Fritjof Helmchen

State-dependent modulation of cross-area sensory processing in mouse neocortex

The paper investigates how behavioral states modulate sensory processing across brain regions in mice during a choice task, identifying state-dependent differences in neural activity and information routing.

Scan field rotation with a K-mirror for fast two-photon imaging along curved planes

This paper introduces an optical modification using a K-mirror and electrically tunable lens to enable fast two-photon imaging along curved planes in biological structures.

Cellular Determinants of CA1 Pyramidal Cell Recruitment during Sharp-Wave Ripples

The paper identifies cellular mechanisms determining CA1 pyramidal cell recruitment during hippocampal ripples, showing depolarization and excitability drive participation differences.

PURELIGHT: a quantitative photon-counting framework unifying intensity and lifetime imaging at video rate across detector technologies

PURELIGHT improves photon efficiency and accuracy in fluorescence microscopy by recovering undistorted intensity and lifetime measurements at high count rates across multiple detector technologies.

aDISCO: A clearing method to enable 3D microscopyof large archival paraffin-embedded human tissue blocks

aDISCO enables 3D microscopy of large archival FFPE human tissue blocks, revealing subtle pathologies in focal cortical dysplasia through deep-learning analysis.

Spike inference from calcium imaging data acquired with GCaMP8 indicators

This study evaluates and optimizes spike inference methods for GCaMP8 calcium imaging data, showing improved detection of high-frequency spikes and real-time activity.

Layer-specific wide-field calcium imaging of neocortical activity

This study uses wide-field calcium imaging to analyze neocortical activity across different layers in mice, revealing layer-specific functional connectivity patterns.

Hippocampal neuronal and astrocytic responses to noradrenaline and natural arousal

This study compares natural arousal and direct locus coeruleus activation in mouse hippocampal CA1, revealing distinct cellular response patterns in astrocytes and neurons.

Deep learning enables feature extraction of 3D collagen architecture in cleared fibrotic tissues

The paper develops a deep learning pipeline for analyzing 3D collagen architecture in cleared fibrotic tissues using optimized clearing, imaging, and a U-Net model.

Contralesional activity reflects compensation, while brainstem detour pathways support skilled motor recovery after stroke

This study shows that contralesional brain activity compensates for stroke damage, while new brainstem pathways support motor recovery in trained mice.

Separable neurocomputational mechanisms underlying multisensory learning

The paper identifies distinct neurocomputational mechanisms for multisensory learning using a novel task and fMRI, showing dissociable networks for statistical learning, reinforcement learning, and outcome surprise.

Coordinated multi-level adaptations across neocortical areas during task learning

This study identifies coordinated multi-level neural adaptations in mouse neocortical areas during task learning, showing increased neuronal responses, population-level changes, and inter-area interactions.

Pythia: Non-random DNA repair allows predictable CRISPR/Cas9 integration and gene editing

The paper introduces Pythia, a tool that uses deep learning to predict CRISPR/Cas9 integration and editing outcomes by leveraging non-random DNA repair patterns.

Brain-wide microstrokes affect the stability of memory circuits in the hippocampus

This study shows that brain-wide microstrokes disrupt hippocampal network stability, leading to cognitive impairments, with stable coding place cells predicting recovery.

Spike rate inference from mouse spinal cord calcium imaging data

The paper evaluates spike rate inference algorithms on spinal cord neurons using ground truth data and finds that retraining improves performance.

A distinct hypothalamus-habenula circuit governs risk preference

The paper identifies a distinct hypothalamus-habenula circuit that governs risk preference in economic decision-making.

Hierarchy of prediction errors shapes the learning of context-dependent sensory representations

The paper develops a computational model to explain how context shapes sensory processing by analyzing prediction errors in mice during tactile discrimination learning.

Investigating microscopic angioarchitecture in the human visual cortex in 3D with angioMASH tissue clearing and labelling

This paper introduces angioMASH, a method to visualize vascular and cytoarchitectonic features in human brain tissue, revealing layer-specific vascular density and orientation differences in visual areas V1 and V2.

Aberrant hippocampal Ca2+ micro-waves following synapsin-dependent adeno-associated viral expression of Ca2+ indicators

The paper reports that common AAV transduction procedures can induce artefactual Ca2+ micro-waves in the hippocampus and provides an alternative method to avoid this issue.

Centripetal integration of past events by hippocampal astrocytes and its regulation by the locus coeruleus

The paper shows that hippocampal astrocytes integrate calcium signals from distal processes to somata, influenced by salient events and locus coeruleus activity.

The Benchtop mesoSPIM: a next-generation open-source light-sheet microscope for large cleared samples

The paper introduces an improved open-source light-sheet microscope, mesoSPIM, with enhanced resolution, throughput, and compatibility with cleared samples.

Behavior-relevant top-down cross-modal predictions in mouse neocortex

This study investigates how the mouse neocortex resolves conflicting top-down predictions and bottom-up sensory inputs during behavior, showing hierarchical predictive coding in somatosensory and posterior parietal cortices.

History information emerges in the cortex during learning

The paper shows history information emerges in the cortex during learning, starting in higher-order areas and propagating to lower-order areas like the barrel cortex.

Reflective multi-immersion microscope objectives inspired by the Schmidt telescope

The paper introduces a novel Schmidt objective for high-resolution imaging in cleared tissues, achieving high NA, long WD, and large FOV with only two optical elements.

Mesoscale brain dynamics reorganizes and stabilizes during learning

The paper shows that during learning, brain regions shift their activity from reward-related actions to reward-predicting stimuli, forming stable mesoscale networks.

Synaptic inhibition in the lateral habenula shapes reward anticipation

This study shows that synaptic inhibition in the lateral habenula of mice is crucial for reward anticipation, as enhancing GABAergic transmission increases anticipatory licking behavior.

Estimating anisotropy directly via neural timeseries

This paper introduces a method to estimate anisotropy from neural timeseries using a generalized Lagrangian model and applies it to murine calcium imaging data.

Conservative Significance Testing of Tripartite Interactions in Multivariate Neural Data

The paper evaluates tripartite interaction metrics in neural data, showing they are biased by impurities and proposes a conservative testing method to reduce false positives.

Unsigned temporal difference errors in cortical L5 dendrites during learning

The paper shows that dendritic responses in L5 pyramidal neurons during learning correspond to unsigned temporal difference error components, with salience signals aiding task learning.

Striatum-projecting prefrontal cortex neurons support working memory maintenance

This study identifies striatum-projecting prefrontal cortex neurons as critical for spatial working memory maintenance in mice.