The Tactile Window to Consciousness is Characterized by Frequency-Specific Integration and Segregation of the Primary Somatosensory Cortex.
Julia Natascha Frey, Philipp Ruhnau, Sabine Leske, Markus Siegel, Christoph Braun, Nathan Weisz
Scientific Reports February 11, 2016 DOI: 10.1038/srep20805 (opens in new tab) via PubMed
Summary
AI-generated from the abstractConscious perception of a faint touch depends not only on brain activity in the sensory cortex but also on the state of larger brain networks just before the stimulus arrives. In a magnetoencephalography study, participants performed a near-threshold tactile detection task. Before correctly detected stimuli, alpha and beta power were reduced in the somatosensory region opposite the stimulated hand, and event-related responses were stronger afterward. Graph analysis revealed that the right primary somatosensory cortex showed increased integration in the theta band and decreased integration in the beta band before detection. These findings suggest that a reduction of irrelevant functional connections helps tune neural pathways for conscious perception.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Population | Human participants performing a near-threshold tactile detection task |
| Key finding | Pre-stimulus network states in the primary somatosensory cortex, characterized by increased theta-band integration and decreased beta-band integration, are associated with conscious perception of near-threshold tactile stimuli. |
Abstract
We recently proposed that besides levels of local cortical excitability, also distinct pre-stimulus network states (windows to consciousness) determine whether a near-threshold stimulus will be consciously perceived. In the present magnetoencephalography study, we scrutinised these pre-stimulus network states with a focus on the primary somatosensory cortex. For this purpose participants performed a simple near-threshold tactile detection task. Confirming previous studies, we found reduced alpha and beta power in the somatosensory region contralateral to stimulation prior to correct stimulus detection as compared to undetected stimuli, and stronger event-related responses following successful stimulus detection. As expected, using graph theoretical measures, we also observed modulated pre-stimulus network level integration. Specifically, the right primary somatosensory cortex contralateral to stimulation showed an increased integration in the theta band, and additionally, a decreased integration in the beta band. Overall, these results underline the importance of network states for enabling conscious perception. Moreover, they indicate that also a reduction of irrelevant functional connections contributes to the window to consciousness by tuning pre-stimulus pathways of information flow.