Improving the efficacy and reliability of rTMS language mapping by increasing the stimulation frequency

OBJECTIVENavigated transcranial magnetic stimulation (nTMS) in combination with diffusion tensor imaging fiber tracking (DTI FT) is increasingly used to locate subcortical language-related pathways. The aim of this study was to establish nTMS-based DTI FT for preoperative risk stratification by evaluating associations between lesion-to-tract distances (LTDs) and aphasia and by determining a cut-off LTD value to prevent surgery-related permanent aphasia.METHODSFifty patients with left-hemispheric, language-eloquent brain tumors underwent preoperative nTMS language mapping and nTMS-based DTI FT, followed by tumor resection. nTMS-based DTI FT was performed with a predefined fractional anisotropy (FA) of 0.10, 0.15, 50% of the individual FA threshold (FAT), and 75% FAT (minimum fiber length [FL]: 100 mm). The arcuate fascicle (AF), superior longitudinal fascicle (SLF), inferior longitudinal fascicle (ILF), uncinate fascicle (UC), and frontooccipital fascicle (FoF) were identified in nTMS-based tractography, and minimum LTDs were measured between the lesion and the AF and between the lesion and the closest other subcortical language-related pathway (SLF, ILF, UC, or FoF). LTDs were then associated with the level of aphasia (no/transient or permanent surgery-related aphasia, according to follow-up examinations).RESULTSA significant difference in LTDs was observed between patients with no or only surgery-related transient impairment and those who developed surgery-related permanent aphasia with regard to the AF (FA = 0.10, p = 0.0321; FA = 0.15, p = 0.0143; FA = 50% FAT, p = 0.0106) as well as the closest other subcortical language-related pathway (FA = 0.10, p = 0.0182; FA = 0.15, p = 0.0200; FA = 50% FAT, p = 0.0077). Patients with surgery-related permanent aphasia showed the lowest LTDs in relation to these tracts. Thus, LTDs of ≥ 8 mm (AF) and ≥ 11 mm (SLF, ILF, UC, or FoF) were determined as cut-off values for surgery-related permanent aphasia.CONCLUSIONSnTMS-based DTI FT of subcortical language-related pathways seems suitable for risk stratification and prediction in patients suffering from language-eloquent brain tumors. Thus, the current role of nTMS-based DTI FT might be expanded, going beyond the level of being a mere tool for surgical planning and resection guidance.

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A Novel Language Paradigm for Intraoperative Language Mapping: Feasibility and Evaluation

Journal of Clinical Medicine ◽

10.3390/jcm10040655 ◽

2021 ◽

Vol 10 (4) ◽

pp. 655

Author(s):

Katharina Rosengarth ◽

Delin Pai ◽

Frank Dodoo-Schittko ◽

Katharina Hense ◽

Teele Tamm ◽

...

Keyword(s):

Healthy Subjects ◽

Intraoperative Complications ◽

Evaluation Study ◽

Awake Craniotomy ◽

Language Mapping ◽

Tumor Patients ◽

Language Functions ◽

Before And After ◽

Assessment Time ◽

Neuropsychological Outcomes

(1) Background—Mapping language using direct cortical stimulation (DCS) during an awake craniotomy is difficult without using more than one language paradigm that particularly follows the demand of DCS by not exceeding the assessment time of 4 s to prevent intraoperative complications. We designed an intraoperative language paradigm by combining classical picture naming and verb generation, which safely engaged highly relevant language functions. (2) Methods—An evaluation study investigated whether a single trial of the language task could be performed in less than 4 s in 30 healthy subjects and whether the suggested language paradigm sufficiently pictured the cortical language network using functional magnetic resonance imaging (fMRI) in 12 healthy subjects. In a feasibility study, 24 brain tumor patients conducted the language task during an awake craniotomy. The patients’ neuropsychological outcomes were monitored before and after surgery. (3) Results—The fMRI results in healthy subjects showed activations in a language-associated network around the (left) sylvian fissure. Single language trials could be performed within 4 s. Intraoperatively, all tumor patients showed DCS-induced language errors while conducting the novel language task. Postoperatively, mild neuropsychological impairments appeared compared to the presurgical assessment. (4) Conclusions—These data support the use of a novel language paradigm that safely monitors highly relevant language functions intraoperatively, which can consequently minimize negative postoperative neuropsychological outcomes.

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Language mapping functions: Improving softmax estimation and word embedding quality

Concurrency and Computation Practice and Experience ◽

10.1002/cpe.6464 ◽

2021 ◽

Author(s):

Emad Rangriz ◽

Vahid Pourahmadi

Keyword(s):

Word Embedding ◽

Language Mapping ◽

Mapping Functions

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MONOSYNAPTIC REFLEX RESPONSE OF INDIVIDUAL MOTONEURONS AS A FUNCTION OF FREQUENCY

The Journal of General Physiology ◽

10.1085/jgp.40.3.435 ◽

1957 ◽

Vol 40 (3) ◽

pp. 435-450 ◽

Cited By ~ 34

Author(s):

David P. C. Lloyd

Keyword(s):

High Frequency ◽

Temporal Summation ◽

Low Frequency ◽

Stimulation Frequency ◽

Monosynaptic Reflex ◽

Reflex Response ◽

High Frequency Stimulation ◽

Low Frequency Stimulation ◽

Frequency Stimulation ◽

Frequency Of Stimulation

An assemblage of individual motoneurons constituting a synthetic motoneuron pool has been studied from the standpoint of relating monosynaptic reflex responses to frequency of afferent stimulation. Intensity of low frequency depression is not a simple function of transmitter potentiality. As frequency of stimulation increases from 3 per minute to 10 per second, low frequency depression increases in magnitude. Between 10 and approximately 60 per second low frequency depression apparently diminishes and subnormality becomes a factor in causing depression. At frequencies above 60 per second temporal summation occurs, but subnormality limits the degree of response attainable by summation. At low stimulation frequencies rhythm is determined by stimulation frequency. Interruptions of rhythmic firing depend solely upon temporal fluctuation of excitability. At high frequency of stimulation rhythm is determined by subnormality rather than inherent rhythmicity, and excitability fluctuation leads to instability of response rhythm. In short, whatever the stimulation frequency, random excitability fluctuation is the factor disrupting rhythmic response. Monosynaptic reflex response latency is stable during high frequency stimulation as it is in low frequency stimulation provided a significant extrinsic source of random bombardment is not present. In the presence of powerful random bombardment discharge may become random with respect to monosynaptic afferent excitation provided the latter is feeble. When this occurs it does so equally at low frequency and high frequency. Thus temporal summation is not a necessary factor. There is, then, no remaining evidence to suggest that the agency for temporal summation in the monosynaptic system becomes a transmitting agency in its own right.

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Steady-State Visual Evoked Potential Classification Using Complex Valued Convolutional Neural Networks

Sensors ◽

10.3390/s21165309 ◽

2021 ◽

Vol 21 (16) ◽

pp. 5309

Author(s):

Akira Ikeda ◽

Yoshikazu Washizawa

Keyword(s):

Steady State ◽

Information Transfer ◽

Visual Evoked Potential ◽

Evoked Potential ◽

Extraction Methods ◽

Stimulation Frequency ◽

Event Related Potential ◽

Spectrum Estimation ◽

Complex Valued ◽

Visual Evoked

The steady-state visual evoked potential (SSVEP), which is a kind of event-related potential in electroencephalograms (EEGs), has been applied to brain–computer interfaces (BCIs). SSVEP-based BCIs currently perform the best in terms of information transfer rate (ITR) among various BCI implementation methods. Canonical component analysis (CCA) or spectrum estimation, such as the Fourier transform, and their extensions have been used to extract features of SSVEPs. However, these signal extraction methods have a limitation in the available stimulation frequency; thus, the number of commands is limited. In this paper, we propose a complex valued convolutional neural network (CVCNN) to overcome the limitation of SSVEP-based BCIs. The experimental results demonstrate that the proposed method overcomes the limitation of the stimulation frequency, and it outperforms conventional SSVEP feature extraction methods.

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LANGUAGE REORGANIZATION IN APHASICS

Neurosurgery ◽

10.1227/01.neu.0000324725.84854.04 ◽

2008 ◽

Vol 63 (3) ◽

pp. 487-497 ◽

Cited By ~ 15

Author(s):

Timothy H. Lucas ◽

Daniel L. Drane ◽

Carl B. Dodrill ◽

George A. Ojemann

Keyword(s):

Brain Injury ◽

Temporal Lobe ◽

Intractable Epilepsy ◽

Cortical Lesions ◽

Language Mapping ◽

Neurosurgical Planning ◽

Anatomic Distribution ◽

And Performance ◽

And Control ◽

Language Profiles

ABSTRACT OBJECTIVE The purpose of this investigation was to determine whether clinical speech deficits after brain injury are associated with functional speech reorganization. METHODS Across an 18-year interval, 11 patients with mild-to-moderate speech deficits underwent language mapping as part of their treatment for intractable epilepsy. These “aphasics” were compared with 14 matched “control” patients with normal speech who also were undergoing epilepsy surgery. Neuroanatomic data were compared with quantitative language profiles and clinical variables. RESULTS Cortical lesions were evident near speech areas in all aphasia cases. As expected, aphasic and control patients were distinguished by quantitative language profiles. The groups were further distinguished by the anatomic distribution of their speech sites. A significantly greater proportion of frontal speech sites was found in patients with previous brain injury, consistent with frontal site recruitment. The degree of frontal recruitment varied as a function of patient age at the time of initial brain injury; earlier injuries were associated with greater recruitment. The overall number of speech sites remained the same after injury. Significant associations were found between the number of the speech sites, naming fluency, and the lesion proximity in the temporal lobe. CONCLUSION Language maps in aphasics demonstrated evidence for age-dependent functional recruitment in the frontal, but not temporal, lobe. The proximity of cortical lesions to temporal speech sites predicted the overall extent of temporal lobe speech representation and performance on naming fluency. These findings have implications for neurosurgical planning in patients with preoperative speech deficits.

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Effects of stimulation frequency, amplitude, and impulse width on muscle fatigue

Muscle & Nerve ◽

10.1002/mus.24893 ◽

2015 ◽

Vol 53 (4) ◽

pp. 608-616 ◽

Cited By ~ 8

Author(s):

Michael Behringer ◽

Sebastian Grützner ◽

Johannes Montag ◽

Molly McCourt ◽

Matthias Ring ◽

...

Keyword(s):

Muscle Fatigue ◽

Stimulation Frequency

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Impairment of preoperative language mapping by lesion location: a functional magnetic resonance imaging, navigated transcranial magnetic stimulation, and direct cortical stimulation study

Journal of Neurosurgery ◽

10.3171/2014.10.jns141582 ◽

2015 ◽

Vol 123 (2) ◽

pp. 314-324 ◽

Cited By ~ 42

Author(s):

Sebastian Ille ◽

Nico Sollmann ◽

Theresa Hauck ◽

Stefanie Maurer ◽

Noriko Tanigawa ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Positive Predictive Value ◽

Predictive Value ◽

Magnetic Stimulation ◽

Cortical Stimulation ◽

Awake Surgery ◽

Navigated Transcranial Magnetic Stimulation ◽

Language Mapping ◽

Direct Cortical Stimulation ◽

Neurosurgical Patients

OBJECT Language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is increasingly used and has already replaced functional MRI (fMRI) in some institutions for preoperative mapping of neurosurgical patients. Yet some factors affect the concordance of both methods with direct cortical stimulation (DCS), most likely by lesions affecting cortical oxygenation levels. Therefore, the impairment of the accuracy of rTMS and fMRI was analyzed and compared with DCS during awake surgery in patients with intraparenchymal lesions. METHODS Language mapping was performed by DCS, rTMS, and fMRI using an object-naming task in 27 patients with left-sided perisylvian lesions, and the induced language errors of each method were assigned to the cortical parcellation system. Subsequently, the receiver operating characteristics were calculated for rTMS and fMRI and compared with DCS as ground truth for regions with (w/) and without (w/o) the lesion in the mapped regions. RESULTS The w/ subgroup revealed a sensitivity of 100% (w/o 100%), a specificity of 8% (w/o 5%), a positive predictive value of 34% (w/o: 53%), and a negative predictive value (NPV) of 100% (w/o: 100%) for the comparison of rTMS versus DCS. Findings for the comparison of fMRI versus DCS within the w/ subgroup revealed a sensitivity of 32% (w/o: 62%), a specificity of 88% (w/o: 60%), a positive predictive value of 56% (w/o: 62%), and a NPV of 73% (w/o: 60%). CONCLUSIONS Although strengths and weaknesses exist for both rTMS and fMRI, the results show that rTMS is less affected by a brain lesion than fMRI, especially when performing mapping of language-negative cortical regions based on sensitivity and NPV.

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Stereoelectroencephalographic language mapping of the basal temporal cortex predicts postoperative naming outcome

Journal of Neurosurgery ◽

10.3171/2020.8.jns202431 ◽

2021 ◽

pp. 1-11

Author(s):

Chifaou Abdallah ◽

Hélène Brissart ◽

Sophie Colnat-Coulbois ◽

Ludovic Pierson ◽

Olivier Aron ◽

...

Keyword(s):

Temporal Lobe ◽

Verbal Fluency ◽

Temporal Cortex ◽

Visual Object ◽

Drug Resistant ◽

Language Mapping ◽

Individual Level ◽

Language Outcome ◽

Temporal Lobe Resection ◽

The Individual

OBJECTIVEIn drug-resistant temporal lobe epilepsy (TLE) patients, the authors evaluated early and late outcomes for decline in visual object naming after dominant temporal lobe resection (TLR) according to the resection status of the basal temporal language area (BTLA) identified by cortical stimulation during stereoelectroencephalography (SEEG).METHODSTwenty patients who underwent SEEG for drug-resistant TLE met the inclusion criteria. During language mapping, a site was considered positive when stimulation of two contiguous contacts elicited at least one naming impairment during two remote sessions. After TLR ipsilateral to their BTLA, patients were classified as BTLA+ when at least one positive language site was resected and as BTLA− when all positive language sites were preserved. Outcomes in naming and verbal fluency tests were assessed using pre- and postoperative (means of 7 and 25 months after surgery) scores at the group level and reliable change indices (RCIs) for clinically meaningful changes at the individual level.RESULTSBTLA+ patients (n = 7) had significantly worse naming scores than BTLA− patients (n = 13) within 1 year after surgery but not at the long-term evaluation. No difference in verbal fluency tests was observed. When RCIs were used, 5 of 18 patients (28%) had naming decline within 1 year postoperatively (corresponding to 57% of BTLA+ and 9% of BTLA− patients). A significant correlation was found between BTLA resection and naming decline.CONCLUSIONSBTLA resection is associated with a specific and early naming decline. Even if this decline is transient, naming scores in BTLA+ patients tend to remain lower compared to their baseline. SEEG mapping helps to predict postoperative language outcome after dominant TLR.

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