Prestimulus Network Integration of Auditory Cortex Predisposes Near-Threshold Perception Independently of Local Excitability.
Sabine Leske, Philipp Ruhnau, Julia Frey, Chrysa Lithari, Nadia Müller, Thomas Hartmann, Nathan Weisz
Cerebral cortex (New York, N.Y. : 1991) December 1, 2015 DOI: 10.1093/cercor/bhv212 (opens in new tab) via PubMed
Summary
AI-generated from the abstractBrain regions crucial for hearing a faint sound are already coupled before the sound arrives, forming pre-established pathways that influence whether the sound is consciously perceived. Using magnetoencephalography and graph theory, the study found that in a near-threshold auditory task, the left auditory cortex behaved like a hub and was more integrated into the brain's functional network prior to conscious perception, while right auditory regions were decoupled from non-auditory areas. Local excitability, measured by decreased alpha power in the auditory cortex, also increased before conscious percepts. These connectivity and excitability states were largely independent of each other.
Study at a glance
| Characteristics | Observational study Peer reviewed |
|---|---|
| Keywords | Meg Auditory consciousness Functional connectivity Graph theory Ongoing oscillations |
| Key finding | Pre-stimulus interhemispheric connectivity in auditory regions and a hub-like role of the left auditory cortex support the framework that pre-established pathways influence auditory conscious perception. |
Abstract
An ever-increasing number of studies are pointing to the importance of network properties of the brain for understanding behavior such as conscious perception. However, with regards to the influence of prestimulus brain states on perception, this network perspective has rarely been taken. Our recent framework predicts that brain regions crucial for a conscious percept are coupled prior to stimulus arrival, forming pre-established pathways of information flow and influencing perceptual awareness. Using magnetoencephalography (MEG) and graph theoretical measures, we investigated auditory conscious perception in a near-threshold (NT) task and found strong support for this framework. Relevant auditory regions showed an increased prestimulus interhemispheric connectivity. The left auditory cortex was characterized by a hub-like behavior and an enhanced integration into the brain functional network prior to perceptual awareness. Right auditory regions were decoupled from non-auditory regions, presumably forming an integrated information processing unit with the left auditory cortex. In addition, we show for the first time for the auditory modality that local excitability, measured by decreased alpha power in the auditory cortex, increases prior to conscious percepts. Importantly, we were able to show that connectivity states seem to be largely independent from local excitability states in the context of a NT paradigm.