Neurons filter their subthreshold input signals. While many cells show low-pass filter characteristics, a prominent number of cell types exhibits band-pass-like filters.

Investigators: Eric Reifenstein
Keywords: [Grid cells] [Spatial memory]

When a rat explores its environment, so called grid cells in the medial entorhinal cortex show increased activity at specific locations that constitute a regular hexagonal grid. As the rat enters and progresses through one of these “grid fields”, spikes occur at successively earlier phases in the LFP's theta rhythm. This phenomenon is called phase precession. We employ data analysis and modeling to investigate the mechanisms and benefits of grid-cell phase precession.

Investigators: Eric Reifenstein
Keywords: [Grid cells] [Spatial memory]

Grasshoppers evolved an auditory system for two reasons: predator avoidance and partner selection. We study how sound information that arrives at a grasshopper's ear is transformed into a neuronal signal, and how this signal in turn is transformed into a sparse, efficient code.
On an average day, jumping from the shade into the sun can easily change a grasshopper's body temperature by 10°C. Given that every neuron's ion channel dynamics are modulated by temperature, maintenance of neuronal functionality across behaviorally relevant temperatures is a non-trivial task. We investigate how neuronal activity can be made robust against temperature fluctuations, even in the presence of temperature-modulated ion channel dynamics.

Investigators: Janina Hesse, Frederic Roemschied
Keywords: [Coding] [Neuronal morphology] [Temperature compensation] [Single-neuron modeling]

Since Hodgkin and Huxley’s model of action potential initiation, the prevailing assumption is that ion channels act independently. They change their open probability in response to a common signal such as the membrane voltage, but do not directly influence each other. Nevertheless, evidence for additional interactions between channels accumulates. We investigate consequences of interactions between voltage-dependent ion channels for the dynamics of excitable membranes. In particular, we want to understand how cooperative and anticooperative gating between ion channels changes basic sub- and suprathreshold voltage dynamics.

Investigators: Ekaterina Zhuchkova, Fabian Santi
Keywords: [Coding] [ion channels] [cooperativity]

Virtually all synaptic input to a neuron arrives at the dendritic tree. A great number of experimental studies have shown that dendrites are endowed with a wide variety of voltage-dependent ion channels. These active membrane properties can underlie a variety of dynamical behaviors, such as backpropagation of somatic action potentials, dendritic spike initiation, and membrane potential resonances and oscillations. Using numerical and analytical approaches, we study how dendritic membrane properties, together with their morphology, affect the integration of synaptic input and thereby shape the computations that single neurons can perform.

Investigators: Michiel Remme, Ekaterina Zhuchkova
Keywords: [Neuronal morphology] [Resonance]