We study high-level visual perception, and its link to attention, memory and social interactions. Methodologically we have the privilege to use behavioural and all available non-invasive brain imaging tools (3T and 9.4T fMRI, EEG) to understand underlying neural processing in the human brain, and test for causal contributions using transcranial magnetic and electric (TMS and tCS) stimulation in our lab. We used state-of-the art methods including machine learning and deep neural networks for stimulus generation and data analysis. Our research questions boil down to three core areas:
When perception deviates from the physical visual input, it opens a unique way to study visual consciousness, decision making and perceptual grouping. We use illusions, bi-stable stimuli and colour vision to examine these processes.
Despite the incessant motion of eyes, head and body we perceive the world as stable. We examine how the brain integrates visual signals with body-related signals (efference copies of muscle-movements, proprioceptive and vestibular signals) to provide perceptual stability. Second, we study how the brain encodes and updates our position in the environment, and how it reconstructs the 3D-space around us based on visual input. - Motion, space, and memory are tightly interlinked.
Most social information is conveyed through visual perception of faces and human bodies. We study how dynamic changes of facial expressions are processed, and how visual and affective brain regions exchange information.
In order to achieve the above aims, we use a range of visual stimuli and tasks. The stimuli include highly controlled stimuli (such as 3D-dotfields), virtual reality, and natural movies. We also use special paradigms such as binocular rivalry and visual illusions in an attempt to dissociate pure processing from processing related to conscious perception, attentional control and decision making.
We are highly interested in understanding the mechanistic reasons that can lead to neglect, autism, ADHD, or schizophrenia. We therefore collaborate with clinicians (Neurologists and Psychiatrists) and examine their patients using our paradigms - purely behaviourally or also using fMRI.
Brain imaging: fMRI and EEG
fMRI data (with 3 Tesla and 9.4 Tesla field strengths for whole-brain and ultra-high resolution imaging) are analyzed using standard statistical approaches as well as using multivariate statistics and support vector machine classification techniques to gain insights into information content that may not lead to net signal changes.
We additionally (and sometimes concurrently with fMRI) record EEG (64 channels, active electrodes) to gain insights on the temporal sequence of processing, as well as into the coding of information in particular frequency-bands or in power-phase-relations.
Brain stimulation: TMS and tCS
Finally, we use neuronavigated transcranial magnetic stimulation (TMS) and transcranial current stimulation (tCS) to disturb perception, attentional processes and associated decision making, in order to test the causal involvement of brain regions or processes identified using non-invasive techniques.
Throughout most experiments we use eye tracking (EyeLink or Arrington).