"Combining Transcranial Brain Stimulation with Neuroimaging for State-dependent Stimulation and Causal Network Interrogation" 

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Til Ole Bergmann, Ph.D.
Associate Professor (W2) of Neurostimulation
Deputy Head of Neuroimaging Center (NIC) 
NeuroImaging Center (NIC), Johannes Gutenberg University Medical Center, Mainz, Germany
Group Leader AG Neurostimulation 
Leibniz Institute for Resilience Research (LIR), Mainz, Germany

*Lunch provided for in-person attendees

ABSTRACT
Functional neuroimaging and electrophysiological techniques, such as functional magnetic resonance imaging (fMRI) as well as electro- and magnetoencephalography (EEG/MEG), serve well to study spontaneous or task-related neuronal activity as correlates of specific cognitive functions in the human brain. However, to infer causality of brain activation for cognition, the former must be manipulated experimentally. This is possible in healthy humans with the help of non-invasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS), transcranial electric stimulation (tES), and since recently also transcranial ultrasound stimulation (TUS). Importantly, NIBS can also be combined with fMRI as well as EEG/MEG, either concurrently (online) or consecutively (offline). Online approaches, assessing the immediate neural response to stimulation, can be used to (i) quantify neuronal network properties such as excitation, inhibition, or connectivity, (ii) interfere with ongoing spontaneous or task-related activity and thus affect behavioral performance, or (iii) modulate the level and timing of neuronal activity, e.g., trying to mimic neuronal oscillations in behaviorally relevant manner. In contrast, offline approaches can be utilized to either (iv) inhibit or (v) facilitate local neuronal excitability via the induction of synaptic plasticity, assessing its subsequent effects on neuronal activity and behavior. In this talk, I will discuss the different approaches and challenges with respect to their combination with fMRI and EEG, in particular concurrent TMS-fMRI and TMS-EEG, and highlight their potential as well as the caveats for inferring causality from NIBS studies in cognitive neuroscience. I will also introduce the novel approach of brain state-dependent brain stimulation, which allows to control NIBS in real-time based on the online assessment of specific oscillatory states, providing a unique opportunity to causally interact with ongoing neuronal oscillations to study its role in information processing and synaptic plasticity.

BIO/RESEARCH
I am a biological psychologist / cognitive neuroscientist interested in the function of neuronal oscillations in cognition, in particular for the organization of information processing and the gating of synaptic plasticity in the wake and sleeping human brain. My methodological focus is on the simultaneous combination of non-invasive transcranial brain stimulation techniques with neuroimaging and electrophysiology and the development of novel approaches, such as brain state-dependent brain stimulation.

I graduated in Psychology at the University of Kiel (Germany), and did my PhD with Prof. Hartwig Siebner on the oscillatory underpinnings of memory consolidation during sleep using concurrent tES-TMS, EEG-fMRI, and TMS-EEG. During a subsequent PostDoc with Prof. Ole Jensen at the Donders Institute for Brain Cognition and Behaviour in Nijmegen (Netherlands) I then studied the function of alpha oscillations for visuospatial attention using concurrent TMS-EEG and tES-MEG approaches. Following an interim faculty appointment at the Institute of Psychology back in Kiel, I moved to Tübingen (Germany) to work with Prof. Ulf Ziemann on real-time EEG-triggered TMS to study the function of the sensorimotor mu-alpha rhythm for corticospinal excitability and with Prof. Jan Born to continue my investigations into the function of sleep-specific oscillations. In 2018, I started my own research group for Neurostimulation at the Leibniz Institute for Resilience Research (LIR) in Mainz (Germany), where we established concurrent TMS-fMRI and further advanced EEG-triggered TMS and the automation of neurostimulation experiments. In November 2020, I was appointed Associate Professor (W2) of Neurostimulation at the Neuroimaging Center (NIC) of the Johannes Gutenberg University Medical Center in Mainz, while keeping an associated research group at the LIR to continue studying the neurobiological correlates of emotional memory processing for resilience. At the NIC, we have recently started to establish transcranial ultrasonic stimulation (TUS) for non-invasive deep brain neuromodulation.