title: The contribution of frequency-specific activity to hierarchical information processing in the human auditory cortex.
abstract: The fact that feed-forward and top-down propagation of sensory information use distinct frequency bands is an appealing assumption for which evidence remains scarce. Here we obtain human depth recordings from two auditory cortical regions in both hemispheres, while subjects listen to sentences, and show that information travels in each direction using separate frequency channels. Bottom-up and top-down propagation dominates in γ- and δ-β (<40 Hz) bands, respectively. The predominance of low frequencies for top-down information transfer is confirmed by cross-regional frequency coupling, which indicates that the power of γ-activity in A1 is modulated by the phase of δ-β activity sampled from association auditory cortex (AAC). This cross-regional coupling effect is absent in the opposite direction. Finally, we show that information transfer does not proceed continuously but by time windows where bottom-up or top-down processing alternatively dominates. These findings suggest that the brain uses both frequency- and time-division multiplexing to optimize directional information transfer.
authors.affiliation: 1] Department of Neuroscience, University of Geneva, Biotech Campus, 9, Chemin des Mines, Geneva 1211, Switzerland [2].
authors.forename: L
authors.initials: L
authors.lastname: Fontolan
authors.affiliation: 1] Department of Psychiatry, Columbia University Medical Center, New York, New York 10032, USA [2].
authors.forename: B
authors.initials: B
authors.lastname: Morillon
authors.affiliation: INSERM U1106-Institut de Neurosciences des Systèmes, Université Aix-Marseille, Marseille 13005, France.
authors.forename: C
authors.initials: C
authors.lastname: Liegeois-Chauvel
authors.affiliation: Department of Neuroscience, University of Geneva, Biotech Campus, 9, Chemin des Mines, Geneva 1211, Switzerland.
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Giraud
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D058256:Brain Waves / Q000502:physiology*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D013060:Speech; D013238:Stereotaxic Techniques