Phase-amplitude coupling supports phase coding in human ECoG
- University of Bonn, Germany
- German Center for Neurodegenerative Diseases, Germany
Abstract
Prior studies have shown that high-frequency activity (HFA) is modulated by the phase of low-frequency activity. This phenomenon of phase-amplitude coupling (PAC) is often interpreted as reflecting phase coding of neural representations, although evidence for this link is still lacking in humans. Here, we show that PAC indeed supports phase-dependent stimulus representations for categories. Six patients with medication-resistant epilepsy viewed images of faces, tools, houses, and scenes during simultaneous acquisition of intracranial recordings. Analyzing 167 electrodes, we observed PAC at 43% of electrodes. Further inspection of PAC revealed that category specific HFA modulations occurred at different phases and frequencies of the underlying low-frequency rhythm, permitting decoding of categorical information using the phase at which HFA events occurred. These results provide evidence for categorical phase-coded neural representations and are the first to show that PAC coincides with phase-dependent coding in the human brain.
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Author details
Reviewing Editor
- Howard Eichenbaum, Boston University, United States
Ethics
Human subjects: The study was conducted according to the latest version of the Declaration of Helsinki and approved by the local ethics committee, and all patients provided written informed consent.
Version history
- Received: April 2, 2015
- Accepted: August 25, 2015
- Accepted Manuscript published: August 26, 2015 (version 1)
- Version of Record published: September 23, 2015 (version 2)
Copyright
© 2015, Watrous et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Phase-amplitude coupling supports phase coding in human ECoG
eLife 4:e07886.
https://doi.org/10.7554/eLife.07886
Further reading
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- Neuroscience
Hippocampal replay – the time-compressed, sequential reactivation of ensembles of neurons related to past experience – is a key neural mechanism of memory consolidation. Replay typically coincides with a characteristic pattern of local field potential activity, the sharp-wave ripple (SWR). Reduced SWR rates are associated with cognitive impairment in multiple models of neurodegenerative disease, suggesting that a clinically viable intervention to promote SWRs and replay would prove beneficial. We therefore developed a neurofeedback paradigm for rat subjects in which SWR detection triggered rapid positive feedback in the context of a memory-dependent task. This training protocol increased the prevalence of task-relevant replay during the targeted neurofeedback period by changing the temporal dynamics of SWR occurrence. This increase was also associated with neural and behavioral forms of compensation after the targeted period. These findings reveal short-timescale regulation of SWR generation and demonstrate that neurofeedback is an effective strategy for modulating hippocampal replay.
