Different Mode of Afferents Determines the Frequency Range of High Frequency Activities in the Human Brain: Direct Electrocorticographic Comparison between Peripheral Nerve and Direct Cortical Stimulation

Katsuya Kobayashi,Susumu Miyamoto,Akio Ikeda,Riki Matsumoto,Akihiro Shimotake,Masao Matsuhashi,Takeharu Kunieda,Takayuki Kikuchi,Kiyohide Usami,Ryosuke Takahashi,Nobuhiro Mikuni,Hidenao Fukuyama

doi:10.1371/journal.pone.0130461

Katsuya Kobayashi, Susumu Miyamoto + Show 10 more

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https://doi.org/10.1371/journal.pone.0130461

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Journal: PLOS ONE	Publication Date: Jun 18, 2015
Citations: 11	License type: CC BY 4.0

Affiliation: Kyoto University, Sapporo Medical University

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Physiological high frequency activities (HFA) are related to various brain functions. Factors, however, regulating its frequency have not been well elucidated in humans. To validate the hypothesis that different propagation modes (thalamo-cortical vs. cortico-coritcal projections), or different terminal layers (layer IV vs. layer II/III) affect its frequency, we, in the primary somatosensory cortex (SI), compared HFAs induced by median nerve stimulation with those induced by electrical stimulation of the cortex connecting to SI. We employed 6 patients who underwent chronic subdural electrode implantation for presurgical evaluation. We evaluated the HFA power values in reference to the baseline overriding N20 (earliest cortical response) and N80 (late response) of somatosensory evoked potentials (HFASEP(N20) and HFASEP(N80)) and compared those overriding N1 and N2 (first and second responses) of cortico-cortical evoked potentials (HFACCEP(N1) and HFACCEP(N2)). HFASEP(N20) showed the power peak in the frequency above 200 Hz, while HFACCEP(N1) had its power peak in the frequency below 200 Hz. Different propagation modes and/or different terminal layers seemed to determine HFA frequency. Since HFACCEP(N1) and HFA induced during various brain functions share a similar broadband profile of the power spectrum, cortico-coritcal horizontal propagation seems to represent common mode of neural transmission for processing these functions.

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In the last decade, advancement in technology has made it possible to analyze ultra slow or high frequency activities (HFAs), or high frequency oscillations (HFOs) in the human brain
By applying single pulse electrical cortical stimulation (SPES) to the cortex connecting to SI, we focused on the HFAs overriding cortical evoked potentials (CCEPs) N1 and N2 components in the SI cortex and compared their feature with HFAs of SEP (HFASEP)
As a post hoc analysis, we focused on the 4 comparisons between the groups: HFASEP(N20) and HFACCEP(N1), HFASEP(N80) and HFACCEP(N2), HFASEP(N20) and HFASEP(N80), and HFACCEP(N1) and HFACCEP(N2)

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Introduction

Advancement in technology has made it possible to analyze ultra slow or high frequency activities (HFAs), or high frequency oscillations (HFOs) in the human brain. Much before the discovery of high gamma activities related with various brain functions, faster activity around 600 Hz was discovered and intensively investigated in somatosensory function by recording somatosensory evoked potentials (SEPs) [19,20,21,22,23,24,25,26,27,28,29]. This activity was different from the aforementioned activities in that it is an evoked activity that overrides the early cortical component (N20) of median nerve SEP. HFASEP seems to play an important role in sensory information processing, and their impairment is reported in patients with multiple sclerosis, migraine and epilepsy [33,34,35,36]

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