Friedrich W Johenning

Friedrich W Johenning
Charité Universitätsmedizin Berlin | Charité · Neuroscience Research Center

MD

About

32
Publications
6,547
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591
Citations
Citations since 2016
14 Research Items
301 Citations
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Introduction
Our in vivo work applies calcium imaging as a proxy for neuronal activity. We use miniaturized head-mounted microscopy to analyze neuronal circuit activity in freely behaving mice. We focus on the hippocampal-entorhinal formation and the olfactory cortex, with research questions related to plasticity, learning, and the sensory representation of food intake.

Publications

Publications (32)
Article
Full-text available
Author Summary Experiences change neuronal circuits, and these circuit changes outlast the initial experiences. This means that, in neurons, the fast electrical activity encoding experiences needs to be transduced into longer-lived biochemical and structural changes. A key mediator between these two timescales of neuronal activity is the Ca2+ ion....
Article
Full-text available
The three-layered primary olfactory (piriform) cortex is the largest component of the olfactory cortex. Sensory and intracortical inputs converge on principal cells in the anterior piriform cortex (aPC). We characterize organization principles of the sensory and intracortical microcircuitry of layer II and III principal cells in acute slices of rat...
Article
Medial entorhinal cortex (MEC) plays an important role in physiological processes underlying navigation, learning, and memory. Excitatory cells in the different MEC layers project in a region-specific manner to the hippocampus. However, the intrinsic microcircuitry of the main excitatory cells in the superficial MEC layers is largely unknown. Using...
Article
Full-text available
The apical dendrite of layer 2/3 pyramidal cells in the piriform cortex receives two spatially distinct inputs: one projecting onto the distal apical dendrite in sensory layer 1a, the other targeting the proximal apical dendrite in layer 1b. We observe an expression gradient of A-type K(+) channels that weakens the backpropagating action potential-...
Article
Full-text available
Intracellular calcium signals have distinct temporal and spatial patterns in neurons in which signal initiation and repetitive spiking occurs predominantly in the neurite. We investigated the functional implications of the coexpression of different isoforms of ryanodine receptors (RyR) and inositol 1,4,5-trisphosphate receptors (InsP3Rs) using immu...
Article
Full-text available
Up-down states (UDS) are synchronous cortical events of neuronal activity during non-REM sleep. Themedial entorhinal cortex (MEC) exhibits robust UDS during natural sleep and under anesthesia. However, lit-tle is known about the generation and propagation of UDS-related activity in the MEC. Here, we dissect thecircuitry underlying UDS generation an...
Article
Dendritic geometry is largely determined during postnatal development and has a substantial impact on neural function. In sensory processing, postnatal development of the dendritic tree is affected by two dominant circuit motifs, ascending sensory feedforward inputs and descending and local recurrent connections. In the three-layered anterior pirif...
Preprint
Full-text available
Dendritic geometry is largely determined during postnatal development and has a substantial impact on neural function. In sensory processing, postnatal development of the dendritic tree is affected by two dominant circuit motifs, ascending sensory feedforward inputs and descending and local recurrent connections. In the three-layered anterior pirif...
Article
Full-text available
The biological mechanisms underlying complex forms of learning requiring the understanding of rules based on previous experience are yet unknown. Previous studies raise the intriguing possibility that improvement in complex learning tasks requires the long-term modulation of intrinsic neuronal excitability, induced by reducing the conductance of th...
Article
Full-text available
The majority of excitatory synapses are located on dendritic spines of cortical glutamatergic neurons. In spines, compartmentalized Ca2+ signals transduce electrical activity into specific long-term biochemical and structural changes. Action potentials (APs) propagate back into the dendritic tree and activate voltage gated Ca2+ channels (VGCCs). Fo...
Data
Calibration of uncaging laser intensity to compensate for interslice variability. (A1) Image of the target dendritic segment (white arrow) and the InSpeck microsphere in close proximity (white square). Scale bar: 50 μm. (A2) Intensity measurement of the bead (light intensity measured in A.U.). Inset: magnification of the bead and illustration of th...
Data
Pie charts of age distributions. The pie charts illustrate the age distribution of the animals measured in our experiments ordered by the figures in which they appear.
Data
Reduction of synaptically evoked compound EPSPs measured at the soma by N- and P/Q-type VGCC block. (A1,B1) Extracellular synaptic paired-pulse stimulation evoked compound EPSPs under baseline conditions (black) and after wash-in of 200 nM AgaIVA (purple) and 1 μM CtxGIVA (blue) 20–25 min after wash-in. (A2,A3,B2,B3) Time plots of normalized, binne...
Data
Activation of NMDARs by two-photon uncaging but not by electrical synaptic stimulation. (A1) Uncaging evoked EPSPs from different spines under control conditions (left panel, mean is depicted in black) and preincubated in D-APV (right panel, mean is depicted in black). (A2) Median boxplot of uncaging evoked uEPSPs under control conditions and in D-...
Data
(A1) Averaged afterdepolarization (ADP) traces 0–5 min and after wash-in of 3 μM TTA-P2 (25–30 min) of a control experiment (black) and when TTA-P2 is washed-in after a 5 min baseline (green). (A2) Time plot of the normalized, binned (1 min) afterdepolarization of an evoked AP under control conditions (black) and when 3 μM TTA-P2 (green) is washed-...
Article
Full-text available
The measurement of activity in vivo and in vitro has shifted from electrical to optical methods. While the indicators for imaging activity have improved significantly over the last decade, tools for analysing optical data have not kept pace. Most available analysis tools are limited in their flexibility and applicability to datasets obtained at dif...
Article
Full-text available
Key points: The genetically encoded fluorescent calcium integrator calcium-modulated photoactivatable ratiobetric integrator (CaMPARI) reports calcium influx induced by synaptic and neural activity. Its fluorescence is converted from green to red in the presence of violet light and calcium. The rate of conversion - the sensitivity to activity - is...
Article
Full-text available
Author Summary Intracellular calcium oscillations and waves are paramount cellular signals. The frequency of global release events regulates, for example, expression of genes. Knowledge about the mechanism of oscillations and the factors that determine their frequency is crucial when aiming at the control of downstream processes. Many experimental...
Article
Full-text available
The presynaptic terminals of synaptic connections are composed of a complex network of interacting proteins that collectively ensure proper synaptic transmission and plasticity characteristics. The key components of this network are the members of the RIM protein family. Here we show that RIM1α can influence short-term plasticity at cerebellar para...
Article
CA3 pyramidal cells receive three main excitatory inputs: the first one is the mossy fiber input, synapsing mainly on the proximal apical dendrites. Second, entorhinal cortex cells form excitatory connections with CA3 pyramidal cells via the perforant path in the stratum lacunosum moleculare. The third input involves the ipsi-and contralateral conn...
Article
Scanning photostimulation is a well-established method for studying the functional microcircuitry in brain slices. Light-evoked responses are thereby taken as an indicator for a connected presynaptic partner. Such an approach thus requires a clear distinction between the photo-evoked and the spontaneous responses. Here we show that, for a data set...
Article
Full-text available
Among the various hippocampal network patterns, sharp wave-ripples (SPW-R) are currently the mechanistically least understood. Although accurate information on synaptic interactions between the participating neurons is essential for comprehensive understanding of the network function during complex activities like SPW-R, such knowledge is currently...
Article
Optical uncaging of caged compounds is a well-established method to study the functional anatomy of a brain region on the circuit level. We present an alternative approach to existing experimental setups. Using a low-magnification objective we acquire images for planning the spatial patterns of stimulation. Then high-magnification objectives are us...
Article
The modulation of synaptic transmission by presynaptic ionotropic and metabotropic receptors is an important means to control and dynamically adjust synaptic strength. Even though synaptic transmission and plasticity at the hippocampal mossy fibre synapse are tightly controlled by presynaptic receptors, little is known about the downstream signalli...
Article
The magnitude and/or duration of nuclear Ca(2+)-transients has been shown to dose-dependently modulate gene transcription upon neuronal activation. This is an attractive model for synapse-to-nucleus communication. In order to encode synaptic information, these nuclear Ca(2+)-transients have to be correlated with changes in synaptic strength rather...
Article
Full-text available
Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] plays an important physiological role as a precursor for the InsP3-mediated intracellular calcium (Ca2+) signalling cascade. It also regulates membrane trafficking, actin function and transmembrane proteins. SJ-1 (synaptojanin-1), a phosphoinositide phosphatase, regulates the turnover of a PtdIn...
Article
A fundamental question in cell biology is how different receptor-mediated signaling cascades, despite utilizing many of the same intracellular components, can generate specific cellular responses. Delmas and colleagues (in this issue of Neuron) address this question in relation to the muscarinic acetylcholine receptor (M(1)AchR) and the B(2) bradyk...
Article
A fundamental question in cell biology is how different receptor-mediated signaling cascades, despite utilizing many of the same intracellular components, can generate specific cellular responses. Delmas and colleagues (in this issue of Neuron) address this question in relation to the muscarinic acetylcholine receptor (M1AchR) and the B2 bradykinin...
Article
Calcium (Ca2+)-mediated signaling is fueled by two sources for Ca2+: Ca2+ can enter through Ca2+ channels located in the plasma membrane and can also be released from intracellular stores. In the present study the intracellular Ca2+ release channel/ryanodine receptor (RyR) from zebrafish skeletal muscle was characterized. Two RyR isoforms could be...

Questions

Question (1)
Question
Usually people use intracellular cesium to block potassium channels, and then add for example TEA to also block them. Is there any knowledge available which potassium channels are targeted by either one ?

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Project (1)
Project
We study the neuronal representation of food intake at different behavioral (before, during and after high- and low velocity feeding) and internal (fed ad libitum, mildly food deprived, strongly food deprived) states. We apply miniaturized microscopy for calcium imaging in freely moving mice. Recently, a clear concept how food intake is processed at the homeostatic level via hypothalamic feedbak loops emerged. Here, we aim at understanding how the perception of food at a sensory level is shaped by feeding at distinct behavioral and internal states. The piriform cortex is an early cortical stage of flavor processing. We have a clear concept of its role in odor identification based on panels of neutral odors sampled without an underlying behavioral motivation. Olfaction is also studied in the context of memory and decision making, where the sniffing usually gives access to a conditioned stimulus that is predicting reward or punishment and preceds behavior (i. e. guiding the decision for a subsequent water reward or signaling an imminent footshock). During feeding, sensory stimuli are processed and evaluated in parallel to the behavioral act of consumption, they constitute a part of the reward as opposed to conditioned stimuli that predict a reward and are dissociated from the behavioral output. We designed experiments to understand the sensory representation of food as a function of the consumptive act.