Lebenslauf

Publikationen

2020

Increased Callosal Connectivity in Reeler Mice Revealed by Brain-Wide Input Mapping of VIP Neurons in Barrel Cortex.
Georg Hafner, Julien Guy, Mirko Witte, Pavel Truschow, Alina Rüppel, Nikoloz Sirmpilatze, Rakshit Dadarwal, Susann Boretius, Jochen F Staiger.
Cerebral Cortex, bhaa280, https://doi.org/10.1093/cercor/bhaa280, 2020.
abstract link

The neocortex is composed of layers. Whether layers constitute an essential framework for the formation of functional circuits is not well understood. We investigated the brain-wide input connectivity of vasoactive intestinal polypeptide (VIP) expressing neurons in the reeler mouse. This mutant is characterized by a migration deficit of cortical neurons so that no layers are formed. Still, neurons retain their properties and reeler mice show little cognitive impairment. We focused on VIP neurons because they are known to receive strong long-range inputs and have a typical laminar bias toward upper layers. In reeler, these neurons are more dispersed across the cortex. We mapped the brain-wide inputs of VIP neurons in barrel cortex of wild-type and reeler mice with rabies virus tracing. Innervation by subcortical inputs was not altered in reeler, in contrast to the cortical circuitry. Numbers of long-range ipsilateral cortical inputs were reduced in reeler, while contralateral inputs were strongly increased. Reeler mice had more callosal projection neurons. Hence, the corpus callosum was larger in reeler as shown by structural imaging. We argue that, in the absence of cortical layers, circuits with subcortical structures are maintained but cortical neurons establish a different network that largely preserves cognitive functions.

2019

Pathway-, layer- and cell-type-specific thalamic input to mouse barrel cortex.
Sermet BS, Truschow P, Feyerabend M, Mayrhofer JM, Oram TB, Yizhar O, Staiger JF, Petersen CCH.
eLife 2019;8:e52665 , 2019.
abstract link

Mouse primary somatosensory barrel cortex (wS1) processes whisker sensory information, receiving input from two distinct thalamic nuclei. The first-order ventral posterior medial (VPM) somatosensory thalamic nucleus most densely innervates layer 4 (L4) barrels, whereas the higher-order posterior thalamic nucleus (medial part, POm) most densely innervates L1 and L5A. We optogenetically stimulated VPM or POm axons, and recorded evoked excitatory postsynaptic potentials (EPSPs) in different cell-types across cortical layers in wS1. We found that excitatory neurons and parvalbumin-expressing inhibitory neurons received the largest EPSPs, dominated by VPM input to L4 and POm input to L5A. In contrast, somatostatin-expressing inhibitory neurons received very little input from either pathway in any layer. Vasoactive intestinal peptide-expressing inhibitory neurons received an intermediate level of excitatory input with less apparent layer-specificity. Our data help understand how wS1 neocortical microcircuits might process and integrate sensory and higher-order inputs.

2012

Unique functional properties of somatostatin-expressing GABAergic neurons in mouse barrel cortex.
Gentet LJ, Kremer Y, Taniguchi H, Huang ZJ, Staiger J, Petersen CCH.
Nat Neurosci 15:607-612, 2012.
abstract link

Neocortical GABAergic neurons have diverse molecular, structural and electrophysiological features, but the functional correlates of this diversity are largely unknown. We found unique membrane potential dynamics of somatostatin-expressing (SOM) neurons in layer 2/3 of the primary somatosensory barrel cortex of awake behaving mice. SOM neurons were spontaneously active during periods of quiet wakefulness. However, SOM neurons hyperpolarized and reduced action potential firing in response to both passive and active whisker sensing, in contrast with all other recorded types of nearby neurons, which were excited by sensory input. Optogenetic inhibition of SOM neurons increased burst firing in nearby excitatory neurons. We hypothesize that the spontaneous activity of SOM neurons during quiet wakefulness provides a tonic inhibition to the distal dendrites of excitatory pyramidal neurons. Conversely, the inhibition of SOM cells during active cortical processing likely enhances distal dendritic excitability, which may be important for top-down computations and sensorimotor integration.