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be conveyed in its internal structure. The particular input line on which the signal
arrives is then no longer critical to its interpretation. One now has an information
processing system in which signals can be liberated from particular wires. Although
there are still definite neuronal pathways and regions where particular kinds of in-
formation converge, these schemes enable processing to be carried out on the level
of neuronal ensembles and populations. They obviate the need for the ultra-precise
and stable point-to-point synaptic connectivities and transmission paths that purely
connectionistic systems require.
15.5.6 Emergent Annotative Tags and Their Uses
Both stimulus-driven and stimulus-triggered temporal response patterns can func-
tion as higher-level annotative “tags” that are added to a signal to indicate that it
has a particular cognitive attribute. Neural signal tags characteristic of a particular
neural assembly would signify that it had been activated. Tags produced by sensory
association cortical areas would connote sensory attributes and conjunctions; those
produced by limbic circuits would indicate hedonic, motivational, and emotive va-
lences, such that these neural signal patterns would bear pragmatic content. A neu-
ral assembly producing a characteristic triggered response pattern could potentially
function as a cognitive timing node (MacKay
1987
).
Neural assemblies could be adaptively tuned to emit new tag patterns that would
mark novel combinations of perceptual, cognitive, conative, and mnemonic activa-
tion. New tags would constitute new symbolic neural signal primitives that are asso-
ciated with new attributes and concepts. The appearance of a particular tag indicates
that a particular state-of-affairs has been detected. Formation of new assemblies
and associated signal tags would be means by which new, dedicated “perceptual
symbols” could be formed from semantically and pragmatically meaningful iconic
sensory representations (Barsalou
1999
).
The global interconnectedness of cortical and subcortical structures permits
widespread sharing of information that has built-up to some minimal threshold of
global relevance, in effect creating a global workspace (Baars
1988
, Dehaene and
Naccache
2001
,Rose
2006
). In response to a particular triggering stimulus, say a
picture of a large dog, the contents of such a global workspace would become suc-
cessively elaborated over time as the signals produced by different sets of neural
assemblies interacted (Fig.
15.8
). Successive assemblies would add their own an-
notations to the circulating pattern associated with various experiences with other
similar animals and these would in turn facilitate or suppress the activation of other
assemblies.
Linkages between particular sensory patterns and motivational evaluations could
be formed that add tags related to previous reward or punishment history, thereby
adding to a sensory pattern a hedonic marker. In this way, these complex, elaborated
neural signal productions could be imbued with pragmatic meanings which could be
conferred on sensory representations that in turn have causal linkages with the exter-
nal world. Neural signal tags with different characteristics could thus differentiate
