Very High-Frequency Oscillations (Over 1000 Hz) of Somatosensory-Evoked Potentials Directly Recorded From the Human Brain

Abstract

The aims of this study were to record high-frequency oscillations (HFOs) associated with somatosensory-evoked potentials from subdural electrodes and to investigate their generators and clinical significance. Six patients who underwent long-term subdural electrode monitoring were studied. Somatosensory-evoked potentials were recorded directly from the subdural electrode after stimulation of the median nerve. Bandpass filter was 10 to 10,000 Hz for conventional somatosensory-evoked potential and 500 to 10,000 Hz for HFO. Three types of HFO were recorded. The first component was early HFO (407-926 Hz), which occurred before N20 peak. The second component was late HFO (408-909 Hz), which occurred after N20 peak. In addition, a novel component was recorded with a range from 1,235 to 2,632 Hz, and this component was termed very HFO. Early and late HFOs were recorded from relatively wide areas centering around the primary motor and primary sensory areas, whereas very HFO was localized around the primary sensory areas. In this study, at least three components of HFO could be identified. Only very HFO was localized around primary sensory areas, suggesting a possibility that very HFO may provide an effective method of identifying the central sulcus.

Altered Cortical Activation in Adolescents With Acute Migraine: A Magnetoencephalography Study

“…In comparison to controls, migraine subjects had a significantly higher likelihood of activation in the SMA and the occipital and ipsilateral sensorimotor cortices. There are reports showing that the brain generates signals around 2,632 Hz in the somatosensory cortex 28 and 2,500 Hz in the epileptic regions. 32 However, those previous reports are based on invasive intracranial recordings and are limited to patients with intractable epilepsy who are surgical candidates.…”

“…8 Recent invasive recordings have shown that a brain with epilepsy generates very-high-frequency activation near 2,632 Hz. 28,32 The examination of high-frequency brain activation may have the potential to provide key information about cortical dysfunction in migraine.…”

“…22,33 Instead of using conventional bandpass filters, this study was designed to use Morlet wavelet to analyze MEG data. 36–38 In comparison to previous MEG publications, 28 the main innovation of the present study was the systematic analyses of neuromagnetic spectrograms in the 3 frequency ranges of 5 to 100 Hz, 100 to 1,000 Hz, and 1,000 to 2,884 Hz. This approach avoided possible bias by subjectively selecting a frequency range.…”

“…This approach avoided possible bias by subjectively selecting a frequency range. 3,5,28,34 The central hypothesis was that neuromagnetic activation in the developing brain with migraine could be identified in multiple frequency ranges. This hypothesis was based on the observation that brain activation in 1 to 30 Hz and 65 to 150 Hz in migraine has been identified using MEG.…”

Non-invasive single-trial EEG detection of evoked human neocortical population spikes

“…Consequently, when utilizing low-noise EEG amplifiers an increase in single-trial hf-EEG power coinciding with the σ-burst in the averaged hf-SEP could be demonstrated , while a previous study with conventional EEG amplifiers failed to demonstrate this increase of single-trial hf-EEG power (Valencia et al, 2006). Furthermore, hf-SEP components at approximately 950 Hz were discovered in non-invasive surface EEG (Scheer et al, 2011;Fedele et al, 2012), previously attainable only by the use of implanted deep electrodes in the thalamus of patients with Parkinson's disease (Klostermann et al, 2002) or subdural recordings (Sakura et al, 2009).…”