Fluctuations in instantaneous frequency predict alpha amplitude during visual perception

Stephanie Nelli,John T Serences,Sirawaj Itthipuripat,Ramesh Srinivasan

doi:10.1038/s41467-017-02176-x

Abstract

Rhythmic neural activity in the alpha band (8–13 Hz) is thought to have an important role in the selective processing of visual information. Typically, modulations in alpha amplitude and instantaneous frequency are thought to reflect independent mechanisms impacting dissociable aspects of visual information processing. However, in complex systems with interacting oscillators such as the brain, amplitude and frequency are mathematically dependent. Here, we record electroencephalography in human subjects and show that both alpha amplitude and instantaneous frequency predict behavioral performance in the same visual discrimination task. Consistent with a model of coupled oscillators, we show that fluctuations in instantaneous frequency predict alpha amplitude on a single trial basis, empirically demonstrating that these metrics are not independent. This interdependence suggests that changes in amplitude and instantaneous frequency reflect a common change in the excitatory and inhibitory neural activity that regulates alpha oscillations and visual information processing.

Highlights

Rhythmic neural activity in the alpha band (8–13 Hz) is thought to have an important role in the selective processing of visual information
Our results suggest that amplitude and frequency are linked, and both metrics likely reflect the operation of a common dynamical system involved in determining the efficiency of visual information processing
Substituting into the above statement, we have AT 1⁄4 AD Ã f ðωeT À ωDÞ (Supplemental Methods). This potential dependence complicates the traditional interpretation of alpha amplitude and instead suggests that shifts in amplitude reflect changes in the instantaneous frequency of the underlying dynamical system, which could arise given changes in oscillatory drive, local dampening, or local characteristic frequency

Summary

Introduction

Rhythmic neural activity in the alpha band (8–13 Hz) is thought to have an important role in the selective processing of visual information. The desynchronization hypothesis focuses on relatively slow changes in alpha amplitude, rapid, cycle-by-cycle fluctuations in alpha oscillations are thought to reflect alterations in the E/I balance and the efficacy of visual information processing[14,24,25,26,35,36,37,38,39] This account, referred to here as the instantaneous frequency account, posits that epochs of neural excitability and efficient visual information processing are associated with a particular phase of ongoing alpha oscillations. Our results suggest that amplitude and frequency are linked, and both metrics likely reflect the operation of a common dynamical system involved in determining the efficiency of visual information processing

Methods

Results

Conclusion