Search

Your search keyword '"Waldman, Zachary J."' showing total 8 results
Start Over Author "Waldman, Zachary J."
8 results on '"Waldman, Zachary J."'

1. Ripple oscillations in the left temporal neocortex are associated with impaired verbal episodic memory encoding

Author

Waldman, Zachary J., Camarillo-Rodriguez, Liliana, Chervenova, Inna, Berry, Brent, Shimamoto, Shoichi, Elahian, Bahareh, Kucewicz, Michal, Ganne, Chaitanya, He, Xiao-Song, Davis, Leon A., Stein, Joel, Das, Sandhitsu, Gorniak, Richard, Sharan, Ashwini D., Gross, Robert, Inman, Cory S., Lega, Bradley C., Zaghloul, Kareem, Jobst, Barbara C., Davis, Katheryn A., Wanda, Paul, Khadjevand, Mehraneh, Tracy, Joseph, Rizzuto, Daniel S., Worrell, Gregory, Sperling, Michael, and Weiss, Shennan A.

Subjects
Quantitative Biology - Neurons and Cognition
Abstract

Background: We sought to determine if ripple oscillations (80-120Hz), detected in intracranial EEG (iEEG) recordings of epilepsy patients, correlate with an enhancement or disruption of verbal episodic memory encoding. Methods: We defined ripple and spike events in depth iEEG recordings during list learning in 107 patients with focal epilepsy. We used logistic regression models (LRMs) to investigate the relationship between the occurrence of ripple and spike events during word presentation and the odds of successful word recall following a distractor epoch, and included the seizure onset zone (SOZ) as a covariate in the LRMs. Results: We detected events during 58,312 word presentation trials from 7,630 unique electrode sites. The probability of ripple on spike (RonS) events was increased in the seizure onset zone (SOZ, p<0.04). In the left temporal neocortex RonS events during word presentation corresponded with a decrease in the odds ratio (OR) of successful recall, however this effect only met significance in the SOZ (OR of word recall 0.71, 95% CI: 0.59-0.85, n=158 events, adaptive Hochberg p<0.01). Ripple on oscillation events (RonO) that occurred in the left temporal neocortex non-SOZ also correlated with decreased odds of successful recall (OR 0.52, 95% CI: 0.34-0.80, n=140, adaptive Hochberg , p<0.01). Spikes and RonS that occurred during word presentation in the left middle temporal gyrus during word presentation correlated with the most significant decrease in the odds of successful recall, irrespective of the location of the SOZ (adaptive Hochberg, p<0.01). Conclusion: Ripples and spikes generated in left temporal neocortex are associated with impaired verbal episodic memory encoding.

Published
2018

2. A method for the topographical identification and quantification of high frequency oscillations in intracranial electroencephalography recordings.

Author

Waldman, Zachary J, Shimamoto, Shoichi, Song, Inkyung, Orosz, Iren, Bragin, Anatol, Fried, Itzhak, Engel, Jerome, Staba, Richard, Sperling, Michael R, and Weiss, Shennan A

Subjects
Humans, Sensitivity and Specificity, Software, Adult, Aged, Middle Aged, Female, Male, Gamma Rhythm, Electrocorticography, Filter ringing, High-frequency oscillation, Ripple, Topography, Wavelet, Clinical Research, Clinical Trials and Supportive Activities, Engineering, Medical and Health Sciences, Psychology and Cognitive Sciences, Neurology & Neurosurgery
Abstract

ObjectiveTo develop a reliable software method using a topographic analysis of time-frequency plots to distinguish ripple (80-200 Hz) oscillations that are often associated with EEG sharp waves or spikes (RonS) from sinusoid-like waveforms that appear as ripples but correspond with digital filtering of sharp transients contained in the wide bandwidth EEG.MethodsA custom algorithm distinguished true from false ripples in one second intracranial EEG (iEEG) recordings using wavelet convolution, identifying contours of isopower, and categorizing these contours into sets of open or closed loop groups. The spectral and temporal features of candidate groups were used to classify the ripple, and determine its duration, frequency, and power. Verification of detector accuracy was performed on the basis of simulations, and visual inspection of the original and band-pass filtered signals.ResultsThe detector could distinguish simulated true from false ripple on spikes (RonS). Among 2934 visually verified trials of iEEG recordings and spectrograms exhibiting RonS the accuracy of the detector was 88.5% with a sensitivity of 81.8% and a specificity of 95.2%. The precision was 94.5% and the negative predictive value was 84.0% (N = 12). Among, 1,370 trials of iEEG recording exhibiting RonS that were reviewed blindly without spectrograms the accuracy of the detector was 68.0%, with kappa equal to 0.01 ± 0.03. The detector successfully distinguished ripple from high spectral frequency 'fast ripple' oscillations (200-600 Hz), and characterize ripple duration and spectral frequency and power. The detector was confounded by brief bursts of gamma (30-80 Hz) activity in 7.31 ± 6.09% of trials, and in 30.2 ± 14.4% of the true RonS detections ripple duration was underestimated.ConclusionsCharacterizing the topographic features of a time-frequency plot generated by wavelet convolution is useful for distinguishing true oscillations from false oscillations generated by filter ringing.SignificanceCategorizing ripple oscillations and characterizing their properties can improve the clinical utility of the biomarker.

Published
2018

3. Utilization of independent component analysis for accurate pathological ripple detection in intracranial EEG recordings recorded extra- and intra-operatively.

Author

Shimamoto, Shoichi, Waldman, Zachary J, Orosz, Iren, Song, Inkyung, Bragin, Anatol, Fried, Itzhak, Engel, Jerome, Staba, Richard, Sharan, Ashwini, Wu, Chengyuan, Sperling, Michael R, and Weiss, Shennan A

Subjects
Humans, Principal Component Analysis, Adolescent, Adult, Child, Female, Male, Signal-To-Noise Ratio, Intraoperative Neurophysiological Monitoring, Electrocorticography, Detector, High-frequency oscillation, Independent component analysis, Ripple, Brain Disorders, Clinical Research, Neurosciences, Engineering, Medical and Health Sciences, Psychology and Cognitive Sciences, Neurology & Neurosurgery
Abstract

ObjectiveTo develop and validate a detector that identifies ripple (80-200 Hz) events in intracranial EEG (iEEG) recordings in a referential montage and utilizes independent component analysis (ICA) to eliminate or reduce high-frequency artifact contamination. Also, investigate the correspondence of detected ripples and the seizure onset zone (SOZ).MethodsiEEG recordings from 16 patients were first band-pass filtered (80-600 Hz) and Infomax ICA was next applied to derive the first independent component (IC1). IC1 was subsequently pruned, and an artifact index was derived to reduce the identification of high-frequency events introduced by the reference electrode signal. A Hilbert detector identified ripple events in the processed iEEG recordings using amplitude and duration criteria. The identified ripple events were further classified and characterized as true or false ripple on spikes, or ripples on oscillations by utilizing a topographical analysis to their time-frequency plot, and confirmed by visual inspection.ResultsThe signal to noise ratio was improved by pruning IC1. The precision of the detector for ripple events was 91.27 ± 4.3%, and the sensitivity of the detector was 79.4 ± 3.0% (N = 16 patients, 5842 ripple events). The sensitivity and precision of the detector was equivalent in iEEG recordings obtained during sleep or intra-operatively. Across all the patients, true ripple on spike rates and also the rates of false ripple on spikes, that were generated due to filter ringing, classified the seizure onset zone (SOZ) with an area under the receiver operating curve (AUROC) of >76%. The magnitude and spectral content of true ripple on spikes generated in the SOZ was distinct as compared with the ripples generated in the NSOZ (p

Published
2018

4. Bimodal coupling of ripples and slower oscillations during sleep in patients with focal epilepsy.

Author

Song, Inkyung, Orosz, Iren, Chervoneva, Inna, Waldman, Zachary J, Fried, Itzhak, Wu, Chengyuan, Sharan, Ashwini, Salamon, Noriko, Gorniak, Richard, Dewar, Sandra, Bragin, Anatol, Engel, Jerome, Sperling, Michael R, Staba, Richard, and Weiss, Shennan A

Subjects
Brain, Humans, Epilepsies, Partial, Brain Mapping, Sleep, Sleep Stages, Female, Male, Brain Waves, Electrocorticography, Epilepsy, Intracranial electroencephalography, Phase-event amplitude coupling, Ripples, Sleep oscillations, Neurosciences, Neurodegenerative, Sleep Research, Brain Disorders, Clinical Research, Clinical Sciences, Neurology & Neurosurgery
Abstract

OBJECTIVE:Differentiating pathologic and physiologic high-frequency oscillations (HFOs) is challenging. In patients with focal epilepsy, HFOs occur during the transitional periods between the up and down state of slow waves. The preferred phase angles of this form of phase-event amplitude coupling are bimodally distributed, and the ripples (80-150 Hz) that occur during the up-down transition more often occur in the seizure-onset zone (SOZ). We investigated if bimodal ripple coupling was also evident for faster sleep oscillations, and could identify the SOZ. METHODS:Using an automated ripple detector, we identified ripple events in 40-60 min intracranial electroencephalography (iEEG) recordings from 23 patients with medically refractory mesial temporal lobe or neocortical epilepsy. The detector quantified epochs of sleep oscillations and computed instantaneous phase. We utilized a ripple phasor transform, ripple-triggered averaging, and circular statistics to investigate phase event-amplitude coupling. RESULTS:We found that at some individual recording sites, ripple event amplitude was coupled with the sleep oscillatory phase and the preferred phase angles exhibited two distinct clusters (p

Published
2017

6. Accuracy of high-frequency oscillations recorded intraoperatively for classification of epileptogenic regions.

Author

Weiss, Shennan A, Staba, Richard J, Sharan, Ashwini, Wu, Chengyuan, Rubinstein, Daniel Y., Das, Sandhitsu, Waldman, Zachary J., Orosz, Iren, Worrell, Gregory, Engel, Jerome, Sperling, Michael R, Weiss, Shennan A, Staba, Richard J, Sharan, Ashwini, Wu, Chengyuan, Rubinstein, Daniel Y., Das, Sandhitsu, Waldman, Zachary J., Orosz, Iren, Worrell, Gregory, Engel, Jerome, and Sperling, Michael R

Abstract

To see whether acute intraoperative recordings using stereo EEG (SEEG) electrodes can replace prolonged interictal intracranial EEG (iEEG) recording, making the process more efficient and safer, 10 min of iEEG were recorded following electrode implantation in 16 anesthetized patients, and 1–2 days later during non-rapid eye movement (REM) sleep. Ripples on oscillations (RonO, 80–250 Hz), ripples on spikes (RonS), sharp-spikes, fast RonO (fRonO, 250–600 Hz), and fast RonS (fRonS) were semi-automatically detected. HFO power and frequency were compared between the conditions using a generalized linear mixed-effects model. HFO rates were compared using a two-way repeated measures ANOVA with anesthesia type and SOZ as factors. A receiver-operating characteristic (ROC) curve analysis quantified seizure onset zone (SOZ) classification accuracy, and the scalar product was used to assess spatial reliability. Resection of contacts with the highest rate of events was compared with outcome. During sleep, all HFOs, except fRonO, were larger in amplitude compared to intraoperatively (p < 0.01). HFO frequency was also affected (p < 0.01). Anesthesia selection affected HFO and sharp-spike rates. In both conditions combined, sharp-spikes and all HFO subtypes were increased in the SOZ (p < 0.01). However, the increases were larger during the sleep recordings (p < 0.05). The area under the ROC curves for SOZ classification were significantly smaller for intraoperative sharp-spikes, fRonO, and fRonS rates (p < 0.05). HFOs and spikes were only significantly spatially reliable for a subset of the patients (p < 0.05). A failure to resect fRonO areas in the sleep recordings trended the most sensitive and accurate for predicting failure. In summary, HFO morphology is altered by anesthesia. Intraoperative SEEG recordings exhibit increased rates of HFOs in the SOZ, but their spatial distribution can differ from sleep recordings. Recording these biomarkers during non-REM sleep offers a more ac

Published
2021

7. Contribution of left supramarginal and angular gyri to episodic memory encoding: An intracranial EEG study.

Author

Rubinstein, Daniel Y., Camarillo-Rodriguez, Liliana, Serruya, Mijail D., Herweg, Nora A., Waldman, Zachary J., Wanda, Paul A., Sharan, Ashwini D., Weiss, Shennan A., Sperling, Michael R., Rubinstein, Daniel Y., Camarillo-Rodriguez, Liliana, Serruya, Mijail D., Herweg, Nora A., Waldman, Zachary J., Wanda, Paul A., Sharan, Ashwini D., Weiss, Shennan A., and Sperling, Michael R.

Abstract

The role of the left ventral lateral parietal cortex (VPC) in episodic memory is hypothesized to include bottom-up attentional orienting to recalled items, according to the dual-attention model (Cabeza et al., 2008). However, its role in memory encoding could be further clarified, with studies showing both positive and negative subsequent memory effects (SMEs). Furthermore, few studies have compared the relative contributions of sub-regions in this functionally heterogeneous area, specifically the anterior VPC (supramarginal gyrus/BA40) and the posterior VPC (angular gyrus/BA39), on a within-subject basis. To elucidate the role of the VPC in episodic encoding, we compared SMEs in the intracranial EEG across multiple frequency bands in the supramarginal gyrus (SmG) and angular gyrus (AnG), as twenty-four epilepsy patients with indwelling electrodes performed a free recall task. We found a significant SME of decreased theta power and increased high gamma power in the VPC overall, and specifically in the SmG. Furthermore, SmG exhibited significantly greater spectral tilt SME from 0.5 to 1.6 s post-stimulus, in which power spectra slope differences between recalled and unrecalled words were greater than in the AnG (p = 0.04). These results affirm the contribution of VPC to episodic memory encoding, and suggest an anterior-posterior dissociation within VPC with respect to its electrophysiological underpinnings.

Published
2020

8. Ripple oscillations in the left temporal neocortex are associated with impaired verbal episodic memory encoding

Author

Waldman, Zachary J., primary, Camarillo-Rodriguez, Liliana, additional, Chervenova, Inna, additional, Berry, Brent, additional, Shimamoto, Shoichi, additional, Elahian, Bahareh, additional, Kucewicz, Michal, additional, Ganne, Chaitanya, additional, He, Xiao-Song, additional, Davis, Leon A., additional, Stein, Joel, additional, Das, Sandhitsu, additional, Gorniak, Richard, additional, Sharan, Ashwini D., additional, Gross, Robert, additional, Inman, Cory S., additional, Lega, Bradley C., additional, Zaghloul, Kareem, additional, Jobst, Barbara C., additional, Davis, Katheryn A., additional, Wanda, Paul, additional, Khadjevand, Mehraneh, additional, Tracy, Joseph, additional, Rizzuto, Daniel S., additional, Worrell, Gregory, additional, Sperling, Michael, additional, and Weiss, Shennan A., additional

Published
2018
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results