Investigating the neuroanatomical and electrophysiological foundations of sustained alertness using combined functional imaging, electroencephalography and invasive electrocorticography in humans.

• Applicant: Dr. Sepideh Sadaghiani
• Subject Area: Human Cognitive and Systems Neuroscience
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 200051955

Sustained, intrinsically maintained alertness denotes a state of heightened reactivity. The neural mechanisms that support this fundamental function remain unclear. Using functional imaging (fMRI) and an alertness-demanding task, we previously observed that neural activity in a network comprising the anterior cingulate cortex, insula and thalamus facilitates subsequent perception. Furthermore, spontaneous fluctuations in the activity of this network (measured by fMRI) were correlated with electrical signatures of sustained alertness, namely upper alpha-band (10-12Hz) oscillation power (measured by concurrent electroencephalography (EEG)). Power in this band was negatively correlated with regions involved in selective attention.These findings suggest a neuroanatomical and electrophysiological basis for sustained alertness in contradistinction to phasic selective attention. The cingulo-insular-thalamic network may maintain alertness by increasing alpha-band synchronization globally across the cortex. Alpha oscillations may improve reactivity and performance by cyclic clearing of information build-up. Conversely, in the presence of information about the relevance of stimulus features, and hence with selective attention, performance would benefit from a focal alpha de-synchronization maximizing feature-specific sensitivity.I will investigate this hypothesis using a detection paradigm that independently manipulates the need for sustained alertness and for feature-selective attention. An fMRI experiment will test whether sustained alertness is a function of the cingulo-insular-thalamic system. Using the same paradigm and EEG, I will probe whether alertness is implemented via distributed alpha synchronization, with selective attention occurring as an embedded, focal de-synchronization. Finally, I will explore how these electrophysiological mechanisms act upon local neural processing using a simplified paradigm and invasive electrophysiology in pre-surgical patients.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Mark d' Esposito