P 29 Brain mechanisms for phenomenal causation and oddball-perceptions – combining fMRI and high-frequent eye-tracking – A potential fundament for the first perceptual treatment of psychotic symptoms?

Abstract

Brain mechanisms for phenomenal causation and oddball-perceptions – combining fMRI and high-frequent eye-tracking: a potential fundament for the first perceptual treatment of psychotic symptoms? Causality is a fundamental aspect of human perception, enabling us to make sense of events occurring in the world. Causality is also an often underestimated, although critical, feature of agency attribution, a fundamental cognitive function that is well-known to be perturbed in psychosis. The neuronal and psychophysiological correlates of causal perception are thus of particular interest for clinical neuroscientific research focused on psychotic symptomatology: Especially for research aimed at the development of potential cognitive or perceptual interventions to the core symptomatology of schizophrenia and malfunctionous agency attributions. The most important paradigm to investigate perceptual causality has been designed more than 70 years ago by Gestalt-Psychologist Albert Michotte (Michotte, 1946/1963). He has first shown that collisions of abstract moving stimuli (so-called “launch-events”), for example a collision of two billiard balls, evoke in healthy humans “Gestalt-perceptions of physical causality”, given that the motion event as a whole is contingent with the laws of mechanics/transfer of momentum (see for review e.g. Wagemans et al., 2006). Previous behavioral research indicates, that patients with psychosis show altered attributions of causality to launch-events (Tschacher and Kupper, 2006). Neuroimaging findings are further suggesting that the dysfunctional causality attributions occur in both physical and social event contexts, and are associated at the neural level with altered functional activity in the frontal cortex, as well as a disconnection of frontal and posterior cortex regions (Blakemore et al., 2003; Wende et al., 2014). However, an important confound of these studies is their reliance on explicit judgments or ratings of causality, making it impossible to infer from the results, if a higher-order cognitive (“top down”) or sensory-perceptual (“bottom up”) dysfunction is underlying the behavioral alterations. Here, eye-tracking can help to investigate the implicit component: Our paradigm is based on eye-movement monitoring at a real-time recording frequency (1 kHz, EyeLink 1000) during the observation of simultaneous launching displays (one launcher collides with two targets; one moves in a causal but non-colinear, the other one in a non-causal but colinear direction; Wende et al., 2015). Ocular (saccadic and pursuit) reactions to causal and non-causal target motions are thus for the first time compared within-trial, enabling us in a behavioral study, to confirm the Gestalt-perception hypothesis of causation (Michotte, 1946/1963), that the human visual system has encapsulated a rapidly operating and sub-attentional mechanism, which accomplishes an implicit detection of physical causality, as distinct from non-causality (“oddballs”): Both saccades (latencies) and smooth-pursuit (velocity) were biased towards the causal target motion (Wende et al., 2015). As a next step, we now aim to combine eye tracking and fMRI in order to investigate the functional neuroanatomy of this causality perception module in both healthy subjects and patients with psychosis. The long-term aim of our study set is the development of an interactive launching paradigm, to train causal inference at the sensory level in psychotic patients.