Welcome to the Hafting-Fyhn lab !

Building a multiphoton microscope ?

The Hafting-Fyhn laboratory — Thu, 22 Dec 2011 10:39:54 +0000

Labrigger.com got a nice overview of the different options for building a two-photon microscope for in vivo imaging.

We are using a moving objective microscope (MOM) scope from Sutter Instr in our lab, and now Josh Trachtenberg and Adrian Cheng from UCLA are offering custom made multiphoton microscopes for in vivo imaging in the same vein as the Sutter/Denk scope. This is an excellent team and they offer a well-designed scope.

Grid cells without theta oscillations!

The Hafting-Fyhn laboratory — Wed, 14 Dec 2011 11:58:19 +0000

Since the discovery of grid cells, there has been a quite interesting debate about different theoretical models trying to explain the mechanisms underlying the formation of grid cells. One of the most popular models is the “two oscillator model” suggesting that the grid cell structure is caused by interference between membrane oscillations at slightly different theta frequencies (Burgess et al., 2007; Hasselmo et.al., 2007). This model has been modified in a number of ways, but to the best of my knowledge, this model has always been biological implausible (e.g. Remme et al., 2010 pedagogically previewed by Ila Fiete (Neuron, 2010)). This fall the debate have been flaring up with a seminal paper by Michael Yartsev in the Ulanovsky lab: Grid cells without theta oscillations in the entorhinal cortex of bats.

Figure from Giocomo and Moser (2011)

Anyway, the Yartsev et al. (2011) paper is much more than just an argument in the two-oscillator debate and definitely worth reading for many reasons. It’s also a reminder about the importance of comparative physiology.

When I met Yartsev in the Champalimaud conference in Portugal this fall, he showed us some fantastic movies of recordings from the flying bats (3D place fields) – so there is more to come….

Since the paper is already old news for some of you (sorry for the slack of my blog posting) – I add a link to a recent comment by Lisa and Edvard:
Giocomo & Moser (2011)

..and the News of views by Laura is also worth reading: Colgin 2011.

PS! I dont think the most important issue is whether a model is right or wrong as long as it initiate and inspire good science.

Ultralight 1.9g microscope for in vivo imaging of free moving mice

The Hafting-Fyhn laboratory — Tue, 13 Sep 2011 12:25:58 +0000

Among a few other labs, the Schnitzer lab has been pushing the technology to make it possible to do advanced microscopy from free-roaming animals. The head-implanted microscopes are now smaller and lighter than electrodes, and the quality and resolution is closing up on the convetional big “table-microscopes”.

So let the lab-rat carry the microscope on it’s head while recording Ca2+ spikes (GCamp). Gosh et al., 2011

Dont miss the snacks in the supplementary figures:

Functional connectomics – mice visual cortex

The Hafting-Fyhn laboratory — Tue, 30 Aug 2011 09:27:45 +0000

Clay Reid’s group just published a seminal paper marking the new era in neuroscience (Bock et al., 2011): Network anatomy and in vivo physiology of visual cortical neurons.

Perhaps the biggest impediment to understanding the mammalian brain is the lack of wiring diagrams of the interconnections in combination with knowledge about the function of single neurons. Previously, most studies of cortical networks has been limited to either structure OR function. Bock et al., has taken one step further with their combination of in vivo physiology and network anatomy. They used two-photon calcium imaging to characterize functional properties of a group of neurons in the mouse primary visual cortex and afterwards large-scale electron microscopy of serial thin sections to trace a portion of these neurons’ local network.

A possible explanation to an old paradox

The Hafting-Fyhn laboratory — Mon, 29 Aug 2011 12:00:10 +0000

Most people recording activity from hippocampal neurons in behaving animals, notice that the place cells tend to burst in a slightly faster frequency than the large theta oscillations seen in the local field potential (LFP).

So how can faster oscillating neurons comprise a slower population oscillation, as reflected by the LFP?

A possible explanation can be found in a recent paper by the Buzsaki lab: Geisler et al., 2010

Very interesting conference in Portugal in September

The Hafting-Fyhn laboratory — Tue, 16 Aug 2011 21:00:12 +0000

Check out the extraordinary list of speakers at the symposium at the Champalimaud Centre for the Unknown.

This is some of the speakers:
Larry Abbott, Silvia Arber, Tobias Bonhoeffer, Gyorgy Buzsaki, Holly Cline, Antonio Damasio, Yang Dan, , Sten Grillner, Michael Hausser, Takao Hensch, Hannah Monyer, Katy Payne, Carl Petersen, Erin Schuman, Mike Shadlen, Carla Shatz, Alcino Silva,Haim Sompolinsky, Lisa Stowers, Leslie Vosshall, Daniel Wolpert etc…

Deadline:
Registration & Abstract Submission: August 31, 2011

The venue:
The Champalimaud Centre for the Unknown is located in a beautiful site of 60,000 m2 in an exclusive zone of Lisbon, on the waterfront of Pedrouços, near the magnificent Tower of Belém. This area, where the river Tagus meets the Atlantic Ocean, is of great historical significance as the great Portuguese pioneers sailed from this location to discover the “unknown” in the XV and XVI centuries. The presence of the Champalimaud Centre for the Unknown leverages this historical heritage by creating an inspirational link between the discoveries of yesteryear and the epic adventure of scientific research.

A tour de force through the entorhinal microcircuit

The Hafting-Fyhn laboratory — Fri, 27 May 2011 12:32:37 +0000

The Michael Brecht lab just published another masterpiece in Neuron: Burgalossi et al., 2011

Ever since Albert Lee showed the world that it is possible to perform patch-clamp recordings from free-moving rats, I have been dreaming about such recordings from entorhinal grid cells. It is extremely difficult to record from hippocampal neurons in free-roaming rats (and when I looked into it a couple of years ago, it was only 3-4 persons/labs that did it worldwide). However, it is a piece of cake to place an electrode in the dorsal hippocampus, compared to the challenge to target the superficial layers of medial entorhinal cortex.

So what is the paper all about ?
Read and enjoy it yourself, and feel free to post your comments here.

Two new cool papers on grid cells and theta oscillations

The Hafting-Fyhn laboratory — Wed, 25 May 2011 10:50:48 +0000

I am delighted to see great science published by my friends and I highly recommend two grid cell papers published back-to-back in science 29th of April 2011. The relation between grid cells and oscillations has been a topic intense speculations, and both the Hasselmo lab and the Leutgeb lab(s) at UCSD has looked at the grid cells while inactivating the medial septum (an area that normally provides rythmic input to the hippocampal formation). Despite the clear findings of these papers – I think it opens for even more debate…

Check out the papers:
Koenig et al., 2011
Brandon et al., 2011

Congratulation to Jill and Stefan Leutgeb with a fantastic start for their new lab at UCSD – you are awesome!

The quest for the connectome – awesome video

The Hafting-Fyhn laboratory — Wed, 18 May 2011 13:17:33 +0000

Kristen Harris gave a very interesting lecture at the Nansen Neuroscience Symposium, and she showed this magnificent video:

The video is based on a reconstruction of a block of hippocampus (maybe the first dense reconstruction in mammalian brain at a few-nanometer (synapse) resolution) published in Neuron 2010 (Mishchenko et al).

The reconstructions are made from serial section transmission electron microscopy in the lab of Kristen Harris at the University of Texas at Austin in collaboration with Terry Sejnowski at the Salk Institute and Mary Kennedy at Caltech. Josef Spacek, Daniel Keller, Varun Chaturvedi, Chandrajit Bajaj, Justin Kinney and Tom Bartol made major contributions to the reconstruction and the video.

Scandinavian Physiological Society Conference in Bergen, August 12 – 14, 2011

The Hafting-Fyhn laboratory — Tue, 03 May 2011 13:11:01 +0000

The deadline for abstract submission has been extended, so it is still possible to submit abstract and join this small & nice meeting in Bergen. For more details: http://tinyurl.com/sps2011.

Some highlights:
“Dendritic Computation” Michael Hausser (Wolfson Institute for Biomedical Research, UCL, England)

David Allan (Univ. of Sydney, Australia)
“Interactions between stretch activated channels and reactive oxygen species; role in Duchenne muscular dystrophy”

Karl-Arne Stokkan (University of Tromsø, Norway)
“Timing of biological rhythms in arctic animals: clocks challenged by an extreme photic environment”

[Preliminary program]