Bitte beachten Sie den abweichenden Termin: Freitag, 20.11.2020, 16:00 - 18:00
Rafael Yuste, Columbia University
The small freshwater cnidarian Hydra vulgaris has one of the simplest nervous systems in the animal kingdom, yet exhibits surprisingly complex behaviors, like somersaulting. Due to its transparency, its complete neural and muscle activity can be effectively imaged. Our goal to take advantage of this experimental angle to "break the neural code" of Hydra: to understand the complete set of transformations from neural activity to muscle activation to behavior.
- Bosch, T.C., et al., Back to the Basics: Cnidarians Start to Fire. Trends Neurosci, 2017. 40(2): p. 92-105.
- Han, S., et al., Comprehensive machine learning analysis of Hydra behavior reveals a stable basal behavioral repertoire. Elife, 2018. 7.
- Dupre, C. and R. Yuste, Non-overlapping Neural Networks in Hydra vulgaris. Curr Biol, 2017.
- Szymanski, J.R. and R. Yuste, Mapping the Whole-Body Muscle Activity of Hydra vulgaris. Curr Biol, 2019. 29(11): p. 1807-1817 e3.
Bitte beachten Sie den abweichenden Termin: Mittwoch, 25.11.2020, 12:00 - 14:00
Pamela Lyon, Southgate Institute of Health, Society and Equity, Flinders University, Australia
The talk will introduce the emerging research program of basal cognition, the rationale behind it, why it is necessary now, and provide two case studies, both of which have implications for decision making. The discovery and further investigation of bioelectrical activity in the bacterium Bacillus subtilis is a prime example of how the basal cognition approach can work. The case study of valence, which also relies on B. subtilis, shows how a theoretical construct in the affective sciences can be applied, with solid biological justification, to simple organisms, even if emotion researchers generally believe that a nervous system, and possibly a brain, is necessary for application of the concept. It is hard to see how decisions can be made at all without valence, an organism’s attraction or repulsion to a state of affairs based on an assessment of advantage or harm to its functioning.
Udo Ernst, Institute for Theoretical Physics, Universität Bremen
Information processing in the visual system is continuously challenged by the high-dimensional stream of sensory signals arriving from the outside world. For making sense of a visual scene, localized image patches have to be stitched together to form global representations, for example for recognizing objects. To facilitate this integration process, the visual system uses selective attention to enhance signals which are behaviorally relevant, while suppressing irrelevant information.
In my presentation I would like to discuss two aspects of visual processing in which decisions play a crucial role. First, I will focus on contour integration which is important for segmenting a visual scene. We studied this process by combining theory and modeling with psychophysical experiments. Human decisions in a contour detection task, in particular systematic perception ‘errors’, were used to constrain models, and turned out to provide the key for uncovering the neural mechanisms underlying this important computational process. In a second example, I will present results of a computational analysis of the temporal dynamics of neurons in area MT, and their modulation by attention. Here we identified a neural mechanism which quantitatively explains the large transient firing rate modulations that are typically observed in response to sudden stimulus changes. Most importantly, we could show that this mechanism allows attention to facilitate change detection independently on the sensory context, thus implementing an important principle of invariance for vision.