I have been creating brain slices from both rats and mice for many many years. In addition, I have created slices from avian brain and human brain. Overall, it is just as easy to create slices from mouse brain. The only down side is that the slices are smaller from mice and so the experimenter has to have "good hands" and practice with the smaller brain. There are several considerations. One important aspect to all this is what type of instrument is used for slicing. We use both the McIlwain slicer and a vibratome. Both have advantages and disadvantages. In addition, the region (s) of interest will make a difference. So if one is looking at the mouse hippocampus, then the area of the hippocampus is proportionately smaller than a rat's hippocampus. If one is working with just cortex, then it doesnt matter so much. Also, another consideration involves whether or not the animal is receiving some sort of stroke or trauma. This will have an effect on the slice, which might make smaller brains more difficult to work with. However, in this case, I would recommend using the vibratome and slicing the entire brain.

There is no difference between mice and rats in terms of viability.

The main difference, is that you get more connected neurones in a 400 um slice from a mice (this is the size issue).

Depending upon the age of the animals you use, you could use the in toto preparation, which works nicely till postnatal day 14.

We use it all the time with low Mg experiments, e.g. Quilichini et al, Neuron, 2012

We've been working with both mouse and rat brain slices for a while, and the only real difference, as Benedict said, was the size. Mouse brains are more delicate and difficult to manipulate, but the overall viability is the same as rat (if not better, we sometimes find).

It is almost the same, the only difference is that mouse brain is a little bit smaller.

Yes, I totally agree with the comments here regarding slices. No problem at all using mouse slices. The hippcampus seems to hold up well in any animal model of study. I would however practice making slices from mice a few times before I used them for an actual experiment as times of dissection tend to be slower for the first several tries as the mouse brain is quite a bit small and more tricky to work with. Since it takes longer the slices aren't as good and therefore your data won't be as well.

Depending on how the hippocampal slices are prepared (dissecting the hippocampus out vs. cutting as a chunk), there are probably some differences between rats and mice. But, all in all, they are not that different. I cut mouse slices (300 ~ 350uM) thinner than rat (400uM); for my purpose (slice patch), they do fine with my standard buffers.

Thanks for these useful comments and valuable contribution.

Benedict, I use a vibrotome to slice the entire brain and get the 400 um slices, including the cortex.

Christophe, I read the interesting article you referred and had a search on the net about this preparation method, but could you please let me know more about in toto preparation?

Norah, may I ask you to give me more hints about the second method of preparation of hippocampal slices---"cutting as a chunk"?

People, I have attached a photo of one of my mouse slices. We do low-Mg experiments on these slices and record the seizure-like events (SLEs) from cortical parts.

Looks like that this slice contains parts of hippocampus as well.

1. Does any body know whether I can record SLEs from hippocampal part of slices like this, without isolating the hippocampal part?

2. If yes, is it possible for hippocampal SLEs to travel to cortical region? If yes, can I record them on cortex using extracellular electrodes?

Thanks all

Before answering your questions, it would be more important to know what your project is. For example, if you want to study seizure propagation, you can use thalamo-cortical slices (e.g. papers from J. Huguenard's group). Hence, it all depends upon your own question.

Regarding the in toto. I designed this prep a long time ago 1997. I tested it also with the whole cortex, and it works. The trick is to dissect out the cortex without damaging it. Not so tough.

Many people have used the prep, mostly with the hippocampus: papers from the groups of K. Staley (Boston); Y. Ben-Ari (Marseilles, France) and S. Williams (Canada).

I worked with mice vs. rats brain slices at the physiological temperatures (37 degrees) over long period of time ( 24 h) and it was obvious that mice brain slices are more sensitive to higher temperatures and can't survive as a long as rat's slices. Keeping them at 32 -34 degrees was a better way to preserve their functional activity.

MR imaging of in situ rat and mouse brain is easy and could be useful, or at least interesting in a translational sense, for initial evaluation prior to your more definitive techniques. See attached proof of concept rat and mouse images. The images were quick and acquired with routine human equipment. Getting better quality would be simple, even without dedicated rodent head coils.

Mark

Here is the attachment

--------- Christophe ---------- I am looking for evidences of critical slowing down, right before seizure initiation. Beside it I am looking at different characteristics of bursting patterns observed in low-MG++ experiments. I am trying to to distinguish different bifurcation patterns observable in cortical and hippocampal slices. To find answer to my questions, I need to be able to record from sources of SLEs---where they are originate from.

----------- People ------------

After reading the answers in this post, I intended to record from hippocampal region of my coronal slices (photo is shown above). I did records from two animals. In one of them(see attached image below) the CA1 region was producing strong activities independent of cortical SLEs (although they were short in duration, 1-3 sec), but in the second animal, hippocampus was inactive, just showing weak reflection of cortical SLEs.

My question is that:

Does anybody recommend me to try sagittal or transversal slicing. Has anybody tried recording mouse long SLEs based on my method, not based on extraction of the hippocampus?

Thanks

Hello everyone, I will take them the most of this question.

This week I started working with mice instead with rats. I am getting used to the mouse hippocampal slices preparation. I tried different ways to make the slices. Eventually I want to study fEPSP between Schaffer collaterals and CA1.

When trying transverse/horizontal slices, I get several slices but the responses are not very big.

When I've made coronal slices, it is much more easy for me to slice because I just glue the whole brain with 1/3 frontal and the cerebellum cut, but the problem is that I don't get as many slices with the hippocampus.

So what I've found better is to cut sagital slices. I separate both hemispheres and then I glue them onto the middle surface. Then I get around 3-5 good slices from each hemisphere and they give me good responses.

Do you think is it fine preparing sagital hippocampal slices from mouse?

Normally I cut 400 µm slices, but do you think could be possible to cut 300 µm for performing extracellular recordings?

Thank you very much for your help!

Diego

Yes I have done many experiments in both rats and mice using low Mg solutions. I have already addressed differences between mice and rats with regard to brain slicing (see my other comments here). I have not noted any major differences in treating rat or mouse slices with Mg. However, perhaps you could make your question more specific. What is your concern?

Sorry I haven't been very clear.

My exact two questions are

1) is it okay if I make sagital slices for mouse hippocampus? Or should I make transversal/horizontal or coronal?

2) For fEPSP recordings in CA3-CA1, the thickness can be 300 µm or should I make 400 µm like with rat?

Thank you

J J Ballesteros, is your attached example No-Mg seizure?

I have been working in both rat and mouse hippocampal-cortex slices (360-400 uM thickness) with MEA array and seems no difference in low-Mg induced epileptiform discharges at 32 degree.

I prepared for electrophysiology acute slices of rat and mice using the same technique (vibratome) without problems. May be in your case it could be interesting to do them with less thickness to get more slices. In other case, it is similar, except for the size.

I have done recording from both rat and mouse hippocampal slices (transverse slices prepared using vibratome), and have not found any significant difference. But I prefer to keep the slice thickness to 400u, as it is essential that you have a sufficient number of intact healthy cells in your slice that respond to stimulation (the top and bottom surfaces of your slice that come in contact with the blade will be all dead/ damaged cells).