Pierre Le Merre

Using Kandel et al., Principles of Neural Science as a stand for monitors is clearly a thing in the field right?

Great that you dive in! Correct. These results are based on L5 wide waveforms unit.

I like the semantically trap but we compare mammalian brains and you want me to extend to arthropods! I mean we are already in muddy waters with mammals so I am not going for a common ancestor further away! 😅

Ha ha! Not sure it would work!

Hi Jan. Unsure what you mean? Like detailed cytoarchitecture of individual a granular mouse cortical columns? Or you have something else in mind?

I attended recently a few good cross-species meetings that were a good start to free up the discussion and go beyond the initial blockade of « the mouse PFC doesn’t exist » and pushing more the debate into scientific grounds: e.g. « how do you define your brain region? »

Yes. I get you. I don’t know what would exactly be the best way to move forward… I see the drift too in mouse studies where it is easy to oversell the results by pushing the homology. We need to be careful and the primate/human community is always here to tell us so.

I get your point. There is definitely a scaling factor as cortex becomes bigger or smaller to take into account.

So as far as it goes I am interested about this region that we refer to as the « mouse PFC » and that is well defined. Comparisons with other species come after and are a complicated endeavor as we see from our extended discussions here (which I enjoy btw!!).

The prefrontal module is itself defined with cytoarchitecture, genetics and connectivity. The borders are clear and it possible to challenge them anytime.

It turns out we have a good atlas system (not the perfect one) in the mouse with the volumetric CCFv3 that regroup few frontal regions: MOs, ACA, PL, ILA, ORBs under the umbrella of PFC module. So this is why I would use the term to refer to these regions.

I understand your point. To me it is more meaningful to use stereotactic coordinates than actual region names when trying to pinpoint where are things in the brain. That being said brain regions are the first order of granularity we have when localizing our dear neurons.

Yes. I would agree S1BF is a special case indeed (having worked on this region myself). So cytoarchitectural borders don’t really have groundings in development, or? Also to be fair, I don’t have the answers myself, just looking for good data arguments!

Interesting. They both grow for sure (from a mouse perspective)

Single-neuron projectome of mouse prefrontal cortex - Nature Neuroscience The authors reconstructed the individual projectomes of 6,357 mouse prefrontal cortical projection neurons, revealing projectome-defined neuron subtypes and organizing principles of axon projections a...

Yes. For example how many lamination patterns (feedforward and feedback) you can find in the agranular mouse PFC? See the work of GAO et al www.nature.com/articles/s41...

Sorry I meant that the cortex is by default six-layered. Nothing to do with the default mode network. My bad for the confusion.

😅. Yes foraging alone would be one way to go at this but cannot be the main drive of granularity in FC….another wild attempt to explain this could be the expansion of FC being too fast leading to « default mode » cortex that is six layered?

In mice granular cortices do a lot of heavy duty job on sensory processing (inherited from their thalamic inputs). Frontal regions are more related to motor functions (rough sketch given the wide spread of motoric related activity in mice). I just wonder what granularity brings to the table in FC…

Is it just that human and primates have larger (more cells, more subnetworks) to support complex cognitive processes or is there something special about the circuits/single neuron dynamics in granular regions?

For sure no granular regions in mice. I also like the evolutionary argument of Preuss and Wise. Granular regions would have appeared with the expansion of frontal regions (ACA and ORB now in mice). I am wondering what granularity brings in term of new functions per se?

Hi Matt! What do you mean when you say they emerge in a functionally dependent way during development ? I had more something like neurodevelopmental gradients in mind.

𝗛𝗼𝘄 𝗱𝗼 𝗯𝗿𝗮𝗶𝗻 𝗮𝗿𝗲𝗮𝘀 𝗿𝗲𝗹𝗮𝘁𝗲𝗱 𝘁𝗼 𝗳𝘂𝗻𝗰𝘁𝗶𝗼𝗻?
"High-resolution activity maps of PFC did NOT align with cytoarchitecturally defined subregions."
Key tenet in neuroscience is that cytoarchitectonic boundaries correspond to functional ones.
NB: study in the mouse
#neuroskyence
doi.org/10.1038/s415...

Curious about it too 😉

Awesome.

Look at that! Looks beautiful. Do you plan to share these data at some point?

New brain maps challenge traditional descriptions of the brain For more than a century, maps of the brain have been based on how brain tissue looks under the microscope. These anatomical maps divide the brain into regions according to structural variations in the...

Activity-based maps of the prefrontal cortex in mice, presented in @natneuro.nature.com today, challenge classical descriptions of the brain. The new maps reveal functional territories that differ from traditional, tissue-based maps. #Neuroscience #Brain 🧪 news.ki.se/new-brain-ma...

I understand your perspective. And of course not. Scientific progress has always been incremental, building on the work of those who came before us. Let's continue doing rigorous science and let the data guide our discussions.

Yes. The devil is in the details. Sharing data. Method transparency. Reproducible quality metrics. These are important (but demanding) efforts to make progress on this old scientific debate among PFCers!

The enhancer paper is just a layer 3 enhancer AAV targeted to the dlPFC or did I miss something.

To my knowledge the fantastic line of work on prefrontal circuits of Amy Arnsten and P. Goldman-Rakic does not directly compare distinct prefrontal regions within each other but focuses more on visual vs. dlPFC (granular vs. granular).