I mentioned in a recent post Murray Shanahan’s model of global broadcast using spiking neurons. In brief, Murrays model contains distinct groups of neurons (which may for example represent different sensory modalities) each of which may encode for many different responses. These groups of neurons are all connected together via a comunications infurstructure which he calls the global workspace. Different cell assemblies in different groups fight for contol of the global workspace and once one particular set gains control its influence is broadcast through the workspace to the entire system.

What is most notable about this model is that the comunications inferstructure is generic and does not contain any specifically meaningfull connections between particular nodes or cell assemblies in the different groups that one may wish to communicate with each other or behave in some kind of complementary fashion. The question therefore arises as to how the different cell assemblies in seperated groups know what they are responding to and how to respond in the appropriate way? I recently put this question to Murray. In his response he was quick to point out that he does not wish to propose a model in which the signals that pass through the global workspace contain information in some kind of language of the brain. However, without meaningful connectivity it is necissary that the activations patterns being passed along this generic communications infurstucture do contain information that allows the recieving cell assemblies to respond appropriately. Murray suggest that the recieving cell assemblies adapt to repond to particular activation patterns in particular ways that are behaviourally beneficial. In addition the cell assemblies which send the signals will adapt in order to take advantage of responses from recieving cell assemblies that are also behaviourally beneficial.

Sounds pretty plausable to me, but pretty a complicated adaptation task as adaption will have to work from bottom up sensory inputs as well as top down global workspace inputs. Nevertheless working out how such sub-systems can adapt to comunicate with each other in this ways sounds like a really cool and interesting area of research.

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