Monaural 40-Hz auditory steady-state magnetic responses can be useful for identifying epileptic focus in mesial temporal lobe epilepsy

Matsubara, Teppei; Ogata, Katsuya; Hironaga, Naruhito; Uehara, Taira; Mitsudo, Takako; Sekiya, Hiroshi; Maekawa, Toshihiko; Tobimatsu, Shozó

doi:10.1016/j.clinph.2018.11.026

Cited by 11 publications

(13 citation statements)

References 67 publications

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“…Consequently, the auditory-evoked response is useful for evaluating cortical activities in functional areas. Recent studies using auditory-evoked magnetic fields reported physiological changes in auditory function in patients with mesial TLE 5 – 7 . The functional connectivity of the ascending reticular activating system (ARAS) may also be disturbed inside the EN in patients with TLE.…”

Section: Introductionmentioning

confidence: 99%

Awake state-specific suppression of primary somatosensory evoked response correlated with duration of temporal lobe epilepsy

Ishida

Jin

Kakisaka

et al. 2020

Sci Rep

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Epilepsy is a network disease. The primary somatosensory cortex (S1) is usually considered to be intact, but could be subclinically disturbed based on abnormal functional connectivity in patients with temporal lobe epilepsy (TLE). We aimed to investigate if the S1 of TLE is abnormally modulated. Somatosensory evoked magnetic fields (SEFs) evoked by median nerve stimulation were recorded in each hemisphere of 15 TLE patients and 28 normal subjects. All responses were separately averaged in the awake state and light sleep using background magnetoencephalography. Latency and strength of the equivalent current dipole (ECD) was compared between the groups for the first (M1) and second peaks. Latencies showed no significant differences between the groups in either wakefulness or light sleep. ECD strengths were significantly lower in TLE patients than in controls only during wakefulness. The reduction of M1 ECD strength in the awake state is significantly correlated with duration of epilepsy. SEFs of TLE patients showed pure ECD strength reduction without latency delay. The phenomenon occurred exclusively during wakefulness, suggesting that a wakefulness-specific modulator of S1 is abnormal in TLE. Repetitive seizures may gradually insult the modulator of S1 distant from the epileptogenic network.

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Section: Introductionmentioning

confidence: 99%

Awake state-specific suppression of primary somatosensory evoked response correlated with duration of temporal lobe epilepsy

Ishida

Jin

Kakisaka

et al. 2020

Sci Rep

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“…In order to evaluate the high-frequency oscillation of the primary auditory cortex, the ASSR was measured by presenting a click high-frequency echo sound of 40 Hz monurally. 3 Eighteen patients with left mTLE, 11 patients with right mTLE, and 16 HC F I G U R E 2 Induced gamma-band responses of phase-locking factors (PLFs) in healthy controls (HC), left medial temporal lobe epilepsy (mTLE), right mTLE, response in primary auditory cortex to high-frequency echo stimuli given to a single ear. The result of time-frequency analysis by ground averaging the induced response (upper row).…”

Section: E S Timati On Of the L Ater Alit Y Of Epilep Ti C Hemis Phmentioning

confidence: 99%

“…Recently, we found that unilateral auditory information processing was affected by hippocampal dysfunction in the recording of auditory stimulus-induced magnetic fields in patients with medial temporal lobe epilepsy. [1][2][3] This means that the recording of the auditory stimulus-induced magnetic field contributes to the estimation of epileptic laterality in medial temporal lobe epilepsy. It also suggests that the hippocampus and the auditory cortex are closely related in auditory processing.…”

Section: Introductionmentioning

confidence: 99%

“…To determine which hippocampus has the strongest epileptic activity, we comprehensively refer to seizure symptoms and findings of interictal EEG, ictal EEG, neuropsychological tests, MRI, PET, Iomazenil‐SPECT, and magnetoencephalography (MEG). Recently, we found that unilateral auditory information processing was affected by hippocampal dysfunction in the recording of auditory stimulus‐induced magnetic fields in patients with medial temporal lobe epilepsy 1‐3 . This means that the recording of the auditory stimulus‐induced magnetic field contributes to the estimation of epileptic laterality in medial temporal lobe epilepsy.…”

Section: Introductionmentioning

confidence: 99%

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Hippocampal modulation of auditory processing in epilepsy

Sekiya

2020

Neurology & Clinical Neurosc

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The hippocampus is anatomically and functionally connected to other brain regions　tightly. Especially in the field of memory research, it has become clear that the connections between the cerebral cortex, thalamus, and hippocampus are regulated via slow‐wave rhythms and high‐frequency oscillation. In addition, the hippocampus, as a limbic system, is more excitable to inputs than the cerebral cortex and has a reverberant circuit structure, which induces long‐lasting neural activity. Because of such characteristics of the hippocampus, it is treated as a key structure in epilepsy. Auditory processing has been shown to be affected by hippocampal activity, and impaired auditory processing function in patients with medial temporal lobe epilepsy has been elucidated using techniques such as cognitive behavior tests and electrophysiological recordings. We recorded the auditory‐induced magnetoencephalography of patients with refractory medial temporal lobe epilepsy and examined which hemisphere was more affected. In contrast to previous language studies, we only used simple tone stimulation, by which we could obtain the laterality information regarding epileptic activity and left‐right difference. In this article, we reviewed the effects of hippocampal activity on brain function, including the findings of our auditory stimulus‐induced magnetic field recordings of medial temporal lobe epilepsy.

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“…Such perturbational approaches have been shown to provide diagnostic value for different conditions and have served as valuable tools throughout the history of neurology and neuroscience research [16]. Altered auditory steady-state evoked responses have been found in patients with schizophrenia [17], bipolar disorder [18], and temporal lobe epilepsy [19]. The complexity of responses to transcranial magnetic stimulation (TMS) can be used to discriminate levels of consciousness [20] and has shown to have significant diagnostic potential in genetic generalized epilepsy [21].…”

Section: Introductionmentioning

confidence: 99%

Active probing to highlight approaching transitions to ictal states in coupled neural mass models

Carvalho

Moraes

Cash

et al. 2020

Preprint

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The extraction of electrophysiological features that reliably forecast the occurrence of seizures is one of the most challenging goals in epilepsy research. Among possible approaches to tackle this problem is the use of active probing paradigms in which responses to stimuli are used to detect underlying system changes leading up to seizures. This work evaluates the theoretical and mechanistic underpinnings of this strategy using a well-studied seizure-generating neural mass model with two coupled populations. Different simulations are done by shifting parameters (excitability, slow inhibition, and coupling gains) towards ictal states while low-frequency probing stimuli are applied to either one or both populations. The correlation between the extracted features and the shifted parameter indicates if the impending transition to the ictal state may be identified in advance. Results show that not only can the response to the probing stimuli forecast seizures but this is true regardless of the altered ictogenic parameter. That is, similar feature changes are highlighted by probing stimuli responses in advance of the seizure including: increased response variance and lag-1 autocorrelation, decreased skewness, and increased mutual information between the outputs of both model subsets. These changes were restricted to the stimulated population, showing a local effect of this perturbational approach. The transition latencies from normal activity to sustained discharges of spikes were not affected, suggesting that stimuli had no pro-ictal effects. However, stimuli were found to elicit interictal-like spikes just before the transition to the ictal state. Furthermore, the observed feature changes highlighted by probing the neuronal populations may reflect the phenomenon of critical slowing down, where increased recovery times from perturbations may signal the loss of a systems’ resilience and are common hallmarks of an impending critical transition. These results provide more evidence that active probing approaches highlight information about underlying system changes involved in ictogenesis and may be able to play a role in assisting seizure forecasting methods which can be incorporated into early-warning systems that ultimately enable closing the loop for targeted seizure-controlling interventions.Author summaryEpilepsy is characterized by spontaneous and recurrent seizures. Developing a method to forecast the occurrence of these events would ease part of the burden to patients by providing warning systems and identifying critical periods for closed-loop seizure suppressing methods. However, this task is far from trivial and doing this in a clinical setting has been a challenge that is not yet solved. A possible way to achieve this is by using active probing paradigms, in which stimuli are used to highlight otherwise hidden changes in brain dynamics that may lead to seizures. In this work, this approach is tested in a computational model with two coupled neuronal populations. Active probing responses highlighted underlying model parameter changes that led neuronal activity closer to seizures, something that was not detected with the passive observation in most evaluated model settings. Observed feature changes revealed higher excitability, longer recovery times from stimuli, and increased synchrony between populations as the threshold to seizure-like activity approached. This indicates that low frequency stimuli may be used to reveal early-warning signs and assist in seizure forecasting methods.

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Monaural 40-Hz auditory steady-state magnetic responses can be useful for identifying epileptic focus in mesial temporal lobe epilepsy

Cited by 11 publications

References 67 publications

Awake state-specific suppression of primary somatosensory evoked response correlated with duration of temporal lobe epilepsy

Awake state-specific suppression of primary somatosensory evoked response correlated with duration of temporal lobe epilepsy

Hippocampal modulation of auditory processing in epilepsy

Active probing to highlight approaching transitions to ictal states in coupled neural mass models

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