A Compact Multiphoton 3D Imaging System for Recording Fast Neuronal Activity

People have been talking about doing this for many years, but this article is the first I’ve seen that describes a practical two-photon microscope that I’ve seen that can image a decent field of view (e.g., 150 microns x 150 microns x 150 microns) at “over 100 volumes per second, at the resolution limit.” And the whole thing — laser included — costs around $40,000. Paper shows sample images as well as schematics and protocols.

— posted by Ed


Multiple-color optical activation, silencing, and desynchronization of neural activity, with single-spike temporal resolution

As alluded to below in Neville’s post… here’s the link to the full paper, with a more complete description.

My lab, the Neuroengineering And Neuromedia Group at the MIT Media Lab, has just released a new neurotechnology. We found that just as the algal protein channelrhodopsin-2 (ChR2) can make neurons excitable by brief pulses of blue light, the mammalian codon-optimized version of the protein halorhodopsin (we abbreviate the mammalian codon-optimized form as Halo) can make neurons silenceable by brief pulses of yellow light. Furthermore, the activity of neurons expressing both Halo and ChR2 can be controlled bi-directionally by pulses of blue and yellow light respectively. This toolbox enables extremely sophisticated new kinds of experiment – such as being able to desynchronize neuronal spiking (without altering mean spike rate)! The paper just came out in PLoSONE, a new PLoS journal that encourages papers to become living documents — any reader can comment on any paper.

You can check out, and then comment on, the paper, “Multiple-color optical activation, silencing, and desynchronization of neural activity, with single-spike temporal resolution,” here.


Cautionary note on FRET

Some surprising and important news from Nature Biotechnology about a common technique in cellular imagining, fluorescence resonance energy transfer, or FRET. Specifically, it looks like ATP/Mg can significantly alter the FRET signal, which has commonly been used for looking at Ca, voltage, and various other binding interactions in neurons:

Given these findings, we predict that fluctuations in free or Mg2+-bound ATP will affect the signal output of most—if not all—CFP-YFP–based FRET indicators.

Continue reading

NIPS Workshop Announcement

If anyone has any additional questions that they think would be good to address at the workshop, leave it as a comment below.

NIPS 2006 Workshop Announcement and Call for Abstracts
Decoding the Neural Code

There is great interest in sensory coding. Studies of sensory coding typically involve recording from sensory neurons during stimulus presentation, and the investigators determine which aspects of the neuronal response are most informative about the stimulus. These studies are left with a decoding problem: are the discovered codes, sometimes quite exotic, ultimately used by the nervous system to guide behavior? In our one-day workshop, researchers with many different backgrounds will evaluate what we know about neuronal decoders and suggest new strategies, both experimental and computational, for addressing the decoding problem.

Each hour, five to six researchers will address a particular question for five minutes, followed by a half-hour discussion. We will also set aside time for a poster session.

We tentatively plan to include the following questions, and are soliciting additional questions from our speakers:
1. Which variables that encode stimuli are actually used to guide behavior?
2. What mechanisms do nervous systems use to decode encoded information?
3. Are motor systems better than sensory systems for experimentally addressing decoding?
4. What computational and experimental techniques are needed to address decoding? For instance, should information theory be used to address decoding as well as encoding?

For information on abstract submission, go to the workshop web site at http://science.ethomson.net/NIPS_workshop.html.

Posted by Eric Thomson

nature vs. nurture

As a psychology instructor who often teaches a course on cognitive psychology, I am intrigued with the whole nature/nurture debate and how it relates to neuropsychology. It seems like we look to nature when we want to control the universe, when we want to follow the rules of:

words and music by Dr. BLT (c)2006

and we turn to the supernatural when we are comfortable with the idea of not having to predict and control everything.