Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Convergence-Divergence Zones

(Damasio; Self Comes to Mind, 144)

 

A convergence-divergence zone (CDZ) is an ensemble of neurons within which many feedforward-feedback loops make contact. (Damasio; Self Comes to Mind, 144)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                 Link to a readable diagram  — Convergence-Divergence Zones Diagram

 

A CDZ receives feedforward connections from sensory areas located earlier in the signal-processing chains, which begin at the entry point of the sensory signals in the cerebral cortex. (Damasio; Self Comes to Mind, 144)

A CDZ sends reciprocal feedback projections to the originating areas. (Damasio; Self Comes to Mind, 144)

A CDZ also sends feedforward projections to regions located in the next connectional level of the chain and receives return projections from them. (Damasio; Self Comes to Mind, 144)

CDZs are microscopic and are located within convergence-divergence regions (CDRegions), which are macroscopic. (Damasio; Self Comes to Mind, 145)

Link to — Convergence Zones for Language

 

Retrieval of Knowledge over Several Iterations of Reactivation Cycles

The function of CDZs consists of re-creating separate sets of neural activity that were once approximately simultaneous during perception -- i.e. that coincided during the time window necessary for us to attend to them and be conscious of them. (Damasio; Self Comes to Mind, 145)

The CDZ would prompt an extremely fast sequence of activations that would make separate neural regions come online in some order, the sequence being imperceptible to consciousness. (Damasio; Self Comes to Mind, 145)

Knowledge retrieval would be based on relatively simultaneous, attended activity in many early cortical regions, engendered over several iterations of such reactivation cycles. (Damasio; Self Comes to Mind, 148)

Research Study — Brain Regions Involved in Decision-Making

 

Disposition Regions

Cell ensembles at the top levels of the processing hierarchies would not hold explicit representation of the maps for objects and events.  Rather, the ensembles would hold know how, i.e. dispositions, for the eventual reconstruction of explicit representations when they become needed. (Damasio; Self Comes to Mind, 140)

Dispositions act on a host of early sensory cortices originally engaged by perception. (Damasio; Self Comes to Mind, 141)

Dispositional space is made up of CDZs and CDRs in association cortices, which are not image making cortices.  The dispositional space guides the image making but is not involved in displaying images themselves. (Damasio; Self Comes to Mind, 151)

Image-Making Regions

The perception or recall of most objects and events depends on activity in varied image-making regions of the brain and often involves parts of the brain related to movement.  This highly dispersed pattern of activity occurs within the image space. (Damasio; Self Comes to Mind, 151)

Dispositional space can be considered to contain "grandmother cells," defined liberally as neurons whose activity correlates with the presence of the specific object but not as neurons whose activity permits, in and of themselves, explicit mental images of objects and events. (Damasio; Self Comes to Mind, 151)

Neurons in anterior medial temporal cortices can respond to unique objects, in perception and recall, with high specificity, suggesting that they receive convergence signals. (Damasio; Self Comes to Mind, 151)

 

A Bow-Tie Model of the cortical network blends well with Convergence-Divergence Zones Architecture.

 

    Return to — Convergence-Divergence Zones Architecture

   

    Return to — Reentry and Recursion

    Return to — Neural Network