Theory and Modelling of the hippocampal formation

One of an animal's first and most fundamental tasks is to know about its location in space. The hippocampal formation is one of the brain areas assumed to be involved in spatial navigation since many cells exhibit space-selective firing rates (place fields and grid fields) and space related temporal firing patterns (theta phase precession; reply, preplay). However, we still lack a satisfactory understanding of how hippocampal subregions integrate sensory input and external cues. Our goal is to develop mathematical theories of neural network interactions, to offer insights on how the hippocampus and related brain areas such as the entorhinal and medial prefrontal cortices wire up to perform the computations necessary for representing, memorizing and planning trajectories in space.

Subproject: Cellular biophysics of Sequence replay

Simultaneous recordings of many place cells reveal sequential activity patterns, which repeat during periods of immobility. In local field potential recordings, these repetitions are accompanied by so called sharp-wave ripples (SWRs). The function of these sequences is assumed to be related to memory consolidation and path planning. To study the function of cellular biophysical properties, we develop a multi-compartmental model of a CA1 pyramidal neuron receiving postsynaptic currents recorded from pyramidal cells in CA1 slices during spontaneous occurring SWRs.

Collaborators: D. Schmitz (Charite Berlin), F. Felmy (TiHo Hannover)
Funding: BCCN Munich

Subproject: Interaction of Brain Areas

Neuronal space representations are not only found in the hippocampus and medial entorhinal cortex. All related brain areas are encoding space either directly via there firing rate or in the firing phase with respect to the theta oscillation (or both). It is unclear why space is so ubiquitously represented and particularly how the different space representations talk to each other. We are working several models addressing the interaction of different brain areas to explain different functions and phenomenons like pattern separation, path planning, phase precession and gridfield formation.

Collaborators: S. Leutgeb (UC San Diego)
Funding: DFG LE2250/5-1