6/11/2012

Multiple dynamic representations in the motor cortex during sensorimotor learning

Multiple dynamic representations in the motor cortex during sensorimotor learning


D. Huber, D. A. Gutnisky, S. Peron, D. H. O’Connor, J. S. Wiegert, L. Tian, T. G. Oertner, L. L. Looger & K. Svoboda


Summary



  • Chronic calcium imaging in learning behavior paradigm.
  • Dynamic plastically change during learning in single neuron.
  • Good model fitting using machine learning algorithm.



Comments


This paper have technical impact rather than scientific impact (chronic imaging).
This team have very high imaging (and behavior task under microscopy) techniques and improve it very very high speed.


About this paper, first, I surprised the speed of learning.
The mice learn the task within at least 3 sessions (200-400 trials per session, maybe 1 session per day) !
If the reason of this high speed learning is whisker related task, I become very very happy ^m^


I wondered why licking related behaviors code in vibrissa primary moter (vM1) area?
I thought "is that mean there may be no specific region for some body parts in M1 area? "


I want to catch up to this team in technical level as fast as possible.

5/29/2012

How to improve creative thinking?

from this article,

Teaching Creative Science Thinking

Robert L. DeHaan, Science, 2011


Q. How to improve creative thinking?


A. Improve associative thinking and increase peer-peer interaction.



Creative thinking defined within two different theoretical frameworks,

from individual insight and/or social phenomenon.


In individual insight, there are two skills for thinking, associative thinking and analytcal thinking.

Associative thinking is more required for creative thinking,

because the ability can convey the solution from completely different fields (?)


In social phenomenon, peer-peer interaction is efficient for creative thinking.

For example, new hypothesis or idea occurred the most frequently, when lab meeting.


This short article is interesting for me,

because it described how to categorize and quantify "Creative", one of the most abstract word,

and how to improve them artificially.


I am not good at psychology, but this inspire me how to quantify abstract data.

5/25/2012

Brain-wide neuronal dynamics during motor adaptation in zebrafish

Brain-wide neuronal dynamics during motor adaptation in zebrafish

Misha B. Ahrens, Jennifer M. Li, Michael B. Orger, Drew N. Robson, Alexander F. Schier, Florian Engert & Ruben Portugues


It is the first article of Whole-Brain Calcium Imaging.

  • whole-brain calcium imaging
  • elavl3:GCaMP2 Tg zebrafish
  • motor adaptation
  • larval zebrafish
  • 3D recnstruction
  • two photon microscopy (3Hz)


Sumarry

The size of larval zebrafish is enough to small to reach the bottom of the brain with 2phton microscopy ( > 1mm).
By using this animal, they achieved to whole-brain (all neuron in central nerve system) imaging of a behaving animal with single-cell resolution.
To achieve this, at first, they took time lapse images of calcium indicator (GCaMP2) at multiple regions using same behavior paradigm.
After that they reconstruct these time lapse images to reference brain.

They recorded calcium responses of larval zebrafish brain during swimming.
Using motor-visual feedback system, they mimicked a strong current (low gain) or weak current (high gain).

They found that

  • States of neural activities change transiently triggered by change of motor visual feedback gain.
  • Response neurons can be classified into 4types; motor-related, motor-off-related, gain-decreased-related, gain-increased-related.
  • and also detected the position of these neurons in whole brain.


Comments

I feel that impact of this article is about technical issue, not scientific issue.

This work is big foot print for whole-brain imaging, one of our (my?) dream.
Of course, there are many problems and limitations.
For example, low sampling ratio, the number of sampling pictures, analysis methods and so on.
The biggest interest for me is "how to apply for mice (and other mammalians)".

To solve these problems, we should improve sensitivity for signal, S/N ratio, laser properties, laser scanning method, lens, image acquisition method, statistical methods for population analysis and ... one by one.

It remain (or increase) many chances to impact to this filed now!

5/21/2012

Choice-specific sequences in parietal cortex during a virtual-navigation decision task

Choice-specific sequences in parietal cortex during a virtual-navigation decision task

Christopher D. Harvey, Philip Coen & David W. Tank



Long time no posting about article.

This is a study for decision making with two-photon calcium imaging.


  • Recording area was 2/3 layers of Posterior Pariental Cortex (PPC) of mice.
  • Calcium indicator was AAV-GCaMP3.
  • Sampling frequency was about 16Hz (256 x 64 pixel).
  • Behavior tasks were performed by their own system (Dombeck DA et al, 2007, Neuron).


Points

Q. Whether brain encode decision as recurrent attractor network with few neurons or high-dimentional dynamics with many neurons?


  • High ratio of PPC neuron (~73%) participates in population activity for decision making 
  • Different neural classes response to different choices 
  • The responses for the decision (working memory?) task is sequentially in PPC.
  • Spatial distribution of Trial preference (left or right) and Time preference (when did it burst) is not clustered.


Comments

I think this study is well controlled.
For example, they performed tracer experiment to identify PPC, because PPC were not identified in mice,
additional behavior experiments to eliminate the possibility that visual stimulus or motor activity affect PPC activity difference between the choices.
They performed many control experiments.

However, I feel scientific achieve seems to be low.
(Of course impact of technical aspect is very high)
I wonder whether there are any statistical analysis method without PCA (principal component analysis) and correlation.
There should be more powerful mathematical methods for population analysis.
But I have no idea now.

Population imaging study like this work will be increase in near future, I guess.

5/20/2012

What's wrong with my mouse?




This book is a famous textbook for mice behavior study.

Constitution of sentence is very simple.
Every chapter described one function.
And in each chapter, it is described about the details of behavior test for the function.

like this

  • Chap1 Sensory
  • Chap2 Learning
    • Morris water maze
    • Fear conditioning
    • Eyeblink conditioning
    • ....
  • Chap3 Emotion
  • ...

5/17/2012

Reading Book: Molecular Cloning

Our lab has "Molecular Cloning" (3rd edition).
Recently, I heard this is a first recommended book for molecular biology beginner.
I will try to read the 1st chapter and all panels in this book.

In chapter 1, authors described about plasmid replication, history and variety of plasmid vectors and host E.coli, and methods of molecular cloning.

There are some interesting stories for me such as the mechanism of plasmid replication, how keep copy number, what is antibiotics, how should we handle long length plasmid and so on.

I am still reading, and plan to read all panels (and chapter1).

5/12/2012

Why I want to be neuroscientist?

Why do I want to be a neuroscientist?

I want to know how I "think".

René Descartes, French philosopher in 1600s, said "I think, therefore I am".
Then I thought "How I think?".
I just want to know what is changing in the brain when I change my recognition and/or create a new idea.

My interest is also important for world society.
There are no critical approach for most (all?) of mental diseases, because it is not still unclear the mechanism of the disease and the normal function.
My research will be contribute to take hints for the therapies.

Some of abilities of computer are far above that of human being such as calculation, memory and precise communication.
But  some abilities are far below that of human such as creativity, flexibility for environmental change and energy usage.
My research will be contribute to inspire the computer functions.



How will I research?

First, observe neural activities,
Second, analyze and extract the important properties,
at Last, reconstruct the system.

I use Imaging methods for observation,
mathematical and statistical methods for analysis,
optogenitic or electronic methods for reconstruction.

I am a biologist.
In this field, Genetic Encoded Calcium Indicators (GECI) and Optogenitic methods spread their application fields.
Benefits of these methods are we can apply the indicators and manipulators in cell-type specific manner in many cell simultaneously and chronically.
It is not achieved by chemical dye injection.

We need to process mass data such as Calcium imaging, multi-electrode electrophysiology and gene-chips.
In my case, I need to handle a much of imaging data.
To handle these data, the importance of statistical methods will be increased.

To complete the research, it should reconstruct the phenomenon to show its causality.
I think there are two ways for the reconstruction, biological methods (optogenetics) and systematic methods (electronics).
In biological methods, we can control the neural activities by using a specific color lights and light sensitive channel proteins.
By using this system, we can control the model animal behaviors and can show causality of the neural activities and the behaviors.

In systematic methods, we can also use computer simulations.
But I think, the mechanism of information processing of animals and computers is too different to mimic each other. (I don't describe in detail here)
Therefore, we will reach the limitation in the future.
 Electronics, constructed from electronic devises such as resistance and condenser, is more flexible and than computer simulation and low energy consuming.



What do I research?

I want to catch the time point of recognition change.

I want to know how change neural activities and mechanisms of the changing when a animal change their behaviors.
I observe a brain of mice performing behavioral task with microscopy imaging.
During the behavior task, the rule of the task is changed (called reversal learning, set-shifting).
I want to catch the change of voltage, calcium ion and other molecular dynamics in single cell or neural population level, when they try to apply the new rules.



I cannot judge whether I can write about our main job, because of collaborators, paper publish and confidentiality problems.
I will write here about reconstruction by electronic methods (it is hobby for me) and papers for my research.