Veranstaltungsarchiv

We’re all aware that the methods we apply shape the results we get. Nevertheless, it is common scientific practice to stick to a (very) small number of experimental tasks, often without explicitly validating (or even stating) the assumptions they imply. I illustrate the potential pitfalls of this practice in three studies picked from my lab’s work: a seemingly simple tactile localization task we’re running to develop a valid clinical task; a tactile-spatial decision task involving limb crossing that addresses some gaps left by previous tactile ”localization” tasks; and an attempt to move a highly controlled movement decision task into a (somewhat) life-like context. For each case, I highlight how unexamined underlying assumptions have led to incorrect, or at least doubtful, interpretations. [mehr]

The same brain can think, feel, and perform differently from one hour to the next. Cognitive neuroscience has traditionally explained this variability through fluctuations in neural activity within the brain itself. Yet the brain is continuously embedded within bodily signals that convey information about physiological state and energy availability. In this talk, I will propose that gut–brain communication contributes to fluctuations in brain function and mental states through two complementary temporal channels. First, rhythmic gastric activity provides a fast interoceptive signal unfolding over tens of seconds. I will present evidence from electrogastrography and neuroimaging showing that this rhythm is coupled to large-scale hemodynamic and electrophysiological brain activity during wakefulness and sleep. I will also show that stomach–brain coupling decreases during highly arousing video stimuli, motivating the possibility that it acts as an “arousal dial” tracking ongoing brain state. Second, I will introduce a complementary model in which metabolic hormones provide a slower channel of gut–brain communication. Fluctuating over minutes to hours, these signals convey information about energy availability and may act as an “energy gauge,” shaping motivation, reward, affect, and cognition. Together, these fast and slow gut-derived signals offer distinct routes through which bodily state may shape brain dynamics, cognition, mood, and mental health. [mehr]

Ultra-high-field (7T) MRI enables high-resolution brain imaging but also exacerbates physiological artifacts and acoustic noise. In this talk, I will present two approaches that exploit timing to improve image quality and acquisition performance. The first project addresses physiological fluctuations in rapid 3D MRI. We developed a semi-randomized phase-encoding strategy that suppresses artifacts from respiration, cardiac pulsation, and eye movements by exploiting their characteristic temporal frequencies. The method was demonstrated in human brain MRI at both 7T and 11.7T, including susceptibility-weighted imaging (SWI), quantitative T2 mapping, and MR angiography. The second project focuses on echo-planar imaging (EPI), the workhorse of functional MRI (fMRI), where the fast acquisitions produce high acoustic noise, particularly at ultra-high field. We show that subtle changes in gradient timing can substantially reduce acoustic energy. Timing optimization can also mitigate imaging ghosting, complementing the reduction in acoustic noise to enable quieter, more robust fMRI. Together, these projects demonstrate that careful timing can enable high-quality, high-resolution neuroimaging while improving patient comfort and extending hardware lifetime. [mehr]

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