Projects

Neural Basis of Action Planning and Action Selection

To isolate the brain processes that underlie the selection and generation of goal directed behavior we resort to functional magnetic resonance imaging (fMRI) during delayed response tasks (see figure). These tasks allow temporally separating planning and decision processes during a "Delay" from representations of both the sensory context they depend on ("Instruction") and the motor acts they ultimately produce ("Response"). Using such task design we show at the level of human posterior parietal and premotor cortex and plans for upcoming finger reaches are encoded (Lindner et al., 2010). These plans are formed in a way that (also) considers the visual consequences of the movement (Pilacinski et al., 2018) as well as information about movement trajectories (Pilacinski & Lindner, 2019). Notably, up to a certain limit, our brain can represent multiple concurrent plans thereby warranting optimal behavioral performance (Schach et al., 2022). Given that such planning activity in posterior parietal and premotor cortex is additionally modulated by decision variables such as reward and punishment (Iyer et al., 2010), makes these areas interesting candidates for the neural monitoring of action selection (e.g. in order to inform brain machine interfaces, etc.). 

Agency Attribution - Mechanisms and Disorders

A key constituent of the "Self" is "agency". Agency refers to our ability to identify whether or not our movements and their sensory consequences are caused by ourselves. Deficits of this ability do, accordingly, dissolve the border between self and non-self, as is for instance the case in certain Schizophrenia patients. A healthy subject can attribute agency to self-produced sensory information on the basis of her own motor commands: these commands allow to predict and, thus, to identify the sensory consequences of her actions. We have shown that deficits of this predictive mechanism (also termed forward model, efference copy, or corollary discharge) explain disorders of the Self in Schizophrenia (Lindner et al., 2005; Synofzik et al., 2010; Roth et al., 2023). We have further shown that sensory predictions are recalibrated by sensory feedback on a short timescale (Synofzik et al., 2006; Wilke et al., 2013). Moreover, this plasticity is mediated by the cerebellum (Lindner et al., 2006; Synofzik et al., 2008; Roth et al., 2013) and, likely, is not only optimizing perceived agency but also motor control. Using 2D virtual reality reach setups (figure; also see Methods) we currently detail the mechanisms of agency attribution, their neural underpinnings, and their disturbance in various neuropsychiatric disease (see here for preliminary results in OCD by Roth et al., 2024).

By recruiting “mirror” regions in the contralateral cerebral hemisphere of prefrontal cortex elderly subjects are able to master challenging cognitive tasks despite cognitive decline. Using highly demanding working memory tasks during fMRI we have shown that such bilateral prefrontal activation is not age-specific but reflects a general coping strategy that is independent of age, task content and brain region (Höller-Wallscheid et al. 2017). Preliminary evidence suggests that such cross-hemispheric recruitment is present also beyond frontal cortex and in tasks other than working memory (Schach et al. 2023). In addition we try to use the so-called “bilateral field advantage effect” as a means to externally trigger bilateral representation and to improve working memory performance despite cognitive decline.

Our holistic perception of the environment is a result of processes, which group the fragments of information arriving at the retina in order to form entities or objects. Studies on simultanagnosia patients, who lost the ability to perceive a visual scene holistically, emphasize the importance of parieto-occipital cortex as substrate for perceptual grouping. To study perceptual (spatial) grouping we utilize a bistable Ternus-Display that does - depending on how sensory information is grouped - lead to the perception of either element motion or group motion: Element motion (a single dot is "jumping" left and right) is commonly perceived in the upper animation of the Ternus diplay on the right while group motion (a group of three dots is "jumping" left and right) is typically perceived in the lower animation. Using this bistable stimulus in combination with fMRI, we provided preliminary evidence that parieto-occipital cortex does indeed serve as a substrate for spatial grouping (Kutscheid et al., 2014).