Phase‐amplitude coupling profiles differ in frontal and auditory cortices of bats

Manfred Kössl,Francisco García‐Rosales,Julio C Hechavarria,Luciana López‐Jury,Yuranny Cabral‐Calderín,Eugenia González‐Palomares

doi:10.1111/ejn.14986

Manfred Kössl, Francisco García‐Rosales + Show 4 more

Open Access

https://doi.org/10.1111/ejn.14986

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Abstract

Neural oscillations are at the core of important computations in the mammalian brain. Interactions between oscillatory activities in different frequency bands, such as delta (1-4Hz), theta (4-8Hz) or gamma (>30Hz), are a powerful mechanism for binding fundamentally distinct spatiotemporal scales of neural processing. Phase-amplitude coupling (PAC) is one such plausible and well-described interaction, but much is yet to be uncovered regarding how PAC dynamics contribute to sensory representations. In particular, although PAC appears to have a major role in audition, the characteristics of coupling profiles in sensory and integration (i.e. frontal) cortical areas remain obscure. Here, we address this question by studying PAC dynamics in the frontal-auditory field (FAF; an auditory area in the bat frontal cortex) and the auditory cortex (AC) of the bat Carollia perspicillata. By means of simultaneous electrophysiological recordings in frontal and auditory cortices examining local-field potentials (LFPs), we show that the amplitude of gamma-band activity couples with the phase of low-frequency LFPs in both structures. Our results demonstrate that the coupling in FAF occurs most prominently in delta/high-gamma frequencies (1-4/75-100Hz), whereas in the AC the coupling is strongest in the delta-theta/low-gamma (2-8/25-55Hz) range. We argue that distinct PAC profiles may represent different mechanisms for neuronal processing in frontal and auditory cortices, and might complement oscillatory interactions for sensory processing in the frontal-auditory cortex network.

Highlights

There is increasing evidence supporting the role of oscillatory activity as instrument of neural computations in the mammalian brain
We address this question by studying Phase-amplitude coupling (PAC) dynamics in the frontal-auditory field (FAF; an auditory area in the bat frontal cortex) and the auditory cortex (AC) of the bat Carollia perspicillata
High-order sensory processing may capitalize on PAC, the latter providing a mechanistic substrate for the parsing of continuous stimuli by accommodating local network activity in the gamma range into slower, behaviourally relevant timescales represented by the low-frequency activity (Giraud & Poeppel, 2012; Hyafil, et al, 2015)

Summary

| INTRODUCTION

There is increasing evidence supporting the role of oscillatory activity as instrument of neural computations in the mammalian brain. Tackling such question can provide valuable insights into the nature of evolutionarily preserved circuits across species In both primates and non-primates there exist structures in the frontal cortex that are strongly responsive to acoustic stimuli (Eiermann & Esser, 2000; Kobler et al, 1987; Medalla & Barbas, 2014; Plakke & Romanski, 2014). Within these structures, the relationship between the phase of low frequency oscillations and the amplitude of high frequency rhythms remains largely unexplored. We argue that distinct PAC profiles in FAF and AC could represent distinct mechanisms of neural processing at the level of sensory and association areas

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION