Phase-amplitude coupling supports phase coding in human ECoG

" 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 w-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." {Credits 1}

" Intriguingly, phase-coding of categorical information extended beyond brain areas associated with higher-order vision. Thus, our findings of category-specificity do not appear to exclusively relate to perception but may also involve other more complex, and idiosyncratic, associations to these stimuli. Our findings are nonetheless in line with prior work (Majima et al., 2014; Yaffe et al., 2014; Zhang et al., 2015) which has found spatially-distributed content-specific representations." {Credits 1}

{Credits 1} 🎪 Watrous, A. J., Deuker, L., Fell, J., & Axmacher, N. (2015). Phase-amplitude coupling supports phase coding in human ECoG. eLife, 4, e07886. doi:10.7554/eLife.07886. Copyright © 2015, Watrous et al. This article is distributed under the terms of the Creative Commons Attribution License.