Against cortical reorganisation, Makin and Krakauer, 2023 (brain rewiring)

Tamar R Makin

MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, United Kingdom

John W Krakauer

Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, United States
The Santa Fe Institute, Santa Fe, United States

Version of Record published
November 21, 2023 (Go to version)

Accepted
November 7, 2023

Received
November 15, 2022

Abstract

Neurological insults, such as congenital blindness, deafness, amputation, and stroke, often result in surprising and impressive behavioural changes.

Cortical reorganisation, which refers to preserved brain tissue taking on a new functional role, is often invoked to account for these behavioural changes. Here, we revisit many of the classical animal and patient cortical remapping studies that spawned this notion of reorganisation.

We highlight empirical, methodological, and conceptual problems that call this notion into doubt. We argue that appeal to the idea of reorganisation is attributable in part to the way that cortical maps are empirically derived. Specifically, cortical maps are often defined based on oversimplified assumptions of ‘winner-takes-all’, which in turn leads to an erroneous interpretation of what it means when these maps appear to change.

Conceptually, remapping is interpreted as a circuit receiving novel input and processing it in a way unrelated to its original function. This implies that neurons are either pluripotent enough to change what they are tuned to or that a circuit can change what it computes. Instead of reorganisation, we argue that remapping is more likely to occur due to potentiation of pre-existing architecture that already has the requisite representational and computational capacity pre-injury. This architecture can be facilitated via Hebbian and homeostatic plasticity mechanisms.

Crucially, our revised framework proposes that opportunities for functional change are constrained throughout the lifespan by the underlying structural ‘blueprint’. At no period, including early in development, does the cortex offer structural opportunities for functional pluripotency.

We conclude that reorganisation as a distinct form of cortical plasticity, ubiquitously evoked with words such as ‘take-over’’ and ‘rewiring’, does not exist.

Link (eLife): https://elifesciences.org/articles/84716

 

Accompanying summary article in Medical Xpress:

Our brains are not able to 'rewire' themselves, despite what most scientists believe, new study argues

Contrary to the commonly held view, the brain does not have the ability to rewire itself to compensate for the loss of sight, an amputation or stroke, for example, say scientists from the University of Cambridge and Johns Hopkins University.

Writing in eLife, Professors Tamar Makin (Cambridge) and John Krakauer (Johns Hopkins) argue that the notion that the brain, in response to injury or deficit, can reorganize itself and repurpose particular regions for new functions, is fundamentally flawed—despite being commonly cited in scientific textbooks. Instead, they argue that what is occurring is merely the brain being trained to use already existing, but latent, abilities.

https://medicalxpress.com/news/2023-11-brains-rewire-scientists.html

 

Important stuff. I think things have been allowed to be veered off-track in this area (as with scientific psychology vs BPS theories filibustering the search for certain terms) over the last decade. Which is a shame because it didn't need the silly pseudo-phil Dr Who time-bending 'what ifs' to be exciting as an area. It needed a scientific approach because what is possible looked at sagely and conservatively tells us a lot about how things do work and develop?

 

I have to admit that I never thought anyone thought there was rewiring - just what they are saying here.

I wonder a bit if this is some trendy straw-man slaying.

There is no meat in the abstract to see if they actually have any novel evidence. Maybe I should read the article.

 

Plenty of detail in the paper itself. They make a good case.
I am still not sure that anyone should be surprised. More a question maybe of debunking some dodgy theories of rehabilitation, which may be well justified.