About this Research Topic
High frequency brain signals open a new avenue for brain research in normal and abnormal conditions.
An important area investigating HFBS is the analyses of high gamma signals (> 70 Hz) elicited by functional tasks or stimuli. High gamma signals have been widely studied in the somatosensory, motor, visual, auditory and language systems. Though frequency ceiling of HFBS remain unknown, HFBS in 2,500 Hz have been detected in the human brain. Conventionally, endogenous HFBS, specifically, high frequency oscillations (HFOs) were considered pathological. However, recent reports have found that endogenous HFBS can also be physiological. Though functional HFBS, such as high gamma, can be distinguished from pathological HFOs by analyzing their relationship with the tasks or stimuli, it is a daunting challenge to distinguish pathological from physiological HFOs at resting state. In fact, the specificity of HFBS in a variety of brain disorder conditions are still not well understood.
The detection of HFBS in the epileptic brain represents another important field of research. Indeed, oscillatory HFBS, such as HFOs (80-600 Hz), ripples (80-250 Hz) and fast ripples (250-600 Hz), have been widely investigated within epileptic patients. On the other hand, non-oscillatory HFBS, such as high frequency spikes, have recently been identified, but its clinical usefulness remains unknown.
Invasive recordings have been conventionally used in the study of HFOs in epilepsy. Recent advances in magnetoencephalography (MEG) and scalp electroencephalography (EEG) have shown promising results for noninvasive detection of HFBS. Though invasive recordings can provide convincing data, its applications are limited to accessible brain areas (low spatial sampling) in surgical patients. Modern MEG and EEG can detect HFBS from the entire brain, which open a new avenue for noninvasive investigation of HFBS for both basic research and clinical applications. However, the accuracy and reliability of noninvasive detection of HFBS are debatable, specifically, additional evidence is needed for noninvasive detection of HFBS from the deep brain areas. To use HFBS in clinical practice, such as guiding epilepsy surgery, clinicians are in urgent need of source imaging of HFBS, which provide precise spatial, temporal, spectral and network information about high frequency brain activity.
This Research Topic focusing on HFBS can advance our understanding of cerebral function and brain disorders, going far beyond merely using low frequency brain activity. Basic research for detection, classification and localization of HFBS have created a set of new technologies (e.g. artificial intelligence models, software packages). HFBS are no longer just a theme of epileptogenic biomarker. HFBS have been identified in many disorders such as migraine, cerebral palsy and many others. Of note, HFBS have the potential to significantly change clinical practice and outcomes (e.g. epilepsy surgery). This Research Topic welcomes manuscripts specifically focusing on:
• Physiological and/or functional HFBS, including evoked/elicited high gamma and endogenous HFOs;
• Pathological and/or pathogenic HFBS in epilepsy, migraine and other disorders;
• Multi-frequency analyses of brain signals from low to very high frequency bands including physiological and/or pathological HFBS;
• Methodology and algorithms for detecting, classifying and localizing HFBS.
An important area investigating HFBS is the analyses of high gamma signals (> 70 Hz) elicited by functional tasks or stimuli. High gamma signals have been widely studied in the somatosensory, motor, visual, auditory and language systems. Though frequency ceiling of HFBS remain unknown, HFBS in 2,500 Hz have been detected in the human brain. Conventionally, endogenous HFBS, specifically, high frequency oscillations (HFOs) were considered pathological. However, recent reports have found that endogenous HFBS can also be physiological. Though functional HFBS, such as high gamma, can be distinguished from pathological HFOs by analyzing their relationship with the tasks or stimuli, it is a daunting challenge to distinguish pathological from physiological HFOs at resting state. In fact, the specificity of HFBS in a variety of brain disorder conditions are still not well understood.
The detection of HFBS in the epileptic brain represents another important field of research. Indeed, oscillatory HFBS, such as HFOs (80-600 Hz), ripples (80-250 Hz) and fast ripples (250-600 Hz), have been widely investigated within epileptic patients. On the other hand, non-oscillatory HFBS, such as high frequency spikes, have recently been identified, but its clinical usefulness remains unknown.
Invasive recordings have been conventionally used in the study of HFOs in epilepsy. Recent advances in magnetoencephalography (MEG) and scalp electroencephalography (EEG) have shown promising results for noninvasive detection of HFBS. Though invasive recordings can provide convincing data, its applications are limited to accessible brain areas (low spatial sampling) in surgical patients. Modern MEG and EEG can detect HFBS from the entire brain, which open a new avenue for noninvasive investigation of HFBS for both basic research and clinical applications. However, the accuracy and reliability of noninvasive detection of HFBS are debatable, specifically, additional evidence is needed for noninvasive detection of HFBS from the deep brain areas. To use HFBS in clinical practice, such as guiding epilepsy surgery, clinicians are in urgent need of source imaging of HFBS, which provide precise spatial, temporal, spectral and network information about high frequency brain activity.
This Research Topic focusing on HFBS can advance our understanding of cerebral function and brain disorders, going far beyond merely using low frequency brain activity. Basic research for detection, classification and localization of HFBS have created a set of new technologies (e.g. artificial intelligence models, software packages). HFBS are no longer just a theme of epileptogenic biomarker. HFBS have been identified in many disorders such as migraine, cerebral palsy and many others. Of note, HFBS have the potential to significantly change clinical practice and outcomes (e.g. epilepsy surgery). This Research Topic welcomes manuscripts specifically focusing on:
• Physiological and/or functional HFBS, including evoked/elicited high gamma and endogenous HFOs;
• Pathological and/or pathogenic HFBS in epilepsy, migraine and other disorders;
• Multi-frequency analyses of brain signals from low to very high frequency bands including physiological and/or pathological HFBS;
• Methodology and algorithms for detecting, classifying and localizing HFBS.
Keywords: High Frequency Oscillations, Ripples, Fast Ripples, Epilepsy, Brain Function, Invasive Recordings, Electroencephalography, Magnetoencephalography
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