@PessoaBrain

How about a thread on Richard Ivry’s comment. I see no problem. Each area has a unique pattern of inputs and outputs and so can perform a unique computation or transformation from inputs to outputs. But TASKS are not performed by areas but by networks. So what is the problem?

@dickretired

There is no problem but science is open to multiple views and not everyone sees the same.

Question: what is actually an area? That's a far from trivial question. In my view your camp has to offer a principled way to understand what an area is; we can't just assume they exist.

It can't be Brodmann right? (methods from over 100 years). Let's engage at the level of ideas, not just say "I see no problem" because that could be the default answer from all sides.

No?

#neuroscience

@PessoaBrain

It may not be Brodmann but it can be cytoarchitecure and myeloarchitecture as in the recentvmap from the Van Essen lab. Areas so defined also correspond to areas as defined by anatomical inputs and outputs and as Mars et al showed these also correspond closely with areas that are activated by tasks. I seriously don’t think that there is a problem here.

@dickretired
I collaborate with comparative neuroanatomists and they fight to death to define areas across species. Also I don't believe MRI is the basis to define much, such as in the Van Essen parcellation. fMRI activation even less useful.
So I see lots of challenges.

@PessoaBrain @dickretired Areas are perhaps useful when one cannot have actual synaptic circuits, but are ultimately not satisfactory. In the fly brain, early work mimicked the anatomical approach in mammals, defining areas and ascribing meaning and function to them; once the cellular was done, areas faded fast other than for referring to large chunks of brain. The brain connectome is also around the corner. Lots of change ahead.

@albertcardona @PessoaBrain @dickretired Interesting insights! When adding high-density functional data to the mouse classical parcellations in cortex, brain regions also tend to blur away. If anatomical connectivity defines the roads that can be taken by neuronal activity, they are not always busy making it harder to delineate big uniform brain regions.

@pierre_le_merre @PessoaBrain @dickretired Thanks for your comment. I am having a hard time understanding the last sentence: did you mean “they are” rather than “they are not”?

@albertcardona @PessoaBrain @dickretired Sorry to be a bit unclear. What I meant is that anatomical connectivity will definitely constrain the flow of activity (as the possible roads to be taken) but these pathways can also be rather inactive, or dynamically active/inactive. So if one tries to define brain regions only by connectivity, a part of the information coming from the dynamical range of interactions might be missing.

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