleep. She had multiple seizures per night. She reports out of body experience, anxiety feeling and chocking sensation followed by back and forth rocking movements. Seizures usually last 30–45 s with a quick recovery from her seizures. Her ictal scalp EEG was non localizing. Her interictal FDG PET scan was normal. Her subtracted ictal-interictal SPECT scan was also non localizing. Her epilepsy protocol 3T brain MRI showed a subtle area of white–grey matter blurring on the DIR pulse sequence which involved the left anterior cingulate gyrus. The patient underwent Stereotactic EEG implantation to confirm seizure localization and for functional mapping. Her ictal intracranial EEG showed an onset of high amplitude repetitive spiking intermixed with low amplitude fast activity in the electrodes located in the left anterior cingulate followed by spread of the same pattern to electrodes in the left insular cortex within less than 500 ms from the onset. Electrical stimulation mapping was performed. Biphasic 50 Hz stimulation starting at 1 mA intensity with increments of 0.5 mA was applied. Results: The patient reported the typical sensation of her aura and early symptoms of her seizures during the stimulation of left anterior cingulate contacts during stimulation with 1–3 mA which was reproducible. She also reported the usual sensation she experiences a few seconds following the onset of her seizures during the stimulation of her left insular electrodes during stimulation with 3–5 mA that was also reproducible. No after- discharge was seen during these stimulation trials. The patient subsequently underwent an open lesionectomy of the anterior cingulate MRI abnormality. Pathology showed focal cortical dysplasia type IIB with dysmorphic neurons and balloon cells. The patient has remained seizure free since surgery. No neurological deficit was seen. Conclusion: Electrical stimulation mapping of SEEG can be used to study the functionality of the cortex as well as the subcortical structures. In addition to localizing eloquent cortex, electrical stimulation of SEEG can support the localization of epileptic network and seizure onset zone. doi:10.1016/j.clinph.2018.04.368
S09. The role of oscillatory activity in attentive speech perception: An Ecog study in epilepsy patients—Mario E. Archila-Meléndez, Vivianne H. Kranen-Mastenbroek *, Giancarlo Valente, João Correia, Erik D. Gommer, Bernadette M. Jansma, Rob P. Rouhl, Mark J. Roberts (Netherlands) ⇑
Presenting author.
Introduction: Activation of neuronal networks is typically associated with a change in spectral power in electric signals within the network. The role of different spectral bands in mediating cognitive processes is still not fully understood. In human language networks, a hierarchical model has been suggested in which different types of linguistic information is transferred in different oscillatory bands. Within that model, attention is assumed to correlate with increase in gamma and decrease in alpha band power. Electrocorticography (ECoG) allows the segregation of neural representations independently of stimulus variation. Aim of the study: Here, for the first time, we investigate whether selective attention to the different components of a syllable (i.e.,
e145
consonants or vowels) modulates the spectral power of oscillatory activity (i.e., broadband gamma and alpha) and whether these changes relate to behavioral performance. Methods: To address this issue, we measured ECoG signals in 11 patients with refractory epilepsy who were undergoing pre-surgical screening. Neuronal responses were measured with intracranial electrodes (i.e., grids, strips, and depth hippocampal electrodes). The patients engaged in cognitive testing in which auditory consonant–vowel syllable sounds were compared with written letters (i. e., delay match-to-sample task). The behavioral relevance of different components of the syllables was manipulated in four levels; attention was directed either to the complete syllable, only to the vowel, only to the consonant, or the syllable sound was irrelevant. Analysis: We calculated: (a) bipolar differentials between each pair of neighboring channels; (b) time–frequency representations of power between 2 and 150 Hz; (c) an index of power change, per trial, relative to power during pre-stimulus baseline period; and (d) average power modulation for two frequency bands (i.e., 5–15 and 70–150 Hz). Results: Presentation of stimuli was associated with an increase in broadband gamma (70–150 Hz) and a decrease in alpha (5–15 Hz) over sensory cortex (i.e., auditory cortex for auditory stimuli, and visual cortex for visual stimuli), while alpha power was increased in domain unspecific cortical areas. Gamma band activity could be robustly mapped to stimulus parameters but was only weakly related to attentional state or behavioral performance. Alpha band activity was more related to cognitive state and performance than to stimulus features. Broadband gamma power changes were related to stimulus physical properties. Conclusion: These results give new insights into the interplay between alpha and gamma oscillations within the human language network, here with a focus on phonological aspects, and the possible role of these oscillations in the processing of sensory stimuli and behavioral performance during selective attention. doi:10.1016/j.clinph.2018.04.369
S10. Clinical and electroencephalographic correlates of ictal spitting—Mayur Chalia (USA)
Introduction: Ictal spitting is a rarely reported, stereotyped nonpurposeful automatism behavior which surfaces during a complex partial seizure. It is similar to other behaviors frequently seen in temporal lobe seizures which include lip smacking, swallowing, and chewing movements. The underlying mechanism of both ictal and post ictal automatisms is unclear. It is hypothesized that this occurs as a result of the activation of areas mediating gastrointestinal function and emotional behavior. Such areas include the amygdala and the insula specifically on the non-dominant side due to the functional asymmetry of the central autonomic network. Methods: Charts and video-EEGs (Electroencephalograms) of a patient with temporal lobe epilepsy were retrospectively reviewed. Video-EEG recordings were reviewed for clinical events including ictal spitting and temporally associated EEG changes. Results: Patient experienced an aura before the onset of seizures in the form of an epigastric sensation followed by spitting. Examination of the video revealed gross spitting. A clear electroencephalographic correlate preceded the clinical event by 10–25 s. Characteristic predominantly fast, high-amplitude theta (5–7 Hz) waves were seen in the right temporal lobe, the hemisphere of seizure onset. The total duration of the seizure was approximately 60 s. The patient had focal EEG findings consistent with focal epilepsy. No evidence of generalized epilepsy or non-epileptic seizure events was identified.
e146
Abstracts / Clinical Neurophysiology 129 (2018) e142–e212
Conclusion: Ictal spitting is a rare feature in epileptic seizures characterized by automatisms. Automatisms are known to have a lateralizing value in temporal lobe epilepsy. The epileptic zone is most frequently found in the right, non-dominant temporal lobe. Extremely rare cases of the seizure involving the left dominant temporal lobe or involving a seizure focus outside of the temporal lobe are reported in literature. doi:10.1016/j.clinph.2018.04.370
S11. EEG source localization of interictal discharges and outcome for LITT for temporal lobe epilepsy—Jason B. Richards *, Lina Barker, Aatif M. Husain, Matthew Luedke, Saurabh R. Sinha, Muhammad Zafar (USA) ⇑
Presenting author.
Introduction: Approximately one-third of patients with epilepsy are intractable to antiepileptic drug therapy. In patients with intractable focal epilepsy, resection or ablation of the seizure focus offers a chance for seizure control. Laser interstitial thermal therapy (LITT) is one type of epilepsy surgery used to ablate the ictal zone. For patients with a presumed mesial temporal lobe focus, this technique can be used to ablate the hippocampus and nearby mesial structures. Seizure outcomes are similar to open surgery, although data is limited. It would be helpful to have factors that can be used to predict who will have a good outcome with LITT versus who might be better served by an open procedure. The precise location of interictal epileptiform discharges (as determined from scalp EEG data and EEG source image, ESI) may be one such factor.We plan to present a case series of 16 patients who underwent LITT for intractable temporal lobe epilepsy at our institution. We hypothesize that patients will have a good outcome if the location of the ESI-determined interictal epileptiform discharge is present within the area of ablation. Methods: In this retrospective case series, subjects were identified using epilepsy center logs. Patients were included if they underwent pre-operative scalp EEG and high-resolution MRI, LITT, postoperative MRI and had a follow-up appointment. Patient’s scalp EEG and highresolution MRI were used to determine the location of the interictal discharge using commercially available software (Curry Neuroimaging Suite, Compumedics, Inc). We then compared the result to post-ablation MRI. The clinical outcomes were determined from the patient’s chart at the follow-up appointment. Results: Using ESI, we modeled the interictal discharges for two patients. Both patients’ scalp EEG showed temporal lobe onset for seizures and interictal discharges. Both underwent LITT of the left mesial temporal lobe. The first patient has been seizure free for one year (Engel 1). ESI suggested a source for interictal epileptiform discharges to be mesial temporal lobe which was included in ablated area as depicted by the post-ablation MRI. The second patient continues to have seizures at her follow-up appointments, although less frequently than before (Engel 2). ESI suggested left lateral temporal lobe interictal epileptiform discharges, which were not included in the ablated area as depicted by post ablation MRI.We ultimately plan to model all 16 patients. Conclusion: Our preliminary results suggest that patient whose source of the interictal epileptiform discharges was located in the ablated volume have a good outcome. We plan to test this conclusion against a broader data to see if this method can be used to predict which patients are likely to have a good outcome. doi:10.1016/j.clinph.2018.04.371
S12. Clinical and neurophysiological profile of adult epilepsy population of Bishkek—Asel Jusupova (Kyrgyzstan) Introduction: Aim of the study is to study clinical and neurophysiological profiles of epilepsy patients of Oktober district of Bishkek. Methods: The study involved 430 patients with epilepsy during 2014–2016y from clinical neurology department of City Hospital and Family Medicine Centers of Oktober district of Bishkek. Results: When evaluating EEG data, it was found that 153 (35.6%) patients had focal epileptic activity, while 107 (24.9%) had generalized. At the same time, 170 (39.5%) patients suffering from epilepsy performing EEG did not reveal any epileptic activity interictallly. In those patients who had epileptic foci in the routine EEG, they were most often recorded in the frontal (14.9% of the total sample size) and in the parieto-occipital region (9.1% of the total sample size). In the analysis of MRI, the lesions of the frontal, temporal and parietal lobes were simultaneously the most frequent (50 cases or 11.6%), moreover, changes were often detected in the medial divisions of the temporal lobe (20 cases or 4.7%). In 126 cases (29.3%) no changes were detected on the MRI. In 57 (13.2%) cases, neuroimaging was not performed. In the group of patients (153) with the focus established according to the EEG data, the greatest correlation (kA = 0.21) between the epileptic focus and the pathological focus on MRI images coincided for the frontal and frontal parietal areas. In the differential analysis of the structure of seizures, depending on the localization of epileptic focus on the EEG, partial seizures prevailed in various combinations (54.5%) in patients with temporoparietal focus, in patients with all other areas EEG focuses most often were observed primary GTCS. Conclusion: The above data clearly demonstrate that, despite the fact that MRI is an obligatory method of investigation in patients with epilepsy, in reality for citizens of Kyrgyzstan, MRI is often inaccessible, is only in private clinics and is costly. Therefore, it is necessary to equip state hospitals with modern MRI devices, which should be one of the priority directions for the development of domestic epileptology. Taking into account that in 39.5% of cases during routine EEG in the surveyed population, it was not possible to detect focal activity for the purpose of timely diagnosis and adequate therapy of AED in the absence of focal activity according to routine EEG data, it is necessary to perform 3 or 6 h video EEG monitoring. doi:10.1016/j.clinph.2018.04.372
S13. Local and distant dysregulation of synchronization around interictal spikes in BECTS—Emilie Bourel-Ponchel *, Mahdi Mahmoudzadeh, Fabrice Wallois (France) ⇑
Presenting author.
Introduction: High Density electroencephalography (HD EEG) is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons to the hypersynchronization of IES in BECTS. Transient distant changes in the dynamics of neurons populations may also interact with neuronal networks involved in various functions that are impaired in BECTS patients. Methods: HD EEG (64 electrodes) of eight well characterized BECTS patients (8 males; mean age: 7.2 years, range: 5–9 years) were analyzed. Unilateral IES were selected in 6 patients. They were bilateral and independent in 2 other patients. This resulted in a total of 10 groups of IES. Time–frequency analysis was performed on HD EEG epochs around the peak of the IES (±1000 ms), including phaselocked and non-phase-locked activities to the IES. The time
inaccessible to subdural electrodes. Our case demonstrates the utility of Stereotactic EEG in localizing seizure onset zone and mapping the function of both cortical and subcortical structures in a patient with drug resistant focal epilepsy. Methods: The patient is a 58 year old right handed woman with a history of drug resistant epilepsy since age 18. Her seizures were predominantly nocturnal and arose out of sleep. She had multiple seizures per night. She reports out of body experience, anxiety feeling and chocking sensation followed by back and forth rocking movements. Seizures usually last 30–45 s with a quick recovery from her seizures. Her ictal scalp EEG was non localizing. Her interictal FDG PET scan was normal. Her subtracted ictal-interictal SPECT scan was also non localizing. Her epilepsy protocol 3T brain MRI showed a subtle area of white–grey matter blurring on the DIR pulse sequence which involved the left anterior cingulate gyrus. The patient underwent Stereotactic EEG implantation to confirm seizure localization and for functional mapping. Her ictal intracranial EEG showed an onset of high amplitude repetitive spiking intermixed with low amplitude fast activity in the electrodes located in the left anterior cingulate followed by spread of the same pattern to electrodes in the left insular cortex within less than 500 ms from the onset. Electrical stimulation mapping was performed. Biphasic 50 Hz stimulation starting at 1 mA intensity with increments of 0.5 mA was applied. Results: The patient reported the typical sensation of her aura and early symptoms of her seizures during the stimulation of left anterior cingulate contacts during stimulation with 1–3 mA which was reproducible. She also reported the usual sensation she experiences a few seconds following the onset of her seizures during the stimulation of her left insular electrodes during stimulation with 3–5 mA that was also reproducible. No after- discharge was seen during these stimulation trials. The patient subsequently underwent an open lesionectomy of the anterior cingulate MRI abnormality. Pathology showed focal cortical dysplasia type IIB with dysmorphic neurons and balloon cells. The patient has remained seizure free since surgery. No neurological deficit was seen. Conclusion: Electrical stimulation mapping of SEEG can be used to study the functionality of the cortex as well as the subcortical structures. In addition to localizing eloquent cortex, electrical stimulation of SEEG can support the localization of epileptic network and seizure onset zone. doi:10.1016/j.clinph.2018.04.368
S09. The role of oscillatory activity in attentive speech perception: An Ecog study in epilepsy patients—Mario E. Archila-Meléndez, Vivianne H. Kranen-Mastenbroek *, Giancarlo Valente, João Correia, Erik D. Gommer, Bernadette M. Jansma, Rob P. Rouhl, Mark J. Roberts (Netherlands) ⇑
Presenting author.
Introduction: Activation of neuronal networks is typically associated with a change in spectral power in electric signals within the network. The role of different spectral bands in mediating cognitive processes is still not fully understood. In human language networks, a hierarchical model has been suggested in which different types of linguistic information is transferred in different oscillatory bands. Within that model, attention is assumed to correlate with increase in gamma and decrease in alpha band power. Electrocorticography (ECoG) allows the segregation of neural representations independently of stimulus variation. Aim of the study: Here, for the first time, we investigate whether selective attention to the different components of a syllable (i.e.,
e145
consonants or vowels) modulates the spectral power of oscillatory activity (i.e., broadband gamma and alpha) and whether these changes relate to behavioral performance. Methods: To address this issue, we measured ECoG signals in 11 patients with refractory epilepsy who were undergoing pre-surgical screening. Neuronal responses were measured with intracranial electrodes (i.e., grids, strips, and depth hippocampal electrodes). The patients engaged in cognitive testing in which auditory consonant–vowel syllable sounds were compared with written letters (i. e., delay match-to-sample task). The behavioral relevance of different components of the syllables was manipulated in four levels; attention was directed either to the complete syllable, only to the vowel, only to the consonant, or the syllable sound was irrelevant. Analysis: We calculated: (a) bipolar differentials between each pair of neighboring channels; (b) time–frequency representations of power between 2 and 150 Hz; (c) an index of power change, per trial, relative to power during pre-stimulus baseline period; and (d) average power modulation for two frequency bands (i.e., 5–15 and 70–150 Hz). Results: Presentation of stimuli was associated with an increase in broadband gamma (70–150 Hz) and a decrease in alpha (5–15 Hz) over sensory cortex (i.e., auditory cortex for auditory stimuli, and visual cortex for visual stimuli), while alpha power was increased in domain unspecific cortical areas. Gamma band activity could be robustly mapped to stimulus parameters but was only weakly related to attentional state or behavioral performance. Alpha band activity was more related to cognitive state and performance than to stimulus features. Broadband gamma power changes were related to stimulus physical properties. Conclusion: These results give new insights into the interplay between alpha and gamma oscillations within the human language network, here with a focus on phonological aspects, and the possible role of these oscillations in the processing of sensory stimuli and behavioral performance during selective attention. doi:10.1016/j.clinph.2018.04.369
S10. Clinical and electroencephalographic correlates of ictal spitting—Mayur Chalia (USA)
Introduction: Ictal spitting is a rarely reported, stereotyped nonpurposeful automatism behavior which surfaces during a complex partial seizure. It is similar to other behaviors frequently seen in temporal lobe seizures which include lip smacking, swallowing, and chewing movements. The underlying mechanism of both ictal and post ictal automatisms is unclear. It is hypothesized that this occurs as a result of the activation of areas mediating gastrointestinal function and emotional behavior. Such areas include the amygdala and the insula specifically on the non-dominant side due to the functional asymmetry of the central autonomic network. Methods: Charts and video-EEGs (Electroencephalograms) of a patient with temporal lobe epilepsy were retrospectively reviewed. Video-EEG recordings were reviewed for clinical events including ictal spitting and temporally associated EEG changes. Results: Patient experienced an aura before the onset of seizures in the form of an epigastric sensation followed by spitting. Examination of the video revealed gross spitting. A clear electroencephalographic correlate preceded the clinical event by 10–25 s. Characteristic predominantly fast, high-amplitude theta (5–7 Hz) waves were seen in the right temporal lobe, the hemisphere of seizure onset. The total duration of the seizure was approximately 60 s. The patient had focal EEG findings consistent with focal epilepsy. No evidence of generalized epilepsy or non-epileptic seizure events was identified.
e146
Abstracts / Clinical Neurophysiology 129 (2018) e142–e212
Conclusion: Ictal spitting is a rare feature in epileptic seizures characterized by automatisms. Automatisms are known to have a lateralizing value in temporal lobe epilepsy. The epileptic zone is most frequently found in the right, non-dominant temporal lobe. Extremely rare cases of the seizure involving the left dominant temporal lobe or involving a seizure focus outside of the temporal lobe are reported in literature. doi:10.1016/j.clinph.2018.04.370
S11. EEG source localization of interictal discharges and outcome for LITT for temporal lobe epilepsy—Jason B. Richards *, Lina Barker, Aatif M. Husain, Matthew Luedke, Saurabh R. Sinha, Muhammad Zafar (USA) ⇑
Presenting author.
Introduction: Approximately one-third of patients with epilepsy are intractable to antiepileptic drug therapy. In patients with intractable focal epilepsy, resection or ablation of the seizure focus offers a chance for seizure control. Laser interstitial thermal therapy (LITT) is one type of epilepsy surgery used to ablate the ictal zone. For patients with a presumed mesial temporal lobe focus, this technique can be used to ablate the hippocampus and nearby mesial structures. Seizure outcomes are similar to open surgery, although data is limited. It would be helpful to have factors that can be used to predict who will have a good outcome with LITT versus who might be better served by an open procedure. The precise location of interictal epileptiform discharges (as determined from scalp EEG data and EEG source image, ESI) may be one such factor.We plan to present a case series of 16 patients who underwent LITT for intractable temporal lobe epilepsy at our institution. We hypothesize that patients will have a good outcome if the location of the ESI-determined interictal epileptiform discharge is present within the area of ablation. Methods: In this retrospective case series, subjects were identified using epilepsy center logs. Patients were included if they underwent pre-operative scalp EEG and high-resolution MRI, LITT, postoperative MRI and had a follow-up appointment. Patient’s scalp EEG and highresolution MRI were used to determine the location of the interictal discharge using commercially available software (Curry Neuroimaging Suite, Compumedics, Inc). We then compared the result to post-ablation MRI. The clinical outcomes were determined from the patient’s chart at the follow-up appointment. Results: Using ESI, we modeled the interictal discharges for two patients. Both patients’ scalp EEG showed temporal lobe onset for seizures and interictal discharges. Both underwent LITT of the left mesial temporal lobe. The first patient has been seizure free for one year (Engel 1). ESI suggested a source for interictal epileptiform discharges to be mesial temporal lobe which was included in ablated area as depicted by the post-ablation MRI. The second patient continues to have seizures at her follow-up appointments, although less frequently than before (Engel 2). ESI suggested left lateral temporal lobe interictal epileptiform discharges, which were not included in the ablated area as depicted by post ablation MRI.We ultimately plan to model all 16 patients. Conclusion: Our preliminary results suggest that patient whose source of the interictal epileptiform discharges was located in the ablated volume have a good outcome. We plan to test this conclusion against a broader data to see if this method can be used to predict which patients are likely to have a good outcome. doi:10.1016/j.clinph.2018.04.371
S12. Clinical and neurophysiological profile of adult epilepsy population of Bishkek—Asel Jusupova (Kyrgyzstan) Introduction: Aim of the study is to study clinical and neurophysiological profiles of epilepsy patients of Oktober district of Bishkek. Methods: The study involved 430 patients with epilepsy during 2014–2016y from clinical neurology department of City Hospital and Family Medicine Centers of Oktober district of Bishkek. Results: When evaluating EEG data, it was found that 153 (35.6%) patients had focal epileptic activity, while 107 (24.9%) had generalized. At the same time, 170 (39.5%) patients suffering from epilepsy performing EEG did not reveal any epileptic activity interictallly. In those patients who had epileptic foci in the routine EEG, they were most often recorded in the frontal (14.9% of the total sample size) and in the parieto-occipital region (9.1% of the total sample size). In the analysis of MRI, the lesions of the frontal, temporal and parietal lobes were simultaneously the most frequent (50 cases or 11.6%), moreover, changes were often detected in the medial divisions of the temporal lobe (20 cases or 4.7%). In 126 cases (29.3%) no changes were detected on the MRI. In 57 (13.2%) cases, neuroimaging was not performed. In the group of patients (153) with the focus established according to the EEG data, the greatest correlation (kA = 0.21) between the epileptic focus and the pathological focus on MRI images coincided for the frontal and frontal parietal areas. In the differential analysis of the structure of seizures, depending on the localization of epileptic focus on the EEG, partial seizures prevailed in various combinations (54.5%) in patients with temporoparietal focus, in patients with all other areas EEG focuses most often were observed primary GTCS. Conclusion: The above data clearly demonstrate that, despite the fact that MRI is an obligatory method of investigation in patients with epilepsy, in reality for citizens of Kyrgyzstan, MRI is often inaccessible, is only in private clinics and is costly. Therefore, it is necessary to equip state hospitals with modern MRI devices, which should be one of the priority directions for the development of domestic epileptology. Taking into account that in 39.5% of cases during routine EEG in the surveyed population, it was not possible to detect focal activity for the purpose of timely diagnosis and adequate therapy of AED in the absence of focal activity according to routine EEG data, it is necessary to perform 3 or 6 h video EEG monitoring. doi:10.1016/j.clinph.2018.04.372
S13. Local and distant dysregulation of synchronization around interictal spikes in BECTS—Emilie Bourel-Ponchel *, Mahdi Mahmoudzadeh, Fabrice Wallois (France) ⇑
Presenting author.
Introduction: High Density electroencephalography (HD EEG) is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons to the hypersynchronization of IES in BECTS. Transient distant changes in the dynamics of neurons populations may also interact with neuronal networks involved in various functions that are impaired in BECTS patients. Methods: HD EEG (64 electrodes) of eight well characterized BECTS patients (8 males; mean age: 7.2 years, range: 5–9 years) were analyzed. Unilateral IES were selected in 6 patients. They were bilateral and independent in 2 other patients. This resulted in a total of 10 groups of IES. Time–frequency analysis was performed on HD EEG epochs around the peak of the IES (±1000 ms), including phaselocked and non-phase-locked activities to the IES. The time