Background oscillatory activity and somatosensory processing
The goal of my research is to identify neuronal correlates of somatosensory processing by means of non-invasive neuroimaging, mainly focussing on the functional role of background oscillatory activity (Nierhaus et al., 2009). Investigating the processing of imperceptible stimuli with EEG and resting-state fMRI revealed a modulatory role of the alpha rhythm for the access to a functional connectivity network subserving conscious experience (Nierhaus et al., 2015, J Neurosci). These neuronal correlates of imperceptible stimulus processing are now further investigated concerning attentional modulation (Project Norman Forschack), the effect of imperceptible stimulation patterns (regular vs. unregular) and their interaction with the processing of conscious stimuli (Project Fivos Iliopoulos).
Another line of research deals with the effect of acupuncture (as complex somatosensory stimulation) on background oscillatory activity. In a first study we were able to show a point-specific effect of acupuncture stimulation on the central alpha rhythm (EEG) and fMRI based functional connectivity (Nierhaus et al. 2015, Frontiers). Different stimulation sites and protocols will be studied for further investigation of these effects.
Attentional modulation of unconscious processing
Unconscious perception eludes conscious access by definition. Is it still possible to influence unconscious brain processing e.g. by selective attention? What are the central neural mechanisms of such an interaction? Can we derive general principles both for conscious and unconscious perception from that? In my dissertation I use tactile stimulation to address these kinds of questions mainly using Psychophysics and Electroencephalography (EEG).
Neural correlates of conscious sensory experiences
Awake humans have a constant stream of conscious experiences, partly driven by sensory stimulations. I conceptualize this stream of conscious experiences as the Club of Consciousness. However, a large fraction of sensory processing and behavior takes place without us experiencing it consciously. This is why I try to understand how the access to the Club of Consciousness is regulated and realized: Who gets rejected? Who is only allowed to knock at the door once? Who is talked about?
In search of the neural mechanism that give rise to conscious experiences, I combine somatosensory stimulation with neuroimaging methods (EEG & fMRI) and apply advanced data analysis to describe functional network topologies.
Interaction of unconscious stimulation patterns with conscious perception
My former academic background is routed on physics and biomedical engineering. In the beginning of my dissertation I looked into the effects of noise stimulation on the detection and transmission of weak electrical input signals in the peripheral and central nervous system. After verifying the effect of stochastic resonance driven detection enhancement through subliminal electrical noise stimulation (Iliopoulos et al., 2014), I am currently studying the mechanisms that underlie perception of subliminal regular (periodic/anticipated) versus subliminal irregular (aleatory/unpredictable) electrical stimulation. By focusing on brain plasticity and short/long term potentiation related mechanisms, our milestone goal is to employ subliminal regular stimulation as a means to somatosensoric pattern learning through subliminal synaptic (Hebbian) learning.