User profiles for F. Helmchen

Fritjof Helmchen

Professor of Neuroscience
Verified email at hifo.uzh.ch
Cited by 31694

Deep tissue two-photon microscopy

F Helmchen, W Denk - Nature methods, 2005 - nature.com
… For laser pulses of width τ occurring at a rate f R , the signal is enhanced by a factor of 1 /
f R ) n − 1 compared to continuous-wave illumination, where n is the number of photons …

[HTML][HTML] Barrel cortex function

D Feldmeyer, M Brecht, F Helmchen… - Progress in …, 2013 - Elsevier
Neocortex, the neuronal structure at the base of the remarkable cognitive skills of mammals,
is a layered sheet of neuronal tissue composed of juxtaposed and interconnected columns. …

Scanning fiber endoscopy with highly flexible, 1 mm catheterscopes for wide‐field, full‐color imaging

…, CJ Engelbrecht, TD Soper, F Helmchen… - Journal of …, 2010 - Wiley Online Library
… Fritjof Helmchen received his master degree in Physics from the University of Heidelberg, …
Helmchen was appointed Professor of Neurophysiology and Co-Director at the Brain …

Resting microglial cells are highly dynamic surveillants of brain parenchyma in vivo

A Nimmerjahn, F Kirchhoff, F Helmchen - Science, 2005 - science.org
… (F) Length changes over time of the two protrusions P1 and P2 indicated in (E). Vertical
dashed lines mark the acquisition times of the images shown in (E). Arrows indicate protrusion …

Sulforhodamine 101 as a specific marker of astroglia in the neocortex in vivo

A Nimmerjahn, F Kirchhoff, JND Kerr, F Helmchen - Nature methods, 2004 - nature.com
Glial cells have been identified as key signaling components in the brain; however, methods
to investigate their structure and function in vivo have been lacking. Here, we describe a …

Fluctuations and stimulus-induced changes in blood flow observed in individual capillaries in layers 2 through 4 of rat neocortex

D Kleinfeld, PP Mitra, F Helmchen… - Proceedings of the …, 1998 - National Acad Sciences
… For a temporal window, T, the image data F(x,t) was transformed to a reference frame that
moved with velocity c. We constructed the matrix F(x + ct, t) with t 0 < t < t 0 + T, where t 0 is the …

[PDF][PDF] Transgenic mice for intersectional targeting of neural sensors and effectors with high specificity and performance

…, A Benucci, A Nagy, A Miyawaki, F Helmchen… - Neuron, 2015 - cell.com
An increasingly powerful approach for studying brain circuits relies on targeting genetically
encoded sensors and effectors to specific cell types. However, current approaches for this …

[PDF][PDF] A miniature head-mounted two-photon microscope: high-resolution brain imaging in freely moving animals

F Helmchen, MS Fee, DW Tank, W Denk - Neuron, 2001 - cell.com
… changes in Calcium green-1 fluorescence ( F/F in the range of 40%–200%) were evoked in
the … Based on these considerations, our strategy tip was collimated with an aspheric lens (f

High-speed in vivo calcium imaging reveals neuronal network activity with near-millisecond precision

…, D Langer, H Kasper, BM Kampa, F Helmchen - Nature …, 2010 - nature.com
Two-photon calcium imaging of neuronal populations enables optical recording of spiking
activity in living animals, but standard laser scanners are too slow to accurately determine …

[PDF][PDF] Ca2+ buffering and action potential-evoked Ca2+ signaling in dendrites of pyramidal neurons

F Helmchen, K Imoto, B Sakmann - Biophysical journal, 1996 - cell.com
The effect of the fluorescent Ca2+ indicator dye Fura-2 on Ca2+ dynamics was studied in
proximal apical dendrites of neocortical layer V and hippocampal CA1 pyramidal neurons in rat …